(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act). ☒

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of ~~October~~July 30, ~~2020,~~2021, the registrant had ~~29,088,670~~38,477,796 common shares, nominal value €0.09 per share, outstanding.

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. All statements other than statements of historical facts contained in this Quarterly Report on Form 10-Q are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. All statements other than statements of historical fact contained in this Quarterly Report on Form 10-Q, including without limitation statements regarding our plans to develop and commercialize our product candidates, the timing of our ongoing or planned clinical trials, the timing of and our ability to obtain and maintain regulatory approvals, the anticipated impact of the COVID-19 pandemic on our business and operations, the clinical utility of our product candidates, our commercialization, marketing and manufacturing capabilities and strategy, our expectations surrounding our collaborations, our expectations about the willingness of healthcare professionals to use our product candidates, the sufficiency of our cash, cash equivalents and investments, and the plans and objectives of management for future operations and capital expenditures are forward-looking statements.

The forward-looking statements in this Quarterly Report on Form 10-Q are only predictions and are based largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this Quarterly Report on Form 10-Q and are subject to a number of known and unknown risks, uncertainties, assumptions and ~~assumptions,~~other important factors, including those described under the sections in this Quarterly Report on Form 10-Q entitled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and elsewhere in this Quarterly Report on Form 10-Q.

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

Our business is subject to numerous risks and uncertainties, including those described in Part II, Item 1A. “Risk Factors” in this Quarterly Report on Form 10-Q. You should carefully consider these risks and uncertainties when investing in our common shares. The principal risks and uncertainties affecting our business include the following:

	September 30, 2020			December 31, 2019			June 30, 2021			December 31, 2020
ASSETS
Current assets:
Cash and cash equivalents	$	139,179		$	197,612		$	311,472		$	163,082
Marketable securities		51,021			42,153			41,280			44,673
Accounts receivable		538			941			1,471			46
Accounts receivable (related party)		1,568			1,711			2,212			1,623
Prepaid expenses and other current assets		9,010			4,951			10,559			8,569
Total current assets		201,316			247,368			366,994			217,993
Marketable securities		—			2,009
Property and equipment, net		3,792			3,715			3,596			4,115
Operating lease right-of-use assets		4,229			5,215			4,762			3,907
Intangible assets, net		2,784			2,876			2,608			2,843
Deferred tax assets		291			288			140			410
Other assets		1,081			1,905			1,483			1,949
Total assets	$	213,493		$	263,376		$	379,583		$	231,217
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:												��
Accounts payable	$	4,720		$	3,029		$	6,160		$	3,126
Accrued expenses		19,819			13,536
Accrued expenses and other liabilities								24,529			21,803
Income taxes payable								—			206
Current portion of lease obligation		1,536			1,380			1,597			1,432
Current portion of deferred revenue		699			941			13,184			625
Current portion of deferred revenue (related party)		18,657			17,901			18,937			19,554
Total current liabilities		45,431			36,787			64,407			46,746
Lease obligation		2,736			3,872			3,198			2,521
Deferred revenue, net of current portion		331			780			25,338			237
Deferred revenue, net of current portion (related party)		80,494			90,637			67,553			79,450
Total liabilities		128,992			132,076			160,496			128,954

Commitments and contingencies - Note 6
Stockholders’ equity:
Common shares, €0.09 par value; 45,000,000 shares authorized; 29,074,536 and 28,882,217 shares issued and outstanding as at September 30, 2020 and December 31, 2019, respectively	$	2,938		$	2,918
Common shares, €0.09 par value; 45,000,000 shares authorized; 38,444,580 and 31,602,953 shares issued and outstanding as at June 30, 2021 and December 31, 2020, respectively							$	3,959		$	3,211
Additional paid-in capital		448,617			441,395			649,627			490,093
Accumulated other comprehensive income		5,094			1,586			3,155			9,071
Accumulated deficit		(372,148	)		(314,599	)		(437,654	)		(400,112	)
Total stockholders’ equity		84,501			131,300			219,087			102,263
Total liabilities and stockholders’ equity	$	213,493		$	263,376		$	379,583		$	231,217

See accompanying notes to the Unaudited Condensed Consolidated Financial Statements.

	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019			2021			2020			2021			2020
Collaboration revenue	$	695		$	2,558		$	1,207		$	4,496		$	5,118		$	184		$	6,717		$	512
Collaboration revenue (related party)		7,875			5,690			19,720			19,061			7,261			5,872			14,012			11,845
Grant revenue		—			(93	)		—			(216	)
Total revenue		8,570			8,155			20,927			23,341			12,379			6,056			20,729			12,357
Operating expenses:
Research and development		17,538			13,511			48,234			36,078			24,612			13,709			45,418			30,696
General and administrative		9,136			8,024			26,061			22,979			10,569			8,043			19,902			16,925
Total operating expenses		26,674			21,535			74,295			59,057			35,181			21,752			65,320			47,621
Operating loss		(18,104	)		(13,380	)		(53,368	)		(35,716	)		(22,802	)		(15,696	)		(44,591	)		(35,264	)
Other income (loss), net:
Other (loss) income, net:
Interest (expense) income, net		(12	)		591			367			1,756			(51	)		99			(133	)		379
Foreign exchange (losses) gains		(4,782	)		3,468			(4,243	)		4,474
Other income (loss), net		(4,794	)		4,059			(3,876	)		6,230
Foreign exchange (losses) gains, net														(4,525	)		(2,346	)		7,678			539
Other (losses) gains, net														52			—			(385	)		—
Total other (loss) income, net														(4,524	)		(2,247	)		7,160			918

Net loss before income taxes		(22,898	)		(9,321	)		(57,244	)		(29,486	)		(27,326	)		(17,943	)		(37,431	)		(34,346	)
Tax expense (benefit)		177			(54	)		305			239
Income tax expense														62			31			111			128
Net loss	$	(23,075	)	$	(9,267	)	$	(57,549	)	$	(29,725	)	$	(27,388	)	$	(17,974	)	$	(37,542	)	$	(34,474	)
Other comprehensive income (loss):
Currency translation adjustment		4,414			(3,561	)		3,508			(4,363	)		3,475			2,201			(5,916	)		(906	)
Comprehensive loss	$	(18,661	)	$	(12,828	)	$	(54,041	)	$	(34,088	)	$	(23,913	)	$	(15,773	)	$	(43,458	)	$	(35,380	)
Net loss per share attributable to common stockholders: Basic and diluted	$	(0.64	)	$	(0.55	)	$	(1.86	)	$	(1.46	)	$	(0.71	)	$	(0.54	)	$	(1.01	)	$	(1.22	)
Weighted-average common shares outstanding: Basic and diluted		29,061			23,403			29,014			23,388			38,376			29,034			37,299			28,990

See accompanying notes to the Unaudited Condensed Consolidated Financial Statements.

	Nine Months Ended September 30,						Six Months Ended June 30,
	2020			2019			2021			2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$	(57,549	)	$	(29,725	)	$	(37,542	)	$	(34,474	)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of property and equipment		830			635			634			532
Amortization of intangible assets		206			173			147			134
Foreign exchange gain		3,828			(2,932	)		(7,611	)		(503	)
Loss on disposal of property and equipment		17			0			0			16
Stock-based compensation expense		6,327			5,188			7,959			3,483
Amortization of discount on investments		(30	)		(452	)
Deferred tax (benefit) expense		(2	)		105
Amortization of premium (discount) on investments								48			(79	)
Deferred tax expense								270			78
Changes in operating assets and liabilities:
Accounts receivable		634			1,473			(2,097	)		681
Operating lease right-of-use assets and lease obligations		2			(124	)		(11	)		3
Prepaid expenses and other current assets		(2,935	)		(3,778	)		(1,852	)		(6,441	)
Accounts payable		1,587			(301	)		3,190			(599	)
Accrued expenses		5,707			(218	)
Accrued expenses and other liabilities								3,207			2,556
Deferred revenue		(14,187	)		(13,348	)		28,704			(9,255	)
Net cash used in operating activities	$	(55,565	)	$	(43,304	)	$	(4,954	)	$	(43,868	)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	$	(49,359	)	$	(49,385	)	$	(24,850	)	$	(28,947	)
Proceeds from maturities of marketable securities		42,831			71,701			28,163			28,181
Purchases of intangible assets		0			(213	)
Purchases of property and equipment		(858	)		(2,079	)		(260	)		(512	)
Net cash (used in) provided by investing activities	$	(7,386	)	$	20,024
Net cash provided by (used in) investing activities							$	3,053		$	(1,278	)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs	$	(164	)	$	0		$	0		$	(164	)
Proceeds from issuance of common stock, net								129,398			0
Proceeds from issuance of common stock - Lilly								16,477			0
Proceeds from stock options exercised		915			48			6,728			893
Repurchase of restricted stock units								(285	)		0
Net cash provided by financing activities	$	751		$	48		$	152,318		$	729
Foreign exchange impact on cash, cash equivalents and restricted cash		3,767			(6,900	)		(2,027	)		(1,107	)
Net decrease in cash, cash equivalents and restricted cash		(58,433	)		(30,132	)
Net increase (decrease) in cash, cash equivalents and restricted cash								148,390			(45,524	)
Cash, cash equivalents, and restricted cash, beginning of period		197,813			164,730			163,283			197,813
Cash, cash equivalents, and restricted cash, end of period	$	139,380		$	134,598		$	311,673		$	152,289
SUPPLEMENTAL DISCLOSURES:
Non-cash right-of-use assets acquired from operating lease obligations							$	1,662		$	0
Income taxes paid	$	235		$	245		$	491		$	25
Non-cash purchases of property, equipment and intangibles	$	5		$	230		$	22		$	35
Non-cash issuance of stock options							$	573		$	0
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents		139,179			134,457		$	311,472		$	152,088
Restricted cash included in non-current other assets		201			141			201			201
	$	139,380		$	134,598		$	311,673		$	152,289

	Common Stock				Additional Paid-In		Accumulated			Accumulated Other Comprehensive			Total Stockholders’			Common Stock				Additional Paid-In			Accumulated			Accumulated Other Comprehensive			Total Stockholders’
	Shares		Amount		Capital		Deficit			Income (Loss)			Equity
Balance at January 1, 2019		23,358,977	$	2,366	$	360,045	$	(259,448	)	$	2,894		$	105,857
Exercise of stock options and vesting of restricted stock units		20,678		2		26		0			0			28
Stock-based compensation		—		0		1,260		0			0			1,260
Currency translation adjustment		—		0		0		0			(1,900	)		(1,900	)
Net loss		—		0		0		(7,083	)		0			(7,083	)
Balance at March 31, 2019		23,379,655	$	2,368	$	361,331	$	(266,531	)	$	994		$	98,162
Exercise of stock options and vesting of restricted stock units		13,632		2		2		0			0			4
Stock-based compensation		—		0		1,860		0			0			1,860
Currency translation adjustment		—		0		0		0			1,098			1,098
Net loss		—		0		0		(13,375	)		0			(13,375	)
Balance at June 30, 2019		23,393,287	$	2,370	$	363,193	$	(279,906	)	$	2,092		$	87,749
Exercise of stock options and vesting of restricted stock units		14,265		1		15		0			0			16
Stock-based compensation		—		0		2,068		0			0			2,068
Currency translation adjustment		—		0		0		0			(3,561	)		(3,561	)
Net loss		—		0		0		(9,267	)		0			(9,267	)
Balance at September 30, 2019		23,407,552	$	2,371	$	365,276	$	(289,173	)	$	(1,469	)	$	77,005
																Shares		Amount		Capital			Deficit			Income (Loss)			Equity
Balance at January 1, 2020		28,882,217	$	2,918	$	441,395	$	(314,599	)	$	1,586		$	131,300			28,882,217	$	2,918	$	441,395		$	(314,599	)	$	1,586		$	131,300
Exercise of stock options and vesting of restricted stock units		127,205		13		589		0			0			602			127,205		13		589			—			—			602
Stock-based compensation		—		0		2,291		0			0			2,291			—		—		2,291			—			—			2,291
Currency translation adjustment		—		0		0		0			(3,107	)		(3,107	)		—		—		—			—			(3,107	)		(3,107	)
Net loss		—		0		0		(16,500	)		0			(16,500	)		—		—		—			(16,500	)		—			(16,500	)
Balance at March 31, 2020		29,009,422	$	2,931	$	444,275	$	(331,099	)	$	(1,521	)	$	114,586			29,009,422		2,931		444,275			(331,099	)		(1,521	)		114,586
Exercise of stock options and vesting of restricted stock units		37,922		4		287		0			0			291			37,922		4		287			0			0			291
Stock-based compensation		—		0		1,192		0			0			1,192			—		0		1,192			0			0			1,192
Currency translation adjustment		—		0		0		0			2,201			2,201			—		0		0			0			2,201			2,201
Net loss		—		0		0		(17,974	)		0			(17,974	)		—		0		0			(17,974	)		0			(17,974	)
Balance at June 30, 2020		29,047,344	$	2,935	$	445,754	$	(349,073	)	$	680		$	100,296			29,047,344	$	2,935	$	445,754		$	(349,073	)	$	680		$	100,296


Balance at January 1, 2021																	31,602,953	$	3,211	$	490,093		$	(400,112	)	$	9,071		$	102,263
Issuance of common stock, net																	5,575,757		610		128,793			—			—			129,403
Issuance of common stock - Lilly																	706,834		77		16,400			0			0			16,477
Exercise of stock options and vesting of restricted stock units																	386,097		42		4,782			—			—			4,824
Repurchase of restricted stock units																	—		—		(285	)		—			—			(285	)
Stock-based compensation																	—		—		3,400			—			—			3,400
Currency translation adjustment																	—		—		—			—			(9,391	)		(9,391	)
Net loss																	—		—		—			(10,154	)		—			(10,154	)
Balance at March 31, 2021																	38,271,641		3,940		643,183			(410,266	)		(320	)		236,537
Exercise of stock options and vesting of restricted stock units		27,192		3		19		0			0			22			172,939		19		1,885			0			0			1,904
Stock-based compensation		—		0		2,844		0			0			2,844			—		0		4,559			0			0			4,559
Currency translation adjustment		—		0		0		0			4,414			4,414			—		0		0			0			3,475			3,475
Net loss		—		0		0		(23,075	)		0			(23,075	)		—		0		0			(27,388	)		0			(27,388	)
Balance at September 30, 2020		29,074,536	$	2,938	$	448,617	$	(372,148	)	$	5,094		$	84,501
Balance at June 30, 2021																	38,444,580	$	3,959	$	649,627		$	(437,654	)	$	3,155		$	219,087

See accompanying notes to the Unaudited Condensed Consolidated Financial Statements.

Merus N.V. is a clinical-stage oncology company developing innovative antibody therapeutics, headquartered in Utrecht, the Netherlands. Merus US, Inc. is a wholly-owned subsidiary of Merus N.V. located at 139 Main Street, Cambridge, Massachusetts, United States (collectively, the “Company”).

Since inception, the Company has generated an accumulated deficit of ~~$372.1~~$437.7 million as of ~~September~~June 30, ~~2020.~~2021. The Company expects to continue to incur significant expenses and operating losses for the foreseeable future as its antibody candidates advance through discovery, pre-clinical development and clinical trials and as it seeks regulatory approval and pursues commercialization of any approved antibody candidate.

As a result, the Company may need additional financing to support its continuing operations. Until the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through public equity offerings, debt financings, or other sources, which may include collaborations, business development and licensing opportunities with third parties. Adequate additional financing may not be available to the Company on acceptable terms, or at all. The Company’s inability to raise capital as and when needed would have a negative impact on its financial condition and ability to pursue its business strategy. The Company will need to generate significant revenues to achieve profitability and may never do so.

On January 21, 2021, the Company completed an offering of common shares in which the Company sold 5,575,757 common shares, including 727,272 common shares pursuant to the underwriters’ option to purchase additional shares, at a price to the public of $24.75 for aggregate net proceeds of $129.4 million.

Based on the Company’s current operating plan, the Company expects that its existing cash and cash equivalents and marketable securities of ~~$190.2~~$352.8 million as of ~~September~~June 30, ~~2020~~2021, will ~~be sufficient to~~ fund ~~its~~the Company’s operations into the second half of ~~2022.~~2024.

The principal accounting policies applied in the preparation of these unaudited condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, ~~2019,~~2020, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, ~~2019,~~2020, filed with the SEC on March 16, ~~2020 (as amended, the~~2021 (the “Annual Report on Form 10-K”). There have been no material changes in the Company’s significant accounting policies during the ~~nine~~six months ended ~~September~~June 30, ~~2020.~~2021.

The Company prepared its unaudited consolidated condensed financial statements in compliance with generally accepted accounting principles in the U.S. ("U.S. GAAP"). Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB").

The unaudited condensed consolidated financial statements include the accounts of Merus N.V. and its wholly owned, controlled subsidiary, Merus US, Inc. All intercompany transactions and balances of subsidiaries have been eliminated in consolidation. In the opinion of management, these financial statements reflect all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the unaudited condensed consolidated financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The three months ended ~~September~~June 30, ~~2020~~2021 and ~~2019~~2020 are referred to as the ~~third~~second quarter of ~~2020~~2021 and ~~2019,~~2020, respectively. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

The unaudited condensed consolidated financial statements presented herein do not contain the required disclosures under U.S. GAAP for annual financial statements. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the annual audited consolidated financial statements and related notes as of and for the year ended December 31, ~~2019,~~2020, included in the Annual Report on Form 10-K.

At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company

is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern.

The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs, and comparing those needs to the current cash, cash equivalent and marketable securities balances. After considering the

Company’s current research and development plans, the timing expectations related to the progress of its clinical-stage programs and its plans to pursue commercialization of any ~~approved~~ antibody candidate, if approved, and after considering its existing cash, cash equivalents and marketable securities as of ~~September~~June 30, ~~2020,~~2021, the Company did not identify conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date these financial statements were issued.

In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The new guidance aligns the requirements for capitalizing implementation costs incurred in a cloud-based hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This ASU isbecame effective for the Company at the beginning of 2021, ~~including interim periods within that reporting period, although early adoption is permitted. The Company does not expect~~but had no impact on amounts or disclosures previously reported or during the ~~impact of adoption to be significant.~~period.

In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808), which clarifies that certain transactions between collaborative arrangement participants should be accounted for as revenue when the collaborative arrangement participant is a customer in the context of a unit of account and precludes recognizing as revenue consideration received from a collaborative arrangement participant if the participant is not a customer. The ASU ~~will be~~became effective for the Company inat the ~~first quarter~~beginning of ~~2021, with early adoption permitted. As of September 30, 2020, none~~2021. None of the Company’s arrangements fall within the scope of ASC ~~808. However, as~~808, the ~~Company may engage in future collaborative arrangements in~~adoption of this standard had no impact on amounts or disclosures previously reported or during the ~~future, this ASU may apply to those new arrangements.~~period.

The following tables summarize the Company’s investments in debt securities and their presentation in the condensed consolidated balance sheet:

	September 30, 2020		December 31, 2019		June 30, 2021		December 31, 2020
	(in thousands)				(in thousands)
Money market funds	$	11,684	$	34,053	$	14,106	$	10,156
Corporate paper and notes		20,751		38,679		43,746		27,978
U.S. government agency securities		9,187		3,987		0		9,150
U.S. treasuries		22,083		1,496		2,534		15,043
Total	$	63,705	$	78,215	$	60,386	$	62,327

Fair value of debt securities	$	63,749	$	78,254	$	60,386	$	62,328

	September 30, 2020		December 31, 2019		June 30, 2021		December 31, 2020
	(in thousands)				(in thousands)
Cash equivalents	$	12,684	$	34,053	$	19,106	$	17,654
Current marketable securities		51,021		42,153		41,280		44,673
Non-current marketable securities		0		2,009
Total	$	63,705	$	78,215	$	60,386	$	62,327

The Company does not intend to sell and believes it is unlikely that the Company will be required to sell the above investments before recovery of their amortized cost bases, which may be at maturity. The Company determined that there was no material change in the credit risk of any of its investments.

The fair value of money market funds is determined based on publicly available market price for these funds (Level 1). The fair value of other debt securities is determined based on the publicly available inputs which includes a market price for the same or similar instruments adjusted for estimates in interest yield (Level 2).

	September 30, 2020		December 31, 2019		June 30, 2021		December 31, 2020
	(In thousands)				(In thousands)
Prepaid clinical and manufacturing costs	$	5,085	$	2,779	$	3,261	$	4,971
Prepaid general and administrative expenses		1,862		789		5,923		2,460
Interest receivable		187		259		7		80
Other		1,876		1,124		1,368		1,058
Total	$	9,010	$	4,951	$	10,559	$	8,569

	September 30, 2020		December 31, 2019		June 30, 2021		December 31, 2020
	(In thousands)				(In thousands)
Accrued research and development expenses	$	14,021	$	6,618	$	19,570	$	15,372
Accrued general and administrative expenses		2,877		2,402		1,885		1,566
Accrued personnel costs		2,905		4,495		2,681		4,854
Other		16		21		393		11
Total	$	19,819	$	13,536	$	24,529	$	21,803

The Company files income tax returns in the U.S. federal and Massachusetts jurisdictions as well as in the Netherlands. The components of the income tax expense (benefit) from continuing operations are as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019			2021			2020			2021			2020
	(In thousands)						(In thousands)						(In thousands)						(In thousands)
U.S. federal	$	126		$	47		$	164		$	145		$	114		$	94		$	(112	)	$	38
U.S. state		131			(48	)		143			(11	)		47			36			(47	)		12
Total current tax expense (benefit)	$	257		$	(1	)	$	307		$	134
Total current income tax (benefit) expense													$	161		$	130		$	(159	)	$	50

U.S. federal	$	(56	)	$	(41	)	$	6		$	81		$	(54	)	$	(63	)	$	207		$	62
U.S. state		(24	)		(12	)		(8	)		24			(45	)		(36	)		63			16
Total deferred tax (benefit) expense	$	(80	)	$	(53	)	$	(2	)	$	105
Total deferred income tax (benefit) expense													$	(99	)	$	(99	)	$	270		$	78

Total tax expense (benefit)	$	177		$	(54	)	$	305		$	239
Total income tax expense													$	62		$	31		$	111		$	128

After consideration of all positive and negative evidence, we believe that it is more-likely-than-not that the Netherlands deferred tax assets, that are not supported by reversing temporary differences, will not be realized. As a result, we established a full valuation allowance against deferred tax assets of the Netherlands.

On April 5, 2018, an unnamed third party ~~and Regeneron Pharmaceuticals Inc., or Regeneron~~ filed ~~notices~~a notice of opposition against the Company’s EP 2604625 patent, entitled “Generation of Binding Molecules,” in the European Opposition Division of the European Patent Office (the “EPO”). The ~~notices~~notice asserted, as applicable, added subject matter, lack of novelty, lack of inventive step, and insufficiency. ~~Regeneron withdrew its opposition pursuant to a global December 20, 2018 settlement with the Company.~~ On August 20, 2018, the Company timely responded to these ~~submissions with respect to the unnamed third party.~~submissions. An opposition hearing was held in June 2019, wherein the EPO revoked the EP 2604625 patent in its entirety under Art. 123(2) EPC. The Company timely appealed that decision in December 2019 before the Technical Board of Appeals for the EPO seeking reinstatement of the patent and proposing auxiliary requests for certain amended claims, with further proceedings to be scheduled in the future. As this opposition proceeding continues, the Company cannot be certain that weit will ultimately prevail.

From time to time, the Company may be involved in various other claims and legal proceedings relating to claims arising out of the Company’s operations. The Company is not currently a party to any material legal proceedings.

~~There have been no changes in~~The Company has noncancelable operating leases for offices and lab spaces expiring at various dates through 2026.

The components of lease expense for the ~~Company’s lease arrangements since December 31, 2019.~~three and six months ended June 30, 2021 and 2020 are as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,				Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019		2021		2020		2021		2020
	(In thousands)				(In thousands)				(In thousands)				(In thousands)
Lease cost
Operating lease cost	$	411	$	398	$	1,203	$	988	$	434	$	396	$	852	$	792
Variable lease cost		93		83		282		178		132		107		223		189
Total lease cost included in operating expenses	$	504	$	481	$	1,485	$	1,166	$	566	$	503	$	1,075	$	981
Other information
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$	412	$	379	$	1,201	$	1,112	$	428	$	396	$	863	$	789

During the six months ended June 30, 2021, the Company signed a lease amendment (the “Amendment”) for offices and lab spaces in Utrecht, Netherlands. The Amendment extended the lease term by approximately 1.5 years ending at the end of March 2023 and did not include additional right-of-use other than the extended lease term.

On January 18, 2021, Eli Lilly and Company, (“Lilly”) agreed to pay the Company a $40.0 million, non-refundable upfront payment, and purchased 706,834 common shares at a stated price per share of $28.295, for an aggregate purchase price of $20.0 million. The Company and Lilly agreed to collaborate with respect to the discovery and research of bispecific antibodies utilizing the Company’s proprietary Biclonics® bispecific technology platform. The collaboration encompasses up to three (3) independent programs directed to the generation of T-cell re-directing bispecific antibodies that bind CD3 and a tumor associated antigen target selected by Lilly to be the subject of each program. At inception of the arrangement, Lilly had selected its first target.

The objective of each program would be to develop a lead compound that Lilly would be able to continue to develop through clinical trials. Lilly agreed to fund the research activities the Company conducts for each program under an agreed research plan and budget. Lilly receives an exclusive, worldwide, royalty-bearing, sublicensable license, under certain patent rights and know-how to exploit certain compounds and products directed to designated targets in combination with CD3, or directed to such designated target(s) alone as a monospecific antibody or monospecific antibody drug conjugate, subject to rights granted by Merus to third parties under one or more existing third party agreements. Merus retains all rights not granted to Eli Lilly. Lilly has certain rights to replace selected targets, including the right to substitute a target selection after initial selection for a period of time. The Company may be entitled to further milestones and royalties in the future dependent on development and commercialization of any resulting product.

The initial term of the arrangement includes a three-year research term for the Company to perform research and development activities, subject to two extension terms of six months at Lilly’s discretion. While the arrangement may be terminated in its entirety or on a program-by-program basis at will by Lilly, there are no direct costs or penalties to Lilly to terminate the arrangement prior to the end of the initial term.

At inception of the arrangement, the Company identified a single performance obligation comprised of a combined delivery of a license and related activities, including research activities associated with the first target and the activities of the joint steering committee. The Company also identified two other combined performance obligations relating to options exercisable by Lilly to select a second and third target to advance selected targets through discovery and research.

The transaction price at inception was comprised of fixed consideration of $43.5 million that was derived from the $40.0 million upfront payment and $20.0 million share purchase proceeds, net of the fair value of shares of the shares delivered to Lilly of $16.5 million, and variable consideration associated with the funding of research services for the first target at inception. All other consideration under the arrangement was determined to be variable consideration and fully constrained at inception.

The fixed consideration was allocated equally amongst the three performance obligations and the variable consideration associated with each target was allocated to the performance obligation of each respective target. The equal allocation of the fixed consideration was based on the estimated standalone selling price of each performance obligation as each was materially the same.

On February 12, 2021, the Company and Lilly completed the initial exchange of fixed consideration and transfer of common shares. The Company initially deferred $43.5 million allocated to the performance obligations to be recognized as revenue over time using a cost-to-cost measure of progress toward the development of a lead compound for each respective target, anticipated to be recognized as revenue within the initial research term, along with research funding. Development milestones, commercialization milestones and

royalties are variable consideration, fully constrained, to be included in the transaction price for each performance obligation and recognized in future periods in accordance with the Company’s revenue recognition policy. The revenue recognized relating to each combined performance obligation is presented in the notes according to the source of consideration received (upfront, reimbursement revenue, milestone), reflective of their differing timing of receipt.

On January 23, 2017, the Company completed the sale of shares and exchange of a ~~license.~~license with Incyte Corporation (“Incyte”). The Company initially deferred $152.6 million of the transaction price allocated to the license and related performance obligation as deferred revenue, to be recognized as revenue over time as the primary benefit of the license to Incyte is access to the Company’s intellectual property covering its Biclonics^® technology platform for the generation of potential product candidates. Development milestones, commercialization milestones and royalties are variable consideration, fully constrained, to be recognized in future periods in accordance with the Company’s revenue recognition policy. Cost reimbursements for research services are recognized as they are performed over time as these are considered a separate performance obligation.

At ~~September~~June 30, ~~2020,~~2021, the Company is currently engaged in clinical development activities for MCLA-145 and developing pre-clinical candidates for the other programs. No development or commercialization milestones have been achieved to date.

On March 14, 2018, the Company granted ONO Pharmaceuticals Co. Ltd. (“ONO”) an exclusive, worldwide, royalty-bearing license, with the right to sublicense, research, test, make, use and market a limited number of bispecific antibody candidates based on the Company’s Biclonics^® technology platform against two undisclosed targets directed to a particular undisclosed target combination. ONO agreed to pay the Company an upfront, non-refundable payment of €0.7 million. In addition, the Company was entitled to €0.3 million intended to compensate the Company for research services already completed upon entering into the agreement, and €0.2 million to be paid to the Company over time for full-time equivalent funding. The Company is entitled to research and development milestones in addition to royalties on future sales. The Company identified performance obligations for: (1) provision of a license for the target combination, and (2) research and development services. The Company concluded that Ono would be able to develop and benefit from the license, independent of the research and development services. Certain of the research and development services are capable of being performed by third parties with an appropriate sub-license, and are recognized over time as these services are delivered. Milestone payments are fully constrained as variable consideration to be recognized in future periods in accordance with the Company’s revenue recognition policy.

Amounts related to the provision of a license are amortized over the intended period of use. ~~The Company received €3.0 million (approximately $3.4 million) for the nine-month period ended September 30, 2019 for development milestones received from Ono based on their progress.~~

In January 2018, the Company granted Simcere Pharmaceuticals Group (“Simcere”) an exclusive license to develop and commercialize up to 3 bispecific antibodies to be produced by Merus utilizing the Company’s Biclonics^® technology platform in China. The Company received an upfront, non-refundable payment of $2.75 million, relating to three separate research programs. The Company may be entitled to future development milestone payments. The Company will be eligible to receive tiered royalty payments on sales of any products resulting from the collaboration in China from Simcere. Simcere will be eligible to receive tiered royalty payments on sales outside of China from the Company.

At inception of the arrangement, the Company identified 3 performance obligations comprised of the combined delivery of a license and performance of research and development activities with respect to each program. The Company performs research and development activities to achieve candidate nomination. The Company concluded that these activities were not distinct from the

underlying license for each program as Simcere would not be able to benefit from the license apart from research and development activities at this phase of development.

The transaction price under the arrangement comprised fixed consideration of $2.75 million. The transaction price was allocated to each separate performance obligation on a relative standalone fair value basis. The Company deferred the portion of the upfront payment allocated to the three performance obligations as deferred revenue, to be recognized over time. Compensation for research and development services prior to candidate nomination are allocated to each program performance obligation and also recognized over time. Development milestone payments allocated to each of the program performance obligations are constrained as variable consideration to be recognized in future periods in accordance with the Company’s revenue recognition policy.

To date, the Company has achieved 2 milestones under this agreement and has received an aggregate of $1.3 million in milestone payments, including a milestone payment of $0.5 million for the quarter ended September 30, 2020, concerning the generation of functional data associated with the second bispecific antibody research program. At September 30, 2020, researchpayments. Research and development ~~for three~~activities are on-going as of ~~the programs is on-going.~~June 30, 2021.

The following tables provide amounts by year indicated and by line item included in the Company's accompanying condensed consolidated financial statements attributable to transactions arising from its collaboration arrangements. The dollar amounts in the tables below are in thousands.

	Related Party			Third Party									Related Party			Third Party
	Incyte			Ono			Other			Total			Incyte			Lilly			Other			Total
CONTRACT ASSETS
Accounts receivable
Balance at January 1, 2020	$	0		$	786		$	0		$	786
Balance at January 1, 2021													$	0		$	0		$	46		$	46
Billings		4,862			0			644			644			3,195			60,254			0			60,254
Cash receipts		(4,903	)		(772	)		(104	)		(876	)		(3,195	)		(60,000	)		0			(60,000	)
Adjustments		0			0			(11	)		(11	)		0			0			0			0
Foreign exchange		41			(14	)		9			(5	)		0			(1	)		(4	)		(5	)
Balance at September 30, 2020		0			0			538			538
Balance at June 30, 2021														0			253			42			295

Unbilled receivables
Balance at January 1, 2020	$	1,711		$	0		$	155		$	155
Balance at January 1, 2021													$	1,623		$	0		$	0		$	0
Accrued receivables		4,690			0			581			581			3,848			1,129			323			1,452
Billings		(4,862	)		0			(644	)		(644	)		(3,194	)		(254	)		0			(254	)
Adjustments		0			0			(94	)		(94	)		0			0			0			0
Foreign exchange		29			0			2			2			(65	)		(17	)		(5	)		(22	)
Balance at September 30, 2020		1,568			0			0			0
Balance at June 30, 2021														2,212			858			318			1,176

CONTRACT LIABILITIES
Deferred revenue
Balance at January 1, 2020	$	108,538		$	336		$	1,385		$	1,721
Balance at January 1, 2021													$	99,004		$	0		$	862		$	862
Allocation of contract consideration														0			43,523			0			43,523
Revenue recognized in the period		(13,415	)		(148	)		(583	)		(731	)		(9,525	)		(4,911	)		(352	)		(5,263	)
Foreign exchange		4,028			8			32			40			(2,989	)		(578	)		(22	)		(600	)
Balance at September 30, 2020		99,151			196			834			1,030
Balance at June 30, 2021														86,490			38,034			488			38,522
Less: current portion		(18,657	)		(196	)		(503	)		(699	)		(18,937	)		(12,716	)		(468	)		(13,184	)
Non-current balance at September 30, 2020		80,494			0			331			331
Non-current balance at June 30, 2021														67,553			25,318			20			25,338

The balance of unbilled receivables predominantly represents reimbursement revenue under the Company’s collaboration arrangements earned in the period to be billed and collected in the next period, generally quarterly. Incyte is a related party as ~~a shareholder, as~~ more fully described in Note 10.

	Three Months Ended September 30, 2020								Three Months Ended June 30, 2021
	(In thousands)								(In thousands)
	Related Party		Third Party						Related Party		Third Party
	Incyte		Ono		Other		Total		Incyte		Lilly		Other			Total
Upfront payments	$	4,683	$	51	$	153	$	204	$	4,791	$	3,765	$	162		$	3,927
Reimbursement revenue		3,192		0		0		0		2,470		869		322			1,191
Milestones		0		0		491		491		0		0		0			0
Total collaboration revenue	$	7,875	$	51	$	644	$	695	$	7,261	$	4,634	$	484		$	5,118
Operating expenses:
Research and development expense	$	666	$	0	$	0	$	0	$	289	$	0	$	0		$	0
General and administrative expense		0		0		0		0		0		0		0			—
Total operating expenses from collaborations	$	666	$	0	$	0	$	0	$	289	$	0	$	0		$	0
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,683	$	51	$	156	$	207	$	4,791	$	3,765	$	162		$	3,927

	Three Months Ended September 30, 2019								Three Months Ended June 30, 2020
	(In thousands)								(In thousands)
	Related Party		Third Party						Related Party		Third Party
	Incyte		Ono		Other		Total		Incyte		Lilly		Other			Total
Upfront payments	$	4,466	$	49	$	167	$	216	$	4,363	$	0	$	284		$	284
Reimbursement revenue		1,224		0		36		36		1,509		0		(105	)		(105	)
Milestones		0		2,224		82		2,306		0		0		5			5
Total collaboration revenue	$	5,690	$	2,273	$	285	$	2,558	$	5,872	$	0	$	184		$	184
Operating expenses:
Research and development expense	$	172	$	0	$	0	$	0	$	612	$	0	$	0		$	0
General and administrative expense		0		0		0		0		0		0		0			0
Total operating expenses from collaborations	$	172	$	0	$	0	$	0	$	612	$	0	$	0		$	0
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,466	$	49	$	249	$	298	$	4,363	$	0	$	289		$	289

	Nine Months Ended September 30, 2020										Six Months Ended June 30, 2021
	(In thousands)										(In thousands)
	Related Party		Third Party								Related Party		Third Party
	Incyte		Ono		Other			Total			Incyte		Lilly		Other			Total
Upfront payments	$	13,414	$	148	$	539		$	687		$	9,525	$	4,911	$	352		$	5,263
Reimbursement revenue		6,306		0		(12	)		(12	)		4,487		1,132		322			1,454
Milestones		0		0		532			532			0		0		0			0
Total collaboration revenue	$	19,720	$	148	$	1,059		$	1,207		$	14,012	$	6,043	$	674		$	6,717
Operating expenses:
Research and development expense	$	1,618	$	0	$	0		$	0		$	648	$	0	$	0		$	0
General and administrative expense		0		0		0			0			0		0		0			0
Total operating expenses from collaborations	$	1,618	$	0	$	0		$	0		$	648	$	0	$	0		$	0
Revenue recognized that was included in deferred revenue at the beginning of the period	$	13,414	$	148	$	582		$	730		$	9,525	$	0	$	352		$	352

	Nine Months Ended September 30, 2019										Six Months Ended June 30, 2020
	(In thousands)										(In thousands)
	Related Party		Third Party								Related Party		Third Party
	Incyte		Ono		Other			Total			Incyte		Lilly		Other			Total
Upfront payments	$	13,393	$	147	$	522		$	669		$	8,731	$	0	$	483		$	483
Reimbursement revenue		5,668		99		119			218			3,114		0		(11	)		(11	)
Milestones		0		3,360		249			3,609			0		0		40			40
Total collaboration revenue	$	19,061	$	3,606	$	890		$	4,496		$	11,845	$	0	$	512		$	512
Operating expenses:
Research and development expense	$	489	$	0	$	0		$	0		$	764	$	0	$	0		$	0
General and administrative expense		0		0		0			0			0		0		0			0
Total operating expenses from collaborations	$	489	$	0	$	0		$	0		$	764	$	0	$	0		$	0
Revenue recognized that was included in deferred revenue at the beginning of the period	$	13,393	$	147	$	771		$	918		$	8,731	$	0	$	523		$	523

Stock-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,				Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019		2020		2019		2021		2020			2021		2020
	(In thousands)				(In thousands)				(In thousands)					(In thousands)
Research and development	$	915	$	766	$	1,677	$	2,351	$	1,850	$	(261	)	$	3,487	$	762
General and administrative		1,929		1,302		4,650		2,837		2,709		1,453			4,472		2,721
Total	$	2,844	$	2,068	$	6,327	$	5,188	$	4,559	$	1,192		$	7,959	$	3,483

The weighted-average grant date fair value of options, estimated as of the grant date using the Black Scholes option pricing model ~~(2019: Hull White),~~ was ~~$11.72~~$17.42 per option ~~(2019: $7.45 per option)~~ for the ~~1,236,484~~1,312,810 options ~~(2019: 1,113,371 options)~~ granted during the ~~nine~~six months ended ~~September~~June 30, ~~2020.~~2021. The ~~significant weighted average valuation inputs included the risk-free interest rate 1.3% (2019: 2.5%), and volatility 86.0% (2019: 87.1%). A weighted average expected term of 6.1 years was~~following assumptions were used in the Black-Scholes option pricing model during the nine months ended September 30, 2020 and the weighted-average contractual term of 10.0 years was used in the Hull White model during the nine months ended September 30, 2019. The Company updates its valuation estimates and methodology to estimate the ~~grant-date~~ fair value of ~~stock-based compensation periodically to reflect observable market data and exercise behavior.~~the options granted during the six months ended June 30, 2021.

In addition, the Company granted ~~46,474~~9,976 RSUs during the ~~nine~~six months ended ~~September~~June 30, ~~2020 (2019: NaN) having~~2021 with a weighted average grant date fair value of ~~$16.00~~$20.15 per unit.

In December 2019, in connection with the departure of Ton Logtenberg, the Chief Executive Officer of the Company, the Company awarded severance benefits, including the following: cash compensation of $0.9 million, a grant of 30,000 RSUs, extended vesting of the executive’s equity incentive awards through June 30, 2021 and extended exercisability of the executive’s equity incentive awards through December 31, 2021. The cash compensation was paid by the Company on January 31, 2020. There were no substantive service conditions associated with the benefits awarded other than the passage of time. The Company incrementally recognized $1.8 million in general and administrative expense associated with these benefits in the consolidated statement of operations for the year ended December 31, 2019.Settlement

In April 2020, Mark Throsby, Ph.D. resigned as the Executive Vice President and Chief Scientific Officer of the Company effective July 31, 2020. In connection with his departure, Mr. Throsby entered into a Settlement Agreement with the Company, pursuant to which Mr. Throsby received a severance payment equal to 8 months of his annual salary and amortized bonus aggregating approximately $0.3 million. Further, subject to Mr. Throsby’s continued compliance with the terms and conditions of the Settlement Agreement, Mr. Throsby’s unvested equity awards ~~will continue~~continued to vest until October 31, 2020 as if Mr. Throsby had continued in full time service with the Company through such date. The post-termination exercise period of Mr. Throsby's options was extended to March 31, 2021. The Company incrementally recognized $0.1 million in respect of the severance payment and a net reversal of $0.4 million of stock-based compensation expense in respect of share-based payments in research and development expense in the consolidated statement of operations in the prior year.

In March 2021, the Company and Mr. Throsby amended the Settlement Agreement, extending the post-termination expiration period of his outstanding options to extend to October 31, 2021, three months following his performance of certain consulting services through July 31, 2021. As a result, additional compensation cost of $0.2 million was recognized for the ~~nine~~quarter ended March 31, 2021. As the modification occurred in Mr. Throsby’s post-employment period, the options cease to be within the scope of ASC 718 and are recharacterized as an issuance of a standalone derivative instrument. The Company recognized a $0.4 million net loss associated with the derivative instrument included as other income in the statement of operations for the six months ended ~~September~~June 30, ~~2020.~~2021.

The Company has entered into the Incyte collaboration and license agreement and the Incyte share subscription agreement with amounts related to transactions under the arrangement disclosed in Note 8 and the arrangement described in the Company’s annual consolidated financial statements for the year ended December 31, ~~2019.~~2020. Incyte is a shareholder with holdings representing approximately ~~11.0%~~9.2% of the outstanding shares of the Company as of ~~September~~June 30, ~~2020,~~2021, and ~~11.1%~~10.1% as of December 31, ~~2019.~~2020.

Item 2.Management’s Discussion and Analysis of Financial Condition and Results of Operations

Our management’s discussion and analysis of our financial condition and results of operations are based upon our unaudited condensed consolidated financial statements included in this Quarterly Report on Form 10-Q, which have been prepared by us in accordance with accounting principles generally accepted in the United States, or U.S. GAAP, and with Regulation S-X promulgated under the Securities Exchange Act of 1934, as ~~amended.~~amended, or Exchange Act. This discussion and analysis is intended to assist in providing an understanding of our financial condition, changes in financial condition and results of operations and should be read in conjunction with these unaudited condensed consolidated financial statements and the notes thereto included elsewhere in this Quarterly Report on Form 10-Q and the discussion and analysis included in our Annual Report on Form ~~10-K.~~10-K for the year ended December 31, 2020, filed with the SEC on March 16, 2021 (the “Annual Report on Form 10-K”). Some of the information contained in this discussion and analysis or set forth elsewhere in this Quarterly Report on Form 10-Q, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. As a result of many factors, including those factors set forth in Part II, Item 1A. Risk Factors of this Quarterly Report on Form 10-Q, our actual results could differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

We are a clinical-stage oncology company developing innovative antibody therapeutics. Our pipeline of full-length human multi-specific antibody candidates are generated from our proprietary technology platforms, which are able to generate a diverse array of antibody binding domains, or Fabs, against virtually any target. Each antibody binding domain consists of a target-specific heavy chain paired with a common light chain. Multiple binding domains can be combined to produce novel bispecific and trispecific antibodies that bind to a wide range of targets and display novel and innovative biology. These platforms referred to as Biclonics^® and Triclonics^TM® ~~allows~~allow us to generate large numbers of diverse panels of bispecific and trispecific antibodies, respectively, which can then be functionally screened in large-scale cell-based assays to identify those unique molecules that possess novel biology, which we believe are best suited for a given therapeutic application. Further, by binding to multiple targets, Biclonics^® and Triclonics^TM® may be designed to provide a variety of mechanisms of action, including simultaneously blocking receptors that drive tumor cell growth and survival and mobilizing the patient’s immune response by engaging T cells, and/or activating various killer cells to eradicate tumors.

Our technology platforms employ an assortment of patented technologies and techniques to generate human antibodies. We utilize our patented MeMo^® mouse to produce a host of antibodies with diverse heavy chains and a common light chain that are capable of binding to virtually any antigen target. We use our patented CH3 domain dimerization technology to generate substantially pure multi-specific antibodies. We also employ our patented Spleen to Screen^® technology to efficiently screen panels of diverse heavy chains, designed to allow us to rapidly identify Biclonics^® and Triclonics^TM® therapeutic candidates with differentiated modes of action for pre-clinical testing and clinical development.

Using our Biclonics^® platform we have produced, and are currently developing, the following candidates: MCLA-128, or zenocutuzumab, for the potential treatment of solid tumors that harbor Neuregulin 1 (NRG1) gene fusions; MCLA-158 for the potential treatment of solid tumors; ~~and~~ MCLA-145, developed in collaboration with Incyte Corporation, for the potential treatment of solid tumors, and ~~a hematological malignancy, B-cell lymphoma.MCLA-117 is a first-in-class Biclonics~~^® T-cell engager antibody that is designed to engage CD3 on T-cells and to bind to and kill AML blasts via the CLEC12A antigen. While we do not plan to continue enrollment into dose expansion cohorts in the MCLA-117 trial, insights from this trial are being used to inform and maximize development of our CD3 T-cell engager platform. We are also developing a late-stage pre-clinical candidate, MCLA-129 ~~in collaboration with Betta Pharmaceuticals,~~ for the potential treatment of solid tumors. Furthermore, we have a pipeline of proprietary antibody candidates in pre-clinical development and intend to further leverage our Biclonics^® technology platform and Triclonics^TM technology platform to identify additional multi-specific antibody candidates and advance them to clinical development.

We are a clinical-stage company and have not generated any revenue from product sales. We expect to incur significant expenses and operating losses for the foreseeable future as we advance our antibody candidates from discovery through pre-clinical development and into clinical trials, and seek regulatory approval and pursue commercialization of any approved antibody candidate. In addition, if we obtain regulatory approval for any of our antibody candidates, if appropriate, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution.

We anticipate that we will require additional financing to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity or debt financings or other sources, which may include collaborations, business development and licensing opportunities with third parties. Adequate additional financing may not be available to us on acceptable terms, or at all. For example, the trading prices for our and other biopharmaceutical companies’ stock have been highly volatile as a result of the COVID-19 pandemic. As a result, we may face difficulties raising capital through sales of our common stock and any such sales may be on unfavorable terms. See “Impact of

COVID-19 Pandemic” below and “Risk Factors—Risks Related to Our Business and Industry—The COVID-19 pandemic caused by the novel coronavirus has and may continue to adversely impact our business, including our pre-clinical studies and clinical trials, financial condition and results of ~~operations.”~~operations” in Part II, Item 1A of this Quarterly Report on Form 10-Q. Our inability to raise capital

as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy. We will need to generate significant revenue to achieve profitability, and we may never do so.

Based on our current operating plan, we expect that our existing cash, cash equivalents and marketable securities of ~~$190.2~~$352.8 million as of ~~September~~June 30, ~~2020~~2021 will be sufficient to fund our operations into the second half of ~~2022.~~2024.

~~NRG1 gene fusion (NRG1+) Cancers:~~ Phase 2 part of the phase 1/2 ~~eNRGy~~ trial ~~clinical data and program~~continues: update planned ~~for Q2 2021~~

by the first half of 2022We continue to enroll patients in the Phase 1/2 eNRGy trial to assess the safety and anti-tumor activity of Zeno monotherapy in NRG1+ cancers. ~~We believe that Zeno continues to demonstrate encouraging single agent activity in NRG1+ cancers and continues to be well tolerated, consistent with previously reported safety~~

On June 4, we shared interim clinical data ~~in the overall patient population treated with Zeno monotherapy. The initial clinical responses reported in late 2019 support the potential for Zeno to be particularly effective~~of our zenocutuzumab (Zeno) program in patients with ~~NRG1+~~NRG1 fusion (NRG1+) cancers at the American Society of Clinical Oncology (ASCO) 2021 Annual Meeting.

We plan to provide a ~~patient population with significant unmet need.~~further clinical and regulatory program update by the first half of 2022.

In August 2020, Zeno was granted Orphan Drug Designation by the U.S. FDA for ~~pancreatic cancer. Pancreatic cancer is estimated to occur in approximately 57,000 patients annually in~~ the ~~U.S., according to the National Cancer Institute SEER database. Pancreatic ductal adenocarcinoma (PDAC), the most common subtype~~treatment of pancreatic cancer ~~is one~~and in January 2021, we announced that Zeno received Fast Track Designation for the treatment of ~~the most aggressive solid tumor cancers and the fourth leading cause of cancer-related deaths.~~

~~We plan to present efficacy data from the eNRGy trial and Early Access Program at a major medical conference in the second quarter of 2021 including results on more than 30~~ patients with ~~NRG1+ pancreatic, non-small cell lung and other cancers with the opportunity for four or more months of follow up. At~~metastatic solid tumors harboring NRG1 gene fusions that ~~time, we plan to also discuss details of the program and overall strategy.~~

~~Clinical trial site activation, patient identification and enrollment, and clinical operations activities for the eNRGy trial~~ have increased since the second quarter of 2020. We previously noted that enrollment and clinical operations activities in this trial have continued, albeit at a slower pace throughout the COVID-19 pandemic. Over 30 clinical trial sites are now open globally, with additional sites planned for the coming months. We expect patient identification and enrollment to continue to accelerate through the our ongoing patient screening and patient identification initiatives, including several programs with clinical support and testing collaborators.

Our comprehensive patient recruitment strategy includes agreements with Caris Life Sciences (Caris), Foundation Medicine Inc., and Tempus Labs Inc., to identify NRG1+ patients and determine suitability of enrollment of these patients in the eNRGy trial and EAP. Separately, we have a collaboration with Caris, through which Caris has agreed to provide tumor DNA and RNA molecular testing, focusedprogressed on pancreatic cancer, which is a patient population that may otherwise not undergo molecular diagnostic testing due to the current lack of personalized, molecularly-driven treatment options for this cancer type.

~~Details~~ ~~of the eNRGy trial, including current trial sites, can be found at www.ClinicalTrials.gov and our trial website at www.nrg1.com, or by calling 1-833-NRG-1234.~~standard-of-care therapy.

Phase 1 trial continues: ~~Update expected by year end~~dose expansion cohorts ongoing: update planned for Q4 2021

The phase 1 open label, multicenter clinical trial of MCLA-158 is ~~currently being evaluated~~ongoing in ~~a Phase 1 open-label, multicenter dose escalation study, including a safety~~the dose expansion ~~phase, in~~phase. Enrollment of patients with ~~solid tumors. The trial is ongoing~~gastro-esophageal and ~~MCLA-158~~head-and-neck cancers continues, and preliminary evidence of antitumor activity has ~~demonstrated a favorable safety profile with no observed dose limiting toxicities to date.~~been observed. We plan to provide an update at a ~~clinical update on~~medical conference in the ~~Phase 1 trial by year end.~~fourth quarter of 2021..

The phase 1, open-label, single-agent clinical trial of MCLA-145 is ~~currently being evaluated in~~ongoing and consists of a ~~Phase 1 open-label, multicenter~~ dose escalation ~~study, including~~phase, to be followed by a ~~safety~~planned dose expansion ~~phase, in patients with solid tumors.~~phase. MCLA-145 is the first drug candidate co-developed under ~~our~~Merus’ global collaboration and license agreement with Incyte Corporation, which permits the development and commercialization of up to 11 bispecific and monospecific antibodies from ~~our Biclonics~~^®the Merus Biclonics® platform. ~~We retain~~Merus retains full rights to develop and commercialize MCLA-145, if approved, in the United ~~States,~~States; and Incyte ~~is responsible for its development~~holds full rights to develop and ~~commercialization~~commercialize MCLA-145 outside the United States. We plan to provide an update at a medical conference in Q4’21..

~~IND-enabling studies~~Phase 1 trial ongoing ~~first patient planned~~in patients with solid tumors.

The phase 1/2, open-label, single-agent clinical trial of MCLA-129 is ongoing and consists of a dose escalation phase, to be ~~dosed in 2021~~

~~We are currently conducting IND-enabling studies of~~followed by planned expansion cohorts evaluating MCLA-129 for the treatment of ~~various~~patients with advanced non-small cell lung cancer (NSCLC) and other solid ~~tumors~~tumors. MCLA-129 is a Biclonics®, which binds to EGFR and c-MET and is being investigated for the treatment of

solid tumors. EGFR is an important oncogenic driver in many cancers, and upregulation of c-MET signaling has been associated with resistance to EGFR inhibition. MCLA-129 is subject to collaboration ~~with~~and license agreement, which permits Betta Pharmaceuticals Co. Ltd. (Betta) ~~and the first patient is planned~~ to be dosed in 2021. We presented preclinical data in late 2019 demonstrating that MCLA-129 inhibited the growth of tyrosine kinase resistant Non-Small Cell Lung Cancer (NSCLC) cell lines and NSCLC tumors in xenograft models. Betta holds exclusive rights toexclusively develop MCLA-129 in China, while ~~we retain~~Merus retains full ex-China rights.

The current COVID-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting our employees, communities, clinical trial sites and business operations, as well as the U.S. and Dutch economies and international financial markets.

While we are currently continuing our ongoing clinical trials, the COVID-19 pandemic and related precautions have directly or indirectly impacted enrollment, new, planned clinical trial site openings, patient visits, and on-site monitoring of our clinical trials and source verification of clinical data required for presentation of clinical data for zenocutuzumab, ~~MCLA-117,~~ MCLA-158, MCLA-145 and ~~MCLA-145.~~MCLA-129. We ~~have observed~~continued to observe a moderate to high impact on clinical trial enrollment and operations as a consequence of the COVID-19 pandemic during the ~~third~~ quarter ended ~~September~~June 30, ~~2020,~~2021, particularly at sites in countries not yet open to recruitment, and to a lesser extent in countries where COVID-19 related restrictions have been eased, with adjustments made to allow remote visits for some patient follow-up, and reduced onsite monitoring by the sponsor or contract research organization (CRO). As a result of the COVID-19 pandemic, we may experience further disruptions that could severely impact our business, preclinical studies and clinical trials. The extent of the impact to our overall clinical development timeline is uncertain at this time and we continue to monitor and assess the COVID-19 pandemic on a regular basis.

As a result of the COVID-19 pandemic, certain of our CROs and third-party suppliers, as well as collaborators in the U.S. and China that are developing or collaborating with us to develop certain of our pre-clinical antibody candidates have been affected. As a result of such impact, we may face difficulties with and delays in performance of certain chemistry manufacturing and controls and testing of our ~~pre-clinical~~ antibody candidates, including ~~MCLA-129, among other undisclosed pre-clinical candidates~~those associated with our collaborations with Incyte, Lilly and Simcere, which may delay or prevent their potential clinical development. While we currently do not anticipate any interruptions in our clinical trial supply of drug candidates, it is possible that the COVID-19 pandemic and response efforts may have an impact in the future on our third-party suppliers and contract manufacturing partners' ability to manufacture our clinical trial supply or source materials necessary for their manufacture.

In response to the spread of COVID-19, on March 18, 2020, we temporarily suspended our laboratory research activities at our facilities in Utrecht, the Netherlands to help secure the safety of our employees and to adhere to government recommendations of social distancing and limited public exposure in connection with the COVID-19 pandemic. We have since re-opened our offices and laboratory in Utrecht, maintaining social distancing and imposing other requirements consistent with government guidance. Further, we have recommended our employees in the U.S. and Netherlands work from home when possible and for those employees working at our offices and laboratory in Utrecht and offices in Cambridge Ma., they are required to maintain social distancing and follow requirements consistent with the guidance provided by the CDC, Federal, state and local regulations for the U.S. and RIVM for the Netherlands. While we use reasonable business practices to mitigate the risk of exposure to COVID-19 while on Company-operated premises, we cannot guarantee that traveling to and from and visiting the ~~office~~offices will not expose employees to infectious ~~agent~~agents or eliminate inherent risks to our workforce and our business operations resulting from COVID-19. Given the uncertainty caused by the COVID-19 pandemic we cannot be certain that we will not suspend our laboratory research activities at our facilities or suspend use of our offices in the future.

At this time, there is significant uncertainty caused by the COVID-19 pandemic and impact of related responses. The future impact of COVID-19 on our business and clinical trials will largely depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the spread of the disease, availability and effectiveness of vaccines, arising variants, and their impact on vaccination efforts, the duration of the pandemic, travel restrictions and social distancing in the Netherlands, the United States and other countries, business closures or business disruptions, the ultimate impact of COVID-19 on financial markets and the global economy, and the effectiveness of actions taken in the Netherlands, the United States and other countries to contain and treat the disease. See “Risk Factors—Risks Related to Our Business and Industry—The COVID-19 pandemic caused by the novel coronavirus has and may continue to adversely impact our business, including our pre-clinical studies and clinical trials, financial condition and results of operations.” in Part II, Item 1A of this Quarterly Report on Form 10-Q.

Refer to Item 1, “Business—Our Collaborations” and Note 12, “Collaborations,” of the notes to our consolidated financial statements included in our Annual Report on Form 10-K ~~for the year ended December 31, 2019, filed with the SEC on March 16, 2020 (as amended, the “Annual~~and Note 8, “Collaborations,” to our unaudited condensed consolidated interim financial statements elsewhere in this Quarterly Report on Form ~~10-K”)~~10-Q for a description of the key terms of our arrangements.

In prior periods, we prepared our financial information in accordance with IFRS. As a consequence of becoming a U.S. domestic issuer as of January 1, 2020, we are required to present our financial information in accordance with U.S. GAAP and expressed in U.S. dollars from that date. The below financial information has been prepared in accordance with U.S. GAAP. The financial information should not be expected to correspond to figures we have previously presented under IFRS.

Comparison of the three and ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 and ~~2019~~2020

	Three Months Ended September 30,								Nine Months Ended September 30,								Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019			Change			2020		2019			Change			2021		2020		Change		2021		2020		Change
	(In millions)								(In millions)								(In millions)						(In millions)
Incyte	$	7.9	$	5.7		$	2.2		$	19.7	$	19.1		$	0.6		$	7.3	$	5.9	$	1.4	$	14.0	$	11.8	$	2.2
Ono		0.1		2.3			(2.2	)		0.1		3.6			(3.5	)
Lilly																		4.6		—		4.6		6.0		—		6.0
Other		0.6		0.3			0.3			1.1		0.9			0.2			0.5		0.2		0.3		0.7		0.5		0.2
Total collaboration revenue		8.6		8.3			0.3			20.9		23.6			(2.7	)
Grant revenue		—		(0.1	)		0.1			—		(0.2	)		0.2
Total revenue		8.6		8.2			0.4			20.9		23.4			(2.5	)		12.4		6.1		6.3		20.7		12.3		8.4

Collaboration revenue for the three months ended ~~September~~June 30, ~~2020~~2021 increased by ~~$0.3~~$6.3 million as compared to the three months ended ~~September~~June 30, ~~2019,~~2020, primarily as a result of an increase ~~in Incyte~~from a Lilly upfront payment amortization and reimbursement ~~revenue~~revenues of ~~$2.0~~$4.6 million due to increased activities, and $0.5 million in other net increases, including the achievement of a Simcere milestone, partially offset by a decrease of $2.2 million in Ono milestone revenue due to the achievement of milestonesthat commenced in the ~~prior year period that did not recur~~first quarter of 2021, and a $1.4 million increase primarily in reimbursement revenues related to Incyte reflecting activities in the ~~current year period.~~period for MCLA-145. The change in exchange rates did not significantly impact collaboration revenue.

Collaboration revenue for the ~~nine~~six months ended ~~September~~June 30, ~~2020 decreased~~2021 increased by ~~$2.7~~$8.4 million as compared to ~~nine~~the six months ended ~~September~~June 30, ~~2019~~2020, primarily as a result of an increase from a ~~decrease~~Lilly upfront payment amortization and reimbursement revenues of ~~$3.4~~$6.0 million ~~in Ono milestone revenue due to the achievement of milestones~~that commenced in the ~~prior year~~first quarter of 2021, and a $2.2 million increase primarily in reimbursement revenues related to Incyte reflecting activities in the period ~~that~~for MCLA-145. The change in exchange rates did not ~~recur in the current year period, partially offset by an increase in Incyte reimbursement revenue of $0.6 million due to increased activities.~~significantly impact collaboration revenue.

As of ~~September~~June 30, ~~2020,~~2021, we had total deferred revenue of ~~$100.2~~$125.0 million, which primarily relates to the upfront payment received under our Incyte collaboration agreement and Lilly collaboration agreement and is expected to be recognized over the next ~~six years.~~five and three years, respectively.

	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019		Change		2020		2019		Change		2021		2020		Change		2021		2020		Change
	(In millions)						(In millions)						(In millions)						(In millions)
Research and development	$	17.5	$	13.5	$	4.0	$	48.2	$	36.1	$	12.1	$	24.6	$	13.7	$	10.9	$	45.4	$	30.7	$	14.7
General and administrative		9.1		8.0		1.1		26.1		23.0		3.1		10.6		8.0		2.6		19.9		16.9		3.0
Total operating expenses	$	26.6	$	21.5	$	5.1	$	74.3	$	59.1	$	15.2	$	35.2	$	21.7	$	13.5	$	65.3	$	47.6	$	17.7

Research and development expense for the three months ended ~~September~~June 30, ~~2020~~2021 increased by ~~$4.0~~$10.9 million as compared to the three months ended ~~September~~June 30, ~~2019,~~2020, primarily as a result of an increase in ~~headcount, higher~~clinical and manufacturing ~~related costs, and higher pre-clinical research and development-related~~ costs related to our programs ~~particularly increases in costs for zenocutuzumab.~~and stock-based compensation.

Research and development expense for the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 increased by ~~$12.1~~$14.7 million as compared to the ~~nine~~six months ended ~~September~~June 30, ~~2019,~~2020, primarily as a result of an increase in ~~manufacturing related costs,~~clinical and ~~higher pre-clinical research and development-related~~manufacturing costs related to our programs ~~particularly increases in costs for zenocutuzumab, offset by decreases in costs for MCLA-145. On a comparative basis,~~and stock-based compensation included in research and development costs for the nine months ended September 30, 2020 decreased by $0.7 million compared to the nine months ended September 30, 2019, primarily due to the modification and forfeiture of awards held by departing executives.compensation.

General and administrative expense for the three months ended ~~September~~June 30, ~~2020~~2021 increased by ~~$1.1~~$2.6 million as compared to the three months ended ~~September~~June 30, ~~2019,~~2020, primarily as a result ~~increases~~of an increase in stock-based compensation ~~insurance, intellectual property related costs~~ and other ~~items,~~personnel related expenses as well as facilities and professional fees, partially offset by ~~a decrease~~decreases in ~~consulting~~legal and IP related costs.

General and administrative expense for the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 increased by ~~$3.1~~$3.0 million as compared to the ~~nine~~three months ended ~~September~~June 30, ~~2019,~~2020, primarily as a result ~~increases~~of an increase in stock-based compensation ~~insurance,~~and other personnel related expenses as well as facilities ~~intellectual property~~and professional fees, partially offset by decreases in legal and IP related costs and ~~other items, partially offset by a decrease in consulting costs.~~travel expenses.

Other income (loss), net consists of interest earned and fees paid on our cash and cash equivalents held on account, accretion of investment earnings and net foreign exchange (losses) gains on our foreign denominated cash, cash equivalents and marketable securities. Other gains or losses relate to the issuance and settlement of financial instruments.

	Three Months Ended September 30,								Nine Months Ended September 30,							Three Months Ended June 30,								Six Months Ended June 30,
	2020			2019			Change		2020		2019		Change			2021			2020			Change		2021			2020		Change
	(In millions)								(In millions)							(In millions)								(In millions)
Current	$	0.3		$	—		$	0.3	$	0.3	$	0.1	$	0.2		$	0.2		$	0.1		$	0.1	$	(0.2	)	$	0.1	$	(0.3	)
Deferred		(0.1	)		(0.1	)		—		—		0.1		(0.1	)		(0.1	)		(0.1	)		—		0.3			0.1		0.2
Total tax expense (benefit), net	$	0.2		$	(0.1	)	$	0.3	$	0.3	$	0.2	$	0.1		$	0.1		$	—		$	0.1	$	0.1		$	0.2	$	(0.1	)

We are subject to income taxes in the Netherlands and the U.S. Our current and deferred tax provision represents taxable income attributed to our U.S. operations as a consequence of allocating income to that jurisdiction. No current or deferred provision for income taxes has been made for income taxes in the Netherlands due to losses for tax purposes. Further, given a history of losses in the Netherlands, no deferred tax assets in excess of deferred tax liabilities are recognized as we believe it is not more likely than not that they will be recovered.

Net loss for the three and ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 was ~~$23.1~~$27.4 million and ~~$57.5~~$37.5 million ~~respectively,~~ compared to net loss for the three and ~~nine~~six months ended ~~September~~June 30, ~~2019~~2020 of ~~$9.3~~$18.0 million and ~~$29.7 million, respectively.~~$34.5 million. The change in net loss was primarily due to the change in collaboration revenue, changes in operating expenses and changes in other income, ~~(loss),~~ net, as discussed above.

As of ~~September~~June 30, ~~2020,~~2021, we had ~~$190.2~~$352.8 million in cash, cash equivalents and marketable securities that are available to fund our current operations. In addition to our existing cash, cash equivalents and marketable securities, we may receive research and development co-funding and are eligible to earn a significant amount of milestone payments under our collaboration agreements and research license agreements. Our ability to earn these payments and the timing of earning these payments is dependent upon the outcome of our research and development activities and is uncertain at this time.

On January 18, 2021, the Company entered into a Collaboration and License Agreement (the “Collaboration Agreement”) and Share Subscription Agreement (the “Subscription Agreement”) with Eli Lilly and Company, an Indiana corporation (“Eli Lilly”). Eli Lilly paid an upfront, non-refundable payment of $40 million, for the rights granted under the Collaboration Agreement within 30 days following the Effective Date. Eli Lilly will fund the research and development activities to be conducted by the Company for each

program under an agreed research plan and budget. With respect to each product arising from each program, the Company is eligible to receive up to $290 million in future contingent development and regulatory milestones and up to $250 million in commercial sales milestones, for a total of up to approximately $1.6 billion for a single product generated from all three programs. The Company is further eligible to receive, on a product-by-product and country-by-country basis, tiered royalties based on the level of worldwide aggregate annual net sales at percentages ranging from the mid-single digits to low double digits until the royalty term expires. In connection with entering into the Collaboration Agreement, pursuant to the Subscription Agreement, on January 18, 2021, Eli Lilly agreed to purchase 706,834 common shares of the Company at a price per share of $28.295 for aggregate gross proceeds to the Company of approximately $20 million. Eli Lilly agreed not to transfer, sell, or otherwise dispose of the Shares for a period of time following the Closing Date, subject to certain customary exceptions.

On January 21, 2021, the Company entered into an underwriting agreement with Jefferies LLC and SVB Leerink LLC, as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the issuance and sale by the Company in a public offering of 4,848,485 common shares of the Company, nominal value €0.09 per share, at a public offering price of $24.75 per share, less underwriting discounts and commissions. The Company also granted the Underwriters an option exercisable for 30 days to purchase up to an additional 727,272 common shares at the public offering price, less underwriting discounts and commissions. On January 21, 2021, the Underwriters exercised this option in full. The closing of the offering occurred on January 25, 2021, resulting in aggregate net proceeds to the Company of $129.4 million.

Our primary uses of capital are, clinical trial costs, chemistry manufacturing and control costs to manufacture and supply drug product for our clinical trials, third-party research and development services, laboratory and related supplies, financial services, legal and other regulatory expenses and general overhead costs.

Because our product candidates are in various stages of clinical and pre-clinical development and the outcome of these efforts is uncertain, we cannot estimate the actual amounts necessary to successfully complete the development and commercialization of our product candidates or whether, or when, we may achieve profitability. In addition, the magnitude and duration of the COVID-19 pandemic and its impact on our liquidity and future funding requirements is uncertain as of the filing date of this Quarterly Report on Form 10-Q, as the pandemic continues to evolve globally. See “Impact of COVID-19 Pandemic” above and “Risk Factors—Risks Related to Our Business and Industry—The COVID-19 pandemic caused by the novel coronavirus has and may continue to adversely impact our business, including our pre-clinical studies and clinical trials, financial condition and results of ~~operations.”~~operations” in Part II, Item 1A of this Quarterly Report on Form 10-Q for a further discussion of the possible impact of the COVID-19 pandemic on our business.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of equity or debt financings, collaboration arrangements, license agreements, other business development opportunities ~~and government grants.~~with third parties.

Except for any obligations of our collaborators or licensees to make license, milestone or royalty payments under our agreements with them, ~~and government grants,~~ we do not have any committed external sources of liquidity and currently have no credit facility. To the extent that we raise additional capital through the future sale of equity or debt, the ownership interest of our stockholders may be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our existing common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise additional funds through collaboration arrangements, license agreements or other business development opportunities in the future, we may have to relinquish valuable rights to our technologies or intellectual property, future revenue streams or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise any additional funds that may be needed through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Based on our current operating plan, research and development plans and our timing expectations related to the progress of our programs, we expect that our existing cash, cash equivalents and marketable securities as of ~~September~~June 30, ~~2020,~~2021 will ~~be sufficient to~~ fund ~~our planned operating expenses and capital expenditure requirements~~the Company’s operations into the second half of ~~2022,~~2024, without giving effect to any potential milestone payments we may receive under our collaboration and license agreements. We have based this estimate on assumptions that may prove to be wrong, particularly as the process of testing product candidates in clinical trials is costly and the timing of progress in these trials is uncertain and in light of the uncertainties associated with the magnitude and duration of the COVID-19 pandemic. As a result, we could use our capital resources sooner than we expect.

	Nine Months Ended September 30,									Six Months Ended June 30,
	2020			2019			Change			2021			2020			Change
	(In millions)									(In millions)
Net cash used in operating activities	$	(55.6	)	$	(43.3	)	$	(12.3	)	$	(5.0	)	$	(43.9	)	$	38.9
Net cash (used in) provided by investing activities		(7.4	)		20.0			(27.4	)
Net cash provided by (used in) investing activities											3.1			(1.3	)		4.4
Net cash provided by financing activities		0.8			—			0.8			152.3			0.7			151.6

Net cash used in operating activities during the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 decreased by ~~$12.3~~$38.9 million as compared to the ~~nine~~six months ended ~~September~~June 30, ~~2019,~~2020, primarily due to operating cash receipts related to revenue arrangements ~~decreasing~~principally from the receipt of payments received from Lilly of which $43.5 million relates to deferred revenue, partially offset by ~~$4.1 million, operating cash out flows related to~~ operating expenses ~~increasing~~during the period.

Net cash provided by ~~$5.1~~investing activities during the six months ended June 30, 2021 principally reflects maturities of marketable securities of $28.2 million ~~and a decrease in cash realized from interest income and foreign exchange~~partially offset by $24.9 million of ~~$2.9 million.~~

purchases of marketable securities. Net cash used in investing activities during the ~~nine~~six months ended ~~September~~June 30, 2020 principally reflects $49.4 million of purchases of marketable securities partially offset by maturities of marketable securities of $42.8 million. Net cash provided by investing activities during the nine months ended September 30, 2019 principally reflects $49.4$28.9 million of purchases of marketable securities, offset by maturities of marketable securities of ~~$71.7~~$28.2 million.

Net cash provided by financing activities during the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 increased primarily ~~reflects~~due to proceeds received from the issuance of common stock of $129.6 million, proceeds from the stock issuance to Lilly of $16.5 million, and an increase in stock option ~~exercises~~exercise proceeds of ~~$0.9~~$5.8 million ~~partially offset by payments of public offering costs of $0.2 million.~~ ~~Net cash provided by financing activities during the nine months ended September 30, 2019 primarily reflects cash received from stock option exercises of less than $0.1 million.~~.

Our critical accounting policies are described under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies” in our Annual Report on Form 10-K and in Note 2 to our consolidated financial statements included in the Annual Report on Form 10-K. As disclosed in Note 2 to our consolidated financial statements included in the Annual Report on Form 10-K, the preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions about future events that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ significantly from those estimates. During the period covered by this Quarterly Report on Form 10-Q, there were no material changes to our critical accounting policies from those discussed in our Annual Report on Form 10-K, other than updating our use of the option pricing model and associated estimates as described in Note 9 to our unaudited condensed consolidated interim financial statements included elsewhere in this Quarterly Report on Form 10-Q.

For detailed information regarding recently issued accounting pronouncements and the expected impact on our condensed consolidated financial statements, see Note 2, Summary of Significant Accounting Policies—Pending Accounting Pronouncements, in the accompanying notes to the unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report on Form 10-Q.

In designing and evaluating our disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives. In addition, the design of disclosure controls and procedures must reflect the fact that there are resource constraints and that management is required to apply judgment in evaluating the benefits of possible controls and procedures relative to their costs.

Our management, with the participation of our principal executive and financial officer, evaluated, as of the end of the period covered by this Quarterly Report on Form 10-Q, the effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) and

15d-15(e) under the Exchange Act). Based on such evaluation, our principal executive and financial officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of ~~September~~June 30, ~~2020.~~2021.

There were no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) during the quarter ended ~~September~~June 30, ~~2020~~2021 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

~~On April 5, 2018, an unnamed third party~~See Note 6, Commitments and ~~Regeneron Pharmaceuticals Inc.~~Contingencies, ~~or Regeneron, filed notices of opposition against our EP 2604625 patent, entitled “Generation of Binding Molecules,”~~ in the European Opposition Division of the European Patent Office, or the EPO. The notices asserted, as applicable, added subject matter, lack of novelty, lack of inventive step, and insufficiency. Regeneron withdrew its opposition pursuant to a global December 20, 2018 settlement with us. On August 20, 2018, we timely respondedaccompanying notes to the ~~submissions with respect to the unnamed third party. An opposition hearing was held~~unaudited condensed consolidated financial statements included elsewhere in June 2019, wherein the EPO revoked the EP 2604625 patent in its entirety under Art. 123(2) EPC. We timely appealed that decision in December 2019 before the Technical Board of Appeals for the EPO seeking reinstatement of the patent and proposing auxiliary requests for certain amended claims, with further proceedings to be scheduled in the future. As this ~~opposition proceeding continues, we cannot be certain that we will ultimately prevail.~~Quarterly Report on Form 10-Q.

From time to time, we may be involved in various ~~other claims and~~ legal proceedings relating to claims arising out of our operations. We are not currently a party to any legal proceedings, which ~~could be~~are deemed to be material.

Careful consideration should be given to the following risk factors, in addition to the other information set forth in this Quarterly Report on Form 10-Q and in other documents that we file with the SEC, in evaluating our company and our business. Investing in our common stock involves a high degree of risk. If any of the following risks and uncertainties actually occurs, our business, prospects, financial condition and results of operations could be materially and adversely affected. The risks described below are not intended to be exhaustive and are not the only risks facing our company. New risk factors can emerge from time to time, and it is not possible to predict the impact that any factor or combination of factors may have on our business, prospects, financial condition and results of operations.

We are a clinical-stage company and have incurred significant losses since our inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

We are a clinical-stage oncology company with a limited operating history. We have incurred net losses of ~~$57.5~~$37.5 million, and ~~$29.7~~$34.5 million for the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 and ~~2019,~~2020, respectively. As of ~~September~~June 30, ~~2020,~~2021, we had an accumulated deficit of ~~$372.1~~$437.7 million. Our losses have resulted principally from expenses incurred in research and development of our antibody candidates and from management and administrative costs and other expenses that we have incurred while building our business infrastructure. We expect to continue to incur significant operating losses for the foreseeable future as we continue our research and development efforts and seek to obtain regulatory approval and commercialization of our antibody candidates. We anticipate that our expenses will increase substantially as we:

We have financed our operations primarily through public offerings and private placements of our common shares and our collaboration and license agreement with ~~Incyte.~~Incyte and Eli Lilly. We have devoted a significant portion of our financial resources and efforts to developing our full-length bispecific antibody therapeutics, which we refer to as ~~Biclonics~~^®Biclonics®, our technology platforms, identifying potential antibody candidates, conducting pre-clinical studies of a variety of candidates, and conducting our clinical trials of zenocutuzumab, ~~MCLA-117,~~ MCLA-158, MCLA-145 and ~~MCLA-145.~~MCLA-129. We are in the early stages of development of our antibody candidates, and we have not completed development of any ~~Biclonics~~^®Biclonics® or any other drugs or biologics.

To become and remain profitable, we must succeed in developing and eventually commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including completing pre-clinical testing and clinical trials of our ~~bispecific~~ antibody candidates, discovering and developing additional ~~bispecific and trispecific~~ antibody candidates, obtaining regulatory approval for any antibody candidates that successfully complete clinical trials, establishing manufacturing and marketing capabilities and ultimately selling any products for which we may obtain regulatory approval. We are only in the preliminary stages of most of these activities. We may never succeed in these activities and, even if we do, may never generate revenue that is significant enough to achieve profitability.

Because of the numerous risks and uncertainties associated with pharmaceutical product and biological development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve profitability. If we are required by the U.S. Food and Drug Administration (FDA), or the European Medicines Agency (EMA), or other regulatory authorities to perform studies in addition to those we currently anticipate, or if there are any delays in completing our clinical trials or the development of any of our antibody candidates, our expenses could increase and commercial revenue could be further delayed.

Even if we do generate product royalties or product sales, we may never achieve or sustain profitability on a quarterly or annual basis. Our failure to sustain profitability could depress the market price of our common shares and could impair our ability to raise capital, expand our business, diversify our product offerings or continue our operations.

We will need additional funding in order to complete development of our antibody candidates and commercialize our products, if approved. If we are unable to raise capital when needed, we could be forced to delay, reduce or eliminate our product development programs or commercialization efforts.

We expect our expenses to increase in connection with our ongoing activities, particularly as we conduct our ongoing clinical trials of zenocutuzumab, MCLA-158, MCLA-145 and ~~MCLA-145, complete the dose expansion phase of our trial of MCLA-117, complete IND-enabling studies for~~ MCLA-129 ~~and potentially enter clinical trials,~~ and continue to research, develop and conduct pre-clinical studies of our other antibody candidates. In addition, if we obtain regulatory approval for any of our antibody candidates, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution. Furthermore, we continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we could be forced to delay, reduce or eliminate our research and development programs or any future commercialization efforts. For example, the trading prices for our and other biopharmaceutical companies’ stock have been highly volatile as a result of the COVID-19 pandemic. As a result, we may face difficulties raising capital through sales of our common stock and any such sales may be on unfavorable terms.

Based on our current operating plan, we expect that our existing cash, cash equivalents and investments as of ~~September~~June 30, ~~2020~~2021 will be sufficient to fund our operations into the second half of ~~2022.~~2024. We have based this estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect. Our future capital requirements will depend on many factors, including:

We depend heavily on the success of our antibody candidates, and we cannot give any assurance that any of our antibody candidates will receive regulatory approval, which is necessary before they can be commercialized. If we, any of our collaborators, or any other strategic partners we may enter into collaboration agreements with for the development and commercialization of our antibody candidates, are unable to commercialize our antibody candidates, or experience significant delays in doing so, our business, financial condition and results of operations will be materially adversely affected.

We have invested a significant portion of our efforts and financial resources in the development of bispecific antibody candidates using our ~~Biclonics~~^®Biclonics® technology platform and in development of multi-specific antibody candidates using our ~~Triclonics~~^TMTriclonics® technology platform. Our ability to generate royalty and product revenues, which we do not expect will occur for at least the next several years, if ever, will depend heavily on the successful development and eventual commercialization of these antibody candidates, which may never occur. We currently generate no revenues from sales of any products, and we may never be able to develop or commercialize a marketable product. Each of our bispecific antibody candidates and pre-clinical trispecific antibody candidates will require additional clinical development, management of clinical, pre-clinical and manufacturing activities, regulatory approval in multiple jurisdictions, obtaining manufacturing supply, including commercial manufacturing supply, building of a commercial organization, substantial investment and significant marketing efforts before we generate any revenues from product sales. We are not permitted to market or promote any of our antibody candidates before we receive regulatory approval from the FDA, the EMA or comparable foreign regulatory authorities, and we may never receive such regulatory approval for any of our antibody candidates. The success of our antibody candidates will depend on several factors, including the following:

If we or our collaborators, as applicable, do not achieve one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully commercialize our antibody candidates, which would materially adversely affect our business, financial condition and results of operations.

We have not previously submitted a Biologics License Application (BLA), to the FDA, a Marketing Authorisation Application (MAA) to the EMA, or similar regulatory approval filings to comparable foreign authorities, for any antibody candidate, and we cannot be certain that any of our antibody candidates will be successful in clinical trials or receive regulatory approval. Further, our antibody candidates may not receive regulatory approval even if they are successful in clinical trials. If we do not receive regulatory approvals for our antibody candidates, we may not be able to continue our operations. Even if we successfully obtain regulatory approvals to market one or more of our antibody candidates, our revenues will be dependent, in part, upon the size of the markets in the territories for which we gain regulatory approval and have commercial rights. If the markets for patient subsets that we are targeting are not as significant as we estimate, we may not generate significant revenues from sales of such products, if approved.

We plan to seek regulatory approval to commercialize our antibody candidates both in the United States and the EU, and potentially in additional foreign countries. While the scope of regulatory approval is similar in other countries, to obtain separate regulatory approval in many other countries we must comply with the numerous and varying regulatory requirements of such countries regarding safety and efficacy and governing, among other things, clinical trials and commercial sales, pricing and distribution of our antibody candidates, and we cannot predict success in these jurisdictions.

The ~~Biclonics~~^®Biclonics® technology platform and ~~Triclonics~~^TMTriclonics® technology platform are unproven, novel approaches to the production of molecules for therapeutic intervention.

We have not received regulatory approval for a therapeutic based on a full-length human bispecific or trispecific IgG approach. We cannot be certain that our approach will lead to the development of approvable or marketable products. In addition, our ~~Biclonics~~^®Biclonics® and ~~Triclonics~~^TMTriclonics® may have different effectiveness rates in various indications and in different geographical areas. Finally, the FDA, the

EMA or other regulatory agencies may lack experience in evaluating the safety and efficacy of products based on Biclonics® and ~~Triclonics~~^TMTriclonics® therapeutics, which could result in a longer than expected regulatory review process, increase our expected development costs and delay or prevent commercialization of our antibody candidates.

Our ~~Biclonics~~^®Biclonics® and ~~Triclonics~~^TMTriclonics® technology platforms rely on third parties for biological materials. Some biological materials have not always ~~meet~~met our expectations or requirements, and any disruption in the supply of these biological materials could materially adversely affect our business. Although we have control processes and screening procedures, biological materials are susceptible to damage and contamination and may contain active pathogens. Improper storage of these materials, by us or any third-party suppliers, may require us to destroy some of our biological raw materials or antibody candidates.

Failure to successfully validate, develop and obtain regulatory approval for companion diagnostics could harm our development strategy.

We may seek to identify patient subsets within a disease category that may derive selective and meaningful benefit from the antibody candidates we are developing. Through collaborations or license agreements, we may develop companion diagnostics to help us to more accurately identify patients within a particular subset, both during our clinical trials and in connection with the commercialization of our antibody candidates, if approved. Companion diagnostics are subject to regulation by the FDA, ~~the EU legislative bodies,~~ and comparable foreign regulatory authorities as medical devices and typically require separate regulatory approval (or clearance, or certification) prior to commercialization. If needed, we intend to develop companion diagnostics in collaboration with or via license agreements with third parties and are potentially dependent on the scientific insights and sustained cooperation and effort of any third-party collaborators in developing and obtaining approval (or clearance, or certification) for companion diagnostics. We and our future collaborators may encounter difficulties in developing and obtaining approval for any companion diagnostics, including issues relating to selectivity/specificity, analytical validation, reproducibility or clinical validation. Any delay or failure by us or our future collaborators to develop or obtain regulatory approval (or clearance, or certification) of companion diagnostics could delay or prevent approval of our antibody candidates. In addition, our potential collaborators may encounter production difficulties that could constrain the supply of the companion diagnostics, and both they and we may have difficulties gaining acceptance of the use of the companion diagnostics in the clinical community. If such companion diagnostics fail to gain market acceptance, it would have an adverse effect on our ability to derive revenues from sales of our products. In addition, the diagnostic company with whom we contract may decide to discontinue selling or manufacturing the companion diagnostic that we anticipate using in connection with development and commercialization of our antibody candidates or our relationship with such diagnostic company may otherwise terminate. We may not be able to enter into arrangements with another diagnostic company to obtain supplies of an alternative companion diagnostic test for use in connection with the development and commercialization of our antibody candidates or do so on commercially reasonable terms, which could adversely affect and/or delay the development or commercialization of our antibody candidates.

Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

Since our inception in 2003, we have devoted a significant portion of our resources to developing zenocutuzumab, ~~MCLA-117,~~ MCLA-158, MCLA-145, MCLA-129 and our other antibody candidates, building our intellectual property portfolio, developing our clinical manufacturing supply chain, generating and enhancing our Biclonics® technology platform, generating our ~~Triclonics~~^TMTriclonics® technology platform, planning our business, raising capital and providing general and administrative support for these operations. While we have ongoing clinical trials for zenocutuzumab, ~~MCLA-117,~~ MCLA-158, ~~and~~ MCLA-145 and ~~ongoing IND-enabling studies for~~ MCLA-129, we have not successfully completed any clinical trials for any antibody candidate. We have not yet demonstrated our ability to successfully complete any Phase 2 clinical trial or any Phase 3 or other pivotal clinical trials, obtain regulatory approvals, manufacture a

commercial scale product or arrange for a third party to do so on our behalf or conduct sales and marketing activities necessary for successful product commercialization. Additionally, we expect our financial condition and operating results to continue to fluctuate significantly from quarter to quarter and year to year due to a variety of factors, many of which are beyond our control. Consequently, any predictions you make about our future success or viability may not be as accurate as they could be if we had a longer operating history.

Raising additional capital may cause dilution to our holders, restrict our operations or require us to relinquish rights to our technologies or antibody candidates.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through equity or debt financings and upfront and milestone payments, if any, received under our existing collaborations and any other future licenses or collaborations, together with our existing cash and cash equivalents. In order to accomplish our business objectives and further develop our product pipeline, we will, however, need to seek additional funds. If we raise additional capital through the sale of equity or convertible debt securities, our existing shareholders’ ownership interests will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our existing shareholders’ rights as holders of our common shares. In addition, the possibility of such issuance may cause the market price of our common shares to decline. Debt financing, if available, may result in increased fixed payment obligations and involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures, declaring dividends, or acquiring, selling or licensing intellectual property rights, which could adversely impact our ability to conduct our business.

If we raise additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our intellectual property, technologies, future revenue streams or antibody candidates or grant licenses on terms that may not be favorable to us. We could also be required to seek funds through arrangements with collaborators or others at an earlier stage than otherwise would be desirable. Any of these occurrences may have a material adverse effect on our business, operating results and prospects.

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our antibody candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. For example, the trading prices for our and other biopharmaceutical companies’ stock have been highly volatile as a result of the COVID-19 pandemic. As a result, we may face difficulties raising capital through sales of our common stock and any such sales may be on unfavorable terms. If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay or discontinue one or more of our research or development programs or the commercialization of any of our antibody candidates, if approved, or be unable to expand our operations or otherwise capitalize on our business opportunities, as desired, which could materially affect our business, financial condition and results of operations.

Our business may become subject to economic, political, regulatory and other risks associated with international operations

As a company based in the Netherlands, our business is subject to risks associated with conducting business internationally. Many of our suppliers and collaborative and clinical trial relationships are located outside the United States. Accordingly, our future results could be harmed by a variety of factors, including:

Exchange rate fluctuations or abandonment of the euro currency may materially affect our results of operations and financial condition.

Due to the international scope of our operations, fluctuations in exchange rates, particularly between the euro and the U.S. dollar, may adversely affect us. Although we are based in the Netherlands, we source research and development, manufacturing, consulting and other services from several countries. Further, potential future revenue may be derived from abroad, particularly from the United States. Additionally, our funding has mainly come from investors and collaborators mainly in the United States. As a result, our business and share price may be affected by fluctuations in foreign exchange rates between the euro and these other currencies, which

may also have a significant impact on our reported results of operations and cash flows from period to period. Currently, we do not have any exchange rate hedging arrangements in place.

In addition, the possible abandonment of the euro by one or more members of the EU could materially affect our business in the future. Despite measures taken by the EU to provide funding to certain EU member states in financial difficulties and by a number of European countries to stabilize their economies and reduce their debt burdens, it is possible that the euro could be abandoned in the future as a currency by countries that have adopted its use. This could lead to the re-introduction of individual currencies in one or more EU member states, or in more extreme circumstances, the dissolution of the EU. The effects on our business of a potential dissolution of the EU, the exit of one or more EU member states from the EU or the abandonment of the euro as a currency, are impossible to predict with certainty, and any such events could have a material adverse effect on our business, financial condition and results of operations.

Risks from improper conduct by our employees, agents, contractors, or collaborators could adversely affect our reputation, business, prospects, operating results, and financial condition.

We cannot ensure that our compliance controls, policies, and procedures will in every instance protect us from acts committed by our employees, agents, contractors, or collaborators that would violate the laws or regulations of the jurisdictions in which we operate, including, without limitation, health care, employment, foreign corrupt practices, trade restrictions and sanctions, environmental, import and export requirements, competition, patient privacy and other privacy laws and regulations. Such improper actions could subject us to civil or criminal investigations, and monetary and injunctive penalties, and could adversely impact our ability to conduct business, operating results, and reputation.

We are subject to a number of anti-corruption laws, including the Foreign Corrupt Practices Act (FCPA) in the United States, the Bribery Act in the United Kingdom and the anti-corruption provisions of the Dutch Criminal Code in the Netherlands. Our failure to comply with anti-corruption laws applicable to us could result in penalties, which could harm our reputation and harm our business, financial condition, results of operations, cash flows or prospects. The FCPA generally prohibits companies and their intermediaries from making improper payments to foreign officials for the purpose of improperly or corruptly obtaining or keeping business, obtaining preferential treatment and/or other undue benefits or advantages. The FCPA also requires public companies to maintain accurate books and records and devise a system of sufficient internal accounting controls. We regularly review and update our policies and procedures and internal controls designed to provide reasonable assurance that we, our employees, distributors and other intermediaries comply with the anti-corruption laws to which we are subject. However, there are inherent limitations to the effectiveness of any policies, procedures and internal controls, including the possibility of human error and the circumvention or overriding of the policies, procedures and internal controls. There can be no assurance that such policies or procedures or internal controls will work effectively at all times or protect us against liability under these or other laws for actions taken by our employees, distributors and other intermediaries with respect to our business.

The Securities and Exchange Commission (SEC) and Department of Justice continue to view FCPA enforcement activities as a high priority. There is no certainty that all of our employees, agents, contractors, or collaborators, or those of our affiliates, will comply with all applicable laws and regulations, particularly given the high level of complexity of these laws. Violations of these laws and

regulations could result in fines, criminal sanctions against us, our officers, or our employees, requirements to obtain export licenses, cessation of business activities in sanctioned countries, implementation of compliance programs, and prohibitions on the conduct of our business. Any such violations could materially damage our reputation, our brand, our international operations, our ability to attract and retain employees, and our business, prospects, operating results, and financial condition.

The United Kingdom’s withdrawal from the European Union may have a negative effect on global economic conditions and financial markets, which could materially affect our financial condition and results of operations.

Following a national referendum and enactment of legislation by the government of the United Kingdom, the United Kingdom formally withdrew from the EU on January 31, 2020 and entered into a transition ~~period during which it will continue its ongoing~~period. On December 24, 2020, the United Kingdom and ~~complex negotiations with~~ the EU ~~relating~~announced that they had agreed to the terms of their future trading relationship in the EU—UK Trade and Cooperation Agreement (“TCA”), which became binding on both the EU and the United Kingdom on January 1, 2021, and was entered into force on May 1, 2021. While agreement on the terms of the TCA has avoided a “no deal” Brexit scenario, and provides in principle for quota- and tariff-free trading of goods, it is nevertheless expected that the TCA will result in the creation of non-tariff barriers (such as increased shipping and regulatory costs and complexities) to the trade in goods between the ~~parties.~~United Kingdom and the EU. Further, the TCA does not provide for the continued free movement of services between the UK and the EU and imposes additional restrictions on the free movement of people between the UK and the EU. The TCA includes provisions affecting pharmaceutical businesses (including on customs and tariffs). In addition, there are some specific provisions concerning pharmaceuticals. These include the mutual recognition of Good Manufacturing Practice (GMP) inspections of manufacturing facilities for medicinal products and GMP documents issued. The TCA does not, however, contain wholesale mutual recognition of UK and EU pharmaceutical regulations and product standards. Significant political and economic uncertainty remains about ~~whether~~how much the terms of the relationship will differ materially from the terms before withdrawal, as well as about the possibility that a so-called “no deal” separation will occur if negotiations are not completed by the end of the transition period.

~~These developments have created significant uncertainty about the future~~ relationship between the United Kingdom and ~~the EU. Lack~~EU will differ as a result of ~~clarity about future U.K. laws and regulations as~~ the United ~~Kingdom determines which EU-derived laws~~Kingdom’s withdrawal.

The United Kingdom’s withdrawal from the EU and regulations to replace or replicate as part of a withdrawal, including financial laws and regulations, tax and free trade agreements, intellectual property rights, supply chain logistics, environmental, health and safety laws and regulations, immigration laws and employment laws, could further decrease foreign direct investment in the ~~United Kingdom, increase costs, depress economic activity and restrict our access to capital. These developments, or the perception that any of them could occur, have~~associated uncertainty has had and may continue to have a significant adverse effect on global economic conditions and the stability of global financial markets, and could significantly reduce global market

liquidity and restrict the ability of key market participants to operate in certain financial markets. Asset valuations, currency exchange rates and credit ratings may be especially subject to increased market volatility. Any of these factors could have a significant adverse effect on our business, financial condition, results of operations and prospects.

Further, the United Kingdom’s withdrawal from the EU has resulted in the relocation of the EMA from the United Kingdom to the Netherlands. This relocation has caused, and may continue to cause, disruption in the administrative and medical scientific links between the EMA and the U.K. Medicines and Healthcare products Regulatory Agency, including delays in granting clinical trial authorization or marketing authorization, disruption of importation and export of active substance and other components of new drug formulations, and disruption of the supply chain for clinical trial product and final authorized formulations. The cumulative effects of the disruption to the regulatory framework may add considerably to the development lead time to marketing authorization and commercialization of products in the EU and/or the United Kingdom.

The COVID-19 pandemic caused by the novel coronavirus has and may continue to adversely impact our business, including our pre-clinical studies and clinical trials, financial condition and results of operations.

In December 2019, a strain of novel coronavirus causing the COVID-19 disease was reported to have surfaced in Wuhan, China. Since then, COVID-19 has spread to throughout the world, including the Netherlands and the United States. In March 2020, the World Health Organization (WHO) characterized COVID-19 as a pandemic. To date, the COVID-19 pandemic has interfered with the normal function of businesses worldwide, including in the form of travel restrictions, shelter-in-place orders and quarantines, office and school closures, bans on public gatherings and employees being encouraged or required to work from home pursuant to guidance provided by national, state and local officials including the U.S. Center for Disease Control and Prevention (CDC) and European local health agencies, including the Dutch National Institute for Health and Environment or Het Rijksinstituut voor Volksgezondheid en Milieu (RIVM). For example, most of our employees located in the Netherlands are ~~not able to~~restricted in the manner of travel to the U.S., where certain of our collaborators and employees are located, which could have an adverse impact on our ability to conduct our business. Similarly, employees located in the U.S. are ~~not able to~~restricted in the manner of travel to the Netherlands under current ~~restrictions.~~guidelines. Additionally, on March 18, 2020, we temporarily suspended our laboratory research activities at our facilities in Utrecht, the Netherlands to help secure the safety of our employees and to adhere to government recommendations of social distancing and limited public exposure in connection with the COVID-19 pandemic. We have since re-opened our offices and laboratory in Utrecht, maintaining social distancing and imposing other requirements consistent with government guidance. Further, we have recommended our employees in the ~~U.S.~~Netherlands and ~~Netherlands~~employees of our subsidiary Merus US, Inc., in the U.S. work from home when ~~possible and for~~possible. For those employees working at our offices and laboratory in Utrecht, ~~and offices in Cambridge Ma.~~ they are required to maintain social distancing and follow requirements consistent with the guidance provided by the RIVM for the Netherlands, and employees of our subsidiary Merus US, Inc. are required to abide by the guidelines of the CDC, and Federal, state and local regulations for the U.S. ~~and RIVM for the Netherlands.~~ While we use reasonable business practices to mitigate the risk of exposure to COVID-19 while on Company-operated premises, we cannot guarantee that traveling to and from and visiting the office will not expose employees to infectious ~~agent~~agents or eliminate inherent risks to our workforce and our business operations resulting from COVID-19. Given the uncertainty caused by the COVID-19 pandemic we cannot be certain that we will not suspend our laboratory research activities at our facilities or suspend use of our offices in the future.

As a result of the COVID-19 pandemic, certain of our contract research organizations (CROs) and third-party suppliers, as well as collaborators in the U.S., Europe and China that are developing or collaborating with us to develop certain of our pre-clinical and clinical-stage antibody candidates have been affected. As a result of such impact, we may face difficulties with and delays in performance of certain

chemistry manufacturing and controls associated with our clinical candidates, including as it relates to sourcing materials required for such manufacture that may be diverted for other purposes associated with COVID-19, or difficulties or delays associated with testing of our pre-clinical antibody candidates ~~including MCLA-129, among other undisclosed pre-clinical candidates~~ associated with our collaborations with Incyte, Eli Lilly and Simcere, which may delay or prevent their potential clinical development. Additionally, our collaborators, CROs and third-party suppliers may in the future experience closures and labor shortages, which may delay or prevent our development of our ~~pre-clinical~~ antibody candidates, including zenocutuzumab, MCLA-158, MCLA-145 and MCLA-129. Moreover, although our collaborators based in China and elsewhere have resumed operations, we may experience labor shortages associated with these chemistry manufacturing and controls, or pre-clinical development activities due to the current restrictions on travel and work globally, which may force us to reduce related workflows until such work and travel restrictions are lifted. Also, there can be no assurances that the applicable governments will not renew or extend these closures.

With respect to our clinical trials, the COVID-19 pandemic and related precautions have directly or indirectly impacted enrollment, new, planned clinical trial site openings, patient visits, and on-site monitoring of our clinical trials and source verification of clinical data required for presentation of clinical data for zenocutuzumab, ~~MCLA-117,~~ MCLA-158, MCLA-145, and ~~MCLA-145. To~~MCLA-129. Over the past year and to date, we have observed a moderate to high impact on clinical trial enrollment and operations as a consequence of the COVID-19 pandemic, particularly atdue to sites in countries ~~not yet open~~that have been closed to recruitment, and to a lesser extent in countries where COVID-19 related restrictions have been eased, with adjustments made to allow remote visits for some patient follow-up, and reduced onsite monitoring by the sponsor or CRO and insufficient source verification of clinical data required for presentation of clinical data. The extent of the impact to our overall clinical development timeline is uncertain at this time and we continue to monitor this impact on a regular basis. As a result of the COVID-19 pandemic, we may experience further disruptions that could severely impact our business, preclinical studies and clinical trials, including:

In addition, the trading prices for our and other biopharmaceutical companies’ stock have been highly volatile as a result of the COVID-19 pandemic. As a result, we may face difficulties raising capital through sales of our common shares and any such sales may be on unfavorable terms. The COVID-19 outbreak continues to rapidly evolve. The extent to which the outbreak further impacts our business, including our preclinical studies and clinical trials, results of operations and financial condition will depend on future developments which are highly uncertain and cannot be predicted with confidence. Such factors include but are not limited to the spread of the disease, the duration of the outbreak, travel restrictions, quarantines, shelter-in-place orders and social distancing in the United States, the Netherlands and other countries, business closures or business disruptions and the effectiveness of actions taken in the United States, the Netherlands and other countries to contain and treat the disease.

Risks Related to the Development and Clinical Testing of Our Antibody Candidates

All of our antibody candidates are in pre-clinical or early-stage clinical development. Clinical drug development is a lengthy and expensive process with uncertain timelines and uncertain outcomes. If clinical trials of our antibody candidates, particularly zenocutuzumab, MCLA-158, MCLA-129 or MCLA-145, which we are developing with Incyte, are prolonged or delayed, we or any collaborators may be unable to obtain required regulatory approvals, and therefore be unable to commercialize our antibody candidates on a timely basis or at all.

To obtain the requisite regulatory approvals to market and sell any of our antibody candidates, we or any collaborator for such candidates must demonstrate through extensive pre-clinical studies and clinical trials that such candidates are safe, pure and ~~effective~~potent in humans. Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain. Failure can occur at any time during the clinical trial process. The results of pre-clinical studies and early-stage clinical trials of our antibody candidates may not be predictive of the results of later-stage clinical trials. Antibody candidates in later stages of clinical trials may fail to show the desired safety and efficacy traits despite having progressed through pre-clinical studies and initial clinical trials. A number of companies in the biopharmaceutical industry have suffered significant setbacks in advanced clinical trials due to lack of efficacy or adverse safety profiles, notwithstanding promising results in earlier trials. Our future clinical trial results may not be successful.

To date, we have not completed any clinical trials required for the approval of any of our antibody candidates. Although we are conducting ongoing clinical trials for zenocutuzumab, MCLA-158, ~~and~~ MCLA-145, and ~~continuing dose escalation for MCLA-117, and are conducting IND-enabling studies for~~ MCLA-129 and pre-clinical studies for other

antibody candidates, we may experience delays in our ongoing clinical trials and we do not know whether planned clinical trials will begin on time, need to be redesigned, enroll patients on time or be completed on schedule, if at all. Clinical trials can be delayed, suspended, or terminated for a variety of reasons, including the following:

In addition, disruptions caused by the COVID-19 pandemic may increase the likelihood that we encounter such difficulties or delays in initiating, enrolling, conducting, reporting on or completing our planned and ongoing clinical trials. We could encounter delays if a clinical trial is paused, suspended or terminated by us, by the IRBs or Ethics Committees of the institutions in which such trials are being conducted, by the Data Review Committee or Data Safety Monitoring Board for such trial or by the FDA, the Competent Authorities

of the ~~EEA~~European Economic Area (EEA) Member States (the 27 EU Member States plus Iceland, Liechtenstein, ~~and~~ Norway ~~and the United Kingdom (until the end of the transition period on December 31, 2020 provided for in the Withdrawal Agreement between the EU~~ and the UK) or other regulatory authorities. Such authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA, EEA Competent Authorities or other regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. If we experience delays in the completion of, or termination of, any clinical trial of our antibody candidates, the commercial prospects of our antibody candidates will be harmed, and our ability to generate product revenues from any of these antibody candidates, if approved, will be delayed. In addition, any delays in completing our clinical trials will increase our costs, slow down our antibody candidate development and approval process and jeopardize our ability to commence product sales and generate revenues. Significant clinical trial delays could also allow our competitors to bring products to market before we do or shorten any periods during which we have the exclusive right to commercialize our antibody candidates and impair our ability to commercialize our antibody candidates, if approved, and may harm our business and results of operations.

Any of these occurrences may harm our business, financial condition and prospects significantly. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our antibody candidates.

Clinical trials must be conducted in accordance with the FDA, ~~the~~ EU, EEA Member States, and other applicable regulatory authorities’ legal requirements, other regulations or guidelines, and are subject to oversight by these governmental agencies and Ethics Committees or IRBs at the medical institutions where the clinical trials are conducted. In addition, clinical trials must be conducted with supplies of our antibody candidates produced under current good manufacturing practice (cGMP) requirements and other regulations. Furthermore, we rely on CROs and clinical trial sites to ensure the proper and timely conduct of our clinical trials and while we have agreements governing their committed activities, we have limited influence over their actual performance. We depend on our collaborators and on medical institutions and CROs to conduct our clinical trials in compliance with good clinical practice (GCP) requirements. To the extent our collaborators or the CROs fail to enroll participants for our clinical trials, fail to conduct the study to GCP standards or are delayed for a significant time in the execution of trials, including achieving full enrollment, we may be affected by increased costs, program delays or both, which may harm our business. In addition, clinical trials that are conducted in countries outside the EUEEA and the United States may subject us to further delays and expenses as a result of increased shipment costs, additional regulatory requirements and the engagement of ~~non-EU~~non-EEA and non-U.S. CROs, as well as expose us to risks associated with clinical investigators who are unknown to the FDA or the ~~EMA,~~EEA Competent Authorities, and different standards of diagnosis, screening and medical care.

Interim, preliminary, and ~~preliminary~~ “top-line” data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publish interim, preliminary or ~~preliminary~~ “top-line” data from our clinical trials. Interim data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data previously published. Further, as a result of the COVID-19 or for other reasons, we may not be able to collect accurate or complete data at the time we collect such preliminary data, including as a result of the inability of sites to properly record data due to staffing limitations or the inability of patients to visit sites at scheduled times, the inability of CROs to access site data or for other reasons. In addition, we may decide to report interim or preliminary analyses of only certain endpoints (e.g., primary subject to investigator review) rather than all ~~endpoints.~~ endpoints (e.g., including secondary subject to central review). As a result, top-line data should be viewed with caution until the final data are available.

Furthermore, the information we choose to publicly disclose regarding a particular study or clinical trial is based on more extensive information, and others may not agree with what we determine is the material or otherwise appropriate information to disclose. Any information we determine not to disclose may ultimately be deemed significant with respect to future decisions, conclusions, views, activities, or otherwise regarding a particular antibody candidate or our business. Others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions, or analyses or may interpret or weigh the importance of data differently, which could impact the value of particular programs, the approvability or commercialization of the particular antibody candidates, and our business in general. As a result, interim, ~~and~~ preliminary or top-line data and analyses should be viewed with caution. Adverse differences between preliminary, top-line or interim data and final data or changes in what is material information regarding the results from a particular study or clinical trial could significantly harm our clinical development and business prospects and cause volatility in the price of our common shares. If the interim, top-line, or preliminary data that we report differ from actual or final results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, operating results, prospects or financial condition.

Our antibody candidates may have serious adverse, undesirable or unacceptable side effects which may delay or prevent marketing approval. If such side effects are identified during the development of our antibody candidates or following approval, if any, we may need to abandon our development of such antibody candidates, the commercial profile of any approved label may be limited, or we may be subject to other significant negative consequences following marketing approval, if any.

Undesirable side effects that may be caused by our antibody candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA, the EMA or other comparable foreign authorities. In February 2015, we commenced a Phase 1/2 clinical trial in Europe of our most advanced antibody candidate, zenocutuzumab, for the treatment of various solid tumors, which was amended to treat patients having solid tumors harboring a NRG1 gene fusion. Additionally, in January 2018 we commenced a Phase 2 clinical trial in Europe and the United States exploring zenocutuzumab, in combination with other agents, in patients with metastatic breast cancer. To date, patients treated

with zenocutuzumab have experienced adverse reactions that may be related to the treatment, including infusion-related reactions, diarrhea, vomiting, fatigue, skin rash, sore mouth and shortness of breath. ~~In May 2016, we commenced~~A further safety update was provided for zenocutuzumab on June 4, 2021, at the American Society of Clinical Oncology, or ASCO, 2021 Annual Meeting, with a ~~Phase 1 clinical trial in Europe~~safety cut-off date of our bispecific antibody MCLA-117. To date, patients treated with MCLA-117 have experienced adverse reactions that may be related to the treatment, most commonly infusion-related reactions including fever, cytokine release syndrome and chills.January 12, 2021. In May 2018 we commenced a Phase 1 clinical trial in Europe of our bispecific antibody MCLA-158 in patients with solid tumors. To date, patients treated with MCLA-158 have experienced adverse reactions that may be related to the treatment, most

commonly infusion-related reactions and skin rash associated with mAb EGFR inhibitors. A further safety update was provided for MCLA-158 on January 15, 2021, at ASCO GI, with a safety data cutoff of September 7, 2020, where safety events were reported for patients treated with MCLA-158 as a single agent across 11 dose levels (5 to 1500mg). In May 2019, we commenced a Phase 1 clinical trial in the United States of our bispecific antibody MCLA-145 developed in collaboration with Incyte. To date, patients treated with MCLA-145 have experienced adverse events irrespective of causality including diarrhea, blood alkaline phosphatase increase, anemia, and hypoalbuminemia, lymphocyte count decrease, and white blood cell count decrease. Febrile neutropenia and elevated liver enzymes have been reported as serious adverse ~~events~~.events.

Results of our trials could reveal a high and unacceptable severity and prevalence of these or other side effects. In such an event, our trials or enrollment could be paused, suspended or terminated and the FDA, the EMA, EEA Competent Authorities, or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our antibody candidates for any or all targeted indications. The drug-related side effects could affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly. Additionally, if any of our antibody candidates receives marketing approval and we or others later identify undesirable or unacceptable side effects caused by such products, a number of potentially significant negative consequences could result, including:

Any of these events could prevent us, our collaborators or our potential future partners from achieving or maintaining market acceptance of the affected antibody candidate, if approved, or could substantially increase commercialization costs and expenses, which in turn could delay or prevent us from generating significant revenue from the sale of our antibody candidates, if approved.

~~Adverse events in the field of oncology could damage public perception of our antibody candidates and negatively affect our business.~~

The commercial success of our products, if any, will depend in part on public acceptance of the use of cancer immunotherapies. Adverse events in clinical trials of our antibody candidates or in clinical trials of others developing similar products and the resulting publicity, as well as any other adverse events in the field of oncology that may occur in the future, could result in a decrease in demand for any products that we may develop.

Future adverse events in oncology or the biopharmaceutical industry could also result in greater governmental regulation, stricter labeling requirements and potential regulatory delays in the testing or approvals of our antibody candidates. Any increased scrutiny could delay or increase the costs of obtaining regulatory approval for our antibody candidates.

We depend on enrollment of patients in our clinical trials for our antibody candidates. If we are unable to enroll patients in our clinical trials, our research and development efforts and business, financial condition and results of operations could be materially adversely affected.

Successful and timely completion of clinical trials will require that we enroll a sufficient number of patient candidates. For our Phase 1/2 clinical trial of zenocutuzumab in solid tumors, we are enrolling up to 90 patients with tumors harboring NRG1 gene fusions. Solid tumors with NRG1 gene fusions occur infrequently, which could result in slow enrollment of clinical trial participants. In the

Phase 1 clinical trial of MCLA-117, we announced in May 2020 we will not continue enrollment into the planned dose expansion cohorts in the trial, but plan to continue enrollment in the dose escalation phase. In the Phase 1 clinical trial of MCLA-158, we plan to enroll approximately 120 adult patients with solid tumors. In the Phase 1 clinical trial of MCLA-145, we plan to enroll approximately 118 adult patients with solid ~~tumors or B-cell lymphoma.~~tumors.In the Phase 1/2 clinical trial of MCLA-129, we plan to enroll approximately 150 adult patients with solid tumors. These trials and other trials we conduct may be subject to delays as a result of patient enrollment taking longer than anticipated or patient withdrawal.

Our clinical trials will also compete with other clinical trials for antibody candidates that are in the same therapeutic areas as our antibody candidates, and this competition will reduce the number and types of patients available to us, because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. Because the number of qualified clinical investigators and clinical trial sites is limited, we expect to conduct some of our clinical trials at the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our clinical trials at such clinical trial sites.

Patient enrollment depends on many factors, including the size and nature of the patient population, eligibility criteria for the trial, the proximity of patients to clinical sites, the design of the clinical protocol, the availability of competing clinical trials, the availability of new drugs approved for the indication the clinical trial is investigating, and clinicians’ and patients’ perceptions as to the potential advantages of the drug being studied in relation to other available therapies. These factors may make it difficult for us to enroll enough patients to complete our clinical trials in a timely and cost-effective manner. Delays in the completion of any clinical trial of our antibody candidates will increase our costs, slow down our antibody candidate development and approval process, delay or potentially

jeopardize our ability to commence product sales and generate revenue and harm our reputation and ability to obtain financing. In addition, some of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our antibody candidates.

We may become exposed to costly and damaging liability claims, either when testing our antibody candidates in the clinic or at the commercial stage; and our product liability insurance may not cover all damages from such claims.

We are exposed to potential product liability and professional indemnity risks that are inherent in the research, development, manufacturing, marketing and use of pharmaceutical products. Currently, we have no products that have been approved for commercial sale; however, the current and future use of antibody candidates by us and our collaborators in clinical trials, and the sale of any approved products in the future, may expose us to liability claims. These claims might be made by patients that use the product, healthcare providers, pharmaceutical companies, our collaborators or others selling such products. Any claims against us, regardless of their merit, could be difficult and costly to defend and could materially adversely affect the market for our antibody candidates or any prospects for commercialization of our antibody candidates, if approved.

Although the clinical trial process is designed to identify and assess potential side effects, it is always possible that a drug, even after regulatory approval, may exhibit unforeseen side effects. If any of our antibody candidates were to cause adverse side effects during clinical trials or after approval of the antibody candidate, we may be exposed to substantial liabilities. Physicians and patients may not comply with any warnings that identify known potential adverse effects and patients who should not use our antibody candidates.

Although we maintain adequate product liability insurance for our antibody candidates, it is possible that our liabilities could exceed our insurance coverage. We intend to expand our insurance coverage to include the sale of commercial products if we obtain marketing approval for any of our antibody candidates. However, we may not be able to maintain insurance coverage at a reasonable cost or obtain insurance coverage that will be adequate to satisfy any liability that may arise. If a successful product liability claim or series of claims is brought against us for uninsured liabilities or in excess of insured liabilities, our assets may not be sufficient to cover such claims and our business operations could be impaired.

Should any of the events described above occur, this could have a material adverse effect on our business, financial condition and results of operations.

The regulatory approval processes of the FDA, the EMA and comparable foreign authorities are lengthy, time consuming and inherently unpredictable, and if we are ultimately unable to obtain regulatory approval for our antibody candidates, our business will be substantially harmed.

The time required to obtain approval by the FDA, the EMA and comparable foreign authorities is unpredictable but typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. In addition, approval policies, regulations, or the type and amount of clinical data necessary to gain approval may change during the course of a antibody candidate’s clinical development and may vary among jurisdictions. We have not obtained regulatory approval for any antibody candidate and it is possible that none of our existing antibody candidates or any antibody candidates we may seek to develop in the future will ever obtain regulatory approval.

Our antibody candidates could fail to receive regulatory approval for many reasons, including the following:

This lengthy approval process as well as the unpredictability of future clinical trial results may result in our failing to obtain regulatory approval to market any of our antibody candidates, which would significantly harm our business, results of operations and prospects.

The FDA, the EMA and other regulatory authorities have substantial discretion in the approval process, and determining when or whether regulatory approval will be obtained for any of our antibody candidates. Even if we believe the data collected from clinical trials of our antibody candidates are promising, such data may not be sufficient to support approval by the FDA, the EMA or any other regulatory authority.

In addition, even if we were to obtain approval, regulatory authorities may approve any of our antibody candidates for fewer or more limited indications than we request, may not approve the price we intend to charge for our products, may grant approval contingent on the performance of costly post-marketing clinical trials, or may approve an antibody candidate with a label that does not include the labeling claims necessary or desirable for the successful commercialization of that antibody candidate. Any of the foregoing scenarios could materially harm the commercial prospects for our antibody candidates.

Fast Track designation by the FDA for zenocutuzumab or potential future Fast Track designation of our other antibody candidates may not actually lead to a faster development or regulatory review or approval process.

We have been granted a Fast Track designation for zenocutuzumab in the United States for the treatment of patients with metastatic solid tumors harboring NRG1 gene fusions that have progressed on standard-of-care therapy, and we may seek additional Fast Track designations for zenocutuzumab or for our other antibody candidates. The Fast Track program is intended to expedite or facilitate the process for reviewing therapeutic candidates that meet certain criteria. Specifically, new biologics are eligible for Fast Track designation if they are intended, alone or in combination with one or more drugs or biologics, to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast Track designation applies to the combination of the product candidate and the specific indication for which it is being studied. With a Fast Track antibody candidate, the FDA may consider for review sections of the BLA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the BLA, the FDA agrees to accept sections of the BLA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the BLA.

Obtaining a Fast Track designation does not change the standards for product approval but may expedite the development or approval process. Even though the FDA has granted such designation for zenocutuzumab for the treatment of patients with metastatic solid tumors harboring NRG1 gene fusions that have progressed on standard-of-care therapy, it may not actually result in faster clinical development or regulatory review or approval. Furthermore, such a designation does not increase the likelihood that zenocutuzumab or any other antibody candidate that may be granted Fast Track designation will receive marketing approval in the United States.

Even if our antibody candidates obtain regulatory approval, we will be subject to ongoing obligations and continued regulatory review, which may result in significant additional expense. Additionally, our antibody candidates, if approved, could be subject to labeling and other restrictions and market withdrawal and we may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with our products.

IfAny regulatory approvals that we may receive for our antibody candidates will require the submission of reports to regulatory authorities and surveillance to monitor the safety and efficacy of the product candidate, may contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, and may include burdensome post-approval study or risk management requirements. For example, the FDA may require a Risk Evaluation and Mitigation Strategy in order to approve our antibody candidates, which could entail requirements for a medication guide, physician training and communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. In addition, if the ~~EMA~~FDA or ~~a comparable~~ foreign regulatory ~~authority approves any of~~authorities approve our antibody candidates, the manufacturing processes, labeling, packaging, distribution, adverse event reporting, storage, advertising, promotion, import, export and recordkeeping for ~~the~~our product candidates will be subject to extensive and ongoing regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as ~~continued~~on-going compliance with cGMPs, and GCPs for any clinical trials that we conduct ~~post-approval, all~~following approval. In addition, manufacturers of ~~which~~drug products and their facilities are subject to continual review and periodic, unannounced inspections by the FDA and other regulatory authorities for compliance with cGMP regulations and standards.

If we or a regulatory authority discover previously unknown problems with a product, such as adverse events of unanticipated severity or frequency, or problems with the facilities where the product is manufactured, a regulatory authority may ~~result in significant expense~~impose restrictions on that product, the manufacturing facility or us, including requiring recall or withdrawal of the product from the market or suspension of manufacturing. In addition, failure to comply with FDA and ~~limit~~other comparable foreign regulatory requirements may subject our company to administrative or judicially imposed sanctions, including:

The occurrence of any event or penalty described above may inhibit our ability to commercialize ~~such products. In addition, any~~our product candidates and generate revenue and could require us to expend significant time and resources in response and could generate negative publicity.

The FDA’s and other regulatory ~~approvals that we receive for our antibody candidates~~authorities’ policies may ~~also be subject to limitations on the approved indicated uses for which the product~~change, and additional government regulations may be ~~marketed~~enacted that could prevent, limit or delay regulatory approval of our product candidates. If we are slow or unable to ~~the conditions of approval, or contain requirements for potentially costly post-marketing testing, including Phase 4 clinical trials, and surveillance~~adapt to ~~monitor the safety and efficacy of the antibody candidate.~~

~~If there are~~ changes in existing requirements or the ~~application~~adoption of ~~legislation~~new requirements or ~~regulatory~~ policies, or if ~~problems~~we are ~~discovered with a product or our manufacture of a product, or if~~not able to maintain regulatory compliance, we or one of our distributors, licensees or co-marketers fails to comply with regulatory requirements, the regulators could take various actions. These include imposing fines on us, imposing restrictions on the product or its manufacture and requiring us to recall or remove the product from the market. The regulators could also suspend or withdraw ourmay lose any marketing authorizations, requiring us to conduct additional clinical trials, change our product labeling or submit additional applications for marketing authorization. If any of these events occurs, our ability to sell such productapproval that we may ~~be impaired,~~have obtained, and we may ~~incur substantial additional expense to comply with regulatory requirements, which could materially adversely affect our business, financial condition and results~~not achieve or sustain profitability.

We also cannot predict the likelihood, nature or extent of ~~operations.~~government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad.

We may not be successful in our efforts to use and expand our ~~Biclonics~~^®Biclonics® technology platform to build a pipeline of antibody candidates or to use our ~~Triclonics~~^TMTriclonics® technology platform to build a pipeline of trispecific antibody candidates.

A key element of our strategy is to use and expand our ~~Biclonics~~^®Biclonics® technology platform to build a pipeline of antibody candidates and progress these antibody candidates through clinical development for the treatment of a variety of different types of diseases. Although our research and development efforts to date have resulted in a pipeline of antibody candidates directed at various cancers, we may not be able to develop antibody candidates that are safe and effective.

Another important element of our strategy is to develop, use and exploit our ~~Triclonics~~^TMTriclonics® technology platform to build a pipeline of trispecific antibody candidates and collaborate with third parties in potentially researching and developing these trispecific antibody candidates through pre-clinical and clinical development for the treatment of a variety of different types of diseases. Although our research and development efforts to date have resulted in proof of concept pre-clinical candidates, we may not be able to develop or monetize these trispecific antibody candidates or demonstrate in the clinic that they are safe and effective. Even if we are successful in continuing to build our bispecific and trispecific pipelines, the potential antibody candidates that we identify may not be suitable for clinical development, including as a result of being shown to have harmful side effects or other characteristics that indicate that they are unlikely to be products that will receive marketing approval and achieve market acceptance. If we do not continue to successfully develop and begin to commercialize our bispecific antibody candidates or if we do not successfully develop, collaborate, license or begin to commercialize our trispecific antibody candidates, we will face difficulty in obtaining product revenues in future periods, which could result in significant harm to our financial position and adversely affect our share price.

Even if we obtain marketing approval of any of our antibody candidates in a major pharmaceutical market such as the United States or the EU, we may never obtain approval or commercialize our products in other major markets, which would limit our ability to realize their full market potential.

In order to market any products in a country or territory, we must establish and comply with numerous and varying regulatory requirements of such countries or territories regarding safety and efficacy. Clinical trials conducted in one country may not be accepted by regulatory authorities in other countries, and regulatory approval in one country does not mean that regulatory approval will be obtained in any other country. Approval procedures vary among countries and can involve additional product testing and validation and additional administrative review periods. Seeking regulatory approvals in all major markets could result in significant delays, difficulties and costs for us and may require additional pre-clinical studies or clinical trials which would be costly and time consuming. Regulatory requirements can vary widely from country to country and could delay or prevent the introduction of our products in those countries. Satisfying these and other regulatory requirements is costly, time consuming, uncertain and subject to unanticipated delays. In addition, our failure to obtain regulatory approval in any country may delay or have negative effects on the process for regulatory approval in other countries. We currently do not have any antibody candidates approved for sale in any jurisdiction, whether in the Netherlands, the United States or any other international markets, and we do not have experience in obtaining regulatory approval in international markets. If we fail to comply with regulatory requirements in international markets or to obtain and maintain required approvals, our target market will be reduced and our ability to realize the full market potential of our products, if any, will be harmed.

Due to our limited resources and access to capital, we must, and have in the past decided to, prioritize development of certain antibody candidates over other potential candidates. These decisions may prove to have been wrong and may adversely affect our revenues.

Because we have limited resources and access to capital to fund our operations, we must decide which antibody candidates to pursue and the amount of resources to allocate to each. Our decisions concerning the allocation of research, collaboration, management and financial resources toward particular compounds, antibody candidates or therapeutic areas may not lead to the development of viable commercial products and may divert resources away from better opportunities. Similarly, our decisions to delay, terminate or collaborate with third parties in respect of certain antibody development programs may also prove not to be optimal and could cause us to miss valuable opportunities. If we make incorrect determinations regarding the market potential of our antibody candidates or misread trends in the biopharmaceutical industry, in particular for our lead antibody candidates, our business, financial condition and results of operations could be materially adversely affected.

Because we are subject to environmental, health and safety laws and regulations, we may become exposed to liability and substantial expenses in connection with environmental compliance or remediation activities which may adversely affect our business and financial condition.

Our operations, including our research, development, testing and manufacturing activities, are subject to numerous environmental, health and safety laws and regulations. These laws and regulations govern, among other things, the importation, storage, controlled use, handling, release and disposal of, and the maintenance of a registry for, hazardous materials and biological materials, such as chemical solvents, human cells, animal byproducts, genetically modified organisms, carcinogenic compounds, mutagenic compounds and compounds that have a toxic effect on reproduction, laboratory procedures and exposure to blood-borne pathogens. If we fail to comply with such laws and regulations, we could be subject to fines or other sanctions.

As with other companies engaged in activities similar to ours, we face a risk of environmental liability inherent in our current and historical activities, including liability relating to releases of or exposure to hazardous or biological materials. Environmental, health and safety laws and regulations are becoming more stringent. We may be required to incur substantial expenses in connection with future environmental compliance or remediation activities, in which case, our production and development efforts may be interrupted or delayed and our financial condition and results of operations may be materially adversely affected.

Our employees, independent contractors, principal investigators, CROs, consultants, vendors and collaborators may engage in misconduct or other improper activities, including noncompliance with applicable law, regulatory standards and requirements, which could have a material adverse effect on our business.

We are exposed to the risk that our employees, independent contractors, principal investigators, CROs, consultants, vendors and collaborators may engage in fraudulent conduct or other illegal activities. Misconduct by these parties could include intentional, reckless and/or negligent conduct or unauthorized activities that violate: (i) the regulations of the FDA, the EMA and other regulatory authorities, including those laws that require the reporting of true, complete and accurate information to such authorities; (ii) manufacturing standards; (iii) federal and state data privacy, security, fraud and abuse and other healthcare laws and regulations in the United States and abroad; or (iv) laws that require the reporting of true, complete and accurate financial information and data. Specifically, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, misconduct, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs and other business arrangements. Activities subject to these laws could also involve the improper use or misrepresentation of information obtained in the course of clinical trials or creating fraudulent data in our pre-clinical studies or clinical trials, which could result in regulatory sanctions and cause serious harm to our reputation. It is not always possible to identify and deter misconduct by employees and other third parties, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to comply with such laws or regulations. Additionally, we are subject to the risk that a person or government could allege such fraud or other misconduct, even if none occurred. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant civil, criminal and administrative penalties, damages, monetary fines, disgorgements, possible exclusion from participation in Medicare, Medicaid and other U.S. federal healthcare programs, individual imprisonment, other sanctions, contractual damages, reputational harm, diminished profits and future earnings, and curtailment of our operations, any of which could adversely affect our ability to operate our business and our results of operations.

Our research and development activities could be affected or delayed as a result of possible restrictions on animal testing.

Certain laws and regulations require us to test our antibody candidates on animals before initiating clinical trials involving humans. Animal testing activities have been the subject of controversy and adverse publicity. Animal rights groups and other organizations and individuals have attempted to stop animal testing activities by pressing for legislation and regulation in these areas and by disrupting these activities through protests and other means. To the extent the activities of these groups are successful, our research and development activities may be interrupted, delayed or become more expensive.

Enacted and future legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our antibody candidates and may affect the prices we may set. The successful commercialization of our antibody candidates will depend in part on the extent to which governmental authorities and health insurers establish adequate coverage and reimbursement levels and pricing policies.

In the United States, the EU, and other foreign jurisdictions, there have been, and we expect there will continue to be, a number of legislative and regulatory changes and proposed changes to the healthcare system that could affect our future results of operations. In particular, there have been and continue to be a number of initiatives at the United States federal and state levels that seek to reduce healthcare costs and improve the quality of healthcare. For example, in March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act (collectively the ACA) was enacted, which substantially changed the way healthcare is financed by both governmental and private insurers. Among the provisions of the ACA, those of greatest importance to the pharmaceutical and biotechnology industries include the following:

Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed the most recent judicial challenge to the ACA ~~as well as efforts~~brought by several states without specifically ruling on the ~~current presidential administration to modify, repeal, or otherwise invalidate all, or certain provisions~~constitutionality of the ACA. ~~For example,~~Prior to the ~~Tax Cuts and Jobs Act~~Supreme Court’s decision, President Biden issued an executive order to initiate a special enrollment period from February 15, 2021 through August 15, 2021 for purposes of ~~2017 (TCJA), includes a provision repealing, the tax-based shared responsibility payment imposed by~~obtaining health insurance coverage through the ACA onmarketplace. The executive order also instructed certain ~~individuals who fail~~governmental agencies to ~~maintain qualifying~~review and reconsider their existing policies and rules that limit access to healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage ~~for all~~through Medicaid or ~~part of a year that is commonly referred to as~~ the “individual mandate.” On December 14, 2018, a U.S. District Court Judge in the Northern District of Texas, ruled that the individual mandate is a critical and inseverable feature of the ACA, and therefore, because it was repealed as part of the TCJA, the remaining provisions of the ACA are invalid as well. On December 18, 2019, the U.S. Court of Appeals for the 5th Circuit upheld the District Court's decision that the individual mandate was unconstitutional but remanded the case back to the District Court to determine whether the remaining provisions of the ACA are invalid as well.ACA. It is unclear how ~~these decisions, subsequent appeals, and~~other healthcare reform measures of the Biden administration or other efforts, if any, to challenge, repeal or replace the ACA will impact ~~the ACA or~~ our business.

In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. For example, the Budget Control Act of 2011 resulted in aggregate reductions of Medicare payments to providers of 2% per fiscal year. These reductions went into effect on April 1, 2013 and, due to subsequent legislative amendments to the statute will remain in effect through ~~2029~~2030, with the exception of a temporary suspension from May 1, 2020 through December 31, 2021, unless additional Congressional action is taken. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, further reduced Medicare payments to several types of providers, including hospitals, imaging centers and cancer treatment centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. These new laws may result in additional reductions in Medicare and other health care funding, which could have a material adverse effect on our future customers and accordingly, our financial operations.

Moreover, payment methodologies, including payment for companion diagnostics, may be subject to changes in healthcare legislation and regulatory initiatives. For example, CMS began bundling the Medicare payments for certain laboratory tests ordered while a

patient received services in a hospital outpatient setting and, beginning in 2018, CMS began paying for clinical laboratory services based on a weighted average of reported prices that private payors, Medicare Advantage plans, and Medicaid Managed Care plans pay for laboratory services. In addition, recently there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed and enacted legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. For example, the 21st Century Cures Act changed the reimbursement methodology for infusion drugs and biologics furnished through durable medical equipment in an attempt to remedy over- and underpayment of certain products. We expect that additional U.S. federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that the U.S. federal government will pay for healthcare products and services, which could result in reduced demand for our antibody candidates or additional pricing pressures.

Individual states in the United States have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. Legally mandated price controls on payment amounts by third-party payors or other restrictions could harm our business, results of operations, financial condition and prospects. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be included in their prescription drug and other healthcare programs. This could reduce the ultimate demand for any future products or put pressure on our product pricing, which could negatively affect our business, results of operations, financial condition and prospects.

In the EU, similar political, economic and regulatory developments may affect our ability to profitably commercialize any future products. In addition to continuing pressure on prices and cost containment measures, legislative developments at the EU or member state level may result in significant additional requirements or obstacles that may increase our operating costs. The delivery of healthcare in the EU, including the establishment and operation of health services and the pricing and reimbursement of medicines, is

almost exclusively a matter for national, rather than EU, law and policy. National governments and health service providers have different priorities and approaches to the delivery of health care and the pricing and reimbursement of products in that context. In general, however, the healthcare budgetary constraints in most EU member states have resulted in restrictions on the pricing and reimbursement of medicines by relevant health service providers. Coupled with ever-increasing EU and national regulatory burdens on those wishing to develop and market products, this could prevent or delay marketing approval of our antibody candidates, restrict or regulate post-approval activities and affect our ability to commercialize any products for which we obtain marketing approval. In international markets, reimbursement and healthcare payment systems vary significantly by country, and many countries have instituted price ceilings on specific products and therapies.

We cannot predict how the policies of changing political administrations could impact, impose significant burdens on, or otherwise materially delay, the FDA’s ability to engage in routine regulatory and oversight activities such as implementing statutes through rulemaking, issuance of guidance, and review and approval of marketing applications. For example, certain policies of the current presidential administration may impact our business and industry. Namely, the current presidential administration has taken several executive actions, including the issuance of a number of Executive Orders. It is difficult to predict how these requirements will be implemented, and the extent to which they will impact the FDA’s ability to exercise its regulatory authority. If these executive actions impose constraints on the FDA’s ability to engage in oversight and implementation activities in the normal course, our business may be negatively impacted.

Finally, policies of the individual government agencies, including the FDA or similar regulatory authorities, may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product candidates. If we or our collaborators are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we or our collaborators are not able to maintain regulatory compliance, our antibody candidates may lose any regulatory approval that may have been obtained and we may not achieve or sustain profitability, which would adversely affect our business.

If we are required by the FDA or similar authorities to obtain approval (or clearance, or certification) of a companion diagnostic test in connection with approval of any of our antibody candidates, and we do not obtain or face delays in obtaining approval (or clearance, or certification) of a diagnostic device, we will not be able to commercialize such product candidate and our ability to generate revenue will be materially impaired.

If safe and effective use of any of our antibody candidates depends on a diagnostic that is not otherwise commercially available, then the FDA may require approval or clearance of that diagnostic, known as a companion diagnostic, at the same time that the FDA approves our antibody candidates, if at all. According to FDA guidance, if the FDA determines that a companion diagnostic device is essential to the safe and effective use of a novel therapeutic product or indication, the FDA generally will not approve the therapeutic product or new therapeutic product indication if the companion diagnostic is not also approved or cleared for that indication. If a satisfactory companion diagnostic is not commercially available, we may be required to develop or obtain one that would be subject to regulatory approval requirements. The process of obtaining or creating such diagnostics is time consuming and costly.

Companion diagnostics are developed in conjunction with clinical programs for the associated product and are subject to regulation as medical devices by the FDA and comparable regulatory authorities, and, to date, the FDA has generally required premarket approval

of companion diagnostics labeled for use with cancer therapies. The approval of a companion diagnostic as part of the therapeutic product’s labeling limits the use of the therapeutic product to only those patients who express the specific genetic alteration that the companion diagnostic was developed to detect.

If the FDA or a comparable regulatory authority requires approval (or clearance, or certification) of a companion diagnostic for any of our antibody candidates, whether before or after such candidate obtains marketing approval, we, and/or future collaborators, may encounter difficulties in developing and obtaining approval for such antibody candidate. Any delay or failure by us or third-party collaborators to develop or obtain regulatory approval (or clearance, or certification) of a companion diagnostic could delay or prevent approval or continued marketing of such antibody candidate.

We may also experience delays in developing a sustainable, reproducible and scalable manufacturing process for the companion diagnostic or in transferring that process to commercial partners or negotiating insurance reimbursement plans, all of which may prevent us from completing our clinical trials or commercializing our product candidate, if approved, on a timely or profitable basis, if at all.

Approval, clearance or certification of companion diagnostics may be subject to further legislative or regulatory reforms notably in the EU. On May 25, 2017, the new In Vitro Medical Devices Regulation (2017/746 or “IVDR”) entered into force. The IVDR repeals and replaces the EU In Vitro Diagnostic Medical Devices Directive. Unlike directives, which must be implemented into the national laws of the EEA Member States, regulations are directly applicable, i.e., without the need for adoption of EEA Member States laws implementing them, in all EEA Member States and are intended to eliminate current differences in the regulation of medical devices among EEA Member States. The IVDR, among other things, is intended to establish a uniform, transparent, predictable and sustainable regulatory framework across the EEA for medical devices and ensure a high level of safety and health while supporting innovation. The IVDR will, however, only become applicable in May 2022.

The regulation of companion diagnostics will be subject to further requirements as of the entry into force of the IVDR which introduces a new classification system for companion diagnostics which are now specifically defined as diagnostic tests that support the safe and effective use of a specific medicinal product, by identifying patients that are suitable or unsuitable for treatment. Companion diagnostics will have to undergo a conformity assessment by a notified body. Before it can issue a CE certificate, the notified body must seek a scientific opinion from the EMA on the suitability of the companion diagnostic to the medicinal product concerned if the medicinal product falls exclusively within the scope of the centralized procedure for the authorization of medicines, or the medicinal product is already authorized through the centralized procedure, or a marketing authorization application for the medicinal product has been submitted through the centralized procedure. For other substances, the notified body can seek the opinion from a national competent authorities or the EMA. These modifications may make it more difficult and costly for us to obtain regulatory clearances or approvals for our companion diagnostics or to manufacture, market or distribute our products after clearance or approval is obtained.

Disruptions at the FDA and other government agencies caused by funding shortages or global health concerns could hinder their ability to hire, retain or deploy key leadership and other personnel, or otherwise prevent new or modified products from being developed, approved or commercialized in a timely manner or at all, which could negatively impact our business.

The ability of the FDA to review and or approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory, and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s ability to perform routine functions. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable. Disruptions at the FDA and other agencies may also slow the time necessary for new drugs and biologics to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. For example, over the last several years, including for 35 days beginning on December 22, 2018, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough critical FDA employees and stop critical activities.

Separately, in response to the global pandemic of COVID-19, on March 10, 2020 the FDA announced its intention to postpone most foreign inspections of manufacturing facilities and products through April 2020, and subsequently, on March 18, 2020, the FDA temporarily postponed routine surveillance inspections of domestic manufacturing facilities. Subsequently, on July 10, 2020 the FDA announced its intention to resume certain on-site inspections of domestic manufacturing facilities subject to a risk-based prioritization system. The FDA intends to use this risk-based assessment system to identify the categories of regulatory activity that can occur within a given geographic area, ranging from mission critical inspections to resumption of all regulatory activities. Additionally, on April 15, 2021, the FDA issued a guidance document in which the FDA described its plans to conduct voluntary remote interactive evaluations of certain drug manufacturing facilities and clinical research sites. According to the guidance, the FDA intends to request such remote interactive evaluations in situations where an in-person inspection would not be prioritized, deemed mission-critical, or where direct inspection is otherwise limited by travel restrictions, but where the FDA determines that remote evaluation would be appropriate. Regulatory authorities outside the United States may adopt similar restrictions or other policy measures in response to the COVID-19 pandemic. If a prolonged government shutdown occurs, or if global health concerns continue to prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews, or other regulatory activities, it could significantly impact

the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

We may be subject to healthcare laws, regulation and enforcement; our failure to comply with these laws could harm our results of operations and financial conditions.

Although we do not currently have any products on the market, if we obtain FDA approval for any of our antibody candidates and begin commercializing those products in the United States, our operations may be directly, or indirectly through our customers and third-party payors, subject to various U.S. federal and state healthcare laws and regulations, including, without limitation, the U.S. federal Anti-Kickback Statute. Healthcare providers, physicians and others play a primary role in the recommendation and prescription of any products for which we obtain marketing approval. These laws may impact, among other things, our proposed sales, marketing and education programs and constrain our financial arrangements and relationships with healthcare providers, physicians and other parties through which we market, sell and distribute our products for which we obtain marketing approval. In addition, we may be subject to ~~patient data privacy and security regulation by both the U.S. federal government and the states in which we conduct our business. Finally, we may be subject to~~ additional healthcare, statutory and regulatory requirements and enforcement by foreign regulatory authorities in jurisdictions in which we conduct our business. The laws that may affect our ability to operate include:

Ensuring that our internal operations and future business arrangements with third parties comply with applicable healthcare laws and regulations could involve substantial costs. It is possible that governmental authorities will conclude that our business practices do not comply with current or future statutes, regulations, agency guidance or case law involving applicable fraud and abuse or other

healthcare laws and regulations. If our operations are found to be in violation of any of the laws described above or any other governmental laws and regulations that may apply to us, we may be subject to significant penalties, including civil, criminal and administrative penalties, damages, fines, exclusion from U.S. government funded healthcare programs, such as Medicare and Medicaid, disgorgement, individual imprisonment, contractual damages, reputational harm, diminished profits, reporting obligations and oversight if we become subject to a corporate integrity agreement or other agreement, and the curtailment or restructuring of our operations. If any of the physicians or other providers or entities with whom we expect to do business is found not to be in compliance with applicable laws, they may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs and imprisonment. If any of the above occur, it could adversely affect our ability to operate our business and our results of operations. Further, defending against any such actions can be costly, time-consuming and may require significant personnel resources. Therefore, even if we are successful in defending against any such actions that may be brought against us, our business may be impaired.

We face potential liability related to the privacy of health information we obtain from clinical trials sponsored by us or our collaborators, from research institutions, and directly from individuals.

Most health care providers, including research institutions from which we or our collaborators obtain patient health information, are subject to privacy and security regulations promulgated under HIPAA, as amended by HITECH. Any person may be prosecuted under HIPAA’s criminal provisions either directly or under aiding-and-abetting or conspiracy principles. Consequently, depending on the facts and circumstances, we could face substantial criminal penalties if we knowingly receive individually identifiable health

information from a HIPAA-covered health care provider or research institution that has not satisfied HIPAA’s requirements for disclosure of individually identifiable health information.

In addition, we may maintain sensitive personally identifiable information, including health information, that we receive throughout the clinical trial process, in the course of our research collaborations, and directly from individuals (or their healthcare providers) who enroll in our patient assistance programs. Even when HIPAA does not apply, according to the Federal Trade Commission (FTC), failing to take appropriate steps to keep consumers’ personal information secure constitutes unfair acts or practices in or affecting commerce in violation of Section 5(a) of the Federal Trade Commission Act. The FTC expects a company’s data security measures to be reasonable and appropriate in light of the sensitivity and volume of consumer information it holds, the size and complexity of its business, and the cost of available tools to improve security and reduce vulnerabilities. Individually identifiable health information is considered sensitive data that merits stronger safeguards. The FTC’s guidance for appropriately securing consumers’ personal information is similar to what is required by the HIPAA Security Rule. As such, we, our collaborators, research institutions, health care providers and other entities that provide personally identifiable information to us may be subject to state information security laws, and state laws requiring notification of affected individuals and state regulators in the event of a breach of personal information, which is a broader class of information than the health information protected by HIPAA.

The United States and global data protection landscape is rapidly evolving, and we may be affected by or subject to new or amended laws and regulations in the future. For example, California recently enacted legislation, the California Consumer Privacy Act (CCPA) which went into effect January 1, 2020. The CCPA, among other things, creates new data privacy obligations for covered companies and provides new privacy rights to California residents, including the right to opt out of certain disclosures of their information. The CCPA also creates a private right of action with statutory damages for certain data breaches, thereby potentially increasing risks associated with a data breach. Although the law includes limited exceptions, including for “protected health information” maintained by a covered entity or business associate, it may regulate or impact our processing of personal information depending on the context. Further, the CPRA was also recently voted into law by California residents. The CPRA will impose additional data protection obligations on covered businesses, including additional consumer rights processes, limitations on data uses, new audit requirements for higher risk data, and opt outs for certain uses of sensitive data. It will also create a new California data protection agency authorized to issue substantive regulations and could result in increased privacy and information security enforcement. The majority of the provisions will go into effect on January 1, 2023, and additional compliance investment and potential business process changes may be required.

Our and our collaborators’ clinical trial programs and research collaborations outside the U.S. may implicate international data protection laws, including, in Europe, the GDPR and local laws further implementing or supplementing the GDPR. The GDPR ~~implements~~imposes more stringent operational requirements for processors and controllers of personal data including requirements for such companies to be able to ensure and be able to demonstrate compliance with the GDPR. If our or our collaborators’ privacy or data security measures fail to comply with the GDPR requirements, we may be subject to litigation, regulatory investigations, enforcement notices requiring us to change the way we use personal data and/or fines of up to €20 million or up to 4% of the total worldwide annual turnover of the preceding financial year, whichever is higher. In addition to statutory enforcement, a non-compliance can lead to compensation claims by affected individuals, negative publicity and a potential loss of business.

Further, following the withdrawal of the United Kingdom from the EU on January 31, 2020, and the expiration of the transition period, from January 1, 2021, we have had to comply with the GDPR and separately the GDPR as implemented in the United Kingdom, with each regime having the ability to fine up to the greater of €20 million/ £17 million or 4% of global turnover. The relationship between the United Kingdom and the EU in relation to certain aspects of data protection law remains unclear, and it is unclear how United Kingdom data protection laws and regulations will develop in the medium to longer term. The European Commission has adopted an adequacy decision in favor of the United Kingdom, enabling data transfers from EU member states to the

United Kingdom without additional safeguards. However, the UK adequacy decision will automatically expire in June 2025 unless the European Commission re-assesses and renews/ extends that decision.

We are also subject to EUEU/national laws on personal data export, as we may transfer personal data from the EUEU/EEA to other jurisdictions which are not considered by the European Commission to offer “adequate” protection of personal data. Such transfers need to be legitimized by a valid transfer mechanism under the GDPR. In addition, in July 2020, the Court of Justice of the ~~European Union, or CJEU, invalidated~~EU (CJEU) limited how organizations could lawfully transfer personal data from the ~~E.U.-U.S.~~EU/EEA to the United States by invalidating the Privacy Shield ~~framework, which was put in place~~for purposes of international transfers and imposing further restrictions on use of the standard contractual clauses (a standard form of contract approved by the ~~U.S. Department of Commerce~~European Commission as an adequate personal data transfer mechanism, and ~~European Commission. Further, the United Kingdom’s decision to leave the EU has created uncertainty with regard~~potential alternative to the ~~status~~Privacy Shield). These restrictions include a requirement for companies to carry out a transfer impact assessment which, among other things, assesses the laws governing access to personal data in the recipient country and considers whether supplementary measures that provide privacy protections additional to those provided under standard contractual clauses will need to be implemented to ensure an essentially equivalent level of data protection to that afforded in the EEA. The European Commission issued revised standard contractual clauses on June 4, 2021 to account for the decision of the ~~UK as an “adequate country”~~CJEU and recommendations made by the European Data Protection Board. The revised standard contractual clauses must be used for ~~the purposes of~~relevant new data transfers ~~outside~~from September 27, 2021; existing standard contractual clauses arrangements must be migrated to the ~~European Economic Area. In particular, it~~revised clauses by December 27, 2022. There is ~~unclear how~~some remaining uncertainty around whether the revised clauses can and must be used for all types of cross-border data transfers to ~~and from the UK will~~jurisdictions without an adequacy decision, particularly whether they can be ~~regulated. While we employ model clauses which remain valid according~~relied on for data transfers to non-EEA entities, where processing is subject to the ~~recent CJEU decision, these changes~~GDPR. As supervisory authorities issue further guidance on personal data export mechanisms, including circumstances where the standard contractual clauses cannot be used, and/or start taking enforcement action, we could suffer additional costs, complaints and/or regulatory investigations or fines, and/or if we are otherwise unable to transfer personal data between and ~~uncertainty~~among countries and regions in ~~this area~~which we operate, it could affect the manner in which we provide our services, the geographical location or segregation of ~~law could require us to make operational changes~~our relevant systems and operations, and could ~~increase costs and may lead to governmental enforcement actions, litigation, fines and penalties or adverse publicity that could have an adverse effect on~~adversely affect our ~~business.~~financial results.

Although we work to comply with applicable laws, regulations and standards, our contractual obligations and other legal obligations, these requirements are evolving and may be modified, interpreted and applied in an inconsistent manner among jurisdictions in which we operate. We are likely to be required to expend significant capital and other resources to ensure ongoing compliance with applicable privacy and data security laws both inside and outside the United States. Claims that we have violated individuals’ privacy rights or breached our contractual obligations regardless of merit and even if we are not found liable, could be expensive and time-consuming to defend and could result in adverse publicity that could harm our business.

Claims that we or any collaborators fail to comply with applicable federal, state, or local, legal or regulatory requirements, could subject us to a range of regulatory actions that could affect our or any collaborators’ ability to seek to commercialize our antibody candidates, if approved. Any threatened or actual government enforcement action could also generate adverse publicity and require that we devote substantial resources that could otherwise be used in other aspects of our business.

We operate in highly competitive and rapidly changing industries, which may result in others discovering, developing or commercializing competing products before or more successfully than we do.

The biopharmaceutical and pharmaceutical industries are highly competitive and subject to significant and rapid technological change. Our success is highly dependent on our ability to discover, develop and obtain marketing approval for new and innovative products on a cost-effective basis and to market them successfully. In doing so, we face and will continue to face intense competition from a variety of businesses, including large, fully integrated pharmaceutical companies, specialty pharmaceutical companies and

biopharmaceutical companies, academic institutions, government agencies and other private and public research institutions in Europe, the United States and other jurisdictions. These organizations may have significantly greater resources than we do and conduct similar research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and marketing of products that compete with our antibody candidates.

With the proliferation of new drugs and therapies into oncology, we expect to face increasingly intense competition as new technologies become available. If we fail to stay at the forefront of technological change, we may be unable to compete effectively. Any antibody candidates that we successfully develop and commercialize will compete with existing therapies and new therapies that may become available in the future. The highly competitive nature of and rapid technological changes in the biotechnology and pharmaceutical industries could render our antibody candidates or our technology obsolete, less competitive or uneconomical. Our competitors may, among other things:

Should any of these factors occur, our business, financial condition and results of operations could be materially adversely affected.

In addition, existing and future collaborators may decide to market and sell products that compete with the antibody candidates that we have agreed to license to them. While we have agreements governing their committed activities, we have limited influence over their actual performance, and any competition by our collaborators could also have a material adverse effect on our future business, financial condition and results of operations.

Smaller and other early stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These third parties compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials, retaining manufacturers to produce clinical trial materials, as well as in acquiring technologies complementary to, or necessary for, our programs.

If we fail to obtain orphan drug designation for our antibody candidates, or obtain or maintain orphan drug exclusivity for our products, or lose such designation for zenocutuzumab in the United States, our competitors may sell products to treat the same conditions and our revenue will be reduced.

Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is intended to treat a rare disease or condition, defined as a patient population of fewer than 200,000 in the United States, or a patient population greater than 200,000 in the United States where there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States. In the EU, ~~the EMA’s Committee for Orphan Medicinal Products grants~~a medicinal product may be designated as orphan ~~drug designation to promote the development of products that are~~if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition ~~affecting not~~affects no more than five in 10,000 persons in the ~~EU. Additionally, designation~~European Union when the application is ~~granted for products intended for~~made, or (b) the ~~diagnosis, prevention or treatment of a life-threatening, seriously debilitating or serious and chronic condition when,~~product, without ~~incentives, it is unlikely that sales of~~ the ~~drug~~benefits derived from orphan status, would not generate sufficient return in the EU ~~would be sufficient~~ to justify ~~the necessary investment in developing the drug or biological product or where~~investment; and (3) there isexists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the ~~medicine must~~product will be of significant benefit to those affected by the condition. During this period, the EMA cannot accept another application for a marketing authorization (MA) or grant a MA or accept an application to extend an existing MA for the same indication, in respect of a similar medicinal product. The application for orphan drug designation must be submitted before the MA application (MAA). The applicant will receive a fee reduction for the MAA if the orphan drug designation has been granted, but not if the designation is still pending at the time the MA is submitted. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process.

In the United States, orphan drug designation entitles a party to potential financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. In addition, if a product receives the first FDA approval for the indication for which it has orphan designation, the product is entitled to orphan drug exclusivity, which means the FDA may not approve any other application to market the same drug for the same indication for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity or where the manufacturer is unable to assure sufficient product quantity. In the EU, orphan drug designation entitles a party to potential financial incentives such as reduction of fees or fee waivers and ten years of market exclusivity following drug or biological product approval. This period may be reduced to six years if the orphan drug designation criteria are no longer met, including where it is shown that the product is sufficiently profitable not to justify maintenance of market exclusivity.

We have obtained orphan drug designation from the FDA for zenocutuzumab for the treatment of patients with pancreatic cancer and potentially ~~plan to~~may seek that or a similar designation from the EMA for ~~our asset~~ zenocutuzumab, and ~~plan to potentially~~we may seek such designation from the FDA and EMA for other clinical assets, where supported by data in the appropriate indications that meet the criteria for orphan status. Even though we obtained orphan designation in the United States for zenocutuzumab and may obtain such designation for other antibody candidates in the United States and/or the EU, we may not be the first to obtain marketing approval for any particular orphan indication due to the uncertainties associated with developing pharmaceutical products. In addition, exclusive marketing rights in the United States may be limited if we seek approval for an indication broader than the orphan-designated indication or may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition. Further, even if we obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from competition because different drugs with different active moieties can be approved for the same condition. Even after an orphan drug is approved, the FDA or the EMA can subsequently approve the same drug with the same active moiety for the same condition if the FDA or the EMA concludes that the later drug is safer, more effective, or makes a major contribution to patient care. Orphan drug designation neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process. In addition, while we intend to seek orphan drug designation, when appropriate, we may not receive such designation.

The successful commercialization of our antibody candidates will depend in part on the extent to which governmental authorities and health insurers establish adequate coverage, reimbursement levels and pricing policies. Failure to obtain or maintain

adequate coverage and reimbursement for our antibody candidates, if approved, could limit our ability to market those products and decrease our ability to generate revenue.

The availability and adequacy of coverage and reimbursement by governmental healthcare programs such as Medicare and Medicaid, private health insurers and other third-party payors are essential for most patients to be able to afford products such as our antibody candidates, assuming approval. Our ability to achieve acceptable levels of coverage and reimbursement for products by governmental authorities, private health insurers and other organizations will have an effect on our ability to successfully commercialize and attract additional collaborators to invest in the development of our antibody candidates. Assuming we obtain coverage for a given product by a third-party payor, the resulting reimbursement payment rates may not be adequate or may require co-payments that patients find unacceptably high. We cannot be sure that coverage and reimbursement in the United States, the EU or elsewhere will be available for any product that we may develop, and any reimbursement that may become available may be decreased or eliminated in the future. Third-party payors increasingly are challenging prices charged for pharmaceutical products and services, and many third-party payors may refuse to provide coverage and reimbursement for particular drugs when an equivalent generic drug or a less expensive therapy is available. It is possible that a third-party payor may consider our antibody candidate and other therapies as substitutable and only offer to reimburse patients for the less expensive product. Even if we show improved efficacy or improved convenience of administration with our antibody candidate, pricing of existing drugs may limit the amount we will be able to charge for our antibody candidate. These payors may deny or revoke the reimbursement status of a given drug product or establish prices for new or existing marketed products at levels that are too low to enable us to realize an appropriate return on our investment in product development. If reimbursement is not available or is available only at limited levels, we may not be able to successfully commercialize our antibody candidates and may not be able to obtain a satisfactory financial return on products that we may develop.

There is significant uncertainty related to the insurance coverage and reimbursement of newly approved products. In the United States, third-party payors, including private and governmental payors, such as the Medicare and Medicaid programs, play an important role in determining the extent to which new drugs and biologics will be covered. The Medicare and Medicaid programs increasingly are used as models for how private payors and other governmental payors develop their coverage and reimbursement policies for drugs and biologics. Some third-party payors may require pre-approval of coverage for new or innovative devices or drug therapies before they will reimburse health care providers who use such therapies. It is difficult to predict at this time what third-party payors will decide with respect to the coverage and reimbursement for our antibody ~~candidates.~~candidates, if approved.

Obtaining and maintaining reimbursement status is time-consuming and costly. No uniform policy for coverage and reimbursement for drug products exists among third-party payors in the United States. Therefore, coverage and reimbursement for drug products can differ significantly from payor to payor. As a result, the coverage determination process is often a time-consuming and costly process that will require us to provide scientific and clinical support for the use of any future products to each payor separately, with no assurance that coverage and adequate reimbursement will be applied consistently or obtained in the first instance. Furthermore, rules and regulations regarding reimbursement change frequently, in some cases at short notice, and we believe that changes in these rules and regulations are likely.

Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe, Canada, and other countries has and will continue to put pressure on the pricing and usage of our antibody candidates, if approved. In many countries, the prices of medical products are subject to varying price control mechanisms as part of national health systems. Other countries allow companies to fix their own prices for medical products, but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our antibody candidates, if approved. Accordingly, in

markets outside the United States, the reimbursement for our products may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenue and profits.

Moreover, increasing efforts by governmental and third-party payors in the United States and abroad to cap or reduce healthcare costs may cause such organizations to limit both coverage and the level of reimbursement for newly approved products and, as a result, they may not cover or provide adequate payment for our antibody candidates, if approved. We expect to experience pricing pressures in connection with the sale of any of our antibody candidates that are approved due to the trend toward managed healthcare, the increasing influence of health maintenance organizations, and additional legislative changes. The downward pressure on healthcare costs in general, particularly prescription drugs and surgical procedures and other treatments, has become very intense. As a result, increasingly high barriers are being erected to the entry of new products.

In addition, even if a pharmaceutical product obtains a marketing authorization in the EU, there can be no assurance that reimbursement for such product will be secured on a timely basis or at all.

Our products may not gain market acceptance, in which case we may not be able to generate product revenues, which will materially adversely affect our business, financial condition and results of operations.

Even if the FDA, the EMA or any other regulatory authority approves the marketing of any antibody candidates that we develop on our own or with a collaborator, physicians, healthcare providers, patients or the medical community may not accept or use them. If these products do not achieve an adequate level of acceptance, we may not generate significant product revenues or any profits from operations. The degree of market acceptance of any of our antibody candidates that are approved will depend on a variety of factors, including:

Failure of our antibody candidates, if approved, to gain market acceptance will have a material adverse impact on our ability to generate revenues to provide a satisfactory, or any, return on our investments. Even if some products achieve market acceptance, the market may prove not to be large enough to allow us to generate significant revenues.

We currently have no marketing, sales or distribution infrastructure. If we are unable to develop sales, marketing and distribution capabilities on our own or through collaborations, we will not be successful in commercializing our antibody candidates.

We currently have no marketing, sales and distribution capabilities because all of our antibody candidates are still in clinical or pre-clinical development. If any of our antibody candidates are approved, we intend either to establish a sales and marketing organization with technical expertise and supporting distribution capabilities to commercialize our antibody candidates, or to outsource this function to a third party. Either of these options would be expensive and time consuming. These costs may be incurred in advance of any approval of our antibody candidates. In addition, we may not be able to hire a sales force that is sufficient in size or has adequate expertise in the medical markets that we intend to target. Any failure or delay in the development of our internal sales, marketing and distribution capabilities would adversely impact the commercialization of any approved products.

To the extent that we enter into collaboration agreements with respect to marketing, sales or distribution, our product revenue may be lower than if we directly marketed or sold any approved products. In addition, any revenue we receive will depend in whole or in part upon the efforts of these third-party collaborators, which may not be successful and are generally not within our control. If we are unable to enter into these arrangements on acceptable terms or at all, we may not be able to successfully commercialize any approved products. If we are not successful in commercializing any approved products, either on our own or through collaborations with one or more third parties, our future product revenue will suffer and we may incur significant additional losses.

We have never commercialized an antibody candidate before and may lack the necessary expertise, personnel and resources to successfully commercialize our products on our own or together with suitable collaborators.

We have never commercialized an antibody candidate, and we currently have no sales force, marketing or distribution capabilities. To achieve commercial success for our antibody candidates, if approved, which we may license to others, we will rely on the assistance and guidance of those collaborators. For antibody candidates for which we retain commercialization rights, we will have to develop our own sales, marketing and supply organization or outsource these activities to a third party. We may rely on outside consultants to provide advice on commercialization strategies, which may fail to deliver or provide effective guidance to maximize any commercial opportunity, if any, that may arise from our antibody candidates.

Factors that may affect our ability to commercialize our antibody candidates on our own include obtaining effective advice from consultants on commercialization strategy, recruiting and retaining adequate numbers of effective sales and marketing personnel, obtaining access to or persuading adequate numbers of physicians to prescribe our antibody candidates and other unforeseen costs associated with creating an independent sales and marketing organization. Developing a sales and marketing organization will be expensive and time-consuming and could delay the launch of our antibody candidates, if approved. We may not be able to build an effective sales and marketing organization. If we are unable to build our own distribution and marketing capabilities or to find suitable partners for the commercialization of our antibody candidates, we may not generate revenues from them or be able to reach or sustain profitability.

Our antibody candidates for which we intend to seek approval as biologic products may face competition sooner than anticipated.

The ACA includes a subtitle called the Biologics Price Competition and Innovation Act of 2009 (BPCIA) which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first approved by the FDA. In addition, the approval of a biosimilar product may not

be made effective by the FDA until 12 years from the date on which the reference product was first approved. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor’s own pre-clinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. The law is complex and is still being interpreted and implemented by the FDA. As a result, its ultimate impact, implementation, and meaning are subject to uncertainty.

We believe that any of our antibody candidates approved as a biological product under a BLA should qualify for the 12-year period of exclusivity. However, there is a risk that this exclusivity could be shortened due to congressional action or otherwise. Other aspects of the BPCIA, some of which may impact the BPCIA exclusivity provisions, have also been the subject of recent litigation. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of our reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

Jurisdictions in addition to the United States have established abbreviated pathways for regulatory approval of biological products that are biosimilar to earlier approved reference products. For example, the EU has had an established regulatory pathway for biosimilars since ~~2005.~~2006.

The increased likelihood of biosimilar competition has increased the risk of loss of innovators’ market exclusivity. Due to this risk, and uncertainties regarding patent protection, if our antibody candidates are approved for marketing, it is not possible to predict the length of market exclusivity for any particular product with certainty based solely on the expiration of the relevant patent(s) or the current forms of regulatory exclusivity. It is also not possible to predict changes in United States regulatory law that might reduce biological product regulatory exclusivity. The loss of market exclusivity for a product would likely materially and negatively affect revenues and we may not generate adequate or sufficient revenues from them or be able to reach or sustain profitability.

We rely, and expect to continue to rely, on third parties, including independent clinical investigators and CROs, to conduct our pre-clinical studies and clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may not be able to obtain regulatory approval for or commercialize our antibody candidates and our business could be substantially harmed.

We have relied upon and plan to continue to rely upon third parties, including independent clinical investigators and third-party CROs, to conduct our pre-clinical studies and clinical trials and to monitor and manage data for our ongoing pre-clinical and clinical programs. We rely on these parties for execution of our pre-clinical studies and clinical trials, and control only certain aspects of their activities. Nevertheless, we are responsible for ensuring that each of our studies and trials is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards, and our reliance on these third parties does not relieve us of our regulatory responsibilities. We and our third-party contractors and CROs are required to comply with GCP requirements, which are regulations and guidelines enforced by the FDA, the Competent Authorities of the Member States of the EEA, and comparable foreign

regulatory authorities for all of our antibody candidates in clinical development. Regulatory authorities enforce these GCPs through periodic inspections of trial sponsors, principal investigators and trial sites. If we or any of our CROs fail to comply with applicable GCPs, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, the EMA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP regulations. In addition, our clinical trials must be conducted with the antibody candidate produced under cGMP regulations. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process.

Further, these investigators and CROs are not our employees and we will not be able to control, other than by contract, the amount of resources, including time, which they devote to our antibody candidates and clinical trials. If independent investigators or CROs fail to devote sufficient resources to the development of our antibody candidates, or if their performance is substandard, it may delay or compromise the prospects for approval and commercialization of any antibody candidates that we develop. Moreover, as a result of the COVID-19 pandemic, certain of our third-party CROs have been affected and in some instances have experienced cessation or mitigation of activity and may experience closures and labor shortages, which may negatively affect our pre-clinical and clinical development activities. In addition, the use of third-party service providers may require us to disclose our proprietary information to these parties, which could increase the risk that this information will be misappropriated.

Our CROs have the right to terminate their agreements with us in the event of an uncured material breach. In addition, some of our CROs have an ability to terminate their respective agreements with us if it can be reasonably demonstrated that the safety of the subjects participating in our clinical trials warrants such termination, if we make a general assignment for the benefit of our creditors or if we are liquidated.

If any of our relationships with these third-party CROs terminate, we may not be able to enter into arrangements with alternative CROs or to do so on commercially reasonable terms. If CROs do not successfully carry out their contractual duties or obligations or meet expected deadlines, if they need to be replaced or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols, regulatory requirements or for other reasons, our clinical trials may be extended, delayed

or terminated and we may not be able to obtain regulatory approval for or successfully commercialize our antibody candidates. As a result, our results of operations and the commercial prospects for our antibody candidates would be harmed, our costs could increase and our ability to generate revenues could be delayed.

Switching or adding additional CROs involves additional cost and requires management time and focus. In addition, there is a natural transition period when a new CRO commences work. As a result, delays occur, which can materially impact our ability to meet our desired clinical development timelines. Additionally, CROs may lack the capacity to absorb higher workloads or take on additional capacity to support our needs. Though we carefully manage our relationships with our CROs, there can be no assurance that we will not encounter similar challenges or delays in the future or that these delays or challenges will not have a material adverse impact on our business, financial condition and prospects.

The collaboration and license agreement, or the Collaboration Agreement, with Incyte Corporation (Incyte) is important to our business. If suitable monospecific or bispecific antibody candidates are not identified for further development and commercialization activities under the Collaboration Agreement, or if we or Incyte fail to adequately perform under the Collaboration Agreement, or if we or Incyte terminate the Collaboration Agreement, the development and commercialization of our antibody candidates would be delayed or terminated and our business would be adversely affected.

If the Collaboration Agreement is terminated with respect to one or more programs, all rights in the terminated programs revert to us, subject to payment to Incyte of a reverse royalty of up to 4% on sales of future products, depending on the stage of development as of the date of termination, if we elect to pursue development and commercialization of monospecific or bispecific antibody candidates arising from the terminated programs.

Termination of the Collaboration Agreement could cause significant delays in our antibody candidate development and commercialization efforts, which could prevent us from commercializing our antibody candidates without first expanding our internal capabilities or entering into another agreement with a third party. Any suitable alternative collaboration or license agreement would take considerable time to negotiate and could also be on less favorable terms to us. In addition, under the Collaboration Agreement, Incyte agreed to conduct certain clinical development activities. If the Collaboration Agreement were to be terminated, and whether or

not we identify another suitable collaborator, we may need to seek additional financing to support the research and development of any terminated antibody candidates so that we may continue development activities, or we may be forced to discontinue development of terminated antibody candidates, each of which could have a material adverse effect on our business.

Under the Collaboration Agreement, with the exception of MCLA-145 where we retain full U.S. rights, we are dependent upon Incyte to successfully develop and commercialize any antibody candidates that are identified for further development under the Collaboration Agreement. With the exception of those programs where we retain certain co-development rights, we have limited ability to influence or control Incyte’s development and commercialization activities or the resources it allocates to development of product candidates identified under the Collaboration Agreement. Our interests and Incyte’s interests may differ or conflict from time to time, or we may disagree with Incyte’s level of effort or resource allocation. Incyte may internally prioritize programs under development within the collaboration differently than we would, or it may not allocate sufficient resources to effectively or optimally develop or commercialize antibody candidates arising from such programs. If these events were to occur, our ability to receive revenue from the commercialization of products arising from such programs would be reduced, and our business would be adversely affected.

The collaboration and license agreement, or the Lilly Collaboration Agreement, with Eli Lilly is important to our business. If suitable monospecific or bispecific antibody candidates are not identified for further development and commercialization activities under the Lilly Collaboration Agreement, or if we or Eli Lilly fail to adequately perform under the Lilly Collaboration Agreement, or if we or Eli Lilly terminate the Lilly Collaboration Agreement, the development and commercialization of our antibody candidates would be delayed or terminated and our business would be adversely affected.

If the Lilly Collaboration Agreement is terminated with respect to one or more programs, depending on the stage of development, certain rights in the terminated programs revert to us.

Termination of the Lilly Collaboration Agreement could cause significant delays in our antibody candidate development and commercialization efforts, which could prevent us from commercializing our antibody candidates without first expanding our internal capabilities or entering into another agreement with a third party. Any suitable alternative collaboration or license agreement would take considerable time to negotiate and could also be on less favorable terms to us. In addition, under the Lilly Collaboration Agreement, Eli Lilly agreed to conduct certain pre-clinical and clinical development activities. If the Lilly Collaboration Agreement were to be terminated, and whether or not we identify another suitable collaborator, we may need to seek additional financing to support the research and development of any terminated antibody candidates so that we may continue development activities, or we may be forced to discontinue development of terminated antibody candidates, each of which could have a material adverse effect on our business.

Under the Lilly Collaboration Agreement, we are dependent upon Eli Lilly to successfully develop and commercialize any antibody candidates that are identified for further development under the Lilly Collaboration Agreement. We have limited ability to influence or control Eli Lilly’s development and commercialization activities or the resources it allocates to development of product candidates identified under the Lilly Collaboration Agreement. Our interests and Eli Lilly’s interests may differ or conflict from time to time, or we may disagree with Eli Lilly’s level of effort or resource allocation. Eli Lilly may internally prioritize programs under development within the collaboration differently than we would, or it may not allocate sufficient resources to effectively or optimally develop or commercialize antibody candidates arising from such programs. If these events were to occur, our ability to receive revenue from the commercialization of products arising from such programs would be reduced, and our business would be adversely affected.

The collaboration and license agreements with Simcere, and Betta Pharma, and the research and license agreement with Ono are important to our business. If our ~~Biclonics~~^®Biclonics® antibodies licensed in these collaboration and license agreements fail to advance or experience unacceptable safety or efficacy results if clinically developed, this could adversely impact the reputation of our platform and our ability to engage in future collaborations.

If our collaboration agreements with Simcere or Betta Pharma or our research and license agreements with Ono are terminated with respect to one or more programs, or the pre-clinical assets associated with these agreements fail to advance into the clinic, or experience negative results with respect to safety, efficacy, manufacturability, or other features of research and development, this could adversely affect the reputation of our ~~Biclonics~~^®Biclonics® technology platform and our ability to engage in future collaborations or licensing agreements. While we have certain contractual provisions in place in our collaboration agreements with Simcere and Betta Pharma that permit us to supervise development efforts associated with our pre-clinical assets ~~out-licensed~~with respect to ~~these entities,~~Simcere, or MCLA-129, with Betta Pharma, which have development and product rights in China, we cannot guarantee that these assets will be developed in China in accordance with our standards as applied to our wholly owned ~~programs.~~programs or in a manner suitable for ex-China development. Ono is currently pursuing at least one antibody program generated by us through use of our proprietary ~~Biclonics~~^®Biclonics® platform in an area outside oncology. To the extent this asset does not successfully advance through clinical development, this may impair our ability to leverage our platform in areas outside oncology or to engage in future license agreements to further expand the use of our platform and generate future revenue. Should any of these collaborations or license agreements fail or be terminated, any suitable alternative collaboration or license agreement would take considerable time to negotiate, if at all, and could also be on less favorable terms to us. If these agreements were to be terminated, and whether or not we identify a suitable alternative collaborator, we may need to seek additional financing to support the research and development of any terminated antibody candidates so that we may continue development activities, or we may be forced to discontinue development of terminated antibody candidates, each of which could, depending on the stage of development and investment, have a material adverse effect on our business.

If we fail to enter into new strategic relationships our business, financial condition, commercialization prospects and results of operations may be materially adversely affected.

Our product development programs and the potential commercialization of our antibody candidates will require substantial additional cash to fund expenses. Therefore, for some of our antibody candidates and with respect to our recently developed ~~Triclonics~~^TMTriclonics® technology platform, we may decide to enter into new collaborations with pharmaceutical or biopharmaceutical companies for the development and potential commercialization of those bispecific and trispecific antibody candidates. For instance, we have license and collaboration agreements with Ono, Incyte, Eli Lilly, Simcere and Betta, under which we have licensed the development and commercialization of certain of our monospecific or bispecific antibody candidates.

We face significant competition in seeking appropriate collaborators. Collaborations are complex and time-consuming to negotiate and document. We may also be restricted under existing and future collaboration agreements from entering into agreements on certain terms with other potential collaborators. We may not be able to negotiate collaborations on acceptable terms, or at all. If that were to occur, we may have to curtail the development of a particular bispecific or trispecific antibody candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of our sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or commercialization activities on our own, we may need to obtain additional capital, which may not be available to us on acceptable terms or at all. If we do not have sufficient funds, we will not be able to bring our antibody candidates to market, further research and develop new trispecific antibody candidates, enhance our ~~Biclonics~~^®

Biclonics® and ~~Triclonics~~^TMTriclonics® technology platforms and generate product revenue. If we do enter into a new collaboration agreement, we could be subject to the following risks, each of which may materially harm our business, commercialization prospects and financial condition:

We currently rely on third-party suppliers and other third parties for production of our antibody candidates and our dependence on these third parties may impair the advancement of our research and development programs and the development of our antibody candidates. Moreover, we intend to rely on third parties to produce commercial supplies of any approved antibody candidate and our commercialization of any of our antibody candidates could be stopped, delayed or made less profitable if those third parties fail to obtain approval of the FDA or comparable foreign regulatory authorities following inspection of their facilities and procedures to manufacture our antibody candidates and products,, fail to provide us with sufficient quantities of antibody product or fail to do so at acceptable quality levels or prices or fail to otherwise complete their duties in compliance with their obligations to us or other parties.

We rely on and expect to continue to rely on third-party contract manufacturing organizations (CMOs) for the supply of cGMP-grade clinical trial materials and commercial quantities of our antibody candidates and products, if approved. Reliance on third-party providers may expose us to more risk than if we were to manufacture antibody candidates ourselves. The facilities used by our CMOs to manufacture our antibody candidates must be approved by the FDA pursuant to inspections that will be conducted after we submit our BLA to the FDA. We have limited control over the manufacturing process of, and beyond contractual terms, we are completely dependent on our CMOs for compliance with cGMP for the manufacture of our antibody candidates. If our CMOs cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or comparable foreign regulatory authorities, or are unable to do so in a timely manner, they will not be able to secure and/or maintain regulatory approval for their manufacturing facilities or may result in delay of our ability to obtain marketing authorization, if any, of our antibody candidates. In addition, we have limited control over the ability of our CMOs to maintain adequate quality control, quality assurance and qualified personnel. If the FDA or a comparable foreign regulatory authority does not approve these facilities for the manufacture of our antibody candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain regulatory approval for or market our antibody candidates, if approved. In addition, any failure to achieve and maintain compliance with these laws, regulations and standards could subject us to the risk that we may have to suspend the manufacturing of our antibody candidates or that obtained approvals could be revoked, which would adversely affect our business and reputation. Furthermore, third-party providers may breach existing agreements they have with us because of factors beyond our control. They may also terminate or refuse to renew their agreement because of their own financial difficulties or business priorities, at a time that is costly or otherwise inconvenient for us. If we were unable to find an adequate replacement or another acceptable solution in time, our clinical trials could be delayed or our commercial activities could be harmed. In addition, the fact that we are dependent on our collaborators, our CMOs and other third parties for the manufacture, filling, storage and distribution of our antibody candidates means that we are subject to the risk that the products may have manufacturing defects that we have limited ability to prevent or control. The sale of products containing such defects could adversely affect our business, financial condition and results of operations.

Growth in the costs and expenses of components or raw materials may also adversely influence our business, financial condition and results of operations. Supply sources could be interrupted from time to time and, if interrupted, there is no guarantee that supplies could be resumed (whether in part or in whole) within a reasonable timeframe and at an acceptable cost or at all.

We rely on our CMOs to purchase from third-party suppliers the materials necessary to produce our antibody candidates for our clinical trials, and will rely on our existing and future collaborators to purchase from third-party suppliers the materials necessary to develop and produce our antibody candidates for future clinical trials and, upon approval, our products for commercialization. There are a limited number of suppliers for raw materials that we use to manufacture our antibody candidates and there may be a need to assess alternate suppliers to prevent a possible disruption of the manufacture of the materials necessary to produce our antibody candidates for our clinical trials, and if approved, ultimately for commercial sale. Apart from contractual measures, we do not have any control over the process or timing of the acquisition of these raw materials by our manufacturers or manufacturers paid by our collaborators. Moreover, we currently do not have any agreements for the commercial production of these raw materials. Although we

generally do not begin a clinical trial unless we believe we have a sufficient supply of an antibody candidate to complete the clinical trial or have secured resupply capacity, any significant delay in the supply of an antibody candidate, or the raw material components thereof, for a planned or an ongoing clinical trial due to the need to replace a third-party manufacturer could considerably delay completion of our clinical trials, product testing and potential regulatory approval of our antibody candidates. If our manufacturers, collaborators or we are unable to purchase these raw materials after regulatory approval has been obtained for our antibody candidates, the commercial launch of our antibody candidates would be delayed or there would be a shortage in supply, which would impair our

ability to generate revenues from the sale of our antibody candidates. Moreover, as a result of the COVID-19 pandemic, third-party manufacturers have been affected, which could disrupt or delay their activities or ability to source materials and as a result we could face difficulty sourcing key components necessary to produce supply of our product candidates, which may negatively affect our pre-clinical and clinical development activities.

We rely on our manufacturers and other subcontractors to comply with and respect the proprietary rights of others in conducting their contractual obligations for us. If our manufacturers or other subcontractors fail to acquire the proper licenses or otherwise infringe third party proprietary rights in the course of completing their contractual obligations to us, we may have to find alternative manufacturers or defend against claims of infringement, either of which would significantly impact our ability to develop, obtain regulatory approval for or market our antibody candidates, if approved.

We rely on patents and other intellectual property rights to protect our technology, including antibody candidates and our ~~Biclonics~~^®Biclonics® technology platform and ~~Triclonics~~^TMTriclonics® technology platform, the enforcement, defense and maintenance of which may be challenging and costly. Failure to enforce or protect these rights adequately could harm our ability to compete and impair our business.

Our commercial success depends in part on obtaining and maintaining patents and other forms of intellectual property rights for our ~~Biclonics~~^®Biclonics® technology platform, ~~Triclonics~~^TMTriclonics® technology platform, our common light chain transgenic ~~murine~~ technology, our ~~CH3 domain~~ dimerization technology, our heavy chain variable regions and binding domains that bind particular antigens, our monospecific antibodies, bispecific antibody, trispecific antibody and antibody clinical candidates, products, their format and methods and host cells used to produce, screen, manufacture and purify those antibody and antibody clinical candidates, the methods for treating patients using those candidates, among other aspects of our technology or on licensing-in such rights. Failure to protect or to obtain, maintain or extend adequate patent and other intellectual property rights could materially adversely affect our ability to develop and market our platform technologies, and antibody candidates.

The patent prosecution process is expensive and time-consuming, and we and our current or future licensors, licensees or collaborators may not be able to prepare, file and prosecute all necessary or desirable patent applications at a reasonable cost or in a timely manner. It is also possible that we or our licensors, licensees or collaborators will fail to identify patentable aspects of inventions made in the course of development and commercialization activities before it is too late to obtain patent protection on them. Further, the issuance, scope, validity, enforceability and commercial value of our and our current or future licensors’, licensees’ or collaborators’ patent rights are highly uncertain. Our and our licensors’ pending and future patent applications may not result in patents being issued which protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. The patent examination process may require us or our licensors, licensees or collaborators to narrow the scope of the claims of our or our licensors’, licensees’ or collaborators’ pending and future patent applications, which may limit the scope of patent protection that may be obtained. We cannot assure you that all of the potentially relevant prior art relating to our patents and patent applications has been found. If such prior art exists, it can invalidate a patent or prevent a patent from issuing from a pending patent application. Even if patents do successfully issue, or have issued and even if such patents cover our ~~Biclonics~~^®Biclonics® technology platform, ~~Triclonics~~^TMTriclonics® technology platform, our common light chain transgenic ~~murine~~ technology, our ~~CH3 domain~~ dimerization technology our heavy chain variable regions and binding domains that bind particular antigens, our monospecific antibodies, bispecific antibody, trispecific antibody and antibody clinical candidates, products, their format and methods and host cells used to produce, screen, manufacture and purify those antibody and antibody clinical candidates, the methods for treating patients using those candidates, and other technologies, third parties may initiate opposition, interference, re-examination, post-grant review, inter partesreview, nullification or derivation action in court or before patent offices, or similar proceedings challenging the validity, enforceability or scope of such patents, which may result in the patent claims being narrowed or invalidated. Our and our licensors’, licensees’ or collaborators’ patent applications cannot be enforced against third parties practicing the technology claimed in such applications unless and until a patent issues from such applications, and then only to the extent the issued claims cover the technology.

Because patent applications are confidential for a period of time after filing, and some remain so until issued, we cannot be certain that we or our licensors were the first to file any patent application related to our technology, including our antibody candidates. Furthermore, if third parties have filed such patent applications on or before March 15, 2013, an interference proceeding can be initiated by such third parties to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. If third parties have filed such applications after March 15, 2013, a derivation proceeding can be initiated by such third parties to determine whether our invention was derived from theirs.

Issued patents covering one or more of our products or the ~~Biclonics~~^®Biclonics® technology or ~~Triclonics~~^TMTriclonics® technology platforms could be found invalid or unenforceable if challenged in court.

To protect our competitive position, we may from time to time need to resort to litigation to enforce or defend any patents or other intellectual property rights owned by or licensed to us, or to determine or challenge the scope or validity of patents or other intellectual property rights of third parties. As enforcement of intellectual property rights is difficult, unpredictable and expensive, we may fail in enforcing our rights—in which case our competitors may be permitted to use our technology without being enjoined, required to pay us any license fees, or compensate us for lost profits or reasonable royalty. In addition, litigation involving our patents carries the risk

that one or more of our patents will be held invalid (in whole or in part, on a claim-by-claim basis) or held unenforceable. Such an adverse court ruling could allow third parties to commercialize technology covered by our patents we seek to enforce, such as those covering our antibody candidates or methods, our ~~Biclonics~~^®Biclonics® technology and ~~Triclonics~~^TMTriclonics® technology platforms, our common light chain transgenic ~~murine~~ technology, or our CH3 domain dimerization technology, among other technologies, and then compete directly with us, without payment to us.

If we were to initiate legal proceedings against a third party to enforce a patent covering our technology, one of our products or methods, the defendant could counterclaim that our patent is invalid and/or unenforceable. In patent litigation in the United States or in certain jurisdictions in Europe, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, for example, lack of utility, novelty, obviousness, non-enablement or lack of written description or as constituting unpatentable subject matter. Grounds for an unenforceability assertion could be an allegation that someone substantively involved in prosecution of the patent withheld but-for material information from the U.S. Patent and Trademark Office (USPTO) or engaged in affirmatively egregious misconduct, during prosecution, with a specific intent to deceive the USPTO. The outcome following legal assertions of invalidity and unenforceability during patent litigation is unpredictable. With respect to the validity question, for example, we cannot be certain that there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we could lose at least part, and perhaps all, of the patent protection on one or more of our technologies, products, methods or certain aspects of our ~~Biclonics~~^®Biclonics® technology and ~~Triclonics~~^TMTriclonics® technology platforms. Such a loss of patent protection could have a material adverse impact on our business. Patents and other intellectual property rights also will not protect our technology if competitors design around our protected technology without infringing our patents or other intellectual property rights.

Intellectual property rights of third parties could adversely affect our ability to commercialize our antibody candidates, such that we could be required to litigate or obtain licenses from third parties in order to develop or market our antibody candidates. Such litigation or licenses could be costly or not available on commercially reasonable terms.

Our competitive position may suffer if patents issued to third parties or other third-party intellectual property rights cover our technology platforms, methods or candidates or elements thereof, our manufacture or uses relevant to our development, or other attributes of our antibody candidates or our ~~Biclonics~~^®Biclonics® technology platform or ~~Triclonics~~^TMTriclonics® technology platform. In such cases, we may not be in a position to develop or commercialize products or bispecific or trispecific antibody candidates unless we successfully pursue litigation, opposition, inter partes, or related post-grant proceedings to nullify or invalidate the third-party intellectual property right concerned, or enter into a license agreement with the intellectual property right holder, if available on commercially reasonable terms. In addition, we are aware of issued patents and/or pending patent applications held by third parties that could be alleged as covering some of our antibody candidates, irrespective of the merits. We believe that if such patents or patent applications (if issued as currently pending) were asserted against us, we would have counterclaims and defenses against such claims, including non-infringement, the affirmative defense of safe harbor designed to protect activity undertaken to obtain federal regulatory approval of a drug, including under 35 U.S.C. § 271(e) and similar foreign exceptions to infringement, and defenses concerning patent invalidity and/or unenforceability. However, if such counterclaims and defenses were not successful and such patents were successfully asserted against us such that they are found to be valid and enforceable, and infringed by our antibody candidates, unless we obtain a license to such patents, which may not be available on commercially reasonable terms or at all, we could be prevented from continuing to develop or commercialize our antibody candidates. We could also be required to pay substantial damages. Similarly, the targets of certain of our antibody candidates have also been the subject of research by many companies, which have filed patent applications or have patents related to such targets and their uses. There can be no assurance any such patents will not be asserted against us or that we will not need to seek licenses from such third parties. We may not be able to secure such licenses on acceptable terms, if at all, and any such litigation would be costly and time-consuming.

It is also possible that we failed to identify relevant patents or applications. For example, U.S. applications filed before November 29, 2000 and certain U.S. applications filed after that date that will not be filed outside the United States remain confidential until patents issue. Patent applications in the United States and elsewhere are published approximately 18 months after the earliest filing for which priority is claimed, with such earliest filing date being commonly referred to as the priority date. Therefore, patent applications covering our products or platform technologies could have been filed by others without our knowledge. Furthermore, we operate in a highly competitive field, and given our limited resources, it is unreasonable to monitor all patent applications purporting to claim broad coverage in the areas in which we are active. Additionally, pending patent applications which have been published can, subject to certain limitations, be later amended in a manner that could cover our platform technologies, our methods, antibody candidates or the use of our bispecific and trispecific antibody candidates.

Third party intellectual property right holders, including our competitors, may actively bring infringement claims against us. The granting of orphan drug status in respect of any of our antibody candidates does not guarantee our freedom to operate and is separate from our risk of possible infringement of third parties’ intellectual property rights. We may not be able to successfully settle or otherwise resolve such potential infringement claims. If we are unable to successfully settle future claims on terms acceptable to us, we may be required to engage or continue costly, unpredictable and time-consuming litigation and may be prevented from or experience substantial delays in marketing any approved products.

If we fail in any such dispute, in addition to being forced to pay damages, we or our licensees may be temporarily or permanently prohibited from commercializing any of our antibody candidates that are held to be infringing or be forced to redesign antibody candidates so that we no longer infringe the third-party intellectual property rights. Any of these events, even if we were ultimately to prevail, could require us to divert substantial financial and management resources that we would otherwise be able to devote to our business.

In addition, if the breadth or strength of protection provided by our or our present or future licensors’, collaborators’ or partners’ patents and patent applications is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future antibody candidates. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation.

Our ability to compete may be adversely affected if we are unsuccessful in defending against any claims by competitors or others that we are infringing upon their intellectual property rights.

The various markets in which we plan to operate are subject to frequent and extensive litigation regarding patents and other intellectual property rights. In addition, many companies in intellectual property-dependent industries, including those producing therapeutics to treat and potentially cure cancer, have employed intellectual property litigation as a means to gain an advantage over their competitors. As a result, we may be required to defend against claims of intellectual property infringement that may be asserted by our competitors against us and, if the outcome of any such litigation is adverse to us, it may affect our ability to compete effectively.

Our involvement in litigation, and in any interferences, opposition, pre and post-grant administrative proceedings or other intellectual property proceedings inside and outside of the United States may divert management from focusing on business operations, could cause us to spend significant amounts of money and may have no guarantee of success. Any potential intellectual property litigation successfully adjudicated against us could also force us to do one or more of the following:

We are aware that significant number of patents and patent applications may exist relating to aspects of therapeutic antibody technologies filed by, and issued to, third parties.

We cannot assure you that we will ultimately prevail if any of this third-party intellectual property is asserted against us.

Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities.

Even if resolved in our favor, litigation or other legal proceedings relating to intellectual property claims may cause us to incur significant expenses and could distract our technical and management personnel from their normal responsibilities. In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, this could have a substantial adverse effect on the price of our common shares. Such litigation or proceedings and the legal costs associated with them, could substantially increase our operating losses and reduce our resources available for development activities. We may not have sufficient financial or other resources to adequately conduct such litigation or proceedings. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their substantially greater financial resources. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could have a material adverse effect on our ability to compete in the marketplace.

We may not be successful in obtaining or maintaining necessary rights to our antibody candidates through acquisitions and in-licenses.

We currently have rights and own our intellectual property, including issued patents and pending patent applications, relating to and covering our antibody candidates and ~~Biclonics~~^®Biclonics® technology and ~~Triclonics~~^TMTriclonics® technology platforms. Because our programs may require the use of proprietary rights held by third parties, the growth of our business may depend in part on our ability to acquire, in-license, maintain or use these proprietary rights. In addition, our antibody candidates may require specific formulations to work effectively and efficiently or companion diagnostics for safely and effective administration of our therapeutic candidates and the rights to these formulations and companion diagnostics may be held by others. We may be unable to acquire or in-license any compositions,

methods of use, processes, or other third-party intellectual property rights from third parties that we may identify as necessary for our antibody candidates. The licensing and acquisition of third-party intellectual property rights is a competitive area, and a number of more established companies are also pursuing strategies to license or acquire third-party intellectual property rights that we may consider attractive. These established companies may have a competitive advantage over us due to their size, cash resources, and greater clinical development and commercialization capabilities.

In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment. If we are unable to successfully obtain a license to third-party intellectual property rights necessary for the development of an antibody candidate or program, we may have to abandon development of that antibody candidate or program and our business and financial condition could suffer.

If our trademarks and trade names are not adequately protected, then we may not be able to build name recognition in our markets of interest and our business may be adversely affected.

Our registered or unregistered trademarks, trade names or service marks may be challenged, infringed, circumvented or declared generic or determined to be infringing on other marks. We may not be able to protect our rights to these trademarks, trade names, and service marks, which we need to build name recognition by potential collaborators, partners or customers in our markets of interest. Over the long term, if we are unable to establish name recognition based on our trademarks, trade names and service marks then we may not be able to compete effectively and our business may be adversely affected. If other entities use trademarks, trade names or service marks similar to ours in different jurisdictions, or have senior rights to ours, it could interfere with our use of our current trademarks, trade names or service marks throughout the world.

If we do not obtain protection under the Hatch-Waxman Amendments and similar non-U.S. legislation for extending the term of patents covering each of our antibody candidates, our business may be materially harmed.

Patents typically have a limited lifespan. In the United States, if all maintenance fees are timely paid, the natural expiration of a patent is generally 20 years from its earliest U.S. non-provisional filing date. Various extensions may be available, but the life of a patent, and the protection it affords, is limited. Even if patents covering our antibody candidates are obtained, once the patent life has expired for a candidate, we may be open to competition from competitive medications, including biosimilar or generic medications. Given the amount of time required for the development, testing and regulatory review of new antibody candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our owned and licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours, causing our revenue from applicable products to be reduced, possibly materially, and potentially harming our ability to recover our investment in such product or obtain a reasonable return on that investment.

Depending upon the timing, duration and conditions of FDA marketing approval of our antibody candidates, one or more of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Amendments, and similar legislation in the EU. The Hatch-Waxman Amendments permit a patent term extension of up to five years for a patent covering an approved product as compensation for effective patent term lost during product development and the FDA regulatory review process. However, we may not receive an extension if we fail to apply within applicable deadlines, fail to apply prior to expiration of relevant patents or otherwise fail to satisfy applicable requirements. Moreover, the length of the extension could be less than we request. If we are unable to obtain patent term extension or the term of any such extension is less than we request, the period during which we can enforce our patent rights for that product will be shortened and our competitors may obtain approval to market competing products sooner. As a result, our revenue from applicable products could be reduced, possibly materially.

We enjoy only limited geographical protection with respect to certain patents and may face difficulties in certain jurisdictions, which may diminish the value of intellectual property rights in those jurisdictions.

We generally file our first patent application (i.e., priority filing) in the Netherlands. International applications under the Patent Cooperation Treaty (PCT) are usually filed within 12 months after the priority filing, where we pursue patent applications in the U.S., across the E.U., and other PCT participating jurisdictions, as based on the PCT filing, national and regional patent applications may be filed in additional jurisdictions where we believe our antibody candidates may be marketed or manufactured or our platform technologies may be utilized. We have so far not filed for patent protection in all national and regional jurisdictions where such

protection may be available. In addition, we may decide to abandon national and regional patent applications before grant. Finally, the grant proceeding of each national/regional patent is an independent proceeding which may lead to situations in which applications might in some jurisdictions be refused by the relevant patent offices, while granted by others. It is also quite common that depending on the country, the scope of patent protection may vary for the same antibody candidate and/or technology.

Competitors may use our and our existing or future licensors’, collaborators’ or partners’ technologies in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories

where we and our existing or future licensors, collaborators or partners have patent protection, but enforcement is not as strong as that in the United States. These products may compete with our antibody candidates or our platform technologies, and our and our existing or future licensors’, collaborators’ or partners’ patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

The laws of some jurisdictions do not protect intellectual property rights to the same extent as the laws in the United States and the EU, and many companies have encountered significant difficulties in protecting and defending such rights in such jurisdictions. If we or our licensors encounter difficulties in protecting, or are otherwise precluded from effectively protecting, the intellectual property rights important for our business in such jurisdictions, the value of these rights may be diminished and we may face additional competition from others in those jurisdictions.

Some countries have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties. In addition, some countries limit the enforceability of patents against government agencies or government contractors. In these countries, the patent owner may have limited remedies, which could materially diminish the value of such patent. If we or any of our licensors is forced to grant a license to third parties with respect to any patents relevant to our business, our competitive position may be impaired and our business and results of operations may be adversely affected.

Intellectual property rights do not necessarily address all potential threats to our competitive advantage.

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have limitations, and may not adequately protect our business, or permit us to maintain our competitive advantage. The following examples are illustrative:

Changes in patent laws or patent jurisprudence could diminish the value of patents in general, thereby impairing our ability to protect our antibody candidates and technology platforms.

As is the case with other biopharmaceutical companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biopharmaceutical industry involve both technological complexity and legal complexity. Therefore, obtaining and enforcing biopharmaceutical patents is costly, time-consuming and inherently uncertain.

In September 2011, the America Invents Act (AIA) was enacted in the United States, resulting in significant changes to the U.S. patent system. An important change introduced by the AIA was a transition to a “first-to-file” system for deciding which party should be granted a patent when two or more patent applications are filed by different parties claiming the same invention, which went into effect on March 16, 2013. Therefore, a third party that now files a patent application in the USPTO before we do could be awarded a

patent covering an invention of ours even if we created the invention before it was created by the third party. While we are cognizant

of the time from invention to filing of a patent application, circumstances could prevent us from promptly filing patent applications for our inventions.

Among some of the other changes introduced by the AIA were changes that limit where a patentee may file a patent infringement suit and providing opportunities for third parties to challenge any issued patent in the USPTO. This applies to all of our U.S. patents, even those issued before March 16, 2013. Because of a lower burden of proof in USPTO proceedings compared to the burden of proof in U.S. federal courts necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action. The AIA and its continued implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications, and the patent applications of our existing and future collaborators or licensors and the enforcement or defense of our issued patents.

Depending on decisions by the U.S. Congress, the federal courts, and the USPTO, the laws and regulations governing patents could change in unpredictable ways that could weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future. Similarly, there is complexity and uncertainty related to European patent laws. For example, the European Patent Convention was amended in April 2010 to limit the time permitted for filing divisional applications. In addition, the EPO patent system is relatively stringent in the type of amendments that are allowed during prosecution. These limitations and requirements could adversely affect our ability to obtain new patents in the future that may be important for our business.

Confidentiality agreements with employees, contractors, agents, consultants, collaborators and others may not adequately prevent disclosure of trade secrets and protect other proprietary information.

We consider proprietary trade secrets and/or confidential know-how and unpatented know-how to be important to our business. We may rely on trade secrets and/or confidential know-how to protect our technology, especially where patent protection is believed to be of limited value. However, trade secrets and/or confidential know-how are difficult to maintain as confidential.

To protect this type of information against disclosure or appropriation by competitors, our policy is to require our employees, consultants, contractors, collaborators and advisors to enter into confidentiality agreements with us. However, current or former employees, consultants, contractors, collaborators and advisers may unintentionally or willfully disclose our confidential information to competitors, and confidentiality agreements may not provide an adequate remedy in the event of unauthorized disclosure of confidential information or we may be unaware of such disclosure to enforce our confidentiality agreements. Enforcing a claim that a third party obtained illegally and is using trade secrets and/or confidential know-how is expensive, time consuming and unpredictable. The enforceability of confidentiality agreements may vary from jurisdiction to jurisdiction. Furthermore, if a competitor lawfully obtained or independently developed any of our trade secrets, we would have no right to prevent such competitor from using that technology or information to compete with us, which could harm our competitive position. Additionally, if the steps taken to maintain our trade secrets are deemed inadequate, we may have insufficient recourse against third parties for misappropriating the trade secret.

Failure to obtain or maintain trade secrets and/or confidential know-how trade protection could adversely affect our competitive position. Moreover, our competitors may independently develop substantially equivalent proprietary information and may even apply for patent protection in respect of the same. If successful in obtaining such patent protection, our competitors could limit our use of our trade secrets and/or confidential know-how.

Under certain circumstances and to guarantee our freedom to operate, we may also decide to publish some know-how to prevent others from obtaining patent rights covering such know-how.

We may be subject to claims by third parties asserting that our employees or we have misappropriated their intellectual property, orclaiming ownership of what we regard as our own intellectual property.

Many of our employees, including our senior management, were previously employed at universities or at other biopharmaceutical companies, including our competitors or potential competitors. Some of these employees executed proprietary rights, non-disclosure and non-competition agreements in connection with such previous employment. Although we take measures including by policy, procedure and contract to try to ensure that our employees do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or these employees have used or disclosed confidential information or intellectual property, including trade secrets or other proprietary information, of any such employee’s former employer. Litigation may be necessary to defend against these claims.

If we fail in prosecuting or defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel or sustain damages. Such intellectual property rights could be awarded to a third party, and we could be required to obtain a license from such third party to commercialize our technology or products. Such a license may not be available on commercially reasonable terms or at all. Even if we successfully prosecute or defend against such claims, litigation could result in substantial costs and distract management.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

Periodic maintenance and annuity fees on any issued patent are due to be paid to the USPTO and foreign patent agencies in several stages over the lifetime of the patent. The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. While an inadvertent lapse can in many cases be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. Non-compliance events that could result in abandonment or lapse of a patent or patent application include failure to respond to official actions within prescribed time limits, non-payment of fees and failure to properly legalize and submit formal documents. If we or our existing or future licensors or collaborators fail to maintain the patents and patent applications covering our antibody candidates, our competitors might be able to enter the market, which would have an adverse effect on our business.

Use of social media could give rise to liability, breaches of data security, or reputational harm.

We and our employees use social media to communicate internally and externally. While we have policies and procedures in place governing employee use of social media, there is risk that the use of social media by us or our employees to communicate about our antibody candidates, technologies or business may give rise to liability, lead to the loss of trade secrets or other intellectual property, or result in public exposure of personal information of our employees, clinical trial patients, customers, and others. Furthermore, negative posts or comments about us, our clinical trials, or our antibody candidates, our technologies, and company generally in social media could seriously damage our reputation, brand image, and goodwill. Any of these events could have a material adverse effect on our business, prospects, operating results, and financial condition and could adversely affect the price of our common shares.

Our computer systems, or those used by our CROs or other contractors or consultants, may fail or suffer security breaches, which could adversely affect our business.

Despite the implementation of security measures, our computer systems and data and those of our current or future CROs or other contractors and consultants are vulnerable to compromise or damage from computer hacking, malicious software, fraudulent activity, employee misconduct, human error, telecommunication and electrical failures, natural disasters, or other cybersecurity attacks or accidents. Future acquisitions could expose us to additional cybersecurity risks and vulnerabilities from any newly acquired information technology infrastructure. Cybersecurity attacks are constantly increasing in frequency and sophistication and are made by groups and individuals with a wide range of motives (including industrial espionage) and expertise, including by organized criminal groups, “hacktivists,” nation states, and others. As a result of the COVID-19 pandemic, we may also face increased cybersecurity risks due to our reliance on internet technology and the number of our employees who are working remotely, which may create additional opportunities for cybercriminals to exploit vulnerabilities. Furthermore, because the techniques used to obtain unauthorized access to, or to sabotage, systems change frequently and often are not recognized until launched against a target, we may be unable to anticipate these techniques or implement adequate preventative measures. Further, as a company with an increasingly global presence, our systems are subject to frequent attacks, which are becoming more commonplace in the industry, including attempted hacking, phishing attempts, such as cyber-related threats involving spoofed or manipulated electronic communications, which increasingly represent considerable risk. Due to the nature of some of ~~these~~the attacks described herein, there is a risk that an attack may remain undetected for a period of time. While we continue to make investments to improve the protection of data and information technology, including in the hiring of IT personnel, and improvements to IT infrastructure and controls, there can be no assurance that our efforts will prevent service interruptions or security breaches.

Any cybersecurity incident could adversely affect our business, by leading to, for example, the loss of trade secrets or other intellectual property, demands for ransom or other forms of blackmail, or the unauthorized disclosure of personal or other sensitive information of our employees, clinical trial patients, customers, and others. Although to our knowledge we have not experienced any material cybersecurity incident to date, if such an event were to occur, it could seriously harm our development programs and our business operations. We could be subject to breach notification requirements, regulatory actions taken by governmental authorities, litigation under laws that protect the privacy of personal information, or other forms of legal proceedings, which could result in significant liabilities or penalties. Further, a cybersecurity incident may disrupt our business or damage our reputation, which could have a material adverse effect on our business, prospects, operating results, share price and shareholder value, and financial condition. We could also incur substantial remediation costs, including the costs of investigating the incident, repairing or replacing damaged systems, restoring normal business operations, implementing increased cybersecurity protections, and paying increased insurance premiums.

For example, the loss of clinical trial data from completed, ongoing or future clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data. If a security breach or other incident were to result in the unauthorized access to or unauthorized use, disclosure, release or other processing of clinical trial data or personal data, it may be necessary to notify individuals, governmental authorities, supervisory bodies, the media, and other parties pursuant to privacy and security laws. Likewise, we rely on our third-party research institution collaborators for research and development of our product candidates and other third parties for the manufacture of our product candidates and to conduct clinical trials, and similar events relating to their information technology systems could also seriously harm our business. Any security compromise affecting us, our

collaborators or our industry, whether real or perceived, could harm our reputation, erode confidence in the effectiveness of our security measures, and lead to regulatory scrutiny. To the extent that any disruption or security breach were to result in a loss of, or damage to, our data or systems, or inappropriate disclosure of confidential or proprietary or personal information, we could incur liability, our competitive position could be harmed, and the further development and commercialization of our product candidates could be delayed.

Our future growth and ability to compete depends on retaining our key personnel, recruiting additional qualified personnel and managing transitions among these personnel, such as the ~~recent transition of our former President and Chief Executive Officer, and recent resignations~~2020 resignation of our former Chief Medical Officer, hiring of our new Chief Medical Officer and resignation of our former Chief Scientific ~~Officer.~~Officer occurring in 2020.

Our success depends upon the contributions of our senior leaders, including our board of directors, our senior management, and other key scientific and technical personnel, many of whom have been instrumental for us and have substantial experience with our ~~therapies~~antibody candidates and related technologies. The loss of key senior management, managers and senior scientists could delay our research and development and clinical trial activities or impair our ability operate the company ~~effectively~~.effectively. In addition, the competition for qualified personnel in the biopharmaceutical and pharmaceutical field is intense, and our future success depends upon our ability to attract, retain and motivate highly-skilled scientific, technical and managerial employees. We face competition for personnel from other companies, universities, public and private research institutions and other organizations. If our recruitment and retention efforts are unsuccessful, it may be difficult for us to implement our business strategy, which could have a material adverse effect on our business. Our success also depends on our ability to manage transitions among our senior management and retain our senior management and other key personnel. In December 2019, Ton Logtenberg, Ph.D., stepped down as an executive director, a position he held since co-founding our company in 2003, and as President, Chief Executive Officer and Principal Financial Officer, and Sven “Bill” Lundberg, M.D. was appointed as an executive director and as President, Chief Executive Officer and Principal Financial Officer as of January 1, 2020. In April 2020, L. Andres Sirulnik, M.D., Ph.D. resigned as Executive Vice President, Chief Medical Officer effective April 24, 2020, and Andrew Joe, M.D., was appointed as ~~senior vice president~~Senior Vice President and Chief Medical Officer, effective July 27, 2020. Further, in April 2020, ~~and~~ Mark Throsby, Ph.D., resigned as the Executive Vice President and Chief Scientific Officer of the Company with an effective date of July 31, 2020. In May 2021, we appointed Dr. Cecile Geuijen as Senior Vice President and Chief Scientific Officer with an effective date of May 3, 2021. These ~~recent~~ changes in our senior management ~~may be~~were disruptive to our business, and if we are unable to continue to manage orderly transitions in these cases or for other key personnel in the future, or if we are unable to ~~recruit suitable replacements for~~adequately integrate the new Chief Scientific Officer, ~~positions,~~ or retain our other existing senior ~~leaders,~~management, managers and senior scientists, our business may be adversely affected.

We expect to expand our development, regulatory and sales and marketing capabilities, and as a result, we may encounter difficulties in managing our growth, which could disrupt our operations.

We expect to continue to experience significant growth in the number of our employees and the scope of our operations, particularly in the areas of drug and clinical development, regulatory affairs and sales and marketing. To manage our growth, we must continue to implement and improve our managerial, operational and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. Due to our limited financial resources and the limited experience of our management team in managing a company with such growth, we may not be able to effectively manage the expansion of our operations or recruit and train additional qualified personnel. The expansion of our operations may lead to significant costs and may divert our management and business development resources. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

~~The price of our common shares may be volatile and may fluctuate due to factors beyond our control.~~

The share price of publicly traded emerging biopharmaceutical and drug discovery and development companies has been highly volatile and is likely to remain highly volatile in the future. The market price of our common shares may fluctuate significantly due to a variety of factors, including:

These and other market and industry factors may cause the market price and demand for our common shares to fluctuate substantially, regardless of our actual operating performance, which may limit or prevent investors from readily selling their common shares and may otherwise negatively affect the liquidity of our common shares. In addition, the stock market in general, and biopharmaceutical companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies.

We will continue to incur increased costs as a result of operating as a public company with limited liability (naamloze vennootschap), and our management team will be required to devote substantial time to new compliance initiatives and corporate governance practices.

As a public company, and particularly after we no longer qualify as an emerging growth company or a smaller reporting company, we will continue to incur significant legal, accounting and other expenses related to our operation as a public company. The Sarbanes-Oxley Act of 2002 (SOX), the Dodd-Frank Wall Street Reform and Consumer Protection Act, the listing requirements of the Nasdaq Global Market, or Nasdaq, and other applicable securities rules and regulations impose various requirements on reporting public companies, including the establishment and maintenance of effective disclosure and financial controls and corporate governance practices. Our board of directors and other personnel will need to continue to devote a substantial amount of time to these compliance initiatives. Moreover, these rules and regulations have and will continue to increase our legal and financial compliance costs and will make some activities more time-consuming and costly.

These rules and regulations are often subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices.

Pursuant to Section 404 of SOX (Section 404) we are required to furnish a report by our management on our internal control over financial reporting with our Annual Report on Form 10-K. While we remain an emerging growth company, we will not be required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. To maintain compliance with Section 404, we engage in a process to document and evaluate our internal control over financial reporting, which is both costly and challenging. In this regard, we continue to dedicate internal resources and have engaged outside consultants and adopted a detailed work plan to assess and document the adequacy of our internal control over financial reporting, continue steps to improve control processes as appropriate, validate through testing that controls are functioning as documented and implement a continuous reporting and improvement process for internal control over financial reporting. Despite our efforts, there is a risk that we will not be able to maintain effective internal control over financial reporting as required by Section 404. Material weaknesses in our internal control over financial reporting could also reduce our ability to obtain financing or could increase the cost of any financing we obtain. If we identify one or more material weaknesses, it could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

Future sales, or the possibility of future sales, of a substantial number of our common shares could adversely affect the price of the shares.

Sales of a substantial number of shares of our common stock in the public market, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock. We have registered and intend to continue to register all common shares that we may issue under our equity compensation plans. Once registered, these common shares can be freely sold in the public market upon issuance, subject to volume limitations applicable to affiliates who hold such shares. In addition, in connection with entering into the Collaboration Agreement, we entered into a Share Subscription Agreement with Incyte, pursuant to which we issued and sold to Incyte 3,200,000 of our common shares. Incyte’s ability to sell these common shares is subject to certain limitations, including limitations on the volume of shares that may be sold during a given time period. On August 21, 2019, we filed a Registration Statement on Form F-3, as amended by Post-Effective Amendment No. 1 to Form F-3 on Form S-3, to register the shares of common stock sold to Incyte. As a result, these shares can be freely sold in the public market. In ~~addition, in~~ connection with entering into a settlement agreement with Regeneron Pharmaceuticals, we entered into a Share Subscription Agreement with Regeneron, pursuant to which we issued and sold to Regeneron 600,000 of our common shares. Regeneron’s ability to sell these common shares is subject to certain limitations, including limitations on the volume of shares that may be sold during a given time period. In addition, in connection with entering into the Lilly Collaboration Agreement, we entered into a Lilly Share Subscription Agreement with Eli Lilly, pursuant to which we issued and sold to Eli Lilly 706,834 of our common shares. Eli Lilly’s ability to sell these common shares is subject to certain limitations, including that Eli Lilly has agreed not to transfer, sell, or otherwise dispose of the shares for a certain period of time following the closing date, subject to certain customary exceptions.

Provisions of our articles of association or Dutch corporate law might deter acquisition bids for us that might be considered favorable and prevent or frustrate any attempt to replace or remove the then board of directors.

Provisions of our articles of association may make it more difficult for a third party to acquire control of us or effect a change in our board of directors. These provisions include:

As of May 1, 2021 a statutory cooling-off period of up to 250 days has been introduced in the Netherlands. When such cooling-off period is invoked, our general meeting of shareholders cannot dismiss, suspend or appoint members of the board of directors (or amend the provisions in our articles of association dealing with those matters) unless those matters would be proposed by the board of directors. This cooling-off period could be invoked by the board of directors in case:

The cooling-off period, if invoked, ends at occurrence of the earliest of the following events:

In addition, shareholders representing at least 3% of our issued share capital may request the Dutch Enterprise Chamber of the Amsterdam Court of Appeals for early termination of the cooling-off period. The Dutch Enterprise Chamber of the Amsterdam Court of Appeals must rule in favor of the request if the shareholders can demonstrate that:

During the cooling-off period, if invoked, the board of directors must gather all relevant information necessary for a careful decision-making process. In this context, the board of directors must at least consult with shareholders representing at least 3% of our issued share capital at the time the cooling-off period was invoked and the works council. Formal statements expressed by these stakeholders during such consultations must be published on our website to the extent these stakeholders have approved that publication.

Ultimately one week following the last day of the cooling-off period, the board of directors must publish a report in respect of its policy and conduct of affairs during the cooling-off period on our website. This report must remain available for inspection by shareholders and others with meeting rights under Dutch law at our office and must be tabled for discussion at the next general meeting of shareholders. This legislation may make it more difficult for a third party or group of third parties to acquire control of us or effect a change in our board of directors.

We adopted an anti-takeover measure pursuant to which our board of directors may, without shareholder approval, issue (or grant the right to acquire) preferred shares. Pursuant to a call option agreement entered into with an independent special purpose foundation, we may issue an amount of preferred shares up to 100% of our issued capital held by third parties immediately prior to the issuance of such preferred shares.

The preferred shares will be issued to the foundation for their nominal value, of which only 25% will be due upon issuance. The voting rights of our shares are based on nominal value and as we expect our shares to continue to trade substantially in excess of nominal value, preferred shares issued at nominal value can obtain significant voting power for a substantially reduced price and thus be used as a defensive measure. These preferred shares will have both a liquidation and dividend preference over our common shares and will accrue cash dividends at a fixed rate. Subject to the foundation exercising its call option under the call option agreement, the board may issue these preferred shares to protect us from influences that we believe do not serve our best interests and threaten to undermine our continuity, independence and identity. These influences may include a third-party acquiring a significant percentage of our common shares, the announcement of a public offer for our common shares, other concentration of control over our common shares or any other form of pressure on us to alter our strategic policies. The foundation’s articles of association provide that it will act to serve the best interests of us, our associated business and all parties connected to us, by opposing any influences that conflict with these interests and threaten to undermine our continuity, independence and identity. This foundation is structured to operate independently of us.

Because we do not expect to pay cash dividends for the foreseeable future, any returns on an investment in our common shares will likely depend entirely upon any future appreciation in the price of our common shares, which is uncertain.

We have not paid any cash dividends since our incorporation. Even if future operations lead to significant levels of distributable profits, we currently intend that any earnings will be reinvested in our business and that cash dividends will not be paid until we have an established revenue stream to support continuing cash dividends. Payment of any future dividends to shareholders will in addition effectively be at the discretion of the general meeting, upon proposal of the board of directors, after taking into account various factors including our business prospects, cash requirements, financial performance and new product development. In addition, payment of future cash dividends may be made only if our shareholders’ equity exceeds the sum of our paid-in and called-up share capital plus the reserves required to be maintained by Dutch law or by our articles of association. Accordingly, investors cannot rely on cash dividend income from our common shares and any returns on an investment in our common shares will likely depend entirely upon any future appreciation in the price of our common shares. In addition, the low trading volume of our common shares may adversely affect the trading price of our common shares, and our shareholders may not be able to sell their common shares for a price higher than the price they paid for our common shares.

Holders of our common shares outside the Netherlands may not be able to exercise preemptive rights.

In the event of an increase in our share capital, holders of our common shares are generally entitled under Dutch law to full preemptive rights, unless these rights are excluded either by a resolution of the general meeting of shareholders, or by a resolution of the board (if the board has been designated by the general meeting of shareholders for this purpose). Certain holders of our common shares outside the Netherlands, in particular U.S. holders of our common shares, may not be able to exercise preemptive rights unless a registration statement under the Securities Act is declared effective with respect to our common shares issuable upon exercise of such rights or an exemption from the registration requirements is available.

The rights of our shareholders may be different from the rights of shareholders in companies governed by the laws of U.S. jurisdictions.

We are a Dutch public company with limited liability (naamloze vennootschap). Our corporate affairs are governed by our articles of association and by the laws governing companies incorporated in the Netherlands. The rights of shareholders and the responsibilities of members of our board may be different from the rights and obligations of shareholders in companies governed by the laws of U.S. jurisdictions. In the performance of its duties, our board is required by Dutch law to consider the interests of our company, its shareholders, its employees and other stakeholders, in all cases with due observation of the principles of reasonableness and fairness. It is possible that some of these parties will have interests that are different from, or in addition to, the interests of our shareholders.

We are not obligated to and do not comply with all the best practice provisions of the Dutch Corporate Governance Code. This may affect the rights of our shareholders.

We are subject to the Dutch Corporate Governance Code (DCGC). The DCGC contains both principles and best practice provisions for board of directors, shareholders and general meetings of shareholders, financial reporting, auditors, disclosure, compliance and enforcement standards. The DCGC applies to all Dutch companies listed on a government-recognized stock exchange, whether in the Netherlands or elsewhere, including Nasdaq. The principles and best practice provisions apply to our board (in relation to role and composition, conflicts of interest and independence requirements, board committees and remuneration), shareholders and the general meeting of shareholders (for example, regarding anti-takeover protection and our obligations to provide information to our shareholders) and financial reporting (such as external auditor and internal audit requirements). We do not comply with all the best practice provisions of the DCGC. As a result, the rights of our shareholders may be affected and our shareholders may not have the same level of protection as a shareholder in another Dutch public company with limited liability (naamloze vennootschap) listed in the Netherlands that fully complies with the DCGC.

We are incorporated under the laws of the Netherlands. Most of our assets are located outside the United States. The United States and the Netherlands currently do not have a treaty providing for the reciprocal recognition and enforcement of judgments, other than arbitration awards, in civil and commercial matters. With respect to choice of court agreements in civil or commercial matters, we note that the Hague Convention on Choice of Court Agreements entered into force for the Netherlands, but has not entered into force for the United States. Consequently, a final judgment for payment given by a court in the United States, whether or not predicated solely upon U.S. securities laws, would not automatically be recognized or enforceable in the Netherlands. In order to obtain a judgment which is enforceable in the Netherlands, the party in whose favor a final and conclusive judgment of the U.S. court has been rendered will be required to file its claim with a court of competent jurisdiction in the Netherlands. Such party may submit to the Dutch court the final judgment rendered by the U.S. court. If and to the extent that the Dutch court finds that the jurisdiction of the U.S. court has been based on grounds which are internationally acceptable and that proper legal procedures have been observed, the court of the Netherlands will, in principle, give binding effect to the judgment of the U.S. court, unless such judgment contravenes

principles of public policy of the Netherlands or is irreconcilable with a judgement of a Dutch court or foreign court that is acknowledged in the Netherlands. Dutch courts may deny the recognition and enforcement of punitive damages or other awards. Moreover, a Dutch court may reduce the amount of damages granted by a U.S. court and recognize damages only to the extent that they are necessary to compensate actual losses or damages. Enforcement and recognition of judgments of U.S. courts in the Netherlands are solely governed by the provisions of the Dutch Code of Civil Procedure (Wetboek van Burgerlijke Rechtsvordering). As a result of the above, it may not be possible for investors to effect service of process within the United States upon us or members of our board or certain experts named herein who are residents of the Netherlands or countries other than the United States or to enforce any judgments against the same obtained in U.S. courts in civil and commercial matters, including judgments under the U.S. federal securities laws.

As of January 1, 2020, we were no longer a foreign private issuer, and we are required to comply with the provisions of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and the rules of Nasdaq applicable to U.S. domestic issuers, which will continue to require us to incur significant expenses and expend time and resources.

As of January 1, 2020, we were no longer a foreign private issuer, and we are required to comply with all of the provisions applicable to a U.S. domestic issuer under the Exchange Act, including filing an annual report on Form 10-K, quarterly periodic reports and current reports for certain events, complying with the sections of the Exchange Act regulating the solicitation of proxies, requiring insiders to file public reports of their share ownership and trading activities and insiders being liable for profit from trades made in a short period of time. We are also no longer exempt from the requirements of Regulation FD promulgated under the Exchange Act related to selective disclosures. We are also no longer permitted to follow our home country’s rules in lieu of the corporate governance obligations imposed by Nasdaq, and are required to comply with the governance practices required by U.S. domestic issuers listed on Nasdaq. We are also required to comply with all other rules of Nasdaq applicable to U.S. domestic issuers, including that our articles of association specify a quorum of no less than one-third of our outstanding voting common shares for meetings of our common shareholders, the solicitation of proxies and the approval by our shareholders in connection with certain events such as the acquisition

of stock or assets of another company, the establishment of or amendments to equity-based compensation plans for employees, a change of control and certain private placements. In addition, we are required to report our financial results under U.S. Generally Accepted Accounting Principles, including our historical financial results, which have previously been prepared in accordance with International Financial Reporting Standards. We expect to continue to incur significant legal, accounting, insurance and other expenses and to expend greater time and resources to comply with these requirements. In addition, we may need to develop our reporting and compliance infrastructure and may face challenges in complying with the new requirements applicable to us.

Our articles of association include a U.S. federal forum selection clause designating federal courts as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our shareholders, which could limit our shareholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers, or employees.

Our articles of association provide that, unless we consent in writing to an alternative forum, the sole and exclusive forum for any complaint asserting a cause of action arising under the Securities Act, to the fullest extent permitted by applicable law, shall be the federal district courts of the United States of America (the “Federal Forum Provision”). The Federal Forum Provision in our articles of association may impose additional litigation costs on shareholders in pursuing any such claims. Additionally, the forum selection clause may limit our shareholders’ ability to bring a claim in a forum that they find favorable for disputes with us or our directors, officers or employees, which may discourage such lawsuits against us and our directors, officers and employees even though an action, if successful, might benefit our shareholders. In addition, while the Delaware Supreme Court ruled in March 2020 that federal forum selection provisions purporting to require claims under the Securities Act be brought in federal court were “facially valid” under Delaware law, there is uncertainty as to whether other courts will enforce our Federal Forum Provision. If the Federal Forum Provision is found to be unenforceable, we may incur additional costs associated with resolving such matters. The Federal Forum Provision may also impose additional litigation costs on shareholders who assert that the provision is not enforceable or invalid. The Court of Chancery of the State of Delaware and the United States District Court for the District of Massachusetts may also reach different judgments or results than would other courts, including courts where a shareholder considering an action may be located or would otherwise choose to bring the action, and such judgments may be more or less favorable to us than our shareholders.

We are an “emerging growth company” and a “smaller reporting company,” and we cannot be certain if the reduced reporting requirements applicable to emerging growth companies and smaller reporting companies will make our common shares less attractive to investors.

We are an emerging growth company, as defined in the Jumpstart Our Business Startups Act and a smaller reporting company under the rules promulgated under the Exchange Act. For as long as we continue to be an emerging growth company, we may take advantage of exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies, including not being required to comply with the auditor attestation requirements of Section 404, exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved, and reduced executive compensation disclosure. We may take advantage of these exemptions until we are no longer an emerging growth company. We could be an emerging growth company for up to five years following the initial public offering of our common shares, although circumstances could cause us to lose that status earlier, including if the aggregate market value of our common shares held by non-affiliates exceeds $700 million as of the end of our second fiscal quarter, in which case we would no longer be an emerging growth company as of the fiscal year-end.

We are also a smaller reporting company, and we will remain a smaller reporting company until the fiscal year following the determination that our voting and non-voting common shares held by non-affiliates is more than $250 million measured on the last business day of our second fiscal quarter, or our annual revenues are more than $100 million during the most recently completed fiscal year and our voting and non-voting common shares held by non-affiliates is more than $700 million measured on the last business day of our second fiscal quarter. Similar to emerging growth companies, smaller reporting companies are able to provide simplified executive compensation disclosure, and have certain other reduced disclosure obligations, including, among other things, being required to provide only two years of audited financial statements and not being required to provide selected financial data or supplemental financial information.

We cannot predict if investors will find our common shares less attractive because we may rely on these exemptions. If some investors find our common shares less attractive as a result, there may be a less active trading market for our common shares and the price of our common shares may be more volatile.

~~If securities or industry analysts publish inaccurate or unfavorable research about our business, the price of our common shares and our trading volume could decline.~~

The trading market for our common shares depends in part on the research and reports that securities or industry analysts publish about us or our business. If one or more of the analysts who cover us downgrade our common shares or publish inaccurate or unfavorable research about our business, the price of our common shares would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us regularly, demand for our common shares could decrease, which might cause the price of our common shares and trading volume to decline.

We may be classified as a passive foreign investment company (PFIC) for U.S. federal income tax purposes, which could result in adverse U.S. federal income tax consequences to U.S. investors in our common shares.

Based on the value of our assets, including goodwill, and composition of our income, assets and operations for the taxable year ~~2019,~~2020, we do not believe we were a PFIC for U.S. federal income tax purposes for that taxable year. A non-U.S. company generally will be considered a PFIC for any taxable year if (i) at least 75% of its gross income is passive income (including interest income), or (ii) at least 50% of the value of its assets (based on an average of the quarterly values of the assets during a taxable year) is attributable to assets that produce or are held for the production of passive income. The value of our assets generally is determined by reference to the market price of our common shares, which may fluctuate considerably. In addition, the composition of our income and assets is affected by how, and how quickly, we spend the cash we raise. It is possible the Internal Revenue Service could determine that we were a PFIC for the taxable year ~~2019.~~2020. If we were to be treated as a PFIC for any taxable year during which a U.S. Holder holds a common share, certain adverse U.S. federal income tax consequences could apply to such U.S. Holder. Once treated as a PFIC, for any taxable year in which a U.S. Holder owns equity in such foreign corporation, a foreign corporation will generally continue to be treated as a PFIC for all subsequent taxable years with respect to such U.S. Holder. If we were to be a PFIC, ~~and a U.S. Holder does not make an election to treat us~~“excess distributions” (as such term is defined in the United States Internal Revenue Code of 1986, as ~~a qualified electing fund (QEF) or a mark-to-market election, excess distributions~~amended (U.S. Tax Code)) to a U.S. Holder, and any gain recognized by a U.S. Holder on a disposition of our ~~ordinary~~common shares would be taxed in anpotentially unfavorable ~~way.~~ways. Among other consequences, our dividends would be taxed at the regular rates applicable to ordinary income, rather than the 20% maximum rate

applicable to certain dividends received by an individual from a qualified foreign corporation, and, to the extent that they constituted excess distributions, certain interest charges may ~~apply. In addition,~~apply, and gains on the sale of our shares would be treated in the same way as excess distributions. In addition, the U.S. Holder would be subject to detailed reporting obligations. The tests for determining PFIC status are applied annually and it is difficult to make accurate predictions of future income and assets, which are relevant to the determination of any future PFIC status. As such, we cannot provide any assurances regarding our PFIC status for any past, current or future taxable years. Further, we cannot provide any assurances that we will furnish to any U.S. Holder information that may be necessary to comply with the aforementioned reporting and tax payment obligations. U.S. Holders should consult their tax advisors regarding the potential application of these rules to their investment in our common ~~shares.~~shares, including the potential availability and advisability of an election to treat us as a qualified electing fund or a mark-to-market election. A “U.S. Holder” is a holder who, for U.S. federal income tax purposes, is a beneficial owner of our common shares and is:

If a U.S. ~~holder~~Holder is treated as owning at least 10% of our common shares, such holder may be subject to adverse U.S. federal income tax consequences.

If a U.S. ~~holder~~Holder is treated as owning (directly, indirectly or constructively) at least 10% of the value or voting power of our common shares, such U.S. ~~holder~~Holder may be treated as a “United States shareholder” with respect to each “controlled foreign corporation” in our group (if any) as such term is defined in the Tax Code. A United States shareholder of a controlled foreign corporation may be required to report annually and include in its U.S. taxable income, as ordinary income, its pro rata share of “Subpart F income,” “global intangible low-taxed income” and investments in U.S. property by controlled foreign corporations, regardless of whether we make any distributions. An individual that is a United States shareholder with respect to a controlled foreign corporation generally would not be allowed certain tax deductions or foreign tax credits that would be allowed to a United States shareholder that is a corporation. Failure to comply with these reporting obligations may subject a United States shareholder to significant monetary penalties and may extend the statute of limitations with respect to such United States shareholder’s U.S. federal income tax return for the year for which reporting was due. We cannot provide any assurances that we will assist investors in determining whether we or

any of our future non-U.S. subsidiaries is treated as a controlled foreign corporation or whether such investor is treated as a United States shareholder with respect to any such controlled foreign corporations. Further, we cannot provide any assurances that we will furnish to any United States shareholders information that may be necessary to comply with the aforementioned reporting and tax payment obligations. U.S. ~~holders~~Holders should consult their tax advisors regarding the potential application of these rules to their investment in our common shares. The risk of being subject to increased taxation may deter our current shareholders from increasing their investment in us and others from investing in us, which could impact the demand for, and value of, our common shares.

~~Comprehensive tax reform legislation could adversely affect our business and financial condition.~~General Risk Factors

~~On December 22, 2017, the U.S. government enacted the TCJA, a comprehensive tax legislation that includes significant changes to the taxation of business entities.~~ The TCJA remains unclear in many respects and has been, and may continue to be, the subject of amendments and technical corrections, as well as interpretations and implementing regulations by the Treasury and Internal Revenue Service, which have lessened or increased certain adverse impacts of the TCJA and may do so in the future. We continue to examine the impact the TCJA may have on our business. The effect of the TCJA on our business, whether adverse or favorable, is uncertain, and may not become evident for some period of time. Holdersprice of our common shares ~~should consult~~may be volatile and may fluctuate due to factors beyond our control.

These and other market and industry factors may cause the market price and demand for our common shares to fluctuate substantially, regardless of our actual operating performance, which may limit or prevent investors from readily selling their ~~legal~~common shares and ~~tax advisors regarding~~may otherwise negatively affect the ~~TCJA~~liquidity of our common shares. In addition, the stock market in general, and biopharmaceutical companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the ~~potential tax consequences~~operating performance of ~~investing~~these companies.

If securities or industry analysts publish inaccurate or unfavorable research about our business, the price of our common shares and our trading volume could decline.

The exhibits filed as part of this Quarterly Report on Form 10-Q are as follows:

Incorporated by Reference to

Filings Indicated

Incorporated by Reference to

Filings Indicated

Exhibit

Number

Exhibit Description

Form

File No.

Exhibit

No.

Filing

Date

Filed/

Furnished

Exhibit Description

Form

File No.

Exhibit

No.

Filing

Date

Filed/

Furnished

3.1

Articles of Association of Merus N.V., as amended on December 5, 2019

6-K

001-37773

12/6/19

10.1

Employment Agreement, dated July 2, 2020 between Andrew Joe and Merus US, Inc.

10-Q

001-37773

10.4

8/6/20

10.2

Open Market Sale Agreement, dated as of August 6, 2020, by and between Merus N.V. and Jefferies LLC

8-K

001-37773

10.1

8/7/20

10.3

Employment Agreement, dated August 20, 2020 between Peter Silverman and Merus N.V.

3.2

Articles of Association of Merus N.V., as amended on May 28, 2021

8-K

001-37773

3.1

5/28/21

10.3.4

English language translation of the Lease dated June 3, 2021, by and between the Registrant and Stichting Incubator Utrecht

31.1

Certification of Principal Executive Officer and Principal Financial Officer pursuant to rules 13a-14(a) and 15d-14(a) under the Securities and Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

32.1

Certification of Principal Executive Officer and Principal Financial Officer Pursuant to 18 U.S.C. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

101.INS

Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document

101.SCH

Inline XBRL Taxonomy Extension Schema Document.

101.CAL

Inline XBRL Taxonomy Calculation Linkbase Document.

101.DEF

Inline XBRL Taxonomy Extension Definition Linkbase Document.

101.LAB

Inline XBRL Taxonomy Label Linkbase Document.

101.PRE

Inline XBRL Taxonomy Presentation Linkbase Document.

��

Inline XBRL Taxonomy Presentation Linkbase Document.

104

Cover Page Interactive Data File (embedded within the Inline XBRL document)

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Large accelerated filer	☐	Accelerated filer	☒
			☐
Non-accelerated filer	☐☒	Smaller reporting company	☒

		Emerging growth company	☒

PART I — FINANCIAL INFORMATION

Item 1. Financial Statements	2

Condensed Consolidated Balance Sheets as of ~~September~~June 30, ~~2020~~2021 and December 31, ~~2019~~2020	2

Condensed Consolidated Statements of Operations and Comprehensive Loss for the three and ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 and ~~2019~~2020	3

Condensed Consolidated Statements of Cash Flows for the ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 and ~~2019~~2020	4

Condensed Consolidated Statements of Changes in Stockholders’ Equity for three and ~~nine~~six months ended ~~September~~June 30, ~~2020~~2021 and ~~2019~~2020	5

Notes to Condensed Consolidated Financial Statements	6

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations	1415

Item 3. Quantitative and Qualitative Disclosures About Market Risk	2021

Item 4. Controls and Procedures	2021

PART II — OTHER INFORMATION

Item 1. Legal Proceedings	2123

Item 1A. Risk Factors	2123

Item 5. Other Information	6165

Item 6. Exhibits	6165

Signatures	6266


	•	We have incurred significant net losses since inception and we expect to continue to incur significant net losses for the foreseeable future.
	•	We have a limited operating history, have not successfully completed any clinical trials, and have no products approved for commercial sale, which may make it difficult for you to evaluate our current business and predict our future success and viability.
	•	We will require substantial additional capital to finance our operations. If we are unable to raise such capital when needed, or on acceptable terms, we may be forced to delay, reduce or eliminate one or more of our research and drug development programs or future commercialization efforts.
	•	The outcome of preclinical testing and early phases of clinical trials may not be predictive of the success of later phases of clinical trials, and the results of our clinical trials may not satisfy the requirements of the FDA, EMA or other comparable foreign regulatory authorities.
	•	The clinical trial and regulatory approval processes are lengthy, time consuming and inherently unpredictable, and we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our product candidates.
	•	Our antibody candidates may have serious adverse, undesirable or unacceptable side effects which may delay or prevent marketing approval. If such side effects are identified during the development of our antibody candidates or following approval, if any, we may need to abandon our development of such antibody candidates, the commercial profile of any approved label may be limited, or we may be subject to other significant negative consequences following marketing approval, if any.


	•	We depend on enrollment of patients in our clinical trials for our antibody candidates, including patients having NRG1 fusion tumors, which are rare, tumorigenic genomic events. If we are unable to enroll patients in our clinical trials, including those having these rare tumorigenic events, our research and development efforts and business, financial condition and results of operations could be materially adversely affected.
	•	We rely, and expect to continue to rely, on third parties, including independent clinical investigators and contract research organizations or CROs, to conduct our pre-clinical studies and clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines, we may not be able to obtain regulatory approval for or commercialize our antibody candidates and our business could be substantially harmed.


	•	Due to our limited resources and access to capital, we must, and have in the past decided to prioritize development of certain antibody candidates over other potential candidates. These decisions may prove to have been wrong and may adversely affect our revenues.
	•	The competition for qualified personnel is particularly intense in our industry. If we are unable to retain or hire key personnel, we may not be able to sustain or grow our business.


	•	We operate in highly competitive and rapidly changing industries, and if our competitors develop and market technologies or products more rapidly than we do or that are more effective, safer or less expensive than the product candidates we develop, our commercial opportunities will be negatively impacted.
	•	Our success depends on our ability to protect our intellectual property and our proprietary technologies. If we are unable to adequately protect our intellectual property and our proprietary technologies, or obtain and maintain issued patents which are sufficient to protect our product candidates, others could compete against us more directly, which would negatively impact our business.


	•	Our existing collaborations are important to our business and future licenses may also be important to us, and if we are unable to maintain any of these collaborations, or if these arrangements are not successful, our business could be adversely affected.
	•	The COVID-19 pandemic caused by the novel coronavirus has and may continue to adversely impact our business, including our pre-clinical studies and clinical trials, financial condition and results of operations.

Volatility	87.2	%
Risk-free interest rate	0.6	%
Expected holding period (in years)	6.1
Dividend yield	-

*	Filed herewith.
**	Furnished herewith.
†	Portions of the exhibit have been omitted. Certain identified information has been excluded from the exhibit because it is both (i) not material and (ii) would be competitively harmful if publicly disclosed.

MERUS N.V.

By:	/s/ Sven A. Lundberg
	Sven (Bill) Ante Lundberg
	President, Chief Executive Officer and Principal Financial Officer