MacroGenics (MGNX) 10-Q 29 Jul 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 26, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-36112
Entity Registrant Name	MACROGENICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	06-1591613
Entity Address, Address Line One	9704 Medical Center Drive
Entity Address, City or Town	Rockville
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20850
City Area Code	301
Local Phone Number	251-5172
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	MGNX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		61,107,288
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001125345
Current Fiscal Year End Date	--12-31

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 188,970	$ 181,131
Marketable securities	108,346	91,400
Accounts receivable	45,248	23,081
Inventory	6,476	0
Prepaid expenses and other current assets	17,956	16,982
Total current assets	366,996	312,594
Property, equipment and software, net	39,395	42,225
Other assets	19,520	23,924
Total assets	425,911	378,743
Current liabilities:
Accounts payable	9,818	8,031
Accrued expenses and other current liabilities	39,174	34,198
Deferred revenue	16,565	4,456
Lease liabilities	4,367	3,988
Total current liabilities	69,924	50,673
Deferred revenue, net of current portion	13,476	6,926
Lease liabilities, net of current portion	23,208	25,260
Other non current liabilities	258	0
Total liabilities	106,866	82,859
Stockholders' equity:
Common stock, $0.01 par value -- 125,000,000 shares authorized, 60,133,447 and 56,244,771 shares outstanding at June 30, 2021 and December 31, 2020, respectively	601	562
Additional paid-in capital	1,181,471	1,067,150
Accumulated other comprehensive income (loss)	1	(7)
Accumulated deficit	(863,028)	(771,821)
Total stockholders' equity	319,045	295,884
Total liabilities and stockholders' equity	$ 425,911	$ 378,743

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares outstanding (in shares)	60,133,447	56,244,771

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenues	$ 30,757	$ 20,257	$ 47,638	$ 33,939
Costs and expenses:
Cost of product sales	22	0	39	0
Research and development	55,780	57,351	108,901	106,245
Selling, general and administrative	15,234	10,216	30,270	20,449
Total costs and expenses	71,036	67,567	139,210	126,694
Loss from operations	(40,279)	(47,310)	(91,572)	(92,755)
Other income	344	425	365	1,146
Net loss	(39,935)	(46,885)	(91,207)	(91,609)
Other comprehensive income (loss):
Unrealized gain (loss) on investments	(10)	(55)	8	1
Comprehensive loss	$ (39,945)	$ (46,940)	$ (91,199)	$ (91,608)
Basic net loss per common share (in usd per share)	$ (0.66)	$ (0.94)	$ (1.56)	$ (1.85)
Diluted net loss per common share (in usd per share)	$ (0.66)	$ (0.94)	$ (1.56)	$ (1.85)
Basic weighted average common shares outstanding (in shares)	60,068,315	50,018,462	58,643,496	49,515,562
Diluted weighted average common shares outstanding (in shares)	60,068,315	50,018,462	58,643,496	49,515,562
Revenue from collaborative and other agreements
Revenues:
Revenues	$ 27,168	$ 15,636	$ 42,352	$ 28,603
Product revenue, net
Revenues:
Revenues	3,203	0	4,090	0
Revenue from government agreements
Revenues:
Revenues	$ 386	$ 4,621	$ 1,196	$ 5,336

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2019		48,958,763
Beginning balance at Dec. 31, 2019	$ 230,628	$ 490	$ 872,204	$ (642,082)	$ 16
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	4,451		4,451
Stock plan related activity (in shares)		172,387
Stock plan related activity	162	$ 2	160
Unrealized gain (loss) on investments	56				56
Net loss	(44,724)			(44,724)
Ending balance (in shares) at Mar. 31, 2020		49,131,150
Ending balance at Mar. 31, 2020	190,573	$ 492	876,815	(686,806)	72
Beginning balance (in shares) at Dec. 31, 2019		48,958,763
Beginning balance at Dec. 31, 2019	230,628	$ 490	872,204	(642,082)	16
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan related activity		$ 2
Net loss	(91,609)
Ending balance (in shares) at Jun. 30, 2020		53,365,003
Ending balance at Jun. 30, 2020	247,784	$ 534	980,924	(733,691)	17
Beginning balance (in shares) at Mar. 31, 2020		49,131,150
Beginning balance at Mar. 31, 2020	190,573	$ 492	876,815	(686,806)	72
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	5,136		5,136
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(46,885)			(46,885)
Issuance of common stock, net of offering costs (in shares)		4,060,482
Issuance of common stock, net of offering costs	96,512	$ 40	96,472
Stock plan related activity (in shares)		173,371
Stock plan related activity	2,503		2,501
Unrealized gain (loss) on investments	(55)				(55)
Net loss	(46,885)
Ending balance (in shares) at Jun. 30, 2020		53,365,003
Ending balance at Jun. 30, 2020	247,784	$ 534	980,924	(733,691)	17
Beginning balance (in shares) at Dec. 31, 2020		56,244,771
Beginning balance at Dec. 31, 2020	295,884	$ 562	1,067,150	(771,821)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	5,243		5,243
Issuance of common stock, net of offering costs (in shares)		3,622,186
Issuance of common stock, net of offering costs	98,200	$ 36	98,164
Stock plan related activity (in shares)		144,249
Stock plan related activity	2,458	$ 2	2,456
Unrealized gain (loss) on investments	18				18
Net loss	(51,272)			(51,272)
Ending balance (in shares) at Mar. 31, 2021		60,011,206
Ending balance at Mar. 31, 2021	350,531	$ 600	1,173,013	(823,093)	11
Beginning balance (in shares) at Dec. 31, 2020		56,244,771
Beginning balance at Dec. 31, 2020	$ 295,884	$ 562	1,067,150	(771,821)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plan related activity (in shares)	1,790,246
Net loss	$ (91,207)
Ending balance (in shares) at Jun. 30, 2021		60,133,447
Ending balance at Jun. 30, 2021	319,045	$ 601	1,181,471	(863,028)	1
Beginning balance (in shares) at Mar. 31, 2021		60,011,206
Beginning balance at Mar. 31, 2021	350,531	$ 600	1,173,013	(823,093)	11
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	6,113		6,113
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(39,935)			(39,935)
Stock plan related activity (in shares)		122,241
Stock plan related activity	2,346	$ 1	2,345
Unrealized gain (loss) on investments	(10)				(10)
Net loss	(39,935)
Ending balance (in shares) at Jun. 30, 2021		60,133,447
Ending balance at Jun. 30, 2021	$ 319,045	$ 601	$ 1,181,471	$ (863,028)	$ 1

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net loss	$ (91,207)	$ (91,609)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	5,510	6,105
Amortization of premiums and discounts on marketable securities	808	(401)
Stock-based compensation	11,356	9,587
Changes in operating assets and liabilities:
Accounts receivable	(22,166)	(6,461)
Inventory	(6,476)	0
Prepaid expenses and other current assets	(974)	3,093
Other assets	4,404	995
Accounts payable	1,668	(1,476)
Accrued expenses and other current liabilities	5,365	3,337
Lease liabilities	(1,673)	(1,534)
Deferred revenue	18,659	(3,767)
Other non current liabilities	0	1,443
Net cash used in operating activities	(74,726)	(80,688)
Cash flows from investing activities
Purchases of marketable securities	(117,546)	(72,199)
Proceeds from sale and maturities of marketable securities	99,800	125,617
Purchases of property, equipment and software	(2,693)	(1,847)
Net cash provided by (used in) investing activities	(20,439)	51,571
Cash flows from financing activities
Proceeds from issuance of common stock, net of offering costs	98,200	96,512
Proceeds from stock option exercises and ESPP purchases	4,910	2,665
Net cash provided by financing activities	103,004	99,177
Net change in cash and cash equivalents	7,839	70,060
Cash and cash equivalents at beginning of period	181,131	126,472
Cash and cash equivalents at end of period	188,970	196,532
Supplemental Cash Flow Information [Abstract]
Property, equipment and software included in accounts payable or accruals	118	0
Retirement Of Treasury Stock	$ (106)	$ 0

Nature of Operations

Nature of Operations	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Description of the business MacroGenics, Inc. (the Company) is incorporated in the state of Delaware. The Company is a biopharmaceutical company focused on developing and commercializing innovative antibody-based therapeutics designed to modulate the human immune response for the treatment of cancer. In December 2020, the U.S. Food and Drug Administration (FDA) approved MARGENZA (margetuximab-cmkb) in combination with chemotherapy for the treatment of adult patients with metastatic HER2-positive breast cancer who have received two or more prior anti-HER2 regimens, at least one of which was for metastatic disease. The Company launched MARGENZA in collaboration with our commercialization partner, Eversana Life Science Services, LLC (Eversana), in March 2021. In addition, the Company has a pipeline of product candidates in human clinical testing that have been created primarily using its proprietary, antibody-based technology platforms. The Company believes its product candidates have the potential to have a meaningful effect on treating patients' unmet medical needs as monotherapy or, in some cases, in combination with other therapeutic agents. Liquidity The Company’s multiple product candidates currently under development will require significant additional research and development efforts that include extensive preclinical studies and clinical testing, and regulatory approval prior to commercial use. As a biotechnology company, the Company has primarily funded its operations with proceeds from the sale of its common stock in equity offerings, revenue from its multiple collaboration agreements, and contracts and grants from the National Institute of Allergy and Infectious Diseases (NIAID). Management regularly reviews the Company’s available liquidity relative to its operating budget and forecast to monitor the sufficiency of the Company’s working capital, and anticipates continuing to draw upon available sources of capital, including equity and debt instruments, to support its product development activities. Based on the Company’s most recent cash flow forecast, the Company believes its current cash, cash equivalents and marketable securities is sufficient to fund its operating plans for a minimum of twelve months from the date that this Quarterly Report was filed. The Company plans to meet its near-term operating requirements primarily through cash and marketable securities on hand, and a combination of product sales and current and future strategic collaborations and alliances and marketing, distribution or licensing arrangements. In the longer term, the Company plans to meet its operating requirements by generating revenue from product sales to the extent its other product candidates receive marketing approval and can be commercialized, or by potential future equity or debt issuances. There can be no assurances that new sources of capital will be available to the Company on commercially acceptable terms, if at all. Also, any future collaborations, strategic alliances and marketing, distribution or licensing arrangements may require the Company to give up some or all rights to a product or technology at less than its full potential value. If the Company is unable to enter into new arrangements or to perform under current or future agreements or obtain additional capital, the Company will assess its capital resources and may be required to delay, reduce the scope of, or eliminate one or more of its product research and development programs or clinical studies, and/or downsize its organization. Similar to the other risk factors pertinent to the Company's business, the COVID-19 pandemic might unfavorably impact the Company's ability to generate such additional funding. Given the uncertainty in the rapidly changing market and economic conditions related to the COVID-19 pandemic, the Company will continue to evaluate the nature and extent of the impact of the pandemic on its business and financial position. Basis of Presentation The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiaries, MacroGenics UK Limited and MacroGenics Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2020 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2021.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies During the six months ended June 30, 2021, the Company adopted the following significant accounting policies in addition to those previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. Inventory The Company outsources the manufacturing of MARGENZA. Prior to FDA approval of MARGENZA in December 2020, the cost of materials and expenses associated with the manufacturing of MARGENZA were recorded as research and development expense. Subsequent to regulatory approval, the Company began capitalizing MARGENZA inventory costs. The Company values its inventories at the lower of cost and estimated net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and third-party contract manufacturing costs, on a first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment is first identified. Such write downs, should they occur, are recorded within the cost of sales in the statement of operations. As of June 30, 2021, the Company’s inventory balance consisted primarily of raw materials purchased and work in progress manufactured after the FDA approval of MARGENZA. Product Revenue, Net The Company entered into a limited number of arrangements with specialty distributors in the United States to distribute MARGENZA. These arrangements are considered to be contracts with customers and are in the scope of Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (ASC 606). The Company has written contracts with each of its customers that have a single performance obligation - to deliver products upon receipt of a customer order - and these obligations are satisfied when delivery occurs and the customer receives the product. The specialty distributors subsequently resell the Company’s product to healthcare providers. Product revenue is recorded net of applicable reserves for variable consideration, including discounts and other allowances. Shipping and handling costs for product shipments occur prior to the customer obtaining control of the goods and are recorded in cost of sales. For the three and six months ended June 30, 2021, the shipping costs incurred were immaterial. Reserves for Variable Consideration Revenue from product sales is recorded at the net sales price, which includes estimates of variable consideration. Components of variable consideration typically include discounts, product returns, provider chargebacks and discounts and government rebates. Variable consideration is estimated following the expected value method in accordance with ASC 606 and includes such factors as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Estimates of the variable consideration were not deemed constrained during the six months ended June 30, 2021. Customer Discounts and Service Fees The Company may provide customers with discounts which are explicitly stated in the contracts. These discounts are recorded as a reduction of revenue in the period the related product revenue is recognized. In addition, these contracts may include written service arrangements whereby the Company pays fees to customers who provide services such as sales order management, data, contract administration and distribution services, at rates which we believe to be consistent with fair market value. The Company has determined such services received to date are not distinct from the Company’s sale of products to its customers and, therefore, these payments have been recorded as a reduction of revenue within the statement of operations. Product Returns Consistent with industry practice, the Company offers the specialty distributors product return rights pursuant to written contracts and/or Company returned goods policies. The Company estimates the amount of its product sales that may be returned by its customers and records an estimated liability and a reduction of revenue in the period the related product revenue is recognized. The Company currently estimates product returns using industry benchmarking as well as other information available, such as visibility into the inventory remaining in the distribution channel, since the Company does not have its own returns experience. The Company's estimates of product returns may be adjusted in the future based on actual returns experience, known or expected changes in the marketplace, or other factors. Provider Chargebacks and Discounts Chargebacks for fees and discounts to healthcare providers represent the estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices charged to customers who directly purchase the product from the Company. In such cases, customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. The reserve for chargebacks is established in the same period that the related revenue is recognized, resulting in a reduction of product revenue. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider by customers, and the Company generally issues credits for such amounts within a few weeks of the customer’s notification to the Company of the resale. Chargebacks consist of credits the Company expects to issue for units that remain in the distribution channel at each reporting period end that the Company expects will be sold to qualified healthcare providers and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates The Company is subject to discount and/or rebate obligations under state Medicaid programs, Medicare and contractual agreements with and statutory obligations to certain Federal and State entities. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period. Customer discounts are recorded as a reduction of accounts receivable on the consolidated balance sheets. Allowance for product returns, provider chargebacks, government and other rebates and service fees are recorded as a component of accrued expenses and other current liabilities on the consolidated balance sheets. Cost of product sales Cost of product sales relates to sales of MARGENZA. These costs include material, manufacturing and shipping costs, as well as royalties payable on net sales of MARGENZA. All product costs incurred prior to FDA approval of MARGENZA in December 2020 were expensed as research and development expense. The Company expects cost of product sales to continue to be positively impacted as the Company sells through inventory that was expensed prior to FDA approval of MARGENZA in December 2020. The Company is currently unable to estimate how long it will be until it begins selling product manufactured post FDA approval. Recent Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). ASU 2019-12 is part of the FASB’s overall simplification initiative and seeks to simplify the accounting for income taxes by updating certain guidance and removing certain exceptions. The updated guidance is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years. The adoption of this standard as of January 1, 2021 had no impact on the Company's consolidated financial statements and related disclosures. The Company has evaluated all other ASUs issued through the date the consolidated financials were issued and believes that the adoption of these ASUs will not have a material impact on the Company's consolidated financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company's financial instruments consist of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. The carrying amount of accounts receivable, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of their short-term nature. The Company accounts for recurring and non-recurring fair value measurements in accordance with FASB Accounting Standards Codification (ASC) 820, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value, establishes a fair value hierarchy for assets and liabilities measured at fair value, and requires expanded disclosures about fair value measurements. The ASC 820 hierarchy ranks the quality of reliability of inputs, or assumptions, used in the determination of fair value and requires assets and liabilities carried at fair value to be classified and disclosed in one of the following three categories: • Level 1 - Fair value is determined by using unadjusted quoted prices that are available in active markets for identical assets and liabilities. • Level 2 - Fair value is determined by using inputs other than Level 1 quoted prices that are directly or indirectly observable. Inputs can include quoted prices for similar assets and liabilities in active markets or quoted prices for identical assets and liabilities in inactive markets. Related inputs can also include those used in valuation or other pricing models, such as interest rates and yield curves that can be corroborated by observable market data. • Level 3 - Fair value is determined by inputs that are unobservable and not corroborated by market data. Use of these inputs involves significant and subjective judgments to be made by a reporting entity - e.g., determining an appropriate adjustment to a discount factor for illiquidity associated with a given security. The Company evaluates financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level at which to classify them each reporting period. This determination requires the Company to make subjective judgments as to the significance of inputs used in determining fair value and where such inputs lie within the ASC 820 hierarchy. Financial assets measured at fair value on a recurring basis were as follows (in thousands): Fair Value Measurements at June 30, 2021 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Total Level 1 Level 2 Assets: Money market funds $ 16,606 $ 16,606 $ — U.S. Treasury securities 79,249 — 79,249 Government-sponsored enterprises 4,537 — 4,537 Corporate debt securities 42,809 — 42,809 Total assets measured at fair value (a) $ 143,201 $ 16,606 $ 126,595 Fair Value Measurements at December 31, 2020 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Total Level 1 Level 2 Assets: Money market funds $ 49,004 $ 49,004 $ — U.S. Treasury securities 60,623 — 60,623 Corporate debt securities 33,776 — 33,776 Total assets measured at fair value (b) $ 143,403 $ 49,004 $ 94,399 (a) Total assets measured at fair value at June 30, 2021 includes approximately $34.9 million reported in cash and cash equivalents on the consolidated balance sheet. (b) Total assets measured at fair value at December 31, 2020 includes approximately $52.0 million reported in cash and cash equivalents on the consolidated balance sheet. The fair value of Level 2 securities is determined from market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These inputs either represent quoted prices for similar assets in active markets or have been derived from observable market data. There were no transfers between levels during the periods presented, and the Company has no Level 3 securities in its portfolio.

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities The following tables summarize the Company's marketable debt securities (in thousands): June 30, 2021 Amortized Gross Gross Fair U.S. Treasury securities $ 79,244 $ 5 $ — $ 79,249 Government-sponsored enterprises 4,537 — — 4,537 Corporate debt securities 24,564 — (4) 24,560 Total $ 108,345 $ 5 $ (4) $ 108,346 December 31, 2020 Amortized Gross Gross Fair U.S. Treasury securities $ 60,630 $ 1 $ (7) $ 60,624 Corporate debt securities 30,777 2 (3) 30,776 Total $ 91,407 $ 3 $ (10) $ 91,400

Inventory

Inventory	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Inventory	Inventory All of the Company's inventory relates to the manufacturing of MARGENZA. The following table sets forth the Company's inventory (in thousands): June 30, 2021 Raw materials $ 607 Work in process 5,869 Total inventory $ 6,476

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Stockholders' Equity	Stockholders' EquityIn November 2020, the Company entered into a sales agreement (Sales Agreement) with an agent to sell, from time to time, shares of its common stock having an aggregate sales price of up to $100.0 million through an “at the market offering” (ATM Offering) as defined in Rule 415 under the Securities Act of 1933, as amended. The shares that were sold under the Sales Agreement were issued and sold pursuant to the Company's shelf registration statement on Form S-3 that was filed with the SEC on November 4, 2020. During the three months ended March 31, 2021, the Company sold 3,622,186 shares of common stock at a weighted average price per share of $27.60, resulting in net proceeds of approximately $98.2 million, net of underwriting discounts and commissions and other offering expenses. In April 2021, the Company entered into Amendment No. 1 to the Sales Agreement which increases the amount of the Company’s common stock that can be sold by the Company through its agent under the ATM Offering, from an aggregate offering price of up to $100.0 million to an aggregate offering price of up to $300.0 million. During the three months ended June 30, 2021, the Company did not sell any shares of common stock related to the ATM Offering.

Collaboration and Other Agreeme

Collaboration and Other Agreements	6 Months Ended
	Jun. 30, 2021
Collaboration and License Agreements [Abstract]
Collaboration and Other Agreements	Collaboration and Other Agreements Incyte Corporation Incyte License Agreement In 2017, the Company entered into an exclusive global collaboration and license agreement with Incyte Corporation (Incyte) for retifanlimab (formerly known as MGA012 and INCMGA0012), an investigational monoclonal antibody that inhibits programmed cell death protein 1 (PD-1) (Incyte License Agreement). Incyte has obtained exclusive worldwide rights for the development and commercialization of retifanlimab in all indications, while the Company retains the right to develop its pipeline assets in combination with retifanlimab. Under the terms of the Incyte License Agreement, Incyte paid the Company an upfront payment of $150.0 million in 2017. In January 2021, Incyte announced that the FDA had accepted for Priority Review its Biologics License Application (BLA) for retifanlimab as a potential treatment for adult patients with locally advanced or metastatic squamous cell carcinoma of the anal canal. The PDUFA target action date for retifanlimab was July 25, 2021. On July 23, 2021, Incyte announced that the FDA had issued a Complete Response Letter (CRL) regarding its BLA for retifanlimab. Incyte’s announcement indicated that the FDA determined that additional data are needed to demonstrate the clinical benefit of retifanlimab for the submitted indication, and that Incyte is reviewing the CRL and will discuss next steps with the FDA. Under the terms of the Incyte License Agreement, Incyte will lead global development of retifanlimab. Assuming successful development and commercialization of retifanlimab by Incyte, the Company could receive up to approximately $420.0 million in development and regulatory milestones and up to $330.0 million in commercial milestones. From the inception of the Incyte License Agreement through June 30, 2021 , the Company has recognized $70.0 million in development milestones under the Incyte License Agreement. If retifanlimab is approved and commercialized, the Company would be eligible to receive tiered royalties of 15% to 24% on any global net sales. The Company retains the right to develop its pipeline assets in combination with retifanlimab, with Incyte commercializing retifanlimab and the Company commercializing its asset(s), if any such potential combinations are approved. In addition, the Company retains the right to manufacture a portion of both companies' global commercial supply needs of retifanlimab, subject to the separate commercial supply agreement. The Company evaluated the Incyte License Agreement under ASC 606 and identified the following two performance obligations under the agreement: (i) the license of retifanlimab and (ii) the performance of certain clinical activities through a brief technology transfer period. The Company determined that the license and clinical activities are separate performance obligations because they are capable of being distinct, and are distinct in the context of the contract. The license has standalone functionality as it is sublicensable, Incyte has significant capabilities in performing clinical trials, and Incyte is capable of performing these activities without the Company's involvement; the Company performed the activities during the transfer period as a matter of convenience. The Company determined that the transaction price of the Incyte License Agreement at inception was $154.0 million, consisting of the consideration to which the Company was entitled in exchange for the license and an estimate of the consideration for clinical activities to be performed. The transaction price was allocated to each performance obligation based on their relative standalone selling price. The standalone selling price of the license was determined using the adjusted market assessment approach considering similar collaboration and license agreements. The standalone selling price for the agreed-upon clinical activities to be performed was determined using the expected cost approach based on similar arrangements the Company has with other parties. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur, as they were determined to relate predominantly to the license granted to Incyte and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. From 2018 through June 30, 2021 , it became probable that a significant reversal of cumulative revenue would not occur for deve lopment milestones totaling $70.0 million related to clinical and regulatory activities related to the further advancement of retifanlimab, including Incyte’s initiation of a Phase 3 clinical trial . Therefore the associated consideration was added to the estimated transaction price. The Company recognized the $150.0 million allocated to the license when it satisfied its performance obligation and transferred the license to Incyte in 2017. The $4.0 million allocated to the clinical activities was recognized ratably as services were performed over a period spanning 2017 and 2018. During the three and six months ended June 30, 2021, it became probable that a significant reversal of cumulative revenue would not occur for $5.0 million and $15.0 million in milestones related to development progress of retifanlimab, respectively, therefore the associated consideration was added to the estimated transaction price and was recognized as revenue. No revenue was recognized under the Incyte License Agreement during the three and six months ended June 30, 2020. Incyte Clinical Supply Agreement The Company also has an agreement with Incyte, which was entered into in 2018, under which the Company is to perform development and manufacturing services for Incyte’s clinical needs of retifanlimab (Incyte Clinical Supply Agreement). The Company evaluated the agreement under ASC 606 and identified one performance obligation under the agreement: to perform services related to the development and manufacturing of the clinical supply of retifanlimab. The transaction price is based on the costs incurred to develop and manufacture drug product and drug substance, and is recognized over time as the services are provided, as the performance by the Company does not create an asset with an alternative use and the Company has an enforceable right to payment for the performance completed to date. The transaction price will be recognized using the input method reflecting the costs incurred (including resources consumed and labor hours expended) related to the manufacturing services. During the three months ended June 30, 2021 and 2020, the Company recognized revenue of $0.7 million and $1.5 million, respectively, for services performed under the Incyte Clinical Supply Agreement. During the six months ended June 30, 2021 and 2020, the Company recognized revenue of $0.8 million and $7.4 million, respectively, for services performed under the Incyte Clinical Supply Agreement. Incyte Commercial Supply Agreement In October 2020, the Company entered into an agreement with Incyte pursuant to which the Company is entitled to manufacture a portion of the global commercial supply needs for retifanlimab (Incyte Commercial Supply Agreement). Unless terminated earlier, the term of the Incyte Commercial Supply Agreement will expire upon the expiration of Incyte’s obligation to pay royalties under the Incyte License Agreement. The Company evaluated this agreement under ASC 606 and identified one performance obligation under the agreement: to perform services related to manufacturing the commercial supply of retifanlimab. The transaction price is based on a fixed price per batch of bulk drug substance to be manufactured and is recognized over time as the services are provided, as the performance by the Company does not create an asset with an alternative use and the Company has an enforceable right to payment for the performance completed to date. The transaction price will be recognized using the input method reflecting the costs incurred (including resources consumed and labor hours expended) related to the manufacturing services. During the three and six months ended June 30, 2021, the Company recognized revenue of $2.8 million and $5.9 million, respectively, for services performed under the Incyte Commercial Supply Agreement. Zai Lab Limited 2018 Zai Lab Agreement In 2018, the Company entered into a collaboration and license agreement with Zai Lab Limited (Zai Lab) under which Zai Lab obtained regional development and commercialization rights in mainland China, Hong Kong, Macau and Taiwan (Zai Lab’s territory) for (i) margetuximab, an immune-optimized anti-HER2 monoclonal antibody, (ii) tebotelimab (formerly known as MGD013), a bispecific DART molecule designed to provide coordinate blockade of PD-1 and LAG-3 for the potential treatment of a range of solid tumors and hematological malignancies, and (iii) an undisclosed multi-specific TRIDENT molecule in preclinical development (2018 Zai Lab Agreement). Zai Lab will lead clinical development of these molecules in its territory. Under the terms of the 2018 Zai Lab Agreement, Zai Lab paid the Company an upfront payment of $25.0 million ($22.5 million after netting value-added tax withholdings of $2.5 million). Assuming successful development and commercialization of margetuximab, tebotelimab and the TRIDENT molecule, the Company could receive up to $140.0 million in development and regulatory milestones, $4.0 million of which ($3.6 million after netting value-added tax withholdings of $0.4 million) was earned during the three months ended March 31, 2020. In addition, Zai Lab would pay the Company tiered royalties at percentage rates of mid-teens to 20% for net sales of margetuximab in Zai Lab’s territory, mid-teens for net sales of tebotelimab in Zai Lab’s territory and 10% for net sales of the TRIDENT molecule in Zai Lab’s territory, which may be subject to adjustment in specified circumstances. The Company evaluated the 2018 Zai Lab Agreement under the provisions of ASC 606 and identified the following material promises under the arrangement for each of the two product candidates, margetuximab and tebotelimab: (i) an exclusive license to develop and commercialize the product candidate in Zai Lab’s territory and (ii) certain research and development activities. The Company determined that each license and the related research and development activities were not distinct from one another, as the license has limited value without the performance of the research and development activities. As such, the Company determined that these promises should be combined into a single performance obligation for each product candidate. Activities related to margetuximab and tebotelimab are separate performance obligations from each other because they are capable of being distinct, and are distinct in the context of the contract. The Company evaluated the promises related to the TRIDENT molecule and determined they were immaterial in context of the contract, therefore there is no performance obligation related to that molecule. The Company determined that the net $22.5 million upfront payment from Zai Lab constituted the entirety of the consideration to be included in the transaction price as of the outset of the arrangement, and the transaction price was allocated to the two performance obligations based on their relative standalone selling price. The standalone selling price of the performance obligations was determined using the adjusted market assessment approach considering similar collaboration and license agreements. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable, and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to royalties will be recognized if and when the related sales occur, as they were determined to relate predominantly to the license granted to Zai Lab and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. Due to the relatively short-term nature of the recognition period, the revenue associated with the tebotelimab performance obligation was recognized on a straight-line basis as the Company performed research and development activities under the agreement. The fixed consideration related to the margetuximab performance obligation was also recognized on a straight-line basis as the Company performed research and development activities under the agreement due to the short-term nature of the recognition period. Straight-line recognition is materially consistent with the pattern of performance of the research and development activities of each product candidate. The variable consideration related to the margetuximab performance obligation was recognized upon certain regulatory achievements during 2020. The Company recognized revenue of $3.6 million during the six months ended June 30, 2020 under the 2018 Zai Lab Agreement. There was no revenue deferred under this agreement as of June 30, 2021 or December 31, 2020. Zai Lab Clinical Supply Agreements During 2019, the Company entered into two agreements under which the Company is to perform manufacturing services for Zai Lab’s clinical needs of margetuximab and tebotelimab (Zai Lab Clinical Supply Agreements). The Company evaluated the agreements under ASC 606 and determined that they should be accounted for as a single contract and identified two performance obligations within that contract: to perform services related to manufacturing the clinical supply of each of margetuximab and tebotelimab. The transaction price is based on the costs incurred to manufacture drug product and drug substance, and is recognized over time as the services are provided, as the performance by the Company does not create an asset with an alternative use and the Company has an enforceable right to payment for the performance completed to date. During the three months ended June 30, 2021 and 2020, the Company recognized revenue of $0.5 million and $0.3 million, respectively, related to the Zai Lab Clinical Supply Agreements. During the six months ended June 30, 2021 and 2020, the Company recognized revenue of $1.6 million and $1.3 million, respectively, related to the Zai Lab Clinical Supply Agreements. 2021 Zai Lab Agreement In June 2021, the Company entered into a collaboration and license agreement with Zai Lab US LLC (collectively with Zai Lab Limited referred herein as Zai Lab) involving collaboration programs and license-only programs (collectively, the Programs) encompassing four separate immuno-oncology molecules (2021 Zai Lab Agreement). The first program covers a lead research molecule that incorporates the Company’s DART platform and binds CD3 and an undisclosed target that is expressed in multiple solid tumors (Lead Program). The second program covers a target to be designated by the Company. For these programs, Zai Lab receives commercial rights in Greater China, Japan, and Korea while the Company receives commercial rights in all other territories. Under the Lead Program, Zai Lab received an option upon reaching a predefined clinical milestone to convert the regional arrangement into a global 50/50 profit share. If Zai Lab elects such option, Zai Lab is to pay the Company $85.0 million plus any research costs incurred by both parties as of the option election date. Zai Lab also obtained exclusive, global licenses from the Company to develop, manufacture and commercialize two additional molecules. Zai Lab granted the Company a worldwide, royalty-free, co-exclusive license to conduct the development activities allocated to the Company. Under the terms of the 2021 Zai Lab Agreement, the Lead Program includes joint research and development services by both the Company and Zai Lab. For the other programs, Zai Lab can separately negotiate and agree with the Company to perform research and development services in the future. In connection with the execution of the 2021 Zai Lab Agreement, Zai Lab will pay the Company an upfront payment of $25.0 million, which was received in July 2021. Additionally, as part of the consideration for the rights granted to Zai Lab under the 2021 Zai Lab Agreement, the Company and Zai Lab entered into a separate stock purchase agreement (Stock Purchase Agreement) whereby Zai Lab agreed to pay the Company approximately $30.0 million to purchase shares of the Company’s common stock, par value $0.01, at a fixed price of $31.30 (Offering) which represented a $10.4 million premium over the share price on the Stock Purchase Agreement date. The Offering closed in July 2021. Assuming successful development and commercialization of the Programs, the Company could receive up to approximately $800.0 million in development and regulatory milestones and $600.0 million in commercial milestones. In addition, Zai Lab would pay the Company tiered royalties at percentage rates of low double digit teens on annual net sales of certain specified products and of mid-single digits to low double digit teens on annual net sales of other specified products in Zai Lab’s territory, which may be subject to specified royalty reduction pursuant to the 2021 Zai Lab Agreement. Per the terms of the 2021 Zai Lab Agreement, the Company may also receive reimbursements from Zai Lab for certain research and development costs incurred by the Company. The Company evaluated the 2021 Zai Lab Agreement under the provisions of ASC 606 and identified the following material promises: (i) exclusive licenses to develop, manufacture and commercialize the products in Zai Lab’s territory for each Program and (ii) certain research and development activities for the Lead Program. The Company determined that for the Lead Program, the license is not distinct from the related research and development activities, considering the early stage of development of the molecule and the Company’s significant expertise in this area and as such, the research and development services are expected to significantly modify and customize the license. Therefore, for the Lead Program, the license and the services were combined into a single performance obligation. Since the other programs each represent distinct intellectual property and there are no other services included in the 2021 Zai Lab Agreement related to these licenses, each license is considered to be a distinct performance obligation. As such, there are four performance obligations included in the 2021 Zai Lab Agreement. The Company concluded that the estimated transaction price is $40.4 million, consisting of the $25.0 million upfront payment, the $10.4 million premium related to the purchase of the Company’s common stock, and the estimated $5.0 million expected to be reimbursed by Zai Lab for research and development activities for the Lead Program. The potential milestone payments were deemed to be fully constrained until the Company concludes that achievement of the milestone is probable, and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to royalties will be recognized if and when the related sales occur, as they were determined to relate predominantly to the license granted to Zai Lab and, therefore, have also been excluded from the transaction price. The Company will re-assess the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. The transaction price of $40.4 million was then allocated to the four performance obligations based on their relative standalone selling price. The standalone selling price of the performance obligations was not directly observable; therefore, the Company estimated the standalone selling price using an adjusted market assessment approach, representing the amount that the Company believes the market is willing to pay for the product or service. The estimate was based on consideration of observable inputs, such as, values of other preclinical collaboration arrangements adjusted for the Company’s estimate of the probability of success for each Program. Revenue related to the Lead Program license and related research and development services performance obligation will be recognized over time as the research and development activities are performed. The Company will utilize a cost-based input method according to costs incurred to date compared to estimated total costs. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligations. The Company recognized revenue allocated to the other programs at a point in time upon transfer of the licenses to Zai Lab in June 2021. During the three and six months ended June 30, 2021, the Company recognized revenue of $14.4 million under the 2021 Zai Lab Agreement. The upfront payment of $25.0 million and the purchase price premium under the Stock Purchase Agreement of $10.4 million were recorded in Accounts receivable as of June 30, 2021 as the Company has an unconditional right to the payments under the 2021 Zai Lab Agreement and the Stock Purchase Agreement. As of June 30, 2021, there was $21.0 million in deferred revenue under the agreements, $13.2 million of which is current and $7.8 million of which is non-current. Janssen Biotech, Inc. In December 2020, the Company entered into a research collaboration and license agreement with Janssen Biotech, Inc. (Janssen) to develop a novel DART molecule (Janssen Agreement). The research collaboration will incorporate the Company’s proprietary DART platform to enable simultaneous targeting of two undisclosed targets in a therapeutic area outside oncology. Under the terms of the Janssen Agreement, Janssen paid the Company an upfront payment of $20.0 million and will be responsible for funding all research and development expenses. The Company will also be eligible to receive up to $312.0 million in potential milestone payments and tiered royalties of up to 10% on worldwide product sales. Subject to the terms of this agreement, the Company granted Janssen an exclusive, royalty-bearing license to develop, manufacture and commercialize the preclinical bispecific molecule and the Company will perform certain research and development activities during a specified research term. The Company evaluated the Janssen Agreement under the provisions of ASC 606 and identified the following material promises under the arrangement: (i) a license to develop the preclinical bispecific molecule and (ii) performing certain research and development activities during the research term. The Company determined that the license and research and development activities are separate performance obligations because they are capable of being distinct, and are distinct in the context of the contract. The license has standalone functionality as Janssen could benefit from the license on its own without the Company’s involvement during the research term. The Company determined that the transaction price of the Janssen Agreement at inception was $22.2 million, consisting of the consideration to which the Company was entitled in exchange for the license and an estimate of the consideration for research and development activities to be performed. The transaction price was allocated to each performance obligation based on their relative standalone selling price. The standalone selling price of the license was determined using the adjusted market assessment approach considering similar collaboration and license agreements as well as current market conditions. The standalone selling price for agreed-upon research and development activities to be performed was determined using the expected cost approach based on similar arrangements the Company has with other parties. This variable consideration is fully constrained until the Company begins its work under the performance obligation. The potential milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur, as they were determined to relate predominantly to the license granted to Janssen and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. The Company recognized the $20.0 million allocated to the license when it satisfied its performance obligation and transferred the license to Janssen in December 2020. The $2.2 million allocated to the research and development activities is being recognized over the Company’s involvement in the research term, which is estimated to be less than two years. During the three and six months ended June 30, 2021, the Company recognized revenue of $0.6 million and $0.9 million, respectively, for research and development activities performed under the Janssen Agreement. I-Mab Biopharma In 2019, the Company entered into a collaboration and license agreement with I-Mab Biopharma (I-Mab) to develop and commercialize enoblituzumab, an immune-optimized, anti-B7-H3 monoclonal antibody that incorporates the Company's proprietary Fc Optimization technology platform (I-Mab Agreement). I-Mab obtained regional development and commercialization rights in mainland China, Hong Kong, Macau and Taiwan (I-Mab's territory), will lead clinical development of enoblituzumab in its territories, and will participate in global studies conducted by the Company. Under the terms of the I-Mab Agreement, I-Mab paid the Company an upfront payment of $15.0 million. Assuming successful development and commercialization of enoblituzumab, the Company could receive up to $135.0 million in development and regulatory milestones. In addition, I-Mab would pay the Company tiered royalties ranging from mid-teens to 20% on annual net sales in I-Mab's territory. The Company evaluated the I-Mab Agreement under the provisions of ASC 606 and identified the following material promises under the arrangement: (i) an exclusive license to develop and commercialize enoblituzumab in I-Mab’s territories, (ii) perform certain research and development activities and (iii) conduct a chronic toxicology study. The Company determined that the license and the related research and development activities were not distinct from one another, as the license has limited value without the performance of the research and development activities. As such, the Company determined that the license and related research and development activities should be combined into a single performance obligation. The Company determined that the $15.0 million upfront payment from I-Mab constituted the entirety of the consideration to be included in the transaction price as of the outset of the arrangement for the license and related research and development activities. The Company has also determined that the chronic toxicology study is distinct from the other promises and has estimated the variable consideration of that performance obligation to be approximately $1.0 million. I-Mab will pay the Company for the cost of this study as the costs are incurred and I-Mab will be entitled to a one-time credit of eighty percent of the total amount of such costs against a future milestone, at which point the Company will reassess the transaction price for that milestone. The potential development and regulatory milestone payments are fully constrained until the Company concludes that achievement of the milestone is probable, and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods, and as such have been excluded from the transaction price. Any consideration related to royalties will be recognized if and when the related sales occur, as they were determined to relate predominantly to the license granted to I-Mab and, therefore, have also been excluded from the transaction price. The Company re-assesses the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. Revenue under the I-Mab Agreement is being recognized using a cost-based input method according to costs incurred to date compared to estimated total costs. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligations. During the three months ended June 30, 2021 and 2020, the Company recognized revenue of $1.7 million and $1.4 million, respectively, under the I-Mab Agreement. During the six months ended June 30, 2021 and 2020, the Company recognized revenue of $2.3 million and $2.5 million, respectively, under the I-Mab Agreement. At June 30, 2021, $9.0 million of revenue was deferred under this agreement, $3.4 million of which was current and $5.6 million of which was non-current. At December 31, 2020, $11.4 million of revenue was deferred under this agreement, $4.5 million of which was current and $6.9 million of which was non-current. NIAID Contract The Company entered into a contract with National Institute of Allergy and Infectious Diseases (NIAID), effective as of September 15, 2015, to perform product development and to advance up to two DART molecules, including MGD014 (NIAID Contract). Under the NIAID Contract, the Company will develop these product candidates for Phase 1/2 clinical trials as therapeutic agents, in combination with latency reversing treatments, to deplete cells infected with human immunodeficiency virus (HIV) infection. NIAID does not receive goods or services from the Company under this contract, therefore the Company does not consider NIAID to be a customer and concluded this contract is outside the scope of ASC 606.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Employee Stock Purchase Plan In May 2017, the Company’s stockholders approved the 2016 Employee Stock Purchase Plan (the 2016 ESPP). The 2016 ESPP is structured as a qualified employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended (IRC), and is not subject to the provisions of the Employee Retirement Income Security Act of 1974. The Company reserved 800,000 shares of common stock for issuance under the 2016 ESPP. The 2016 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 10% of their eligible compensation, subject to any plan limitations. The 2016 ESPP provides for six-month offering periods ending on May 31 and November 30 of each year. At the end of each offering period, employees are able to purchase shares at 85% of the fair market value of the Company’s common stock on the last day of the offering period. During the six months ended June 30, 2021, 12,305 shares of common stock were purchased under the 2016 ESPP. Employee Stock Option Plans Effective February 2003, the Company implemented the 2003 Equity Incentive Plan (2003 Plan), and it was amended and approved by the Company's stockholders in 2005. Stock options granted under the 2003 Plan may be either incentive stock options as defined by the IRC, or non-qualified stock options. In 2013, the 2003 Plan was terminated, and no further awards may be issued under the plan. Any shares of common stock subject to awards under the 2003 Plan that expire, terminate, or are otherwise surrendered, canceled, forfeited or repurchased without having been fully exercised, or resulting in any common stock being issued, will become available for issuance under the 2013 Stock Incentive Plan (2013 Plan), up to a specified number of shares. As of June 30, 2021, under the 2003 Plan, there were options to purchase an aggregate of 203,138 shares of common stock outstanding at a weighted average exercise price of $2.98 per share. In October 2013, the Company implemented the 2013 Plan. The 2013 Plan provides for the grant of stock options and other stock-based awards, as well as cash-based performance awards. The number of shares of common stock reserved for issuance under the 2013 Plan will automatically increase on January 1 of each year from January 1, 2014 through and including January 1, 2023, by the lesser of (a) 1,960,168 shares, (b) 4.0% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or (c) the number of shares of common stock determined by the Company's Board of Directors. During the six months ended June 30, 2021, the maximum number of shares of common stock authorized to be issued by the Company under the 2013 Plan was increased to 13,856,781. If an option expires or terminates for any reason without having been fully exercised, if any shares of restricted stock are forfeited, or if any award terminates, expires or is settled without all or a portion of the shares of common stock covered by the award being issued, such shares are available for the grant of additional awards. However, any shares that are withheld (or delivered) to pay withholding taxes or to pay the exercise price of an option are not available for the grant of additional awards. As of June 30, 2021, there were options to purchase an aggregate of 8,407,760 shares of common stock outstanding at a weighted average exercise price of $21.92 per share under the 2013 Plan. The following stock-based compensation expense was recognized for the periods indicated (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 3,058 $ 2,589 $ 5,785 $ 5,023 Selling, general and administrative 3,012 2,506 5,571 4,564 Total stock-based compensation expense $ 6,070 $ 5,095 $ 11,356 $ 9,587 The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated: Six Months Ended June 30, 2021 2020 Expected dividend yield 0% 0% Expected volatility 86.2% -86.7% 67.3% - 108.8% Risk-free interest rate 0.6% - 1.4% 0.5% - 1.8% Expected term 6.25 years 6.25 years The following table summarizes stock option activity during the six months ended June 30, 2021: Shares Weighted- Weighted-Average Aggregate Outstanding, December 31, 2020 7,258,353 $ 21.48 6.8 Granted 1,790,246 20.72 Exercised (250,175) 18.35 Forfeited or expired (187,526) 16.36 Outstanding, June 30, 2021 8,610,898 21.48 7.0 $ 53,928 As of June 30, 2021: Exercisable 4,957,615 22.96 5.6 25,634 Vested and expected to vest 8,194,010 21.58 6.9 50,662 The weighted-average grant-date fair value of options granted during the six months ended June 30, 2021 and 2020 was $15.11 and $8.30, respectively. The total intrinsic value of options exercised during the six months ended June 30, 2021 and 2020 was approximately $1.8 million and $2.6 million, respectively. The total cash received for options exercised during the six months ended June 30, 2021 and 2020 was approximately $4.6 million and $2.4 million, respectively. The total fair value of shares vested in the six months ended June 30, 2021 and 2020 was approximately $8.1 million and $7.4 million, respectively. As of June 30, 2021, the total unrecognized compensation expense related to unvested stock options, net of related forfeiture estimates, was approximately $40.9 million, which the Company expects to recognize over a weighted-average period of approximately 2.7 years. Restricted Stock Units During 2019, the Company awarded restricted stock units (RSUs) under the 2013 Plan to all employees with at least six months of service as of the date of grant except executive officers. Each RSU entitles the holder to receive one share of the Company's common stock when the RSU vests. The RSUs vest in two equal installments on the first and second anniversary of the grant date. Compensation expense is recognized on a straight-line basis. The following table summarizes RSU activity during the six months ended June 30, 2021: Shares Weighted-Average Grant Date Fair Value Outstanding, December 31, 2020 209,250 $ 15.92 Granted 10,500 29.17 Exercised (7,500) 23.68 Forfeited or expired (17,400) 15.32 Outstanding, June 30, 2021 194,850 16.39 At June 30, 2021, there was $0.8 million of total unrecognized compensation cost related to unvested RSUs, which the Company expects to recognize over a remaining weighted-average period of approximately 1.3 years.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesOn September 13, 2019, a securities class action complaint was filed in the U.S. District Court for the District of Maryland by Todd Hill naming the Company, its Chief Executive Officer, Dr. Koenig, and its Chief Financial Officer, Mr. Karrels, as defendants for allegedly making false and materially misleading statements regarding the Company’s SOPHIA trial. On August 17, 2020, the Employees’ Retirement System of the City of Baton Rouge and Parish of East Baton Rouge was appointed as Lead Plaintiff, and on October 16, 2020, the Lead Plaintiff filed an amended complaint. The amended complaint asserts a putative class period stemming from February 6, 2019 to June 4, 2019. The Company filed a Motion to Dismiss on November 30, 2020. Plaintiff filed an Opposition brief on January 29, 2021, to which the Company filed a timely reply. The Company intends to vigorously defend against this action. However, the outcome of this legal proceeding is uncertain at this time and the Company cannot reasonably estimate a range of loss, if any. Accordingly, the Company has not accrued any liability associated with this action.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiaries, MacroGenics UK Limited and MacroGenics Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2020 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 25, 2021.
Inventory	Inventory The Company outsources the manufacturing of MARGENZA. Prior to FDA approval of MARGENZA in December 2020, the cost of materials and expenses associated with the manufacturing of MARGENZA were recorded as research and development expense. Subsequent to regulatory approval, the Company began capitalizing MARGENZA inventory costs. The Company values its inventories at the lower of cost and estimated net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and third-party contract manufacturing costs, on a first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment is first identified. Such write downs, should they occur, are recorded within the cost of sales in the statement of operations. As of June 30, 2021, the Company’s inventory balance consisted primarily of raw materials purchased and work in progress manufactured after the FDA approval of MARGENZA.
Product Revenue, Reserves for Variable Consideration, Customer Discounts and Services Fees, Product Returns, Provider Chargebacks and Discounts, and Government Rebates	Product Revenue, Net The Company entered into a limited number of arrangements with specialty distributors in the United States to distribute MARGENZA. These arrangements are considered to be contracts with customers and are in the scope of Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (ASC 606). The Company has written contracts with each of its customers that have a single performance obligation - to deliver products upon receipt of a customer order - and these obligations are satisfied when delivery occurs and the customer receives the product. The specialty distributors subsequently resell the Company’s product to healthcare providers. Product revenue is recorded net of applicable reserves for variable consideration, including discounts and other allowances. Shipping and handling costs for product shipments occur prior to the customer obtaining control of the goods and are recorded in cost of sales. For the three and six months ended June 30, 2021, the shipping costs incurred were immaterial. Reserves for Variable Consideration Revenue from product sales is recorded at the net sales price, which includes estimates of variable consideration. Components of variable consideration typically include discounts, product returns, provider chargebacks and discounts and government rebates. Variable consideration is estimated following the expected value method in accordance with ASC 606 and includes such factors as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Estimates of the variable consideration were not deemed constrained during the six months ended June 30, 2021. Customer Discounts and Service Fees The Company may provide customers with discounts which are explicitly stated in the contracts. These discounts are recorded as a reduction of revenue in the period the related product revenue is recognized. In addition, these contracts may include written service arrangements whereby the Company pays fees to customers who provide services such as sales order management, data, contract administration and distribution services, at rates which we believe to be consistent with fair market value. The Company has determined such services received to date are not distinct from the Company’s sale of products to its customers and, therefore, these payments have been recorded as a reduction of revenue within the statement of operations. Product Returns Consistent with industry practice, the Company offers the specialty distributors product return rights pursuant to written contracts and/or Company returned goods policies. The Company estimates the amount of its product sales that may be returned by its customers and records an estimated liability and a reduction of revenue in the period the related product revenue is recognized. The Company currently estimates product returns using industry benchmarking as well as other information available, such as visibility into the inventory remaining in the distribution channel, since the Company does not have its own returns experience. The Company's estimates of product returns may be adjusted in the future based on actual returns experience, known or expected changes in the marketplace, or other factors. Provider Chargebacks and Discounts Chargebacks for fees and discounts to healthcare providers represent the estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices charged to customers who directly purchase the product from the Company. In such cases, customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. The reserve for chargebacks is established in the same period that the related revenue is recognized, resulting in a reduction of product revenue. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider by customers, and the Company generally issues credits for such amounts within a few weeks of the customer’s notification to the Company of the resale. Chargebacks consist of credits the Company expects to issue for units that remain in the distribution channel at each reporting period end that the Company expects will be sold to qualified healthcare providers and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates The Company is subject to discount and/or rebate obligations under state Medicaid programs, Medicare and contractual agreements with and statutory obligations to certain Federal and State entities. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimates of future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel at the end of each reporting period. Customer discounts are recorded as a reduction of accounts receivable on the consolidated balance sheets. Allowance for product returns, provider chargebacks, government and other rebates and service fees are recorded as a component of accrued expenses and other current liabilities on the consolidated balance sheets.
Cost of Product Sales	Cost of product sales Cost of product sales relates to sales of MARGENZA. These costs include material, manufacturing and shipping costs, as well as royalties payable on net sales of MARGENZA. All product costs incurred prior to FDA approval of MARGENZA in December 2020 were expensed as research and development expense. The Company expects cost of product sales to continue to be positively impacted as the Company sells through inventory that was expensed prior to FDA approval of MARGENZA in December 2020. The Company is currently unable to estimate how long it will be until it begins selling product manufactured post FDA approval.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). ASU 2019-12 is part of the FASB’s overall simplification initiative and seeks to simplify the accounting for income taxes by updating certain guidance and removing certain exceptions. The updated guidance is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years. The adoption of this standard as of January 1, 2021 had no impact on the Company's consolidated financial statements and related disclosures.
Fair Value of Financial Instruments	The Company's financial instruments consist of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. The carrying amount of accounts receivable, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of their short-term nature. The Company accounts for recurring and non-recurring fair value measurements in accordance with FASB Accounting Standards Codification (ASC) 820, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value, establishes a fair value hierarchy for assets and liabilities measured at fair value, and requires expanded disclosures about fair value measurements. The ASC 820 hierarchy ranks the quality of reliability of inputs, or assumptions, used in the determination of fair value and requires assets and liabilities carried at fair value to be classified and disclosed in one of the following three categories: • Level 1 - Fair value is determined by using unadjusted quoted prices that are available in active markets for identical assets and liabilities. • Level 2 - Fair value is determined by using inputs other than Level 1 quoted prices that are directly or indirectly observable. Inputs can include quoted prices for similar assets and liabilities in active markets or quoted prices for identical assets and liabilities in inactive markets. Related inputs can also include those used in valuation or other pricing models, such as interest rates and yield curves that can be corroborated by observable market data. • Level 3 - Fair value is determined by inputs that are unobservable and not corroborated by market data. Use of these inputs involves significant and subjective judgments to be made by a reporting entity - e.g., determining an appropriate adjustment to a discount factor for illiquidity associated with a given security.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Financial Assets Measured at Fair Value on a Recurring Basis	Financial assets measured at fair value on a recurring basis were as follows (in thousands): Fair Value Measurements at June 30, 2021 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Total Level 1 Level 2 Assets: Money market funds $ 16,606 $ 16,606 $ — U.S. Treasury securities 79,249 — 79,249 Government-sponsored enterprises 4,537 — 4,537 Corporate debt securities 42,809 — 42,809 Total assets measured at fair value (a) $ 143,201 $ 16,606 $ 126,595 Fair Value Measurements at December 31, 2020 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Total Level 1 Level 2 Assets: Money market funds $ 49,004 $ 49,004 $ — U.S. Treasury securities 60,623 — 60,623 Corporate debt securities 33,776 — 33,776 Total assets measured at fair value (b) $ 143,403 $ 49,004 $ 94,399 (a) Total assets measured at fair value at June 30, 2021 includes approximately $34.9 million reported in cash and cash equivalents on the consolidated balance sheet. (b) Total assets measured at fair value at December 31, 2020 includes approximately $52.0 million reported in cash and cash equivalents on the consolidated balance sheet.

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Marketable Securities	The following tables summarize the Company's marketable debt securities (in thousands): June 30, 2021 Amortized Gross Gross Fair U.S. Treasury securities $ 79,244 $ 5 $ — $ 79,249 Government-sponsored enterprises 4,537 — — 4,537 Corporate debt securities 24,564 — (4) 24,560 Total $ 108,345 $ 5 $ (4) $ 108,346 December 31, 2020 Amortized Gross Gross Fair U.S. Treasury securities $ 60,630 $ 1 $ (7) $ 60,624 Corporate debt securities 30,777 2 (3) 30,776 Total $ 91,407 $ 3 $ (10) $ 91,400

Inventory (Tables)

Inventory (Tables)	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory	All of the Company's inventory relates to the manufacturing of MARGENZA. The following table sets forth the Company's inventory (in thousands): June 30, 2021 Raw materials $ 607 Work in process 5,869 Total inventory $ 6,476

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation Expense	The following stock-based compensation expense was recognized for the periods indicated (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Research and development $ 3,058 $ 2,589 $ 5,785 $ 5,023 Selling, general and administrative 3,012 2,506 5,571 4,564 Total stock-based compensation expense $ 6,070 $ 5,095 $ 11,356 $ 9,587
Valuation Assumptions Using the Black-Scholes Option-Pricing Model	The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated: Six Months Ended June 30, 2021 2020 Expected dividend yield 0% 0% Expected volatility 86.2% -86.7% 67.3% - 108.8% Risk-free interest rate 0.6% - 1.4% 0.5% - 1.8% Expected term 6.25 years 6.25 years
Stock Option and Restricted Stock Unit Activity	The following table summarizes stock option activity during the six months ended June 30, 2021: Shares Weighted- Weighted-Average Aggregate Outstanding, December 31, 2020 7,258,353 $ 21.48 6.8 Granted 1,790,246 20.72 Exercised (250,175) 18.35 Forfeited or expired (187,526) 16.36 Outstanding, June 30, 2021 8,610,898 21.48 7.0 $ 53,928 As of June 30, 2021: Exercisable 4,957,615 22.96 5.6 25,634 Vested and expected to vest 8,194,010 21.58 6.9 50,662
Schedule of RSU Activity	The following table summarizes RSU activity during the six months ended June 30, 2021: Shares Weighted-Average Grant Date Fair Value Outstanding, December 31, 2020 209,250 $ 15.92 Granted 10,500 29.17 Exercised (7,500) 23.68 Forfeited or expired (17,400) 15.32 Outstanding, June 30, 2021 194,850 16.39

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Securities	$ 108,346	$ 91,400
Fair Value Measurements, Recurring Basis
Assets:
Cash and cash equivalents	34,900	52,000
Total assets measured at fair value	143,201	143,403
Fair Value Measurements, Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	16,606	49,004
Fair Value Measurements, Recurring Basis | Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	126,595	94,399
Fair Value Measurements, Recurring Basis | Money market funds
Assets:
Cash and cash equivalents	16,606	49,004
Fair Value Measurements, Recurring Basis | Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	16,606	49,004
Fair Value Measurements, Recurring Basis | Money market funds | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Fair Value Measurements, Recurring Basis | U.S. Treasury securities
Assets:
Securities	79,249	60,623
Fair Value Measurements, Recurring Basis | U.S. Treasury securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Securities	0	0
Fair Value Measurements, Recurring Basis | U.S. Treasury securities | Significant Other Observable Inputs (Level 2)
Assets:
Securities	79,249	60,623
Fair Value Measurements, Recurring Basis | Government-sponsored enterprises
Assets:
Securities	4,537
Fair Value Measurements, Recurring Basis | Government-sponsored enterprises | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Securities	0
Fair Value Measurements, Recurring Basis | Government-sponsored enterprises | Significant Other Observable Inputs (Level 2)
Assets:
Securities	4,537
Fair Value Measurements, Recurring Basis | Corporate debt securities
Assets:
Securities	42,809	33,776
Fair Value Measurements, Recurring Basis | Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Securities	0	0
Fair Value Measurements, Recurring Basis | Corporate debt securities | Significant Other Observable Inputs (Level 2)
Assets:
Securities	$ 42,809	$ 33,776

Marketable Securities (Details)

Marketable Securities (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 108,345,000	$ 91,407,000
Gross Unrealized Gains	5,000	3,000
Gross Unrealized Losses	(4,000)	(10,000)
Fair Value	108,346,000	91,400,000
Allowance for credit loss related to available-for-sale debt securities	0	0
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	79,244,000	60,630,000
Gross Unrealized Gains	5,000	1,000
Gross Unrealized Losses	0	(7,000)
Fair Value	79,249,000	60,624,000
Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,537,000
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	4,537,000
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,564,000	30,777,000
Gross Unrealized Gains	0	2,000
Gross Unrealized Losses	(4,000)	(3,000)
Fair Value	$ 24,560,000	$ 30,776,000

Inventory (Details)

Inventory (Details) $ in Thousands	Jun. 30, 2021USD ($)
Inventory Disclosure [Abstract]
Raw materials	$ 607
Work in process	5,869
Total inventory	$ 6,476

Stockholders' Equity (Details)

Stockholders' Equity (Details) - At the Market Offering - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended
	Apr. 30, 2021	Nov. 30, 2020	Mar. 31, 2021
Class of Stock [Line Items]
Maximum amount available for issuance		$ 100
Number of shares sold (in shares)			3,622,186
Sales of stock purchase price (in dollars per share)			$ 27.60
Proceeds of stock sale			$ 98.2
Maximum amount available for issuance, increase	$ 300

Collaboration and Other Agree_2

Collaboration and Other Agreements - Incyte Corporation (Details)	3 Months Ended		6 Months Ended		12 Months Ended	24 Months Ended	42 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2017USD ($)performanceObligation	Dec. 31, 2018USD ($)	Jun. 30, 2021USD ($)
Collaboration And Other Agreements [Line Items]
Revenues	$ 30,757,000	$ 20,257,000	$ 47,638,000	$ 33,939,000
Incyte Corporation | Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment					$ 150,000,000
Potential development and regulatory milestone payments under agreement					420,000,000
Potential commercial milestone payments under agreement					$ 330,000,000
Development and regulatory milestones recognized	5,000,000		15,000,000				$ 70,000,000
Number of performance obligations | performanceObligation					2
Collaborative agreement transaction price					$ 154,000,000
Variable consideration recognized						$ 4,000,000
Maximum | Incyte Corporation | Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)					24.00%
Minimum | Incyte Corporation | Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)					15.00%
Revenues From License Agreements | Incyte Corporation | Incyte MGA012 Agreement
Collaboration And Other Agreements [Line Items]
Revenues					$ 150,000,000
Revenues From License Agreements | Incyte Corporation | Incyte MGA012 Agreement - Clinical activities
Collaboration And Other Agreements [Line Items]
Revenues		0		0
Revenues From License Agreements | Incyte Corporation | Incyte MGA012 Clinical Services
Collaboration And Other Agreements [Line Items]
Revenues	700,000	$ 1,500,000	800,000	$ 7,400,000
Revenues From License Agreements | Incyte Corporation | Incyte MGA012 Supply Agreement
Collaboration And Other Agreements [Line Items]
Revenues	$ 2,800,000		$ 5,900,000

Collaboration and Other Agree_3

Collaboration and Other Agreements - Zai Lab (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2018	Jun. 15, 2021	Dec. 31, 2020
Collaboration And Other Agreements [Line Items]
Revenues	$ 30,757	$ 20,257		$ 47,638	$ 33,939
Common stock, par value (in dollars per share)	$ 0.01			$ 0.01				$ 0.01
Deferred revenue, current	$ 16,565			$ 16,565				$ 4,456
Deferred revenue, net of current portion	13,476			13,476				6,926
2018 Zai Lab Agreement | Zai Labs
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment						$ 25,000
Non-refundable upfront payment, net of tax withholding						22,500
Nonrefundable payment tax withholding						$ 2,500
Potential development and regulatory milestone payments under agreement			$ 140,000
Revenues			4,000
Revenues, net of tax withholding			3,600		3,600
Revenues, tax withholding			$ 400
Deferred revenue	0			0				$ 0
Zai Lab Clinical Supply Agreements | Zai Labs
Collaboration And Other Agreements [Line Items]
Revenues	500	$ 300		1,600	$ 1,300
Zai Lab Agreement, Margetuximab | Zai Labs | Maximum
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)						20.00%
Zai Lab Agreement, TRIDENT molecule | Zai Labs
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)						10.00%
2021 Zai Lab Agreements | Zai Labs
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment				25,000
Potential development and regulatory milestone payments under agreement							$ 800,000
Revenues	14,400			14,400
Deferred revenue	21,000			21,000
Opt-in fee							$ 85,000
Proceeds of stock sale				30,000
Sales of stock purchase price (in dollars per share)							$ 31.30
Potential commercial milestone payments under agreement							$ 600,000
Collaborative agreement transaction price							$ 40,400
Variable consideration recognized				5,000
Deferred revenue, current	13,200			13,200
Deferred revenue, net of current portion	$ 7,800			7,800
2021 Zai Lab Agreements | Zai Labs | Additional Paid-In Capital
Collaboration And Other Agreements [Line Items]
Premium received on stock purchase				$ 10,400

Collaboration and Other Agree_4

Collaboration and Other Agreements - Janssen (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Collaboration And Other Agreements [Line Items]
Revenues		$ 30,757	$ 20,257	$ 47,638	$ 33,939
Janssen Biotech Inc | Janssen Collaboration and License Agreement
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment	$ 20,000
Potential milestone payments and royalties on product sales	$ 312,000
Potential proceeds from royalties (percent)	10.00%
Collaborative agreement transaction price	$ 22,200
Clinical trial activities selling price amount	2,200
Janssen Biotech Inc | Janssen Collaboration and License Agreement | Revenues From License Agreements
Collaboration And Other Agreements [Line Items]
Revenues	$ 20,000
Janssen Biotech Inc | Janssen Collaboration and License Agreement | Revenue From Performance of the Research and Development Activities
Collaboration And Other Agreements [Line Items]
Revenues		$ 600		$ 900

Collaboration and Other Agree_5

Collaboration and Other Agreements - I-Mab Biopharma (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
Collaboration And Other Agreements [Line Items]
Revenues	$ 30,757	$ 20,257	$ 47,638	$ 33,939
Deferred revenue, current	16,565		16,565			$ 4,456
Deferred revenue, net of current portion	13,476		13,476			6,926
I-Mab | I-Mab Biopharma Collaboration and License Agreement
Collaboration And Other Agreements [Line Items]
Non-refundable upfront payment					$ 15,000
Potential development and regulatory milestone payments under agreement					135,000
Estimated variable consideration					$ 1,000
Revenues	1,700	$ 1,400	2,300	$ 2,500
Deferred revenue	9,000		9,000			11,400
Deferred revenue, current	3,400		3,400			4,500
Deferred revenue, net of current portion	$ 5,600		$ 5,600			$ 6,900
I-Mab | I-Mab Biopharma Collaboration and License Agreement | Maximum
Collaboration And Other Agreements [Line Items]
Potential proceeds from royalties (percent)					20.00%

Collaboration and Other Agree_6

Collaboration and Other Agreements - NIAID Contract (Details)	Sep. 15, 2015USD ($)Molecule	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2017USD ($)
Collaboration And Other Agreements [Line Items]
Revenues		$ 30,757,000	$ 20,257,000	$ 47,638,000	$ 33,939,000
NIAID
Collaboration And Other Agreements [Line Items]
Commercialization of molecules | Molecule	2
Base period amount	$ 7,500,000
Additional development funding options under agreement	17,000,000
Total potential value	$ 24,500,000
Proceeds from additional development funding options under agreement						$ 10,800,000
Revenues From Grants | NIAID
Collaboration And Other Agreements [Line Items]
Revenues		$ 400,000	$ 4,600,000	$ 1,200,000	$ 5,300,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2017	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		8,610,898		8,610,898		7,258,353
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 21.48		$ 21.48		$ 21.48
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 6,070	$ 5,095	$ 11,356	$ 9,587
2016 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)	800,000
Payroll deduction discount	10.00%
Purchase price of common stock percent of the fair market value	85.00%
Common stock purchased (in shares)				12,305
2003 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		203,138		203,138
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 2.98		$ 2.98
Stock Incentive Plan 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)		13,856,781		13,856,781
Potential annual increase in shares reserved for future issuance (in shares)		1,960,168		1,960,168
Potential annual increase in shares reserved for future issuance as percentage of outstanding share				4.00%
Options outstanding (in shares)		8,407,760		8,407,760
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 21.92		$ 21.92
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 3,058	2,589	$ 5,785	5,023
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 3,012	$ 2,506	$ 5,571	$ 4,564

Stock-Based Compensation - Opti

Stock-Based Compensation - Option Pricing Assumptions (Details)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected term	6 years 3 months	6 years 3 months
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	86.20%	67.30%
Risk-free interest rate	0.60%	0.50%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	86.70%	108.80%
Risk-free interest rate	1.40%	1.80%

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Shares
Shares, Outstanding, Beginning Balance (in shares)	7,258,353
Shares, Granted (in shares)	1,790,246
Shares, Exercised (in shares)	(250,175)
Shares, Forfeited or expired (in shares)	(187,526)
Shares, Outstanding, Ending Balance (in shares)	8,610,898		7,258,353
Shares, Exercisable (in shares)	4,957,615
Shares, Vested and expected to vest (in shares)	8,194,010
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Outstanding, Beginning Balance (in dollars per share)	$ 21.48
Weighted- Average Exercise Price, Granted (in dollars per share)	20.72
Weighted- Average Exercise Price, Exercised (in dollars per share)	18.35
Weighted- Average Exercise Price, Forfeited or expired (in dollars per share)	16.36
Weighted- Average Exercise Price, Outstanding, Ending Balance (in dollars per share)	21.48		$ 21.48
Weighted- Average Exercise Price, Exercisable (in dollars per share)	22.96
Weighted- Average Exercise Price, Vested and expected to vest (in dollars per share)	$ 21.58
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted- Average Remaining Contractual Term, Outstanding	7 years		6 years 9 months 18 days
Weighted- Average Remaining Contractual Term, Exercisable	5 years 7 months 6 days
Weighted- Average Remaining Contractual Term, Vested and expected to vest	6 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 53,928
Aggregate Intrinsic Value, Exercisable	25,634
Aggregate Intrinsic Value, Vested and expected to vest	$ 50,662
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 15.11	$ 8.30
Intrinsic value of options exercised	$ 1,800	$ 2,600
Cash received for options exercised	4,600	2,400
Fair value of shares vested	8,100	$ 7,400
Unrecognized compensation expense related to non-vested stock-options, net of related forfeiture estimates	$ 40,900
Unrecognized compensation expense recognition period	2 years 8 months 12 days

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Unit Activity (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Weighted-Average Grant Date Fair Value
Unrecognized compensation expense recognition period	2 years 8 months 12 days
Restricted Stock Units
Shares
Beginning Balance (in shares)	209,250
Granted (in shares)	10,500
Exercised (in shares)	(7,500)
Forfeited or expired (in shares)	(17,400)
Ending Balance (in shares)	194,850
Weighted-Average Grant Date Fair Value
Beginning Balance (in dollars per share) | $ / shares	$ 15.92
Granted (in dollars per share) | $ / shares	29.17
Exercised (in dollars per share) | $ / shares	23.68
Forfeited or expired (in dollars per share) | $ / shares	15.32
Ending Balance (in dollars per share) | $ / shares	$ 16.39
Awards granted in period (in shares)	10,500
Total unrecognized compensation cost | $	$ 0.8
Unrecognized compensation expense recognition period	1 year 3 months 18 days