Merus (MRUS) 10-Q 6 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Registrant Name	Merus N.V.
Trading Symbol	MRUS
Entity Central Index Key	0001651311
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		29,057,121
Entity File Number	001-37773
Entity Incorporation, State or Country Code	P7
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	Yalelaan 62
Entity Address, City or Town	Utrecht
Entity Address, Postal Zip Code	3584 CM
Entity Address, Country	NL
City Area Code	+31 85
Local Phone Number	016 2500
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common shares, nominal value €0.09 per share
Security Exchange Name	NASDAQ

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 152,088	$ 197,612
Marketable securities	45,278	42,153
Accounts receivable	142	941
Accounts receivable (related party)	1,809	1,711
Prepaid expenses and other current assets	12,087	4,951
Total current assets	211,404	247,368
Marketable securities		2,009
Property and equipment, net	3,617	3,715
Operating lease right-of-use assets	4,531	5,215
Intangible assets, net	2,731	2,876
Deferred tax assets	210	288
Other assets	1,168	1,905
Total assets	223,661	263,376
Current liabilities:
Accounts payable	2,362	3,029
Accrued expenses	15,931	13,536
Current portion of lease obligation	1,451	1,380
Current portion of deferred revenue	727	941
Current portion of deferred revenue (related party)	17,844	17,901
Total current liabilities	38,315	36,787
Lease obligation	3,119	3,872
Deferred revenue, net of current portion	457	780
Deferred revenue, net of current portion (related party)	81,474	90,637
Total liabilities	123,365	132,076
Stockholders’ equity:
Common shares	2,935	2,918
Additional paid-in capital	445,754	441,395
Accumulated other comprehensive (loss) income	680	1,586
Accumulated deficit	(349,073)	(314,599)
Total stockholders’ equity	100,296	131,300
Total liabilities and stockholders’ equity	$ 223,661	$ 263,376

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - € / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common shares, par value	€ 0.09	€ 0.09
Common shares, authorized	45,000,000	45,000,000
Common shares, issued	29,047,344	28,882,217
Common shares, outstanding	29,047,344	28,882,217

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total revenue	$ 6,056	$ 6,357	$ 12,357	$ 15,186
Operating expenses:
Research and development	13,709	10,768	30,696	22,567
General and administrative	8,043	8,214	16,925	14,955
Total operating expenses	21,752	18,982	47,621	37,522
Operating loss	(15,696)	(12,625)	(35,264)	(22,336)
Other income (loss), net:
Interest income, net	99	535	379	1,165
Foreign exchange gains (losses)	(2,346)	(1,214)	539	1,006
Other income (loss), net	(2,247)	(679)	918	2,171
Net loss before income taxes	(17,943)	(13,304)	(34,346)	(20,165)
Tax expense	31	71	128	293
Net loss	(17,974)	(13,375)	(34,474)	(20,458)
Other comprehensive income (loss):
Currency translation adjustment	2,201	1,098	(906)	(802)
Comprehensive loss	$ (15,773)	$ (12,277)	$ (35,380)	$ (21,260)
Net loss per share attributable to common stockholders: Basic and diluted	$ (0.54)	$ (0.52)	$ (1.22)	$ (0.91)
Weighted-average common shares outstanding: Basic and diluted	29,034	23,388	28,990	23,380
Collaboration Revenue [Member]
Total revenue from contracts with customers	$ 184	$ 336	$ 512	$ 1,938
Collaboration Revenue (Related Party) [Member]
Total revenue from contracts with customers	$ 5,872	6,144	$ 11,845	13,371
Grant Revenue [Member]
Total revenue from contracts with customers		$ (123)		$ (123)

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (34,474)	$ (20,458)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of property and equipment	532	393
Amortization of intangible assets	134	112
Foreign exchange gain	(503)	(789)
Loss on disposal of property and equipment	16	0
Stock-based compensation expense	3,483	3,120
Amortization of discount on investments	(79)	(365)
Deferred tax expense	78	158
Changes in operating assets and liabilities:
Accounts receivable	681	1,648
Operating lease right-of-use assets and lease obligations	3	(143)
Prepaid expenses and other current assets	(6,441)	(2,739)
Accounts payable	(599)	(1,323)
Accrued expenses	2,556	(318)
Deferred revenue	(9,255)	(8,576)
Net cash used in operating activities	(43,868)	(29,280)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(28,947)	(34,417)
Proceeds from maturities of marketable securities	28,181	50,934
Purchases of intangible assets	0	(178)
Purchases of property and equipment	(512)	(770)
Net cash (used in) provided by investing activities	(1,278)	15,569
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs	(164)	0
Proceeds from stock options exercised	893	31
Net cash provided by financing activities	729	31
Foreign exchange impact on cash, cash equivalents and restricted cash	(1,107)	(701)
Net decrease in cash, cash equivalents and restricted cash	(45,524)	(14,381)
Cash, cash equivalents, and restricted cash, beginning of period	197,813	164,730
Cash, cash equivalents, and restricted cash, end of period	152,289	150,349
SUPPLEMENTAL DISCLOSURES:
Income taxes paid	25	171
Non-cash purchases of property, equipment and intangibles	35	230
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents	152,088	150,209
Restricted cash included in non-current other assets	201	140
Cash, cash equivalents, and restricted cash, end of period	$ 152,289	$ 150,349

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2018	$ 105,857	$ 2,366	$ 360,045	$ (259,448)	$ 2,894
Beginning balance, shares at Dec. 31, 2018		23,358,977
Exercise of stock options and vesting of restricted stock units	28	$ 2	26	0	0
Exercise of stock options and vesting of restricted stock units, shares		20,678
Stock-based compensation	1,260	$ 0	1,260	0	0
Currency translation adjustment	(1,900)	0	0	0	(1,900)
Net loss	(7,083)	0	0	(7,083)	0
Ending balance at Mar. 31, 2019	98,162	$ 2,368	361,331	(266,531)	994
Ending balance, shares at Mar. 31, 2019		23,379,655
Beginning balance at Dec. 31, 2018	105,857	$ 2,366	360,045	(259,448)	2,894
Beginning balance, shares at Dec. 31, 2018		23,358,977
Currency translation adjustment	(802)
Net loss	(20,458)
Ending balance at Jun. 30, 2019	87,749	$ 2,370	363,193	(279,906)	2,092
Ending balance, shares at Jun. 30, 2019		23,393,287
Beginning balance at Mar. 31, 2019	98,162	$ 2,368	361,331	(266,531)	994
Beginning balance, shares at Mar. 31, 2019		23,379,655
Exercise of stock options and vesting of restricted stock units	4	$ 2	2	0	0
Exercise of stock options and vesting of restricted stock units, shares		13,632
Stock-based compensation	1,860	$ 0	1,860	0	0
Currency translation adjustment	1,098	0	0	0	1,098
Net loss	(13,375)	0	0	(13,375)	0
Ending balance at Jun. 30, 2019	87,749	$ 2,370	363,193	(279,906)	2,092
Ending balance, shares at Jun. 30, 2019		23,393,287
Beginning balance at Dec. 31, 2019	131,300	$ 2,918	441,395	(314,599)	1,586
Beginning balance, shares at Dec. 31, 2019		28,882,217
Exercise of stock options and vesting of restricted stock units	602	$ 13	589	0	0
Exercise of stock options and vesting of restricted stock units, shares		127,205
Stock-based compensation	2,291	$ 0	2,291	0	0
Currency translation adjustment	(3,107)	0	0	0	(3,107)
Net loss	(16,500)	0	0	(16,500)	0
Ending balance at Mar. 31, 2020	114,586	$ 2,931	444,275	(331,099)	(1,521)
Ending balance, shares at Mar. 31, 2020		29,009,422
Beginning balance at Dec. 31, 2019	131,300	$ 2,918	441,395	(314,599)	1,586
Beginning balance, shares at Dec. 31, 2019		28,882,217
Currency translation adjustment	(906)
Net loss	(34,474)
Ending balance at Jun. 30, 2020	100,296	$ 2,935	445,754	(349,073)	680
Ending balance, shares at Jun. 30, 2020		29,047,344
Beginning balance at Mar. 31, 2020	114,586	$ 2,931	444,275	(331,099)	(1,521)
Beginning balance, shares at Mar. 31, 2020		29,009,422
Exercise of stock options and vesting of restricted stock units	291	$ 4	287	0	0
Exercise of stock options and vesting of restricted stock units, shares		37,922
Stock-based compensation	1,192	$ 0	1,192	0	0
Currency translation adjustment	2,201	0	0	0	2,201
Net loss	(17,974)	0	0	(17,974)	0
Ending balance at Jun. 30, 2020	$ 100,296	$ 2,935	$ 445,754	$ (349,073)	$ 680
Ending balance, shares at Jun. 30, 2020		29,047,344

Overview

Overview	6 Months Ended
	Jun. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Overview	1. Overview 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 $349.1 million as of June 30, 2020. 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 with third parties and business development opportunities. 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. Based on the Company’s current operating plan, the Company expects that its existing cash and cash equivalents and marketable securities of $197.4 million as of June 30, 2020 will be sufficient to fund its operations into the second half of 2022.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies 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, and the notes thereto, which are included in the Company’s 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 Report on Form 10-K”). There have been no material changes in the Company’s significant accounting policies during the six months ended June 30, 2020. Basis of Presentation 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 June 30, 2020 and 2019 are referred to as the second quarter of 2020 and 2019, 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, included in the Annual Report on Form 10-K. Going Concern 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 , and after considering its existing cash, cash equivalents and marketable securities as of June 30, 2020 , 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 . Pending Accounting Pronouncements 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 In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808)

Investments in Debt Securities

Investments in Debt Securities	6 Months Ended
	Jun. 30, 2020
Debt Securities [Abstract]
Investments in Debt Securities	3. Investments in Debt Securities The following tables summarize the Company’s investments in debt securities and their presentation in the condensed consolidated balance sheet: June 30, 2020 December 31, 2019 (in thousands) Money market funds $ 21,906 $ 34,053 Corporate paper and notes 30,749 38,679 U.S. government agency securities 2,498 3,987 U.S. treasuries 12,031 1,496 Total $ 67,184 $ 78,215 Fair value of debt securities $ 67,355 $ 78,254 June 30, 2020 December 31, 2019 (in thousands) Cash equivalents $ 21,906 $ 34,053 Current marketable securities 45,278 42,153 Non-current marketable securities — 2,009 Total $ 67,184 $ 78,215 The Company does not intend to sell and it is unlikely that the Company will be required to sell the above investments before recovery of their amortized cost bases, which may be 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).

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	6 Months Ended
	Jun. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Supplemental Balance Sheet Information	4. Supplemental Balance Sheet Information Prepaid expenses and other current assets consisted of the following: June 30, 2020 December 31, 2019 (In thousands) Prepaid clinical and manufacturing costs $ 5,379 $ 2,779 Prepaid general and administrative expenses 2,910 789 Interest receivable 155 259 Other 3,643 1,124 Total $ 12,087 $ 4,951 Accrued expenses consisted of the following: June 30, 2020 December 31, 2019 (In thousands) Accrued research and development expenses $ 11,780 $ 6,618 Accrued general and administrative expenses 1,932 2,402 Accrued personnel costs 2,206 4,495 Other 13 21 Total $ 15,931 $ 13,536

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	5. Income Taxes 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 June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) U.S. federal $ 94 $ 44 $ 38 $ 98 U.S. state 36 17 12 37 Total current tax (benefit) expense $ 130 $ 61 $ 50 $ 135 U.S. federal $ (63 ) $ 17 $ 62 $ 122 U.S. state (36 ) (7 ) 16 36 Total deferred tax expense $ (99 ) $ 10 $ 78 $ 158 Total tax expense $ 31 $ 71 $ 128 $ 293 After consideration of all positive and negative evidence, we believe that it is more-likely-than-not that the Netherlands deferred tax assets will not be realized that are not supported by reversing temporary differences. As a result, we established a full valuation allowance against deferred tax assets of the Netherlands.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Litigation On April 5, 2018, an unnamed third party and Regeneron Pharmaceuticals Inc., or Regeneron filed notices 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 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. An opposition hearing was held 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, the Company cannot be certain that the Company 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.

Leases

Leases	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Leases	7. Leases There have been no changes in the Company’s lease arrangements since December 31, 2019. Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) Lease cost Operating lease cost $ 396 $ 347 $ 792 $ 590 Variable lease cost 107 44 189 95 Total lease cost included in operating expenses $ 503 $ 391 $ 981 $ 685 Other information Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows $ 396 $ 493 $ 789 $ 733

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborations	8. Collaborations Incyte On January 23, 2017, the Company completed the sale of shares and exchange of a license. The Company initially deferred $152.6 million of the transaction price allocated to the license and related activities 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 ® At June 30, 2020, 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. ONO On March 14, 2018, the Company granted 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 ® Amounts related to the provision of a license are amortized over the intended period of use. The Company received €1.0 million (approximately $1.1 million) for the quarter ended March 31, 2019 for development milestones received from Ono based on their progress. Simcere In January 2018, the Company granted Simcere an exclusive license to develop and commercialize three bispecific antibodies to be produced by Merus utilizing the Company’s Biclonics ® At inception of the arrangement, the Company identified three 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 one milestone under this agreement and has received an aggregate of $0.8 million in milestone payments. At June 30, 2020, research and development for three of the programs is on-going. Contract Assets and Liabilities 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 Incyte Ono Other Total CONTRACT ASSETS Accounts receivable Balance at January 1, 2020 $ — $ 786 $ — $ 786 Billings 2,952 — 150 150 Cash receipts (2,027 ) (772 ) — (772 ) Adjustments — — (11 ) (11 ) Foreign exchange (27 ) (14 ) 3 (11 ) Balance at June 30, 2020 898 — 142 142 Unbilled receivables Balance at January 1, 2020 $ 1,711 $ — $ 155 $ 155 Accrued receivables 2,163 — 94 94 Billings (2,952 ) — (150 ) (150 ) Adjustments — — (94 ) (94 ) Foreign exchange (11 ) — (5 ) (5 ) Balance at June 30, 2020 911 — — — CONTRACT LIABILITIES Deferred revenue Balance at January 1, 2020 $ 108,538 $ 336 $ 1,385 $ 1,721 Revenue recognized in the period (8,732 ) (97 ) (426 ) (523 ) Foreign exchange (488 ) (2 ) (12 ) (14 ) Balance at June 30, 2020 99,318 237 947 1,184 Less: current portion (17,844 ) (196 ) (531 ) (727 ) Non-current balance at June 30, 2020 81,474 41 416 457 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. Contract Revenues and Expenses Three Months Ended June 30, 2020 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 4,363 $ 48 $ 236 $ 284 Reimbursement revenue 1,509 — (105 ) (105 ) Milestones — — 5 5 Total collaboration revenue $ 5,872 $ 48 $ 136 $ 184 Operating expenses: Research and development expense $ 612 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 612 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 4,363 $ 48 $ 242 $ 290 Three Months Ended June 30, 2019 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 4,465 $ 50 $ 167 $ 217 Reimbursement revenue 1,679 — 83 83 Milestones — — 36 36 Total collaboration revenue $ 6,144 $ 50 $ 286 $ 336 Operating expenses: Research and development expense $ 162 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 162 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 4,465 $ 50 $ 203 $ 253 Six Months Ended June 30, 2020 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 8,731 $ 97 $ 386 $ 483 Reimbursement revenue 3,114 — (11 ) (11 ) Milestones — — 40 40 Total collaboration revenue $ 11,845 $ 97 $ 415 $ 512 Operating expenses: Research and development expense $ 764 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 764 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 8,731 $ 97 $ 426 $ 523 Six Months Ended June 30, 2019 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 8,927 $ 99 $ 366 $ 465 Reimbursement revenue 4,444 99 71 170 Milestones — 1,136 167 1,303 Total collaboration revenue $ 13,371 $ 1,334 $ 604 $ 1,938 Operating expenses: Research and development expense $ 317 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 317 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 8,927 $ 99 $ 533 $ 632

Employee Benefits

Employee Benefits	6 Months Ended
	Jun. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Employee Benefits	9. Employee Benefits Stock-Based Compensation Stock-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) Research and development $ (261 ) $ 757 $ 762 $ 1,585 General and administrative 1,453 1,103 2,721 1,535 Total $ 1,192 $ 1,860 $ 3,483 $ 3,120 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 $11.91 per option (2019: $7.16 per option) for the 1,062,317 options (2019: 1,009,671 options) granted during the six months ended June 30, 2020. The significant weighted average valuation inputs included the risk-free interest rate 1.5% (2019: 2.6%), and volatility 85.6% (2019: 87.4%). A weighted average expected term of 6.1 years was used in the Black-Scholes option pricing model during the six months ended June 30, 2020 and the weighted-average contractual term of 10.0 years was used in the Hull White model during the six months ended June 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. In addition, the Company granted 46,474 RSUs during the six months ended June 30, 2020 (2019: none) having a weighted average grant date fair value of $16.00 per unit. Executive Settlement s 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. 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 has entered into a Settlement Agreement with the Company, pursuant to which Mr. Throsby will be entitled to receive 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 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 for the three and six months ended June 30, 2020.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	10. Related Party Transactions 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. Incyte is a shareholder with holdings representing approximately 11.0% of the outstanding shares of the Company as of June 30, 2020, and 11.1% as of December 31, 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Preparation	Basis of Presentation 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 June 30, 2020 and 2019 are referred to as the second quarter of 2020 and 2019, 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, included in the Annual Report on Form 10-K.
Going Concern	Going Concern 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 , and after considering its existing cash, cash equivalents and marketable securities as of June 30, 2020 , 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 .
Pending Accounting Pronouncements	Pending Accounting Pronouncements 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 In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808)

Investments in Debt Securities

Investments in Debt Securities (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Securities [Abstract]
Summary of Investments in Debt Securities in Condensed Consolidated Balance Sheet	The following tables summarize the Company’s investments in debt securities and their presentation in the condensed consolidated balance sheet: June 30, 2020 December 31, 2019 (in thousands) Money market funds $ 21,906 $ 34,053 Corporate paper and notes 30,749 38,679 U.S. government agency securities 2,498 3,987 U.S. treasuries 12,031 1,496 Total $ 67,184 $ 78,215 Fair value of debt securities $ 67,355 $ 78,254 June 30, 2020 December 31, 2019 (in thousands) Cash equivalents $ 21,906 $ 34,053 Current marketable securities 45,278 42,153 Non-current marketable securities — 2,009 Total $ 67,184 $ 78,215

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	6 Months Ended
	Jun. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: June 30, 2020 December 31, 2019 (In thousands) Prepaid clinical and manufacturing costs $ 5,379 $ 2,779 Prepaid general and administrative expenses 2,910 789 Interest receivable 155 259 Other 3,643 1,124 Total $ 12,087 $ 4,951
Summary of Accrued Expenses	Accrued expenses consisted of the following: June 30, 2020 December 31, 2019 (In thousands) Accrued research and development expenses $ 11,780 $ 6,618 Accrued general and administrative expenses 1,932 2,402 Accrued personnel costs 2,206 4,495 Other 13 21 Total $ 15,931 $ 13,536

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Summary of Components of Expense for (Benefit) from Income Taxes	The components of the income tax expense (benefit) from continuing operations are as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) U.S. federal $ 94 $ 44 $ 38 $ 98 U.S. state 36 17 12 37 Total current tax (benefit) expense $ 130 $ 61 $ 50 $ 135 U.S. federal $ (63 ) $ 17 $ 62 $ 122 U.S. state (36 ) (7 ) 16 36 Total deferred tax expense $ (99 ) $ 10 $ 78 $ 158 Total tax expense $ 31 $ 71 $ 128 $ 293

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Summary of Components of Lease Cost	Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) Lease cost Operating lease cost $ 396 $ 347 $ 792 $ 590 Variable lease cost 107 44 189 95 Total lease cost included in operating expenses $ 503 $ 391 $ 981 $ 685 Other information Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows $ 396 $ 493 $ 789 $ 733

Collaborations (Tables)

Collaborations (Tables)	6 Months Ended
	Jun. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Company's Accompanying Condensed Consolidated Financial Statements Attributable to Transactions Arising From Collaboration Arrangements	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 Incyte Ono Other Total CONTRACT ASSETS Accounts receivable Balance at January 1, 2020 $ — $ 786 $ — $ 786 Billings 2,952 — 150 150 Cash receipts (2,027 ) (772 ) — (772 ) Adjustments — — (11 ) (11 ) Foreign exchange (27 ) (14 ) 3 (11 ) Balance at June 30, 2020 898 — 142 142 Unbilled receivables Balance at January 1, 2020 $ 1,711 $ — $ 155 $ 155 Accrued receivables 2,163 — 94 94 Billings (2,952 ) — (150 ) (150 ) Adjustments — — (94 ) (94 ) Foreign exchange (11 ) — (5 ) (5 ) Balance at June 30, 2020 911 — — — CONTRACT LIABILITIES Deferred revenue Balance at January 1, 2020 $ 108,538 $ 336 $ 1,385 $ 1,721 Revenue recognized in the period (8,732 ) (97 ) (426 ) (523 ) Foreign exchange (488 ) (2 ) (12 ) (14 ) Balance at June 30, 2020 99,318 237 947 1,184 Less: current portion (17,844 ) (196 ) (531 ) (727 ) Non-current balance at June 30, 2020 81,474 41 416 457
Summary of Company's Collaboration Arrangements Earned in Period to Be Billed and Collected in Next Period	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. Contract Revenues and Expenses Three Months Ended June 30, 2020 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 4,363 $ 48 $ 236 $ 284 Reimbursement revenue 1,509 — (105 ) (105 ) Milestones — — 5 5 Total collaboration revenue $ 5,872 $ 48 $ 136 $ 184 Operating expenses: Research and development expense $ 612 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 612 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 4,363 $ 48 $ 242 $ 290 Three Months Ended June 30, 2019 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 4,465 $ 50 $ 167 $ 217 Reimbursement revenue 1,679 — 83 83 Milestones — — 36 36 Total collaboration revenue $ 6,144 $ 50 $ 286 $ 336 Operating expenses: Research and development expense $ 162 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 162 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 4,465 $ 50 $ 203 $ 253 Six Months Ended June 30, 2020 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 8,731 $ 97 $ 386 $ 483 Reimbursement revenue 3,114 — (11 ) (11 ) Milestones — — 40 40 Total collaboration revenue $ 11,845 $ 97 $ 415 $ 512 Operating expenses: Research and development expense $ 764 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 764 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 8,731 $ 97 $ 426 $ 523 Six Months Ended June 30, 2019 (In thousands) Related Party Third Party Incyte Ono Other Total Upfront payments $ 8,927 $ 99 $ 366 $ 465 Reimbursement revenue 4,444 99 71 170 Milestones — 1,136 167 1,303 Total collaboration revenue $ 13,371 $ 1,334 $ 604 $ 1,938 Operating expenses: Research and development expense $ 317 $ — $ — $ — General and administrative expense — — — — Total operating expenses from collaborations $ 317 $ — $ — $ — Revenue recognized that was included in deferred revenue at the beginning of the period $ 8,927 $ 99 $ 533 $ 632

Employee Benefits (Tables)

Employee Benefits (Tables)	6 Months Ended
	Jun. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Summary of Stock-based Compensation Expense Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss	Stock-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (In thousands) (In thousands) Research and development $ (261 ) $ 757 $ 762 $ 1,585 General and administrative 1,453 1,103 2,721 1,535 Total $ 1,192 $ 1,860 $ 3,483 $ 3,120

Overview - Additional Informati

Overview - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated deficit	$ (349,073)	$ (314,599)
Cash and cash equivalents and marketable securities	$ 197,400

Investments in Debt Securitie_2

Investments in Debt Securities - Summary of Investments in Debt Securities in Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Held To Maturity Securities [Line Items]
Total	$ 67,184	$ 78,215
Fair value of debt securities	67,355	78,254
Cash equivalents [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	21,906	34,053
Current marketable securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	45,278	42,153
Non-current marketable securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	0	2,009
Money market funds [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	21,906	34,053
Corporate paper and notes [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	30,749	38,679
U.S. government agency securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	2,498	3,987
U.S. treasuries [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	$ 12,031	$ 1,496

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Current [Abstract]
Prepaid clinical and manufacturing costs	$ 5,379	$ 2,779
Prepaid general and administrative expenses	2,910	789
Interest receivable	155	259
Other	3,643	1,124
Total	$ 12,087	$ 4,951

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued research and development expenses	$ 11,780	$ 6,618
Accrued general and administrative expenses	1,932	2,402
Accrued personnel costs	2,206	4,495
Other	13	21
Total	$ 15,931	$ 13,536

Income Taxes - Summary of Compo

Income Taxes - Summary of Components of Expense for (Benefit) from Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
U.S. federal	$ 94	$ 44	$ 38	$ 98
U.S. state	36	17	12	37
Total current tax (benefit) expense	130	61	50	135
U.S. federal	(63)	17	62	122
U.S. state	(36)	(7)	16	36
Total deferred tax expense	(99)	10	78	158
Total tax expense	$ 31	$ 71	$ 128	$ 293

Leases - Summary of Components

Leases - Summary of Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lease cost
Operating lease cost	$ 396	$ 347	$ 792	$ 590
Variable lease cost	107	44	189	95
Total lease cost included in operating expenses	503	391	981	685
Other information
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$ 396	$ 493	$ 789	$ 733

Collaborations - Additional Inf

Collaborations - Additional Information (Details) $ in Thousands, € in Millions	Aug. 31, 2018USD ($)	Mar. 14, 2018EUR (€)	Jan. 23, 2017USD ($)	Jan. 31, 2018USD ($)AntibodyPerformanceObligationMilestone	Mar. 31, 2019USD ($)	Mar. 31, 2019EUR (€)	Jun. 30, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestones received					$ 1,100	€ 1
Incyte Collaboration and License Agreement | License and Related Activities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborations, transaction price as deferred revenue			$ 152,600
Second ONO Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment receivable | €		€ 0.7
Payment to compensate research services | €		0.3
Over time payment for full time equivalent funding | €		€ 0.2
Simcere Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of bispecific antibodies under collaboration and license agreement | Antibody				3
Non-refundable upfront payment received				$ 2,750
Collaborations, transaction price as revenue				$ 2,750
Milestone payments received	$ 800
Number of milestones achieved | Milestone				1
Description of transaction price under fixed consideration							research and development for three of the programs is on-going
Simcere Collaboration and License Agreement | License and Performance | Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of performance obligation | PerformanceObligation				3

Collaborations - Summary of Com

Collaborations - Summary of Company's Accompanying Condensed Consolidated Financial Statements Attributable to Transactions Arising From Collaboration Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	$ 4,363	$ 4,465	$ 8,731	$ 8,927
Ono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	48	50	97	99
Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	242	203	426	533
Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	290	$ 253	523	$ 632
Accounts Receivable | Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			0
Billings			2,952
Cash receipts			(2,027)
Adjustments			0
Foreign exchange			(27)
Balance at June 30, 2020	898		898
Accounts Receivable | Ono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			786
Billings			0
Cash receipts			(772)
Adjustments			0
Foreign exchange			(14)
Balance at June 30, 2020	0		0
Accounts Receivable | Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			0
Billings			150
Cash receipts			0
Adjustments			(11)
Foreign exchange			3
Balance at June 30, 2020	142		142
Accounts Receivable | Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			786
Billings			150
Cash receipts			(772)
Adjustments			(11)
Foreign exchange			(11)
Balance at June 30, 2020	142		142
Unbilled Receivables | Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			1,711
Accrued receivables			2,163
Billings			(2,952)
Adjustments			0
Foreign exchange			(11)
Balance at June 30, 2020	911		911
Unbilled Receivables | Ono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			0
Accrued receivables			0
Billings			0
Adjustments			0
Foreign exchange			0
Balance at June 30, 2020	0		0
Unbilled Receivables | Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			155
Accrued receivables			94
Billings			(150)
Adjustments			(94)
Foreign exchange			(5)
Balance at June 30, 2020	0		0
Unbilled Receivables | Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2020			155
Accrued receivables			94
Billings			(150)
Adjustments			(94)
Foreign exchange			(5)
Balance at June 30, 2020	0		0
Deferred Revenue | Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Foreign exchange			(488)
Balance at January 1, 2020			108,538
Revenue recognized in the period			(8,732)
Balance at June 30, 2020	99,318		99,318
Less: current portion	(17,844)		(17,844)
Non-current balance at June 30, 2020	81,474		81,474
Deferred Revenue | Ono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Foreign exchange			(2)
Balance at January 1, 2020			336
Revenue recognized in the period			(97)
Balance at June 30, 2020	237		237
Less: current portion	(196)		(196)
Non-current balance at June 30, 2020	41		41
Deferred Revenue | Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Foreign exchange			(12)
Balance at January 1, 2020			1,385
Revenue recognized in the period			(426)
Balance at June 30, 2020	947		947
Less: current portion	(531)		(531)
Non-current balance at June 30, 2020	416		416
Deferred Revenue | Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Foreign exchange			(14)
Balance at January 1, 2020			1,721
Revenue recognized in the period			(523)
Balance at June 30, 2020	1,184		1,184
Less: current portion	(727)		(727)
Non-current balance at June 30, 2020	$ 457		$ 457

Collaborations - Summary of C_2

Collaborations - Summary of Company's Collaboration Arrangements Earned in Period to Be Billed and Collected in Next Period (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 13,709	$ 10,768	$ 30,696	$ 22,567
General and administrative	8,043	8,214	16,925	14,955
Total operating expenses	21,752	18,982	47,621	37,522
Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments	4,363	4,465	8,731	8,927
Reimbursement revenue	1,509	1,679	3,114	4,444
Milestones	0	0	0	0
Total collaboration revenue	5,872	6,144	11,845	13,371
Operating expenses:
Research and development	612	162	764	317
General and administrative	0	0	0	0
Total operating expenses	612	162	764	317
Revenue recognized in the period	4,363	4,465	8,731	8,927
Ono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments	48	50	97	99
Reimbursement revenue	0	0	0	99
Milestones	0	0	0	1,136
Total collaboration revenue	48	50	97	1,334
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	48	50	97	99
Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments	236	167	386	366
Reimbursement revenue	(105)	83	(11)	71
Milestones	5	36	40	167
Total collaboration revenue	136	286	415	604
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	242	203	426	533
Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payments	284	217	483	465
Reimbursement revenue	(105)	83	(11)	170
Milestones	5	36	40	1,303
Total collaboration revenue	184	336	512	1,938
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	$ 290	$ 253	$ 523	$ 632

Employee Benefits - Summary of

Employee Benefits - Summary of Stock-based Compensation Expense Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 1,192	$ 1,860	$ 3,483	$ 3,120
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	(261)	757	762	1,585
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 1,453	$ 1,103	$ 2,721	$ 1,535

Employee Benefits - Additional

Employee Benefits - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 31, 2020	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Apr. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average fair value of options granted			$ 11.91	$ 7.16
Share-based payment award, fair value assumptions, method used			Black Scholes option pricing model	Hull White
Number of options granted			1,062,317	1,009,671
Risk-free interest rate			1.50%	2.60%
Expected volatility			85.60%	87.40%
Weighted average expected term			6 years 1 month 6 days
Weighted-average contractual term				10 years
Severance payment			$ 0.1
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Net reversal of stock-based compensation expense		$ 0.4	$ 0.4
Postemployment Retirement Benefits
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Executive settlements, cash compensation to be paid					$ 0.9	$ 0.3
Executive settlements, cash compensation paid	$ 0.9
Executive settlements expense					$ 1.8
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average fair value of options granted			$ 16
Share-based compensation, RSUs granted			46,474	0
RSUs | Postemployment Retirement Benefits
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant of RSUs					30,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details)	Jun. 30, 2020	Dec. 31, 2019
Incyte | Merus N V [Member]
Related Party Transaction [Line Items]
Ownership percentage	11.00%	11.10%