C4 Therapeutics (CCCC) 10-Q 12 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 10, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	CCCC
Entity Registrant Name	C4 Therapeutics, Inc.
Entity Central Index Key	0001662579
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		43,029,500
Entity File Number	001-39567
Entity Tax Identification Number	47-5617627
Entity Address, Address Line One	490 Arsenal Way
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	617
Local Phone Number	231-0700
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 63,434	$ 90,549
Short-term investments	135,979
Accounts receivable	4,141	4,623
Prepaid expenses and other current assets	5,370	1,595
Total current assets	208,924	96,767
Property and equipment, net	3,580	4,463
Right-of-use asset	13,544	14,453
Restricted cash	2,577	2,577
Other assets	502
Total assets	229,127	118,260
Current liabilities:
Accounts payable	5,264	5,385
Accrued expenses and other current liabilities	9,830	6,671
Deferred revenue, current	23,915	20,705
Operating lease liability, current	1,000	880
Total current liabilities	40,009	33,641
Deferred revenue, net of current	61,083	72,718
Operating lease liability, net of current	12,097	12,869
Warrant liability	5,465
Long-term debt	9,877
Total liabilities	128,531	119,228
Commitments and Contingencies (see Note 5 and Note 8)
Redeemable convertible preferred stock value	256,520	110,995
Stockholders’ deficit:
Common stock, par value of $0.0001 per share; 370,000,000 and 180,000,000 shares authorized as of September 30, 2020 and December 31, 2019; 1,634,121 and 1,426,641 shares issued and outstanding as of September 30, 2020 and December 31, 2019	1	1
Additional paid-in capital	6,095	5,524
Accumulated other comprehensive loss	8
Accumulated deficit	(162,028)	(117,488)
Total stockholders’ deficit	(155,924)	(111,963)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	229,127	118,260
Series Seed Redeemable Convertible Preferred Stock
Current liabilities:
Redeemable convertible preferred stock value	1,000	1,000
Series A Redeemable Convertible Preferred Stock
Current liabilities:
Redeemable convertible preferred stock value	109,995	$ 109,995
Series B Redeemable Convertible Preferred Stock
Current liabilities:
Redeemable convertible preferred stock value	$ 145,525

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Redeemable convertible preferred stock, shares authorized	264,000,000	146,760,000
Redeemable convertible preferred stock, shares issued	256,003,042	113,145,900
Redeemable convertible preferred stock, shares outstanding	256,003,042	113,145,900
Redeemable convertible preferred stock, liquidation value	$ 256,520	$ 110,995
Common stock, par value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	370,000,000	180,000,000
Common stock, shares issued	1,634,121	1,426,641
Common stock, shares outstanding	1,634,121	1,426,641
Series Seed Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value per share	$ 0.0005	$ 0.0005
Redeemable convertible preferred stock, shares authorized	4,000,000	4,000,000
Redeemable convertible preferred stock, shares issued	4,000,000	4,000,000
Redeemable convertible preferred stock, shares outstanding	4,000,000	4,000,000
Redeemable convertible preferred stock, liquidation value	$ 1,000	$ 1,000
Redeemable convertible preferred stock, redemption value	$ 1,000	$ 1,000
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value per share	$ 0.0005	$ 0.0005
Redeemable convertible preferred stock, shares authorized	110,000,000	110,000,000
Redeemable convertible preferred stock, shares issued	109,145,900	109,145,900
Redeemable convertible preferred stock, shares outstanding	109,145,900	109,145,900
Redeemable convertible preferred stock, liquidation value	$ 109,995	$ 109,995
Redeemable convertible preferred stock, redemption value	$ 109,995	$ 109,995
Series B Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value per share	$ 0.0005	$ 0.0005
Redeemable convertible preferred stock, shares authorized	150,000,000	0
Redeemable convertible preferred stock, shares issued	142,857,142	0
Redeemable convertible preferred stock, shares outstanding	142,857,142	0
Redeemable convertible preferred stock, liquidation value	$ 145,525	$ 0
Redeemable convertible preferred stock, redemption value	$ 145,525	$ 0

Condensed Consolidated Statemen

Condensed Consolidated Statement of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue from collaboration agreements	$ 8,447	$ 5,364	$ 24,933	$ 13,172
Operating expenses:
Research and development	23,935	12,948	58,007	32,042
General and administrative	2,861	2,417	8,472	6,083
Total operating expenses	26,796	15,365	66,479	38,125
Operating loss	(18,349)	(10,001)	(41,546)	(24,953)
Other income (expense), net:
Interest income (expense)	(352)	558	(170)	1,454
Amortization of debt discount	(203)		(229)
Change in fair value of warrant liability	(3,141)		(3,141)
Other (expense) income, net	43	(1)	44	323
Total other income (expense), net	(3,653)	557	(3,496)	1,777
Loss before income taxes	(22,002)	(9,444)	(45,042)	(23,176)
Income tax expense (benefit)	(167)	650	(502)	900
Net loss	(21,835)	(10,094)	(44,540)	(24,076)
Other comprehensive loss:
Unrealized gain (loss) on short-term investments	(10)	5	8	(4)
Comprehensive loss	(21,845)	(10,089)	(44,532)	(24,080)
Accrual of preferred stock dividends	(5,212)	(2,201)	(10,363)	(6,531)
Net loss attributable to common stockholders	$ (27,047)	$ (12,295)	$ (54,903)	$ (30,607)
Net loss per share attributable to common stockholders—basic and diluted (Note 12)	$ (17.55)	$ (8.93)	$ (36.76)	$ (22.59)
Weighted-average number of shares used in computed net loss per share —basic and diluted	1,540,902	1,376,365	1,493,521	1,354,734

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Redeemable Convertible Preferred Stock and Stockholder's Deficit - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Series Seed Redeemable Convertible Preferred Stock	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock
Beginning balance at Dec. 31, 2018	$ (79,750)	$ 1	$ 3,638		$ (83,389)
Redeemable convertible preferred stock, Beginning balance, Shares at Dec. 31, 2018						4,000,000	109,145,900
Redeemable convertible preferred stock, Beginning balance at Dec. 31, 2018						$ 1,000	$ 109,995
Beginning balance, Shares at Dec. 31, 2018		1,338,956
Exercise of stock options	260		260
Exercise of stock options, Shares		87,928
Stock-based compensation	913		913
Repurchase of common stock	(20)		(20)
Repurchase of common stock, Shares		(6,112)
Net loss	(24,076)				(24,076)
Ending balance at Sep. 30, 2019	(102,673)	$ 1	4,791		(107,465)
Redeemable convertible preferred stock, Ending balance, Shares at Sep. 30, 2019						4,000,000	109,145,900
Redeemable convertible preferred stock, Ending balance at Sep. 30, 2019						$ 1,000	$ 109,995
Ending balance, Shares at Sep. 30, 2019		1,420,772
Beginning balance at Jun. 30, 2019	(93,409)	$ 1	3,957	$ 4	(97,371)
Redeemable convertible preferred stock, Beginning balance, Shares at Jun. 30, 2019						4,000,000	109,145,900
Redeemable convertible preferred stock, Beginning balance at Jun. 30, 2019						$ 1,000	$ 109,995
Beginning balance, Shares at Jun. 30, 2019		1,354,373
Exercise of stock options	213		213
Exercise of stock options, Shares		72,511
Stock-based compensation	627		627
Repurchase of common stock	(6)		(6)
Repurchase of common stock, Shares		(6,112)
Net unrealized gain on available- for-sale securities	(4)			(4)
Net loss	(10,094)				(10,094)
Ending balance at Sep. 30, 2019	(102,673)	$ 1	4,791		(107,465)
Redeemable convertible preferred stock, Ending balance, Shares at Sep. 30, 2019						4,000,000	109,145,900
Redeemable convertible preferred stock, Ending balance at Sep. 30, 2019						$ 1,000	$ 109,995
Ending balance, Shares at Sep. 30, 2019		1,420,772
Beginning balance at Dec. 31, 2019	$ (111,963)	$ 1	5,524		(117,488)
Redeemable convertible preferred stock, Beginning balance, Shares at Dec. 31, 2019	113,145,900					4,000,000	109,145,900	0
Redeemable convertible preferred stock, Beginning balance at Dec. 31, 2019	$ 110,995					$ 1,000	$ 109,995
Beginning balance, Shares at Dec. 31, 2019		1,426,641
Issuance of Series B convertible preferred stock								$ 145,525
Issuance of Series B convertible preferred stock, Shares								142,857,142
Exercise of stock options	795		795
Exercise of stock options, Shares		251,466
Stock-based compensation	713		713
Repurchase of common stock	(210)		(210)
Repurchase of common stock, Shares		(43,986)
Vested stock option settlement	(727)		(727)
Unrealized loss on investments	8			8
Net loss	(44,540)				(44,540)
Ending balance at Sep. 30, 2020	$ (155,924)	$ 1	6,095	8	(162,028)
Redeemable convertible preferred stock, Ending balance, Shares at Sep. 30, 2020	256,003,042					4,000,000	109,145,900	142,857,142
Redeemable convertible preferred stock, Ending balance at Sep. 30, 2020	$ 256,520					$ 1,000	$ 109,995	$ 145,525
Ending balance, Shares at Sep. 30, 2020		1,634,121
Beginning balance at Jun. 30, 2020	(135,065)	$ 1	5,129	(2)	(140,193)
Redeemable convertible preferred stock, Beginning balance, Shares at Jun. 30, 2020						4,000,000	109,145,900	138,571,428
Redeemable convertible preferred stock, Beginning balance at Jun. 30, 2020						$ 1,000	$ 109,995	$ 141,026
Beginning balance, Shares at Jun. 30, 2020		1,490,336
Issuance of Series B convertible preferred stock								$ 4,499
Issuance of Series B convertible preferred stock, Shares								4,285,714
Exercise of stock options	530		530
Exercise of stock options, Shares		164,057
Stock-based compensation	436		436
Repurchase of common stock, Shares		(20,272)
Unrealized loss on investments	10			10
Net loss	(21,835)				(21,835)
Ending balance at Sep. 30, 2020	$ (155,924)	$ 1	$ 6,095	$ 8	$ (162,028)
Redeemable convertible preferred stock, Ending balance, Shares at Sep. 30, 2020	256,003,042					4,000,000	109,145,900	142,857,142
Redeemable convertible preferred stock, Ending balance at Sep. 30, 2020	$ 256,520					$ 1,000	$ 109,995	$ 145,525
Ending balance, Shares at Sep. 30, 2020		1,634,121

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Cash flows used in operating activities:
Net loss		$ (44,540)	$ (24,076)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:
Depreciation and amortization		1,252	1,173
Stock-based compensation expense		713	913
Loss on disposal of fixed assets			9
Unrealized loss on short-term investments		(53)
Accretion of discount on investments		8
Reduction in carrying amount of right-of-use assets		910	850
Amortization of debt discount	$ 203	229
Change in fair value of warrant liability	3,141	3,141
Changes in operating assets and liabilities:
Accounts receivable		482	83,846
Prepaid expenses, other current assets and other assets		(1,798)	(655)
Accounts payable		(132)	3,071
Accrued expenses and other liabilities		3,157	1,729
Operating lease liability		(651)	(544)
Deferred revenue		(8,425)	(398)
Net cash provided by (used in) operating activities		(45,710)	65,918
Cash flows used in investing activities:
Purchases of property and equipment		(359)	(1,422)
Purchase of short-term investments		(135,926)	(14,902)
Proceeds received from maturities of short-term investments			14,902
Net cash used in investing activities		(136,284)	(1,422)
Cash flows provided by financing activities:
Proceeds from the issuance of Series B convertible preferred stock, net of issuance costs of $4,473		145,525
Proceeds from the issuance of common stock		764	206
Financing costs paid in connection with initial public offering		(2,446)
Vested stock option settlement		(727)
Repurchase of common stock		(210)	(40)
Proceeds from long-term debt, net of issuance costs of $527		11,973
Net cash provided by financing activities		154,879	166
Net increase (decrease) in cash, cash equivalents and restricted cash		(27,115)	64,662
Cash, cash equivalents and restricted cash at beginning of period		93,126	38,888
Cash, cash equivalents and restricted cash at end of period	66,011	66,011	103,550
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents and restricted cash at end of period	66,011	66,011	103,550
Less restricted cash	(2,577)	(2,577)	(2,577)
Cash and cash equivalents at end of the period	$ 63,434	63,434	100,973
Supplemental disclosures of non-cash investing and financing activities:
Capital expenditures in accounts payable		10	98
Accrued deferred initial public offering costs		474
Stock option exercises included in prepaid and other current assets		33	$ 53
Fair value of warrants issued in connection with debt issuance		$ 5,465

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Statement Of Cash Flows [Abstract]
Stock issuance costs	$ 4,473
Long-term debt, net of issuance costs	$ 527

The Company

The Company	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company	(1) The Company C4 Therapeutics, Inc. (together with its subsidiary, the “Company”) is a biopharmaceutical company focused on harnessing the body’s natural regulation of protein levels to develop novel therapeutic candidates to target and eliminate disease-causing proteins for the treatment of cancer, neurodegenerative conditions and other diseases. The Company was incorporated in Delaware on October 7, 2015 and has its principal office in Watertown, Massachusetts. The Company is subject to risks common to other life science companies in the early development stage including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing and compliance with the Food and Drug Administration (“FDA”) and other government regulations. If the Company does not successfully advance its programs into and through human clinical trials and/or enter into collaborations for its programs and commercialize any of its product candidates, the Company may be unable to produce product revenue or achieve profitability. Initial Public Offering As further described in Note 13, in October 2020, the Company completed an initial public offering (IPO) of its common stock. Liquidity The Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company has incurred recurring losses since its inception, including net losses of $44.5 million and $24.1 million for the nine months ended September 30, 2020 and 2019, respectively. In addition, as September 30, 2020, the Company had an accumulated deficit of $162.0 million. To date, the Company has not generated any revenue from product sales as none of its product candidates has been approved for commercialization. The Company expects to continue to generate operating losses for the foreseeable future. The Company’s primary activities since inception have been focused around research and development activities, building the Company’s intellectual property, recruiting personnel and raising capital to support these activities. Through September 30, 2020, the Company has funded its operations primarily with proceeds received from the sale of redeemable convertible preferred stock (collectively, the “Preferred Stock”) and through its collaboration agreements. In addition, the Company has cash and cash equivalents and short-term investments of $199.4 million as of September 30, 2020. M anagement considers that there are no conditions or events, in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern for a period of at least one year from the date the condensed consolidated financial statements are issued. condensed Reverse Stock Split On September 25, 2020, the Company’s effected a one-for-8.4335 reverse stock split of its issued and outstanding common stock and stock options, and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. Accordingly, all issued and outstanding common stock, options to purchase common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented except as otherwise stated. COVID-19 Pandemic The impact of the COVID-19 coronavirus outbreak on the Company’s financial performance will depend on future developments, including the duration and spread of the outbreak and related governmental advisories and restrictions. These developments and the impact of COVID-19 on the financial markets and the overall economy are highly uncertain and cannot be predicted. If the financial markets and/or the overall economy are impacted for an extended period, the Company’s results may be materially adversely affected. The Company is currently unable to determine the extent of the impact of the pandemic to its operations and financial condition, as the Company has not yet started any clinical trials. Once the Company begins its clinical trials, it will assess any potential delays as a result of the pandemic, as well as their financial impact.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	(2) Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United Stated (“US GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These condensed consolidated financial statements include the accounts of C4 Therapeutics, Inc. and its subsidiary C4T Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related interim disclosures are unaudited. These unaudited condensed consolidated financial statements include all adjustments necessary, consisting of only normal recurring adjustments, to fairly state the financial position and the results of the Company’s operations and cash flows for interim periods in accordance with U.S. GAAP. Interim period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and unaudited condensed consolidated statements included in the Company’s prospectus related to the Company’s IPO effective on October 1, 2020, pursuant to Rule 424(b) under the Securities Act (the “Prospectus”). Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2019, which are included in the Prospectus. An update and supplement to these accounting policies follows. Short-Term Investments The Company classifies all short-term investments with an original maturity when purchased of greater than three months as available-for-sale. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest income. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities, are included in interest income. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary. The Company’s short-term investments as of September 30, 2020 of $136.0 million consisted entirely of US Treasury securities. Deferred Offering Costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings, including the IPO, as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ (deficit) equity as a reduction of proceeds generated as a result of the offering. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the condensed consolidated statements of operations and comprehensive loss. The Company had $2.9 million of deferred offering costs related to the IPO as of September 30, 2020. Warrant Liability In connection with the Company’s completion of a financing involving the sale of shares of Series B redeemable convertible preferred stock (the “Series B Financing”) in June and July 2020 and the entry into the Term Loan (see note 8), the Company issued a warrant to purchase shares of its Series B Preferred Stock. The Company classified the warrant as a liability on its consolidated balance sheet. The Company remeasures this warrant liability to fair value at each reporting date and recognizes changes in the fair value of the warrant liability as a component of other income (expense), net in the consolidated statement of operations and comprehensive loss. The Company utilized the Black-Scholes option-pricing model, which incorporates assumptions and estimates, to value these warrants. The Company assesses these assumptions and estimates on a quarterly basis. Estimates and assumptions impacting the fair value measurement include the fair value per share of the underlying redeemable convertible Series B Preferred Stock or common stock issuable upon exercise of the warrant, remaining contractual term of the warrant, risk-free interest rate, expected dividend yield and expected volatility of the price of the underlying redeemable convertible preferred stock or common stock. See Note 13.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	(3) Fair Value Measurements In accordance with authoritative guidance on fair value measurements and disclosures under U.S. GAAP, the Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that distinguishes between assumptions based on market data (observable inputs) and our own assumptions (unobservable inputs). The hierarchy consists of three levels: Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, directly or indirectly, for substantially the full term of the asset or liability. Level 3 – Unobservable inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date. The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine these fair values as of September 30, 2020 and December 31, 2019 (in thousands): DESCRIPTION SEPTEMBER 30, 2020 QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 3) Asset Cash and cash equivalents (money market funds) $ 63,434 $ 63,434 $ — $ — Short-term investments 135,979 135,979 — — Total financial assets $ 199,413 $ 199,413 $ — $ — Liability Warrants $ 5,465 $ — $ — $ 5,465 Total financial liabilities $ 5,465 $ — $ — $ 5,465 DESCRIPTION DECEMBER 31, 2019 QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 3) Asset Cash and cash equivalents (money market funds) $ 90,549 $ 90,549 $ — $ — Total financial assets $ 90,549 $ 90,549 $ — $ — The Company’s warrant liability represented a Level 3 investment as of September 30, 2020 (see Note 8). The Company classifies its money market funds, which are valued based on quoted market prices in active markets, with no valuation adjustment, as Level 1 assets within the fair value hierarchy. Short-term investments consist of U.S. Treasury securities, are classified as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities, and are valued based on quoted market prices in active markets, with no valuation adjustment. As of September 30, 2020 and December 31, 2019, none of the Company’s available-for-sale investments that were in an unrealized loss position had been in an unrealized loss position for more than 12 months. During the three and nine months ended September 30, 2020, the Company did not recognize any other-than-temporary impairment losses. There have been no transfers between fair value levels during the three and nine months ended September 30, 2020 and 2019.

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	(4) Property and Equipment Property and equipment consisted of the following (in thousands): SEPTEMBER 30, 2020 DECEMBER 31, 2019 Laboratory equipment $ 7,038 $ 6,766 Computer equipment 223 167 Furniture and fixtures 805 797 Office equipment 179 167 Leasehold improvements 541 520 Total 8,786 8,417 Less: accumulated depreciation (5,207 ) (3,954 ) Property and equipment, net $ 3,580 $ 4,463 Total depreciation and amortization expense for the nine-month periods ended September 30, 2020 and 2019 was $1.3 million and $1.2 million respectively. Primarily all of the depreciation and amortization expense was recorded in research and development expenses for the three and nine months ended September 30, 2020 and 2019.

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	(5) Leases In July 2017, the Company entered into a lease of office and laboratory space for its headquarters at 490 Arsenal Way in Watertown, Massachusetts (the “Watertown Lease”). The Watertown Lease commenced in April 2018 with rent commencing in May 2018. The Company recognized operating lease costs of $3.1 million and $3.0 million for the nine months ended September 30, 2020 and 2019, respectively. The Company incurred approximately $0.5 million in costs for leasehold improvements for the nine months ended September 30, 2019. The Company incurred no costs for leasehold improvements for the nine months ended September 30, 2020. The Watertown Lease required the Company to provide collateral in the amount of $2.6 million, which is recorded as restricted cash on the accompanying condensed consolidated balance sheets. As of December 31, 2019, assets under the Watertown Lease classified as right-of-use assets on the Company’s condensed consolidated balance sheet were $14.5 million, net of accumulated amortization. Liabilities under the Watertown Lease were $13.8 million, of which $0.9 million were classified as operating lease liability, current, and $12.9 million were classified as operating lease liability, net of current, on the Company’s condensed consolidated balance sheet. As of September 30, 2020, assets under the Watertown Lease classified as right-of-use assets on the Company’s condensed consolidated balance sheet were $13.5 million, net of accumulated amortization. Liabilities under the Watertown Lease were $13.1 million, of which $1.0 million were classified as operating lease liability, current, and $12.1 million were classified as operating lease liability, net of current, on the Company’s condensed consolidated balance sheet. Additionally, the Company recorded right-of-use amortization of $0.9 million for the nine months ended September 30, 2020 and 2019. The elements of lease costs under the Watertown Lease were as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Lease cost: Operating lease cost $ 637 637 $ 1,912 $ 1,912 Variable lease cost 419 366 1,207 1,087 Total lease cost 1,056 1,003 3,119 2,999 Other information: Operating cash flows for operating liabilities $ 551 535 $ 1,654 $ 1,606 Operating lease liabilities arising from obtaining right-of- use assets — — — — Weighted average remaining lease term 7.5 years 8.5 years 7.5 years 8.5 years Weighted average discount rate 10 % 10 % 10 % 10 % As of September 30, 2020, undiscounted minimum future lease payments under non-cancelable leases were as follows: (in thousands): FUTURE OPERATING LEASE PAYMENTS 2020 (1) $ 551 2021 2,272 2022 2,340 2023 2,410 2024 2,483 Thereafter 8,833 Total lease payments 18,889 Less imputed interest (5,792 ) Total operating lease liabilities at September 30, 2020 $ 13,097 (1) For the three months ended December 31, 2020.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	(6) Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following as of September 30, 2020 and December 31, 2019 (in thousands): SEPTEMBER 30, 2020 DECEMBER 31, 2019 Accrued research and development 5,387 $ 2,615 Accrued compensation and benefits 2,727 3,048 Accrued professional fees 1,552 728 Other 164 280 Total accrued expenses and other current liabilities $ 9,830 $ 6,671

Collaboration and License Agree

Collaboration and License Agreements	9 Months Ended
	Sep. 30, 2020
Collaboration And License Agreements [Abstract]
Collaboration and License Agreements	(7) Collaboration and License Agreements Roche Collaboration and License Agreement Original Roche Agreement Structure In March 2016, the Company entered into a license agreement (the “Original Roche Agreement”) with Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (“Roche”). Pursuant to the terms of the Original Roche Agreement, the Company and Roche agreed to collaborate on research activities to develop novel treatments in the field of targeted protein degradation (“TPD”) using the Company’s degrader technology. Under the terms of the Original Roche Agreement, the Company initially developed TPD therapeutics that utilize degrader technology for up to ten target proteins until the earlier of the exercise of the option right or termination for the last available target. On a target-by target basis, after successful completion of a defined preclinical development phase, Roche had an exclusive option to pursue further clinical development and commercialization. In exchange for a $15.0 million nonrefundable upfront payment and additional fees for dedicated personnel, the Company performed initial research and development services for drug discovery and preclinical development, provided a non-exclusive research and development license to its technology and participated on the joint research committee (the “Roche JRC”). For each target option exercised by Roche, the Company was eligible to receive up to $277.0 million in research, development and commercial milestone payments, with the commercial milestones being dependent on underlying net sales. Roche was also required to pay the Company up to $150.0 million in one-time sales-based payments for the first product to achieve certain levels of net sales. In addition, Roche was required to pay the Company royalties, at percentages from the mid-single digits to the low double-digits, on a licensed product-by licensed product basis, on worldwide net product sales. The research and development was to be performed by the Company over an estimated period of approximately 42 months per target according to the research plan. Roche also reimbursed the Company for up to five full-time equivalents (“FTEs”) (“FTE Funding”) per target unless otherwise agreed upon by the Roche JRC. Restated Roche Agreement Structure On December 22, 2018, the Company and Roche executed the Amended and Restated Roche License Agreement (the “Restated Roche Agreement”). Under the Restated Roche Agreement, the Company has a more active role in the manufacturing and commercialization of the targets, whereby if certain co-development and co-detailing rights are opted into by the Company, the parties will split future development costs in return for the rights to a larger share of future earnings from commercialization of the target. The target structure was revised to six potential targets, three of which were nominated as of the execution of the Restated Roche Agreement and represent continuations of the initial preclinical research and development efforts begun under the Original Roche Agreement and three additional targets that were not nominated as of the execution of the Restated Roche Agreement. Roche maintained its option rights to license and commercialize these six targets. For certain targets, Roche is required to pay the Company fees of $2.0 million and $3.0 million upon the progression of targets to the lead series identification achievement and good laboratory practice (“GLP”) toxicology (“Tox”) study phase, respectively. For each target option exercised by Roche, the Company is eligible to receive up to $275.0 million in research and development milestones per target and commercial milestone payments, with the commercial milestones being dependent on underlying net sales. Roche is also required to pay the Company up to $150.0 million per target in one-time sales-based payments if the target achieves certain levels of net sales. In addition, Roche is required to pay the Company royalties, at percentages from the mid-single digits to the low double-digits, on a licensed product-by licensed product basis, on worldwide net product sales. Under the Restated Roche Agreement: ∎ the Company received additional upfront consideration of $40.0 million from Roche; ∎ the Company has an option for co-development and co-detailing rights, whereby it would be required to provide additional financial support in return for the rights to a larger share of future earnings from commercializing one or more of the six targets; ∎ Roche will no longer provide FTE reimbursement; rather, it will make annual research plan payments of $1.0 million for each active research plan; and ∎ Adjustments were made to the option exercise fees, whereby certain targets now have option exercise fees of $7.0 million to $12.0 million (those progressed up to Phase 1 or through the GLP Tox studies, respectively) and others have $20.0 million (those progressed through clinical trials). The collaboration is managed by a joint research committee. The Company has control over the committee and may terminate the Restated Roche Agreement on a target-by-target or product-by-product basis under several scenarios, upon at least 90 days’ prior written notice. Restated Roche Agreement Accounting The Restated Roche Agreement is a modification of the Original Roche Agreement under Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers, or ASC 606 as both the scope and price of the contract were changed under the Restated Roche Agreement and new, distinct performance obligations were created for targets that have different standalone selling prices based on the Company’s revised obligations. The Restated Roche Agreement was not determined to be a separate contract for accounting purposes. The modification was accounted for as if it were a termination of the existing contract and the creation of a new contract, for which the unrecognized consideration from the Original Roche Agreement is added to the new transaction price promised as part of the Restated Roche Agreement and will be recognized as revenue prospectively, as the new performance obligations are satisfied. The Company made this determination after considering the performance obligations under the Restated Roche Agreement. When the amendment was signed, the contract was restructured such that the Company would pursue some of the same targets, but would have additional material responsibility to potentially develop the targets beyond the option exercise point, to either Phase 1 completion or to a point where the Company will exercise its co-development and co-detailing options and more fully share in the costs and future revenues. The $40.0 million upfront payment, $13.5 million of expected research plan funding payments, plus $6.4 million of remaining deferred revenue from the Original Roche Agreement represent the transaction price as of the outset of the arrangement. The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Roche, is a customer. The Company identified the following promises at the outset of the Restated Roche Agreement: (1) a non-exclusive royalty-free license to use the Company’s intellectual property to conduct research and development activities; (2) research and development services under the research plan for the three initial targets; (3) participation on the Roche JRC; (4) option rights to initiate a research plan for three additional targets; (5) an option to obtain a non-exclusive commercial license to intellectual property and know-how generated from the collaboration, subject to certain exclusivity requirements; (6) option rights to develop, commercialize and manufacture products related to any of the six targets; and (7) rights for Roche to substitute targets prior to completion of a research plan, limited to six exchanges in total across the arrangement and subject to approval by the Roche JRC. The Roche JRC has equal representation from both parties, but the Company holds final decision-making authority in the event of a disagreement until the time at which Roche licenses a target and leads development efforts. The six potential targets were determined to be distinct from one another, as Roche can derive benefit from each target independent of the others. For each target, the Company determined that the research and development license and research and development services were not distinct from one another, because the research and development services are essential to the license. Roche would receive little to no economic benefit from the license if it did not obtain the research services. Participation on the Roche JRC to oversee the research and development activities and the technology transfer associated with the Original Roche Agreement were determined to be quantitatively and qualitatively immaterial. The Company evaluated Roche’s option rights to initiate a research plan for three additional targets as well as the option rights to license and commercialize each target to determine whether they provide Roche with any material rights. The Company concluded that each of the options were issued with an option exercise fee that represented a significant and incremental discount and therefore provide material rights for six of the six targets—three material rights from the option to license the three initial targets at the end of their research terms and three material rights from the option to initiate a research plan for the three additional targets along with the option to license such at the end of their research terms. The consideration allocated to the option rights to initiate the three additional targets is deferred until the underlying option is exercised, at which point the Company will begin recognizing revenue for these targets. The non-exclusive, limited commercial license to the intellectual property and know-how generated from the collaboration was determined to be immaterial and, as such, no consideration was allocated to it. Based on these assessments, the Company identified twelve performance obligations, including three research services performance obligations, six material rights for the options to purchase a commercial license for six targets and three material rights for the option to initiate research services for the uninitiated three targets as of the outset of the arrangement. The first three performance obligations primarily comprise: (1) the non-exclusive research and development license and (2) the research and development services for the target, including the related substitution rights. The Company included the $40.0 million upfront payment, $13.5 million of expected research plan funding payments ($1.0 million per active target per year, for a maximum of $3.0 million per target), and $6.4 million of remaining deferred revenue from the Original Roche Agreement in the transaction price as of the outset of the arrangement. The Company also achieved a milestone for the identification of lead series for target 2 in April 2019, resulting in a milestone payment of $2.0 million, which was added to the transaction price and recognized cumulatively. The transaction price of $61.9 million was allocated to the performance obligations based on the estimated stand-alone selling prices at the time of the amendment. For each performance obligation, the stand-alone selling price was determined considering the expected cost of the research and development services and a reasonable margin for the respective services. The material rights from the option rights were valued based on the estimated discount at which the option is priced and the Company’s estimated probability of the options’ exercise as of the time of the amendment. The Company allocated the following amounts of the total transaction price to the performance obligations as of the amendment date, including the $2.0 million milestone achieved in April 2019: ∎ $28.6 million to the research and development performance obligations for targets 1-3; and ∎ $4.7 million to the three material rights, related to the three targets initiated at the outset of the Restated Roche Agreement, which will not begin revenue recognition until the option is exercised or expires. ∎ $28.6 million to the option to nominate targets 4-6 and the three material rights related to these options. The Company will recognize the portion of the transaction price allocated to each of the research and development performance obligations as the research and development services are provided, using an input method, according to costs incurred as related to the research and development activities for each individual program and the costs expected to be incurred in the future to satisfy that individual performance obligation. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation. Amounts due to the Company that have not yet been received are recorded as accounts receivable and amounts received that have not yet been recognized as revenue are recorded in deferred revenue on the Company’s consolidated balance sheet. Biogen Collaboration Research and License Agreement In December 2018, the Company entered into a collaboration research and license agreement (the “Biogen License Agreement”) with Biogen MA, Inc. (“Biogen”). Pursuant to the terms of the Biogen License Agreement, the Company and Biogen agreed to collaborate on research activities to develop novel treatments in the field of TPD using the Company’s degrader technology. Under the terms of the Biogen License Agreement, the Company will initially develop TPD therapeutics that utilize degrader technology for up to five target proteins over a period of 54 months. On a target-by-target basis, after successful completion of a defined target evaluation period, Biogen assumes full rights and responsibility to each degrader to meet certain criteria against a target. Biogen also has the option to pay an additional $62.5 million to extend the contract and select up to five additional targets for development. In exchange for the non-exclusive research license from Biogen as well as a $45.0 million nonrefundable upfront payment, the Company will grant a license to develop, commercialize and manufacture products related to each of the targets (which is contingent on not cancelling the contract), will perform initial research services for drug discovery, provide a non-exclusive research and commercial license to its intellectual property and will participate on the joint steering committee (the “Biogen JSC”). The Company will also be obligated to participate in early research activities for other potential targets or “sandbox activities,” at Biogen’s election up to a maximum amount; any work performed for these services will be reimbursed by Biogen, and Biogen will reimburse the Company for certain FTE costs. Biogen is also required to pay the Company up to $35.0 million per target in development milestones and $26.0 million per target in one-time sales-based payments for the first product to achieve certain levels of net sales. In addition, Biogen is required to pay the Company royalties on a licensed product-by-licensed product basis, on worldwide net product sales. The collaboration is managed by the Biogen JSC, which Biogen has control over, and Biogen may terminate the Biogen License Agreement on a target-by-target or product-by-product basis under several scenarios, upon at least 90 days’ prior written notice. The nonrefundable upfront cash payment of $45.0 million is not creditable against any of the target development milestone fees. The research will be performed by the Company over 54 months according to the research plan approved by the Biogen JSC. Biogen License Agreement Accounting The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Biogen, is a customer. The Company identified the following promises under the arrangement: (1) a non-exclusive, royalty-free license to use the Company’s intellectual property to conduct research activities; (2) an upfront license to develop, commercialize and manufacture products related to each of the targets (which is contingent on not cancelling the contract); (3) research services for preclinical activities under the research plan; (4) participation on the Biogen JSC; and (5) substitution rights for Biogen via “sandbox activities” to replace targets prior to a program reaching completion of a research plan, limited to five exchanges in total. Substitution is dependent on the original target failing to meet certain criteria; Biogen may only replace a target in this specific scenario. The Company also determined that Biogen’s ability to terminate the Agreement at-will with 90 days’ notice is not representative of a substantive purchase option to continue to the research and does not provide a material right in the form of a continuous renewal option. The Company determined that the licenses and research activities were not distinct from one another, as the licenses have limited value without the performance of the research activities by the Company. Participation on the Biogen JSC to oversee the research activities and the technology transfer associated with the Biogen License Agreement were determined to be quantitatively and qualitatively immaterial and therefore are excluded from performance obligations. Based on these assessments, the Company identified one performance obligation at the outset of the Biogen License Agreement, representing a combined performance obligation consisting of (1) the licenses, (2) the research activities for the target evaluation phase for all five targets and (3) the joint research plan phase for each target. The Company will recognize the transaction price as the research and development services are provided, using an input method, according to costs incurred as related to the research and development activities for the costs expected to be incurred in the future to satisfy that individual performance obligation. The transfer of control occurs over this time period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation. Biogen also has the option to fund sandbox activities in exchange for consideration, whereby the Company will perform discovery-type research at Biogen’s election to develop other potential targets that may be used as replacement targets for the initially nominated targets or two additional targets under the Biogen Agreement. Revenues earned under this option, if initiated, will be recognized as services are performed and are not included in the transaction price. Sandbox research activities will be reimbursed on an FTE basis at market rates, which is adjusted for changes in the “Consumer Price Index” each year. The sandbox activities constitute additional research that can be purchased on an a la carte basis at an amount consistent with standalone selling price. The Company recognizes revenue as the services performed for the sandbox activities are performed and recognized $0.6 and $0.2 million of revenue for the three months ended September 30, 2020 and 2019, respectively, and $2.0 and $0.2 million of revenue for the nine months ended September 30, 2020 and 2019, respectively, related to the sandbox activities. The Company recognizes FTE reimbursement related to sandbox activities as revenue as the hours are incurred each quarter. Amounts due to the Company that have not yet been received are recorded as accounts receivable and amounts received that have not yet been recognized as revenue are recorded in deferred revenue on the Company’s consolidated balance sheet. Calico Collaboration and License Agreement In March 2017, the Company entered into a collaboration and license agreement (the “Calico License Agreement”) with Calico Life Sciences LLC (“Calico”) whereby the Company and Calico agreed to collaborate to develop and commercialize small molecule protein degraders for diseases of aging, including cancer for a five-year period ending in March 2022 (the “research term”). Under the terms of the Calico License Agreement, the Company will initially develop and commercialize small molecule protein degraders for up to five target proteins over the research term. On a target-by-target basis, after successful completion of a defined target evaluation period, Calico has an exclusive option to pursue further pre-clinical development and commercialization via a joint research plan for each target. Under the Calico License Agreement, Calico paid an upfront amount of $5.0 million and certain annual payments totaling $5.0 million through June 30, 2020, and pays target initiation fees and reimburses the Company for a number of FTEs, depending on the stage of the research, at specified market rates. Upon completion of the required discovery research and development services on any target, Calico is entitled to pursue commercial development of that target. The Company will perform initial research services for drug discovery and preclinical development, provide a non-exclusive research and commercial license to its IP and will participate on the Calico joint research committee (the “CJRC”). For each target, the Company is eligible to receive up to $132.0 million in potential research, development and commercial milestone payments, on sales of all products resulting from the collaboration efforts. Calico is also required to pay the Company up to $65.0 million in one-time sales-based payments for the first product to achieve certain levels of net sales. In addition, Calico is required to pay the Company royalties, at percentages in the mid-single digits, on a licensed product-by-licensed product basis, on worldwide net product sales. The Calico License Agreement is managed by a joint research committee (the “CJRC”). Calico has control over the CJRC and may terminate the Calico License Agreement on a target-by-target or product-by-product basis under several scenarios, upon prior written notice. The nonrefundable upfront and certain annual payments are not creditable against any other payments. Calico will reimburse the Company for a contractually defined number of FTEs (“Calico FTE Funding”) per target depending on the phase of development, unless otherwise agreed upon by the CJRC. The research will be performed by the Company over the research term in accordance with the research plan. Calico License Agreement Accounting The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Calico, is a customer. The Company identified the following promises under the arrangement: (1) the non-exclusive, royalty-free research license and commercial license, which function for purposes of the arrangement as a license and are therefore analyzed together; (2) the target evaluation research services for all five targets; (3) the joint research plan research services related to targets 1 and 2, which were nominated at the execution of the Calico License Agreement; (4) the target initiation rights/options associated with targets 3, 4 and 5, subject to nomination; and (5) the joint research plan services associated with targets 3, 4 and 5, subject to nomination and payment of the target initiation fees from (4). The Company determined that the license and research activities were not distinct from one another, as the license has limited value without the performance of the research activities by the Company. Participation on the CJRC to oversee the R&D activities and the technology transfer associated with the Calico License Agreement were determined to be quantitatively and qualitatively immaterial and therefore are excluded from performance obligations. The Company determined that the option rights to nominate the targets were not distinct from one another or from the other promises in the arrangement, specifically the research license and research services. The Company evaluated the target initiation rights for targets 3, 4 and 5 and the research services associated with the joint research plan nomination for these targets to determine whether they provide Calico with any material rights. The Company concluded that these options were not issued at a significant and incremental discount and therefore do not provide material rights. Based on these assessments, the Company identified one performance obligation at the outset of the Calico License Agreement, which consists of: (1) the non-exclusive license and (2) the research activities for the target evaluation phase for all five targets and the joint research plan phase for targets 1 and 2. Under the Calico License Agreement, the transaction price determined by the Company is the upfront amount plus the committed anniversary payments and the target initiation fees related to the targets nominated at the execution of the Calico License Agreement. Based on the ability of Calico to cancel the arrangement for any reason, Calico effectively has an option for continued access to the Company’s research license and procurement of research services that they can cancel at any time. Under the Calico License Agreement, the Company amortized the upfront fee received on a straight-line basis over the period services are available to the counterparty (i.e. the contractual term of five years). Straight-line amortization of the upfront payment was considered the best measure of progress because the customer has access to research and development services throughout the period. Incremental fees for research and development services are paid at agreed upon FTE rates and recognized in the period incurred. Amounts due to the Company that have not yet been received are recorded as accounts receivable and amounts received that have not yet been recognized as revenue are recorded in deferred revenue on the Company’s consolidated balance sheet. The following tables summarize the impact of the collaboration and license agreements on the Company’s condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019 and the Company’s condensed consolidated balance sheet as of September 30, 2020 and December 31, 2019. Revenue from collaboration agreements for the three and nine months ended September 30, 2020 and 2019 in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Restated Roche Agreement $ 1,395 1,762 $ 7,424 $ 3,875 Biogen License Agreement 3,525 642 6,827 1,707 Calico License Agreement 3,527 2,960 10,682 7,590 $ 8,447 $ 5,364 $ 24,933 $ 13,172 The Company achieved $4.0 million in milestones under the Biogen Agreement in June 2020, which was recorded as accounts receivable and deferred revenue at that time. The Company received payment of these milestones from Biogen in August 2020. Financial information related to the collaboration and license agreements consisted of the following in the Company’s condensed consolidated balance sheet as of September 30, 2020 and December 31, 2019 (in thousands): AS OF SEPTEMBER 30, 2020 (unaudited) DESCRIPTION ACCOUNTS RECEIVABLE DEFERRED REVENUE, CURRENT DEFERRED REVENUE, NET OF CURRENT DEFERRED REVENUE, TOTAL Restated Roche Agreement $ 583 $ 7,821 $ 31,286 $ 39,107 Biogen License Agreement 631 13,694 28,597 42,291 Calico License Agreement 2,927 2,400 1,200 3,600 $ 4,141 $ 23,915 $ 61,083 $ 84,998 AS OF DECEMBER 31, 2019 DESCRIPTION ACCOUNTS RECEIVABLE DEFERRED REVENUE, CURRENT DEFERRED REVENUE, NET OF CURRENT DEFERRED REVENUE, TOTAL Restated Roche Agreement $ — $ 12,164 $ 32,784 $ 44,948 Biogen License Agreement 275 6,141 36,934 43,075 Calico License Agreement 4,348 2,400 3,000 5,400 $ 4,623 $ 20,705 $ 72,718 $ 93,423

Long-term Debt and Warrant Liab

Long-term Debt and Warrant Liability	9 Months Ended
	Sep. 30, 2020
Long Term Debt And Warrant Liability [Abstract]
Long-term Debt and Warrant Liability	(8) Long-term Debt and Warrant Liability On June 5, 2020, contemporaneously with the completion of the Series B Financing (see Note 9), the Company entered into a Credit Agreement with Perceptive Life Sciences Master Fund LTD., an affiliate of Perceptive Credit Holdings III, LP (“Perceptive”) that provides for an aggregate principal borrowing amount of up to $20.0 million, available in two tranches of $12.5 million and $7.5 million (such arrangement, the “Term Loan”). The Company drew down on the first tranche of $12.5 million in June 2020, bearing interest at a variable rate of 11.25%, which was calculated based on the one-month LIBOR rate, which, per the Credit Agreement, can never be below 1.75%, plus an applicable margin, which was initially determined to be 9.5%. The Term Loan matures on September 5, 2024, unless it is accelerated in accordance with its terms. The Company will make interest-only payments until December 5, 2022, at which point the Company will make payments of principal equal to 2% of the Term Loan until maturity. If the Company pays off the Term Loan prior to the Maturity Date, it will be required to pay a $5.0 million prepayment fee. In connection with the Term Loan, the Company is required to maintain a balance of at least $3.0 million in C4 Therapeutics, Inc. parent companies bank account while the Term Loan is outstanding. The Credit Agreement allows for prepayment in full of the outstanding principal of the Term Loan at any time. Any prepayment shall be in a minimum principal amount of $0.5 million and in multiples of $0.1 million in excess of that amount, plus accrued interest and a prepayment fee, which would be calculated based on the terms of the Credit Agreement. The Company paid a closing fee of $0.3 million in connection with its entry into the Credit Agreement. The aggregate principal amount of debt outstanding as of September 30, 2020 was $12.5 million. As of September 30, 2020, the unamortized debt discount was $2.6 million. The carrying value of the long-term debt, net of issuance costs and the debt discount related to the warrants to purchase shares of the Company’s equity securities (as discussed below) that were issued in connection with the entry into the Credit Agreement, was $9.7 million. In connection with the Term Loan, the Company issued a warrant to purchase up to 2,857,142 shares of the Company’s Series B preferred stock to Perceptive at an exercise price per share of $1.05. The warrants are exercisable at any time prior to the ten-year anniversary of the closing date under the Credit Agreement. The Company determined that the warrant is liability-classified and will be remeasured to fair value each reporting period, with changes recorded in the statement of operations and comprehensive loss. The Company determined the fair value of this warrant to be $5.5 million using the Black-Scholes model based on the following assumptions as of September 30, 2020: AS OF SEPTEMBER 30, 2020 Stock price $ 2.26 Exercise price $ 1.05 Expected term (in years) 9.75 Volatility 75 % Risk-free interest rate 0.69 % Dividend yield —

Stockholder_s Equity

Stockholder’s Equity	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Stockholder’s Equity	(9) Stockholder’s Equity Certificate of Incorporation As of September 30, 2020, the terms of the Company’s equity securities were defined in the Company’s Fourth Amended and Restated Certificate of Incorporation, which was filed with the Secretary of the State of Delaware on June 3, 2020 (the “Fourth Charter”). Under the Fourth Charter, the Company was authorized to issue Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock, each of which had a par value of $0.0005 per share and which are referred to collectively as Preferred Stock. On October 6, 2020, in connection with the consummation of the IPO, the Company filed its Fifth Amended and Restated Certificate of Incorporation with the Secretary of the State of Delaware. The summary below relates to the Company’s Fourth Charter. Reverse Stock Split As described in Note 1, on September 25, 2020 the Company effected a one-for-8.4335 reverse stock split of its issued and outstanding common stock, stock options and common stock warrants and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. Accordingly, all issued and outstanding common stock, options to purchase common stock and per share amounts contained in the condensed consolidated financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented. Common Stock Features of the Common Stock Under the Fourth Charter, the Company’s common stock had a par value of $0.0001 and the holders of common stock were entitled to one vote for each share held at all meetings of stockholders and written actions in lieu of meetings provided. The Fourth Charter also provided that all dividends shall be declared and paid pro rata according to the number of shares held by each holder of common stock. In the event of a liquidation, dissolution or winding up of the Company, the common stock ranks behind the Preferred Stock in terms of distribution of assets. The holders of the common stock have no preemptive or other subscription rights, and there are no redemption or sinking fund provisions with respect to such stock. Preferred Stock In June and July 2020, the Company closed a $150.0 million Series B Financing with existing and new investors. As part of the Series B Financing, the Company issued 142,857,142 shares of its Series B preferred stock at a purchase price of $1.05 per share, for aggregate gross proceeds of $150.0 million. Of the amounts above, 138,571,428 shares were issued for gross proceeds of $145.5 million, less related offering costs of $4.5 million in June 2020, and 4,285,714 shares were issued for proceeds of $4.5 million in July 2020. As of September 30, 2020 and December 31, 2019, Preferred Stock consisted of the following (in thousands, except share data): SEPTEMBER 30, 2020 PREFERRED STOCK AUTHORIZED PREFERRED STOCK ISSUED AND OUTSTANDING CARRYING VALUE LIQUIDATION VALUE COMMON STOCK ISSUABLE UPON CONVERSION Series Seed Preferred Stock 4,000,000 4,000,000 $ 1,000 $ 1,000 474,298 Series A Preferred Stock 110,000,000 109,145,900 109,995 109,995 12,941,857 Series B Convertible Preferred Stock 150,000,000 142,857,142 145,525 145,525 16,939,224 264,000,000 256,003,042 $ 256,520 $ 256,520 30,355,379 DECEMBER 31, 2019 PREFERRED STOCK AUTHORIZED PREFERRED STOCK ISSUED AND OUTSTANDING CARRYING VALUE LIQUIDATION VALUE COMMON STOCK ISSUABLE UPON CONVERSION Series Seed Preferred Stock 4,000,000 4,000,000 $ 1,000 $ 1,000 474,298 Series A Preferred Stock 110,000,000 109,145,900 109,995 109,995 12,941,857 FF Preferred Stock 32,760,000 — — — — 146,760,000 113,145,900 $ 110,995 $ 110,995 13,416,155 The following is a summary of the rights and privileges of the holders of Preferred Stock as of September 30, 2020 and December 31, 2019, which is comprised of shares of Series Seed preferred stock, Series A preferred stock and Series B preferred stock, each of which has a par value of $0.0005 per share: Conversion As of September 30, 2020, all outstanding shares of Preferred Stock were convertible into common stock on a 8.4335-to-one basis at any time at the option of the holder and were mandatorily convertible upon the consummation of a qualified initial public offering, which was defined as an underwritten public offering resulting in at least $50.0 million in gross proceeds to the Company (see Note 13). Voting All shares of Preferred Stock have voting rights that provide for voting on an as-converted to common stock basis, with each share entitled to the number of votes equal to the number of whole shares into which such share is then convertible. As a result, under the Fourth Charter, as of September 30, 2020, every 8.4335 shares of Preferred Stock was entitled to one vote. Redemption The Preferred Stock was not redeemable except in the event of a liquidation. The Series Seed Preferred Stock, Series A Preferred Stock, and Series B Preferred Stock were entitled to receive liquidation payments at their respective issuance prices together with any accrued but unpaid dividends in preference to the common stock. Because the Series Seed Preferred Stock, Series A Preferred Stock, and Series B Preferred Stock were only mandatorily redeemable upon the occurrence of a liquidation event and the preferred stockholders had control of the Company’s board of directors, they are classified in the mezzanine section of the Company’s condensed consolidated balance sheet. Dividends The Series B Preferred Stock had dividend preference over all shares of common stock or Preferred Stock. Under the Fourth Charter, the holders of the Series B Preferred Stock then outstanding were entitled to receive, first or simultaneously, a dividend on each outstanding share of Series B Preferred Stock in an amount at least equal to the greater of the amount of accrued dividends on the Series B Preferred Stock and the amount that would be paid to holders of Series B Preferred Stock on an as-converted to common stock basis or other shares pursuant to the dividend granted. The Series A Preferred Stock had similar dividend preference over the common stock. The Series Seed Preferred Stock is eligible to receive dividends on a pro rata as-converted basis in proportion to the number of shares of common stock that would be held upon conversion to common stock. Series A Preferred Stock and Series B Preferred Stock accrue dividends at a rate of $0.08 and $0.084 per annum, respectively, and are payable only if and when declared by the Company’s board of directors or in the event of a liquidation.

Share-based Compensation

Share-based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Compensation	(10) Stock-based Compensation On December 28, 2015, the Company’s board of directors adopted the C4 Therapeutics, Inc. 2015 Incentive Stock Option and Grant Plan (the “2015 Plan”) and reserved 2,525,327 shares of common stock for issuance under this plan. As of April 2019, the shares reserved increased to 3,614,753. On June 3, 2020, the number of shares reserved for issuance under the 2015 Plan was increased to 5,058,203. As of September 30, 2020, 2,364,975 shares remained available for future grant under the 2015 Plan. Following the IPO, no further awards will be granted under the 2015 Plan, though this plan does remain in effect as to previously granted awards. The 2015 Plan authorizes the board of directors or a committee of the board of directors to grant incentive stock options, nonqualified stock options and restricted stock awards to eligible employees, outside directors and consultants of the Company. Options generally vest over a period of five or eight years, with a cliff vesting at one year and quarterly vesting thereafter and options that lapse or are forfeited are available to be granted again. The contractual life of all options is generally ten years from the date of grant. In connection with the issuance of stock options, the Company recorded stock-based compensation expense of $0.4 million and $0.6 million for the three months ended September 30, 2020 and 2019, respectively and $0.7 million and $0.9 million for the nine months ended September 30, 2020 and 2019, respectively. Stock-based compensation expense for the three and nine months ended September 30, 2020 and 2019 was classified in the Company’s condensed consolidated statement of operations and comprehensive loss as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Research and development $ 345 $ 118 $ 620 $ 272 General and administrative 91 509 93 641 Total stock-based compensation expense $ 436 $ 627 $ 713 $ 913 Stock option activity under the 2015 Plan is summarized as follows: NUMBER OF OPTIONS WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS) AGGREGATE INTRINSIC VALUE Outstanding as of December 31, 2019 2,368,950 $ 4.35 8.11 $ 10,309 Granted 1,467,424 4.98 Exercised (251,466 ) 3.17 2,442 Cancelled or forfeited (1,229,054 ) 4.52 Outstanding as of September 30, 2020 2,355,854 4.82 8.89 $ 11,367 Options exercisable as of December 31, 2019 733,310 3.40 7.41 $ 2,275 Options exercisable as of September 30, 2020 365,732 4.04 7.28 $ 6,949 President and Chief Executive Officer Termination On March 3, 2020 (“Separation Date”), the employment of the Company’s then current president and chief executive officer (“CEO”) terminated. The Company repurchased all of the CEO’s outstanding shares of common stock, which had been issued upon his exercise of previously granted stock options, for total consideration of $0.1 million. The CEO also relinquished his right to purchase shares of common stock upon the exercise of stock options that were vested as of his termination date, in exchange for total consideration paid by the Company of $0.8 million. The Company recorded the repurchase liability once the termination was deemed probable on March 3, 2020. The Company recognized the repurchase price of these shares of common stock and the relinquishment of these vested options in additional-paid-in-capital. 2020 Stock Option and Incentive Plan On September 8, 2020, the Company’s board of directors adopted the C4 Therapeutics, Inc. 2020 Stock Option and Incentive Plan (the “2020 Plan”), which became effective on September 30, 2020. There are 6,567,144 shares of common stock reserved for issuance under the 2020 Plan. Under the 2020 Plan, the compensation committee of the Company’s board of directors (or its designee) is authorized to grant a broad range of equity-based awards, including stock options, stock appreciation rights (“SARs”), restricted stock awards (“RSAs”), restricted stock units (“RSUs”), performance awards and stock bonus awards to the Company’s officers, employees, directors and other key persons, including consultants. Following the effectiveness of the 2020 Plan, the Company ceased making grants under the 2015 Plan. However, the 2015 Plan continues to govern the terms and conditions of the outstanding awards granted under it. Shares of common stock subject to awards granted under the 2015 Plan that cease to be subject to such awards by forfeiture or otherwise after the termination of the 2015 Plan will be available for issuance under the 2020 Plan. As of September 30, 2020, no awards had been made under the 2020 Plan. On September 8, 2020, the Company’s board of directors adopted the C4 Therapeutics, Inc. 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which became effective on September 30, 2020 for use by the Company following the IPO. There are 437,809 shares of common stock reserved for issuance under the 2020 ESPP. All employees meeting eligibility requirements defined in the plan may participate in the 2020 ESPP by purchasing shares of the Company’s common stock. To participate in the 2020 ESPP, eligible employees will authorize payroll deductions of up to 15% of their eligible compensation during an offering period. The Company may hold one of more offering periods each year during which employees will be able to purchase shares under the 2020 ESPP. As of September 30, 2020, the Company had not held any offering periods and no shares had been issued under the 2020 ESPP.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	(11) Income Taxes During the nine months ended September 30, 2020 and 2019, the Company recorded a full valuation allowance on federal and state deferred tax assets since management does not forecast the Company to be in a profitable position in the near future. As a result of the COVID-19 pandemic, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted on March 27, 2020 to provide relief for taxpayers. The CARES Act contain a significant number of provisions that may impact on the Company’s accounting for income taxes. The Company has considered several key corporate provisions within the CARES Act, has evaluated its potential impact and as a result recorded a tax benefit of $0.2 million and $0.5 million for the three and nine month periods ended September 30, 2020, respectively, related to an anticipated refund to be received for federal taxes incurred for the year ending December 31, 2019. The refund is expected to be received when the Company files its fiscal year 2020 tax returns which are due October 15, 2021. Accordingly, the Company has recorded the receivable of $0.5 million in other long-term assets on the Company’s unaudited condensed consolidated balance sheet as of September 30, 2020.

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Loss Per Share	(12) Loss Per Share Basic and diluted loss per share is computed by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding (in thousands, except share and per share data): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Numerator: Net loss $ (21,835 ) $ (10,094 ) $ (44,540 ) $ (24,076 ) Accrual of preferred stock dividends (5,212 ) (2,201 ) (10,363 ) (6,531 ) Net loss attributable to common stockholders $ (27,047 ) $ (12,295 ) $ (54,903 ) $ (30,607 ) Denominator: Weighted-average common stock outstanding 1,540,902 1,376,365 1,493,521 1,354,734 Net loss per share attributable to common stockholders $ (17.55 ) $ (8.93 ) $ (36.76 ) $ (22.59 )

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	(13) Subsequent Events The Company has evaluated subsequent events from the balance sheet date through the issuance date of these condensed consolidated financial statements and has not identified any events requiring disclosure, except as noted below. IPO On October 1, 2020, the SEC declared the Company’s registration statement on Form S-1, as amended (the “Registration Statement”) effective. On October 6, 2020, the Company closed the IPO, at which time the Company issued 11,040,000 shares of its common stock at a price to the public of $19.00 per share (which number includes 1,440,000 shares of common stock that were issued to the underwriters for the IPO when they exercised in full their overallotment option). Upon the closing of the IPO, all outstanding shares of the Company’s Preferred Stock automatically converted into 30,355,379 shares of common stock. Net proceeds from the IPO, including the exercise in full of the underwriters’ option to purchase additional shares, were $191.1 million, after deducting underwriting discounts and commissions of $14.7 million and expenses of approximately $4.0 million. Subsequent to the closing of the IPO, there were no shares of Preferred Stock outstanding. In connection with the closing of the IPO, the Company filed its Fifth Amended and Restated Certificate of Incorporation, which provides that the Company’s authorized capital stock consists of 150,000,000 shares designated as common stock and 10,000,000 shares designated as preferred stock, all of which have a par value of $0.0001 per share. Conversion of Preferred Stock and Series B Warrant Upon on the completion of the Company’s IPO on October 6, 2020, all outstanding shares of the Company’s Preferred Stock were converted into shares of common stock using the exchange rate set forth in the Fourth Charter, as amended, which provided that every 8.4335 shares of Preferred Stock converted into one share of common stock. As a result, no shares of preferred stock are presently outstanding and the Company does not have any present plans to issue any shares of preferred stock. In addition, as described in Note 8, in June 2020, the Company issued a warrant to purchase 2,857,142 shares of its Series B Preferred Stock to its lender, Perceptive Credit Holdings III, LP. Upon completion of the Company’s IPO, this warrant was automatically converted into a warrant exercisable for 338,784 shares of the Company’s common stock. Stock Options In September 2020, the Company approved the issuance of stock options under the 2020 Plan to Marc A. Cohen, the Company’s Co-Founder, Executive Chairman and (at that time) interim Chief Executive Officer, and Andrew Hirsch, the Company’s President, Director and Chief Executive Officer-elect, representing 1.5% and 3.5%, respectively, of the Company’s fully-diluted shares measured at the time of Company’s IPO (calculated to include the shares sold in the IPO but to exclude the shares reserved for future awards under the 2020 Plan and the 2020 ESPP following the IPO). Upon the IPO, the Company determined that Mr. Cohen’s award was for 725,002 shares and Mr. Hirsch’s award was for 1,691,672 shares. These grants, were approved in September 2020. Upon the effectiveness of the Registration Statement on October 1, 2020, these awards were deemed granted and the exercise price was established at $19.00 per share. These options vest quarterly over four years subject to cliff vesting after six months. Mr. Cohen’s award is subject to full acceleration upon a sale of the Company and Mr. Hirsch’s award is subject to full acceleration upon a sale of the Company and the termination of his employment thereafter pursuant to the terms of his employment agreement, subject to Mr. Hirsch’s execution of an effective release of claims in favor of the Company. In addition to these awards, in September 2020, the Company also approved the grant of 192,681 stock options to the Company’s directors and certain employees. Ultimately, when the Registration Statement was declared effective on October 1, 2020, these awards were deemed granted and the exercise price was established at $19.00 per share. These shares will vest over one- to four-year periods, subject to the recipient maintaining a business relationship with the Company through the applicable vesting date.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United Stated (“US GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These condensed consolidated financial statements include the accounts of C4 Therapeutics, Inc. and its subsidiary C4T Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ deficit for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related interim disclosures are unaudited. These unaudited condensed consolidated financial statements include all adjustments necessary, consisting of only normal recurring adjustments, to fairly state the financial position and the results of the Company’s operations and cash flows for interim periods in accordance with U.S. GAAP. Interim period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and unaudited condensed consolidated statements included in the Company’s prospectus related to the Company’s IPO effective on October 1, 2020, pursuant to Rule 424(b) under the Securities Act (the “Prospectus”).
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2019, which are included in the Prospectus. An update and supplement to these accounting policies follows.
Short-Term Investments	Short-Term Investments The Company classifies all short-term investments with an original maturity when purchased of greater than three months as available-for-sale. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive loss. The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization is included in interest income. Realized gains and losses and declines in value judged to be other than temporary on available-for-sale securities, are included in interest income. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary. The Company’s short-term investments as of September 30, 2020 of $136.0 million consisted entirely of US Treasury securities.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings, including the IPO, as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ (deficit) equity as a reduction of proceeds generated as a result of the offering. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the condensed consolidated statements of operations and comprehensive loss. The Company had $2.9 million of deferred offering costs related to the IPO as of September 30, 2020.
Warrant Liability	Warrant Liability In connection with the Company’s completion of a financing involving the sale of shares of Series B redeemable convertible preferred stock (the “Series B Financing”) in June and July 2020 and the entry into the Term Loan (see note 8), the Company issued a warrant to purchase shares of its Series B Preferred Stock. The Company classified the warrant as a liability on its consolidated balance sheet. The Company remeasures this warrant liability to fair value at each reporting date and recognizes changes in the fair value of the warrant liability as a component of other income (expense), net in the consolidated statement of operations and comprehensive loss. The Company utilized the Black-Scholes option-pricing model, which incorporates assumptions and estimates, to value these warrants. The Company assesses these assumptions and estimates on a quarterly basis. Estimates and assumptions impacting the fair value measurement include the fair value per share of the underlying redeemable convertible Series B Preferred Stock or common stock issuable upon exercise of the warrant, remaining contractual term of the warrant, risk-free interest rate, expected dividend yield and expected volatility of the price of the underlying redeemable convertible preferred stock or common stock. See Note 13.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine these fair values as of September 30, 2020 and December 31, 2019 (in thousands): DESCRIPTION SEPTEMBER 30, 2020 QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 3) Asset Cash and cash equivalents (money market funds) $ 63,434 $ 63,434 $ — $ — Short-term investments 135,979 135,979 — — Total financial assets $ 199,413 $ 199,413 $ — $ — Liability Warrants $ 5,465 $ — $ — $ 5,465 Total financial liabilities $ 5,465 $ — $ — $ 5,465 DESCRIPTION DECEMBER 31, 2019 QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 2) SIGNIFICANT OTHER OBSERVABLE INPUTS (LEVEL 3) Asset Cash and cash equivalents (money market funds) $ 90,549 $ 90,549 $ — $ — Total financial assets $ 90,549 $ 90,549 $ — $ —

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following (in thousands): SEPTEMBER 30, 2020 DECEMBER 31, 2019 Laboratory equipment $ 7,038 $ 6,766 Computer equipment 223 167 Furniture and fixtures 805 797 Office equipment 179 167 Leasehold improvements 541 520 Total 8,786 8,417 Less: accumulated depreciation (5,207 ) (3,954 ) Property and equipment, net $ 3,580 $ 4,463

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Lessee Lease Description [Line Items]
Undiscounted Minimum Future Lease Payments Under Non-cancelable Leases	As of September 30, 2020, undiscounted minimum future lease payments under non-cancelable leases were as follows: (in thousands): FUTURE OPERATING LEASE PAYMENTS 2020 (1) $ 551 2021 2,272 2022 2,340 2023 2,410 2024 2,483 Thereafter 8,833 Total lease payments 18,889 Less imputed interest (5,792 ) Total operating lease liabilities at September 30, 2020 $ 13,097 (1) For the three months ended December 31, 2020.
Watertown Lease
Lessee Lease Description [Line Items]
Summary of Lease Costs	The elements of lease costs under the Watertown Lease were as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Lease cost: Operating lease cost $ 637 637 $ 1,912 $ 1,912 Variable lease cost 419 366 1,207 1,087 Total lease cost 1,056 1,003 3,119 2,999 Other information: Operating cash flows for operating liabilities $ 551 535 $ 1,654 $ 1,606 Operating lease liabilities arising from obtaining right-of- use assets — — — — Weighted average remaining lease term 7.5 years 8.5 years 7.5 years 8.5 years Weighted average discount rate 10 % 10 % 10 % 10 %

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following as of September 30, 2020 and December 31, 2019 (in thousands): SEPTEMBER 30, 2020 DECEMBER 31, 2019 Accrued research and development 5,387 $ 2,615 Accrued compensation and benefits 2,727 3,048 Accrued professional fees 1,552 728 Other 164 280 Total accrued expenses and other current liabilities $ 9,830 $ 6,671

Collaboration and License Agr_2

Collaboration and License Agreements (Tables)	9 Months Ended
	Sep. 30, 2020
Collaboration And License Agreements [Abstract]
Schedule of Revenue from Collaboration Agreements	Revenue from collaboration agreements for the three and nine months ended September 30, 2020 and 2019 in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Restated Roche Agreement $ 1,395 1,762 $ 7,424 $ 3,875 Biogen License Agreement 3,525 642 6,827 1,707 Calico License Agreement 3,527 2,960 10,682 7,590 $ 8,447 $ 5,364 $ 24,933 $ 13,172
Schedule of Financial Information Related to Collaboration and License Agreements	Financial information related to the collaboration and license agreements consisted of the following in the Company’s condensed consolidated balance sheet as of September 30, 2020 and December 31, 2019 (in thousands): AS OF SEPTEMBER 30, 2020 (unaudited) DESCRIPTION ACCOUNTS RECEIVABLE DEFERRED REVENUE, CURRENT DEFERRED REVENUE, NET OF CURRENT DEFERRED REVENUE, TOTAL Restated Roche Agreement $ 583 $ 7,821 $ 31,286 $ 39,107 Biogen License Agreement 631 13,694 28,597 42,291 Calico License Agreement 2,927 2,400 1,200 3,600 $ 4,141 $ 23,915 $ 61,083 $ 84,998 AS OF DECEMBER 31, 2019 DESCRIPTION ACCOUNTS RECEIVABLE DEFERRED REVENUE, CURRENT DEFERRED REVENUE, NET OF CURRENT DEFERRED REVENUE, TOTAL Restated Roche Agreement $ — $ 12,164 $ 32,784 $ 44,948 Biogen License Agreement 275 6,141 36,934 43,075 Calico License Agreement 4,348 2,400 3,000 5,400 $ 4,623 $ 20,705 $ 72,718 $ 93,423

Long-term Debt and Warrant Li_2

Long-term Debt and Warrant Liability (Tables)	9 Months Ended
	Sep. 30, 2020
Long Term Debt And Warrant Liability [Abstract]
Summary of Assumptions to Determine Fair Value of Warrant	The Company determined the fair value of this warrant to be $5.5 million using the Black-Scholes model based on the following assumptions as of September 30, 2020: AS OF SEPTEMBER 30, 2020 Stock price $ 2.26 Exercise price $ 1.05 Expected term (in years) 9.75 Volatility 75 % Risk-free interest rate 0.69 % Dividend yield —

Stockholder_s Equity (Tables)

Stockholder’s Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Schedule of Preferred Stock	As of September 30, 2020 and December 31, 2019, Preferred Stock consisted of the following (in thousands, except share data): SEPTEMBER 30, 2020 PREFERRED STOCK AUTHORIZED PREFERRED STOCK ISSUED AND OUTSTANDING CARRYING VALUE LIQUIDATION VALUE COMMON STOCK ISSUABLE UPON CONVERSION Series Seed Preferred Stock 4,000,000 4,000,000 $ 1,000 $ 1,000 474,298 Series A Preferred Stock 110,000,000 109,145,900 109,995 109,995 12,941,857 Series B Convertible Preferred Stock 150,000,000 142,857,142 145,525 145,525 16,939,224 264,000,000 256,003,042 $ 256,520 $ 256,520 30,355,379 DECEMBER 31, 2019 PREFERRED STOCK AUTHORIZED PREFERRED STOCK ISSUED AND OUTSTANDING CARRYING VALUE LIQUIDATION VALUE COMMON STOCK ISSUABLE UPON CONVERSION Series Seed Preferred Stock 4,000,000 4,000,000 $ 1,000 $ 1,000 474,298 Series A Preferred Stock 110,000,000 109,145,900 109,995 109,995 12,941,857 FF Preferred Stock 32,760,000 — — — — 146,760,000 113,145,900 $ 110,995 $ 110,995 13,416,155

Share-based Compensation (Table

Share-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-based Compensation Expense	Stock-based compensation expense for the three and nine months ended September 30, 2020 and 2019 was classified in the Company’s condensed consolidated statement of operations and comprehensive loss as follows (in thousands): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Research and development $ 345 $ 118 $ 620 $ 272 General and administrative 91 509 93 641 Total stock-based compensation expense $ 436 $ 627 $ 713 $ 913
Summary of Stock Option Activity	Stock option activity under the 2015 Plan is summarized as follows: NUMBER OF OPTIONS WEIGHTED- AVERAGE EXERCISE PRICE WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS) AGGREGATE INTRINSIC VALUE Outstanding as of December 31, 2019 2,368,950 $ 4.35 8.11 $ 10,309 Granted 1,467,424 4.98 Exercised (251,466 ) 3.17 2,442 Cancelled or forfeited (1,229,054 ) 4.52 Outstanding as of September 30, 2020 2,355,854 4.82 8.89 $ 11,367 Options exercisable as of December 31, 2019 733,310 3.40 7.41 $ 2,275 Options exercisable as of September 30, 2020 365,732 4.04 7.28 $ 6,949

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Loss Per Share	Basic and diluted loss per share is computed by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding (in thousands, except share and per share data): THREE MONTHS ENDED SEPTEMBER 30, NINE MONTHS ENDED SEPTEMBER 30, 2020 2019 2020 2019 Numerator: Net loss $ (21,835 ) $ (10,094 ) $ (44,540 ) $ (24,076 ) Accrual of preferred stock dividends (5,212 ) (2,201 ) (10,363 ) (6,531 ) Net loss attributable to common stockholders $ (27,047 ) $ (12,295 ) $ (54,903 ) $ (30,607 ) Denominator: Weighted-average common stock outstanding 1,540,902 1,376,365 1,493,521 1,354,734 Net loss per share attributable to common stockholders $ (17.55 ) $ (8.93 ) $ (36.76 ) $ (22.59 )

The Company - Additional Inform

The Company - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ 44,540	$ 24,076
Accumulated deficit	162,028		$ 117,488
Cash and cash equivalents and short term investments	$ 199,400
Reverse stock split	one-for-8.4335

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	Sep. 30, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Short-term investments	$ 135,979
IPO
Summary Of Significant Accounting Policies [Line Items]
Deferred offering costs	$ 2,900

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Asset
Cash and cash equivalents (money market funds)	$ 63,434	$ 90,549
Short-term investments	135,979
Total financial assets	199,413	90,549
Liability
Warrants	5,465
Total financial liabilities	5,465
Quoted Prices in Active Markets for Identical Assets (Level 1)
Asset
Cash and cash equivalents (money market funds)	63,434	90,549
Short-term investments	135,979
Total financial assets	199,413	$ 90,549
Significant Other Observable Inputs (Level 3)
Liability
Warrants	5,465
Total financial liabilities	$ 5,465

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Available-for-sale-investments in unrealized loss position, more than 12 months	$ 0	$ 0	$ 0
Other-than-temporary impairment losses recognized	0	0
Fair value, assets, level 1 to level 2 transfers, amount	0	0		$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0		0
Fair value, liabilities, level 1 to level 2 transfers, amount	0	0		0
Fair value, liabilities, level 2 to level 1 transfers, amount	0	0		0
Fair value, assets, level 1 to level 3 transfers, amount	0	0		0
Fair value, assets, level 3 to level 1 transfers, amount	0	0		0
Fair value, liabilities, level 1 to level 3 transfers, amount	0	0		0
Fair value, liabilities, level 3 to level 1 transfers, amount	0	0		0
Fair value, assets, level 2 to level 3 transfers, amount	0	0		0
Fair value, assets, level 3 to level 2 transfers, amount	0	0		0
Fair value, liabilities, level 2 to level 3 transfers, amount	0	0		0
Fair value, liabilities, level 3 to level 2 transfers, amount	$ 0	$ 0		$ 0

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8,786	$ 8,417
Less: accumulated depreciation	(5,207)	(3,954)
Property and equipment, net	3,580	4,463
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,038	6,766
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	223	167
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	805	797
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	179	167
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 541	$ 520

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Abstract]
Depreciation and amortization	$ 1,252	$ 1,173

Leases - Additional Information

Leases - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Lessee Lease Description [Line Items]
Right-of-use assets		$ 13,544,000		$ 13,544,000		$ 14,453,000
Liabilities under lease		13,097,000		13,097,000
Operating lease liability, current		1,000,000		1,000,000		880,000
Operating lease liability, net of current		12,097,000		12,097,000		12,869,000
Right-of-use amortization				910,000	$ 850,000
Watertown Lease
Lessee Lease Description [Line Items]
Operating lease costs		637,000	$ 637,000	1,912,000	1,912,000
Costs for leasehold improvements				0	500,000
Right-of-use assets		13,500,000		13,500,000		14,500,000
Liabilities under lease		13,100,000		13,100,000		13,800,000
Operating lease liability, current		1,000,000		1,000,000		900,000
Operating lease liability, net of current		12,100,000		12,100,000		$ 12,900,000
Right-of-use amortization				900,000	900,000
Watertown Lease | Restricted Cash
Lessee Lease Description [Line Items]
Lease collateral amount		$ 2,600,000		$ 2,600,000
Watertown Lease | Office and Laboratory Space
Lessee Lease Description [Line Items]
Lease commencement date	2018-04
Lessee operating lease, description				In July 2017, the Company entered into a lease of office and laboratory space for its headquarters at 490 Arsenal Way in Watertown, Massachusetts (the “Watertown Lease”). The Watertown Lease commenced in April 2018 with rent commencing in May 2018
Rent commencing date	2018-05
Operating lease costs				$ 3,100,000	$ 3,000,000

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs (Details) - Watertown Lease - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease cost:
Operating lease cost	$ 637	$ 637	$ 1,912	$ 1,912
Variable lease cost	419	366	1,207	1,087
Total lease cost	1,056	1,003	3,119	2,999
Other information:
Operating cash flows for operating liabilities	$ 551	$ 535	$ 1,654	$ 1,606
Weighted average remaining lease term	7 years 6 months	8 years 6 months	7 years 6 months	8 years 6 months
Weighted average discount rate	10.00%	10.00%	10.00%	10.00%

Leases - Undiscounted Minimum F

Leases - Undiscounted Minimum Future Lease Payments Under Non-cancelable Leases (Details) $ in Thousands	Sep. 30, 2020USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2020	$ 551
2021	2,272
2022	2,340
2023	2,410
2024	2,483
Thereafter	8,833
Total lease payments	18,889
Less imputed interest	(5,792)
Total operating lease liabilities at September 30, 2020	$ 13,097

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued research and development	$ 5,387	$ 2,615
Accrued compensation and benefits	2,727	3,048
Accrued professional fees	1,552	728
Other	164	280
Total accrued expenses and other current liabilities	$ 9,830	$ 6,671

Collaboration and License Agr_3

Collaboration and License Agreements - Additional Information (Details)	Dec. 22, 2018USD ($)Target	Apr. 30, 2019USD ($)	Dec. 31, 2018USD ($)ProteinTarget	Mar. 31, 2016USD ($)ProteinReimbursement	Sep. 30, 2020USD ($)TargetExchangePerformanceobligationTargetProtein	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)TargetExchangeMaterialRightPerformanceobligationTargetProtein	Sep. 30, 2019USD ($)	Jun. 30, 2020USD ($)
Original Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment							$ 40,000,000
Expected research plan funding payments							13,500,000
Remaining deferred revenue					$ 6,400,000		$ 6,400,000
Original Roche Agreement | Roche JRC | Research and Development License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable upfront payment and additional fees				$ 15,000,000
Estimated period to perform research and development				42 months
Original Roche Agreement | Roche JRC | Research, Development and Commercial Milestone Payments | Research and Development License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				$ 277,000,000
Original Roche Agreement | Maximum | Roche
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targeted protein degradation | Protein				10
Original Roche Agreement | Maximum | Roche JRC | Research and Development License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of reimbursements in full-time equivalents | Reimbursement				5
Original Roche Agreement | Maximum | Roche JRC | One-Time Sales-Based Payments | Research and Development License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive				$ 150,000,000
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of potential targets | Target	6				6		6
Number of target nominated as of the execution of the Restated Roche Agreement | Target	3
Number of target not nominated as of the execution of the Restated Roche Agreement | Target	3
Additional upfront consideration received	$ 40,000,000
Annual research plan payments receivables	1,000,000
Collaboration description							The Company has control over the committee and may terminate the Restated Roche Agreement on a target-by-target or product-by-product basis under several scenarios, upon at least 90 days’ prior written notice.
Number of initial targets | Target					3		3
Number of additional targets | Target							3
Number of targets | Target					6		6
Number of exchanges | Exchange					6		6
Number of additional targets | Target					3		3
Number of performance obligation | Performanceobligation					12		12
Restated Roche Agreement | Lead Series Identification Achievement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees	2,000,000
Restated Roche Agreement | Good Laboratory Practice (“GLP”) Toxicology (“Tox”) Study Phase
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees	3,000,000
Restated Roche Agreement | Progressed Through Clinical Trials
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees	20,000,000
Restated Roche Agreement | Option to License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of material rights | MaterialRight							3
Restated Roche Agreement | Option to Initiate Research Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of additional targets | Target							3
Number of material rights | MaterialRight							3
Restated Roche Agreement | Research Services Performance Obligations
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of performance obligation | Performanceobligation					3		3
Restated Roche Agreement | Commercial License for Six Targets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets | Target					6		6
Number of performance obligation | Performanceobligation					6		6
Restated Roche Agreement | Research Services for Uninitiated Three Targets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targets | Target					3		3
Number of performance obligation | Performanceobligation					3		3
Restated Roche Agreement | Maximum | Research, Development and Commercial Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	275,000,000
Restated Roche Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount eligible to receive	150,000,000
Restated Roche Agreement | Maximum | Progressed Through Clinical Trials
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees	12,000,000
Restated Roche Agreement | Minimum | Progressed Through Clinical Trials
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Option exercise fees	$ 7,000,000
Restated Roche Agreement Accounting
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment							$ 40,000,000
Expected research plan funding payments							13,500,000
Remaining deferred revenue					$ 6,400,000		6,400,000
Amount of expected research plan funding payments of per active target per year							1,000,000
Restated Roche Agreement Accounting | Target Two
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment received		$ 2,000,000
Transaction price allocated to performance obligations					61,900,000		$ 61,900,000
Restated Roche Agreement Accounting | Targets 3
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of material rights | MaterialRight							3
Transaction price allocated to performance obligations					4,700,000		$ 4,700,000
Restated Roche Agreement Accounting | Targets 4-6
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated to performance obligations					28,600,000		28,600,000
Restated Roche Agreement Accounting | Targets 1-3
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated to performance obligations					$ 28,600,000		28,600,000
Restated Roche Agreement Accounting | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount of expected research plan funding payments of per target							$ 3,000,000
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of additional targets | Target							2
Number of targets | Target					5		5
Number of performance obligation | Performanceobligation					1		1
Agreement date			2018-12
Research agreement, period			54 months				54 months
Additional payment on extension of contract			$ 62,500,000
Nonrefundable upfront payment							$ 45,000,000
Written notice period for termination of agreement							90 days
Revenue recognized					$ 600,000	$ 200,000	$ 2,000,000	$ 200,000
Biogen License Agreement | Accounts Receivable and Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment									$ 4,000,000
Biogen License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of targeted protein degradation | Protein			5
Additional targets for development | Target			5
Biogen License Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							26,000,000
Biogen License Agreement | Maximum | Research And Development Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							$ 35,000,000
Biogen License Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice period for termination of agreement							90 days
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment							$ 5,000,000
Number of targets | Target					5		5
Number of performance obligation | Performanceobligation					1		1
Research term								5 years
Annual Payments							$ 5,000,000
Contractual term							5 years
Calico License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of target proteins | TargetProtein					5		5
Calico License Agreement | Maximum | One-Time Sales-Based Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							$ 65,000,000
Calico License Agreement | Maximum | Potential Research, Development and Commercial Milestone Payments
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received							$ 132,000,000

Collaboration and License Agr_4

Collaboration and License Agreements - Schedule of Revenue from Collaboration Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from collaboration agreements	$ 8,447	$ 5,364	$ 24,933	$ 13,172
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from collaboration agreements	1,395	1,762	7,424	3,875
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from collaboration agreements	3,525	642	6,827	1,707
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from collaboration agreements	$ 3,527	$ 2,960	$ 10,682	$ 7,590

Collaboration and License Agr_5

Collaboration and License Agreements - Schedule of Financial Information Related to Collaboration and License Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
ACCOUNTS RECEIVABLE	$ 4,141	$ 4,623
DEFERRED REVENUE, CURRENT	23,915	20,705
DEFERRED REVENUE, NET OF CURRENT	61,083	72,718
DEFERRED REVENUE, TOTAL	84,998	93,423
Restated Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
ACCOUNTS RECEIVABLE	583
DEFERRED REVENUE, CURRENT	7,821	12,164
DEFERRED REVENUE, NET OF CURRENT	31,286	32,784
DEFERRED REVENUE, TOTAL	39,107	44,948
Biogen License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
ACCOUNTS RECEIVABLE	631	275
DEFERRED REVENUE, CURRENT	13,694	6,141
DEFERRED REVENUE, NET OF CURRENT	28,597	36,934
DEFERRED REVENUE, TOTAL	42,291	43,075
Calico License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
ACCOUNTS RECEIVABLE	2,927	4,348
DEFERRED REVENUE, CURRENT	2,400	2,400
DEFERRED REVENUE, NET OF CURRENT	1,200	3,000
DEFERRED REVENUE, TOTAL	$ 3,600	$ 5,400

Long-term Debt and Warrant Li_3

Long-term Debt and Warrant Liability - Additional Information (Details) - USD ($)	Jun. 05, 2020	Sep. 30, 2020	Sep. 30, 2020	Jun. 30, 2020
Long Term Debt And Warrant Liability [Line Items]
Exercise price per share		$ 1.05	$ 1.05
Change in fair value of warrant liability		$ 3,141,000	$ 3,141,000
Series B Preferred Stock
Long Term Debt And Warrant Liability [Line Items]
Warrant issued to purchase shares				2,857,142
Term Loan | Series B Preferred Stock
Long Term Debt And Warrant Liability [Line Items]
Exercise price per share		$ 1.05	$ 1.05
Change in fair value of warrant liability			$ 5,500,000
Term Loan | Maximum | Series B Preferred Stock
Long Term Debt And Warrant Liability [Line Items]
Warrant issued to purchase shares		2,857,142	2,857,142
Credit Agreement with Perceptive Life Sciences Master Fund LTD | Term Loan
Long Term Debt And Warrant Liability [Line Items]
Interest at variable rate	11.25%
Description of Variable Rate Basis			one-month LIBOR rate, which, per the Credit Agreement, can never be below 1.75%
Applicable margin rate	9.50%
Maturity date	Sep. 5, 2024
Date until which interest only payments are made	Dec. 5, 2022
Percentage of principal payments until maturity	2.00%
Prepayment fee	$ 5,000,000
Prepayment minimum principal amount	500,000
Prepayment principal amount multiples	100,000
Closing fee in connection with entry into Credit Agreement	300,000
Aggregate principal amount of debt outstanding		$ 12,500,000	$ 12,500,000
Unamortized debt discount		2,600,000	2,600,000
Carrying value of long-term debt, net of issuance costs and debt discount related to warrants to purchase shares of equity securities that were issued in connection with entry into Credit Agreement		$ 9,700,000	$ 9,700,000
Credit Agreement with Perceptive Life Sciences Master Fund LTD | Term Loan | Maximum
Long Term Debt And Warrant Liability [Line Items]
Aggregate principal amount	20,000,000
Credit Agreement with Perceptive Life Sciences Master Fund LTD | Term Loan | Minimum
Long Term Debt And Warrant Liability [Line Items]
Balance to be maintained in bank account while debt is outstanding	3,000,000
Credit Agreement with Perceptive Life Sciences Master Fund LTD | Term Loan | Tranche One
Long Term Debt And Warrant Liability [Line Items]
Aggregate principal amount	12,500,000
Amount withdrawn				$ 12,500,000
Credit Agreement with Perceptive Life Sciences Master Fund LTD | Term Loan | Tranche Two
Long Term Debt And Warrant Liability [Line Items]
Aggregate principal amount	$ 7,500,000

Long-term Debt and Warrant Li_4

Long-term Debt and Warrant Liability - Summary of Assumptions to Determine Fair Value of Warrant (Details)	Sep. 30, 2020$ / shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Stock price	$ 2.26
Exercise price	$ 1.05
Expected term (in years)	9 years 9 months
Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.75
Risk-free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.0069

Stockholder's Equity - Addition

Stockholder's Equity - Additional Information (Details) $ / shares in Units, $ in Thousands	Sep. 25, 2020	Jul. 31, 2020USD ($)shares	Jun. 30, 2020USD ($)shares	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019$ / sharesshares
Stockholders Equity [Line Items]
Reverse stock split				one-for-8.4335
Stock split conversion ratio	0.118574732
Common stock, par value per share				$ 0.0001	$ 0.0001
Common stock voting right				one vote for each share
Proceeds from issuance of convertible preferred stock | $				$ 145,525
Redeemable convertible preferred stock, shares issued | shares				256,003,042	113,145,900
Stock issuance costs | $				$ 4,473
Redeemable convertible preferred stock conversion basis				8.4335-to-one
Redeemable convertible preferred stock conversion ratio | shares				8.4335
Proceeds from issuance underwritten public offering | $				$ 50,000
Redeemable convertible preferred stock voting right				every 8.4335 shares of Preferred Stock was entitled to one vote
Series Seed Preferred Stock
Stockholders Equity [Line Items]
Redeemable convertible preferred stock, par value per share				$ 0.0005	$ 0.0005
Redeemable convertible preferred stock, shares issued | shares				4,000,000	4,000,000
Series A Preferred Stock
Stockholders Equity [Line Items]
Redeemable convertible preferred stock, par value per share				$ 0.0005	$ 0.0005
Redeemable convertible preferred stock, shares issued | shares				109,145,900	109,145,900
Redeemable convertible preferred stock dividends rate per annum				$ 0.08
Series B Convertible Preferred Stock
Stockholders Equity [Line Items]
Redeemable convertible preferred stock, par value per share				$ 0.0005	$ 0.0005
Proceeds from issuance of convertible preferred stock | $		$ 4,500	$ 145,500	$ 150,000
Redeemable convertible preferred stock, shares issued | shares		4,285,714	138,571,428	142,857,142	0
Shares issued price per share				$ 1.05
Stock issuance costs | $			$ 4,500
Redeemable convertible preferred stock dividends rate per annum				$ 0.084

Stockholder's Equity - Schedule

Stockholder's Equity - Schedule of Preferred Stock (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jul. 31, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
PREFERRED STOCK AUTHORIZED	264,000,000			146,760,000
PREFERRED STOCK ISSUED	256,003,042			113,145,900
PREFERRED STOCK OUTSTANDING	256,003,042			113,145,900
CARRYING VALUE	$ 256,520			$ 110,995
LIQUIDATION VALUE	$ 256,520			$ 110,995
COMMON STOCK ISSUABLE UPON CONVERSION	30,355,379			13,416,155
Series Seed Preferred Stock
Class Of Stock [Line Items]
PREFERRED STOCK AUTHORIZED	4,000,000			4,000,000
PREFERRED STOCK ISSUED	4,000,000			4,000,000
PREFERRED STOCK OUTSTANDING	4,000,000		4,000,000	4,000,000	4,000,000	4,000,000	4,000,000
CARRYING VALUE	$ 1,000		$ 1,000	$ 1,000	$ 1,000	$ 1,000	$ 1,000
LIQUIDATION VALUE	$ 1,000			$ 1,000
COMMON STOCK ISSUABLE UPON CONVERSION	474,298			474,298
Series A Preferred Stock
Class Of Stock [Line Items]
PREFERRED STOCK AUTHORIZED	110,000,000			110,000,000
PREFERRED STOCK ISSUED	109,145,900			109,145,900
PREFERRED STOCK OUTSTANDING	109,145,900		109,145,900	109,145,900	109,145,900	109,145,900	109,145,900
CARRYING VALUE	$ 109,995		$ 109,995	$ 109,995	$ 109,995	$ 109,995	$ 109,995
LIQUIDATION VALUE	$ 109,995			$ 109,995
COMMON STOCK ISSUABLE UPON CONVERSION	12,941,857			12,941,857
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
PREFERRED STOCK AUTHORIZED	150,000,000			0
PREFERRED STOCK ISSUED	142,857,142	4,285,714	138,571,428	0
PREFERRED STOCK OUTSTANDING	142,857,142		138,571,428	0
CARRYING VALUE	$ 145,525		$ 141,026
LIQUIDATION VALUE	$ 145,525			$ 0
COMMON STOCK ISSUABLE UPON CONVERSION	16,939,224
FF Preferred Stock
Class Of Stock [Line Items]
PREFERRED STOCK AUTHORIZED				32,760,000

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($) $ in Thousands	Oct. 01, 2020	Mar. 03, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 03, 2020	Apr. 30, 2019	Dec. 28, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense			$ 436	$ 627	$ 713	$ 913
Payments for repurchase of common stock		$ 100			$ 210	$ 40
Payments for relinquishment of right to purchase common stock upon exercise of stock options		$ 800
2015 Incentive Stock Option and Grant Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation, common stock shares reserved for issuance							5,058,203	3,614,753	2,525,327
Common stock, shares remained available for future grant			2,364,975		2,364,975
Awards granted					1,467,424
Stock-based compensation, options vesting description					Options generally vest over a period of five or eight years, with a cliff vesting at one year and quarterly vesting thereafter and options that lapse or are forfeited are available to be granted again.
Contractual life of options from the date of grant					10 years
2015 Incentive Stock Option and Grant Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation, options vesting period					5 years
2015 Incentive Stock Option and Grant Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation, options vesting period					8 years
2015 Incentive Stock Option and Grant Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted	0
2020 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation, common stock shares reserved for issuance			6,567,144		6,567,144
Awards granted					0
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation, common stock shares reserved for issuance			437,809		437,809
Maximum authorized payroll deduction percentage of eligible compensation for eligible employees					15.00%
Shares issued under employee stock purchase plan					0

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 436	$ 627	$ 713	$ 913
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	345	118	620	272
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 91	$ 509	$ 93	$ 641

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) - 2015 Incentive Stock Option and Grant Plan $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options, Outstanding as of December 31, 2019 | shares	2,368,950
Number of options, Granted | shares	1,467,424
Number of options, Exercised | shares	(251,466)
Number of options, Cancelled or forfeited | shares	(1,229,054)
Number of options, Outstanding as of September 30, 2020 | shares	2,355,854	2,368,950
Number of options, Options exercisable | shares	365,732	733,310
Weighted-average exercise price, Outstanding as of December 31, 2019 | $ / shares	$ 4.35
Weighted-average exercise price, Granted | $ / shares	4.98
Weighted-average exercise price, Exercised | $ / shares	3.17
Weighted-average exercise price, Cancelled or forfeited | $ / shares	4.52
Weighted-average exercise price, Outstanding as of September 30, 2020 | $ / shares	4.82	$ 4.35
Weighted-average exercise price, Options exercisable | $ / shares	$ 4.04	$ 3.40
Weighted average remaining contractual term (in years), Options outstanding	8 years 10 months 20 days	8 years 1 month 9 days
Weighted average remaining contractual term (in years), Options exercisable	7 years 3 months 10 days	7 years 4 months 28 days
Aggregate intrinsic value, Outstanding as of December 31, 2019 | $	$ 10,309
Aggregate intrinsic value, Exercised | $	2,442
Aggregate intrinsic value, Outstanding as of September 30, 2020 | $	11,367	$ 10,309
Aggregate intrinsic value, Options exercisable | $	$ 6,949	$ 2,275

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax [Line Items]
Tax benefit	$ (167)	$ 650	$ (502)	$ 900
Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”)
Income Tax [Line Items]
Tax benefit	(200)		(500)
Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) | Other Long-Term Assets
Income Tax [Line Items]
Tax receivables	$ 500		$ 500

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (21,835)	$ (10,094)	$ (44,540)	$ (24,076)
Accrual of preferred stock dividends	(5,212)	(2,201)	(10,363)	(6,531)
Net loss attributable to common stockholders	$ (27,047)	$ (12,295)	$ (54,903)	$ (30,607)
Denominator:
Weighted-average common stock outstanding	1,540,902	1,376,365	1,493,521	1,354,734
Net loss per share attributable to common stockholders	$ (17.55)	$ (8.93)	$ (36.76)	$ (22.59)

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 06, 2020	Oct. 01, 2020	Sep. 30, 2020	Sep. 30, 2020	Oct. 07, 2020	Jun. 30, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Outstanding shares of preferred stock automatically converted			30,355,379	30,355,379			13,416,155
Expenses				$ 4,473
Common stock, shares authorized			370,000,000	370,000,000			180,000,000
Common stock, par value per share			$ 0.0001	$ 0.0001			$ 0.0001
2020 Stock Option and Incentive Plan | Stock Options
Subsequent Event [Line Items]
Stock-based compensation, options vesting description				These options vest quarterly over four years subject to cliff vesting after six months. Mr. Cohen’s award is subject to full acceleration upon a sale of the Company and Mr. Hirsch’s award is subject to full acceleration upon a sale of the Company and the termination of his employment thereafter pursuant to the terms of his employment agreement, subject to Mr. Hirsch’s execution of an effective release of claims in favor of the Company.
2020 Stock Option and Incentive Plan | Stock Options | Co-founder, Executive Chairman and Interim Chief Executive Officer
Subsequent Event [Line Items]
Percentage of fully-diluted shares for issuance of stock option			1.50%
2020 Stock Option and Incentive Plan | Stock Options | President, Director and Chief Executive Officer-elect
Subsequent Event [Line Items]
Percentage of fully-diluted shares for issuance of stock option			3.50%
2020 Stock Option and Incentive Plan | Stock Options | Directors And Certain Employees
Subsequent Event [Line Items]
Stock-based compensation, options vesting description				These shares will vest over one- to four-year periods, subject to the recipient maintaining a business relationship with the Company through the applicable vesting date.
Number of additional shares approved for grant			192,681
Series B Preferred Stock
Subsequent Event [Line Items]
Warrant issued to purchase shares						2,857,142
Subsequent Event | 2020 Stock Option and Incentive Plan | Stock Options
Subsequent Event [Line Items]
Stock option, exercise price		$ 19
Stock-based compensation, options vesting period		4 years
Subsequent Event | 2020 Stock Option and Incentive Plan | Stock Options | Directors And Certain Employees
Subsequent Event [Line Items]
Number of shares awarded		192,681
Stock option, exercise price		$ 19
Subsequent Event | 2020 Stock Option and Incentive Plan | Stock Options | Directors And Certain Employees | Minimum
Subsequent Event [Line Items]
Stock-based compensation, options vesting period		1 year
Subsequent Event | 2020 Stock Option and Incentive Plan | Stock Options | Directors And Certain Employees | Maximum
Subsequent Event [Line Items]
Stock-based compensation, options vesting period		4 years
Subsequent Event | IPO
Subsequent Event [Line Items]
Preferred stock, outstanding	0				0
Common stock, shares authorized	150,000,000
Preferred stock, shares authorized	10,000,000
Common stock, par value per share	$ 0.0001
Preferred stock, par value	$ 0.0001
Number of preferred stock converted in to one common stock	8.4335
Subsequent Event | IPO | 2020 Stock Option and Incentive Plan | Stock Options | Co-founder, Executive Chairman and Interim Chief Executive Officer
Subsequent Event [Line Items]
Number of shares awarded	725,002
Subsequent Event | IPO | 2020 Stock Option and Incentive Plan | Stock Options | President, Director and Chief Executive Officer-elect
Subsequent Event [Line Items]
Number of shares awarded	1,691,672
Subsequent Event | Common Stock | IPO
Subsequent Event [Line Items]
Initial public offering closing date	Oct. 6, 2020
Issued shares of common stock	11,040,000
Shares issued price per share	$ 19
Outstanding shares of preferred stock automatically converted	30,355,379
Net proceeds including exercise in full of underwriters option to purchase additional shares	$ 191,100
Underwriting discounts and commissions	14,700
Expenses	$ 4,000
Subsequent Event | Common Stock | IPO | Warrant Exercisable
Subsequent Event [Line Items]
Number of warrants converted into shares	338,784
Subsequent Event | Underwriters for IPO Exercised in full Overallotment Option | Common Stock | IPO
Subsequent Event [Line Items]
Issued shares of common stock	1,440,000