Karuna Therapeutics (KRTX) 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 15, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	KRTX
Entity Registrant Name	Karuna Therapeutics, Inc.
Entity Central Index Key	0001771917
Current Fiscal Year End Date	--12-31
Entity File Number	001-38958
Entity Tax Identification Number	27-0605902
Entity Address, Address Line One	33 Arch Street
Entity Address, Address Line Two	Suite 3110
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02110
City Area Code	857
Local Phone Number	449-2244
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		27,018,734
Entity Shell Company	false
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.0001 Par Value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2,231
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement for its 2021 Annual Meeting of Stockholders, which the registrant intends to file with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2020, are incorporated by reference into Part III of this Annual Report on Form 10-K.

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 53,048	$ 208,929
Investment securities, available-for-sale	269,282	180,468
Prepaid expenses and other current assets	21,864	3,309
Deferred offering costs	405
Total current assets	344,599	392,706
Restricted cash	157	123
Property and equipment, net	449	195
Right-of-use lease assets - operating, net	2,420
Total assets	347,625	393,024
Current liabilities:
Accounts payable (includes $0 and $51 at December 31, 2020 and 2019, respectively, due to related parties)	865	547
Accrued expenses	5,144	2,353
Current portion of deferred lease obligation		58
Current portion of operating lease liability	844
Total current liabilities	6,853	2,958
Deferred lease obligation, net of current portion		150
Operating lease liability, net of current portion	1,841
Total liabilities	8,694	3,108
Commitments and Contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and 0 shares outstanding at December 31, 2020 and 2019
Common stock, $0.0001 par value; 150,000,000 shares authorized at December 31, 2020 and 2019; 26,988,458 and 26,012,754 shares issued and outstanding at December 31, 2020 and 2019, respectively	3	3
Additional paid-in capital	482,955	465,420
Accumulated deficit	(144,066)	(75,512)
Accumulated other comprehensive income	39	5
Total stockholders’ equity	338,931	389,916
Total liabilities and stockholders’ equity	$ 347,625	$ 393,024

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Accounts payable to related party	$ 0	$ 51
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	26,988,458	26,012,754
Common stock, shares outstanding	26,988,458	26,012,754

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 43,408	$ 24,536	$ 11,536
General and administrative	28,408	20,869	2,974
Total operating expenses	71,816	45,405	14,510
Loss from operations	(71,816)	(45,405)	(14,510)
Other income (expense), net:
Interest income	3,305	2,517	25
Interest income (expense), net (Note 5)		11	(407)
Accretion of debt discount (Note 5)		(945)	(2,176)
Change in fair value of derivative (Note 5)		(135)	(444)
Total other income (expense), net	3,305	1,448	(3,002)
Net loss before income taxes	(68,511)	(43,957)	(17,512)
Income tax provision	(43)	0	0
Net loss attributable to common stockholders	$ (68,554)	$ (43,957)	$ (17,512)
Net loss per share, basic and diluted (Note 8)	$ (2.59)	$ (3.68)	$ (4,378,000)
Weighted average common shares outstanding used in computing net loss per share, basic and diluted	26,446,006	11,958,152	4

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (68,554)	$ (43,957)	$ (17,512)
Other comprehensive income:
Unrealized gains on available-for-sale investments	34	5
Comprehensive loss	$ (68,520)	$ (43,952)	$ (17,512)

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Initial Public Offering	Secondary Public Offering	Common Stock	Common StockInitial Public Offering	Common StockSecondary Public Offering	Additional Paid In Capital	Additional Paid In CapitalInitial Public Offering	Additional Paid In CapitalSecondary Public Offering	Accumulated Deficit	Accumulated Other Comprehensive Income	Series Seed, A and B Redeemable Convertible Preferred Stock	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock
Temporary Equity, beginning balance at Dec. 31, 2017												$ 1
Temporary Equity, beginning balance, shares at Dec. 31, 2017												4,412,500
Beginning balance at Dec. 31, 2017	$ (13,368)						$ 675			$ (14,043)
Temporary Equity, Issuance of redeemable convertible preferred stock, net of issuance costs													$ 41,964
Temporary Equity, Issuance of redeemable convertible preferred stock, net of issuance costs, shares													3,126,700
Stock-based compensation expense	958						958
Exercise of common warrants, shares				12
Net loss	(17,512)									(17,512)
Temporary Equity, ending balance at Dec. 31, 2018												$ 41,965
Temporary Equity, ending balance, shares at Dec. 31, 2018												7,539,200
Ending balance at Dec. 31, 2018	(29,922)						1,633			(31,555)
Ending balance, shares at Dec. 31, 2018				12
Temporary Equity, Issuance of redeemable convertible preferred stock, net of issuance costs														$ 81,927
Temporary Equity, Issuance of redeemable convertible preferred stock, net of issuance costs, shares														5,422,845
Issuance of common stock		$ 93,044	$ 234,224		$ 1			$ 93,043	$ 234,224
Issuance of common stock, shares					6,414,842	2,600,000
Temporary Equity, Automatic conversion of preferred stock												$ (123,892)
Temporary Equity, Automatic conversion of preferred stock, shares												(12,962,045)
Automatic conversion of preferred stock	123,892			$ 2			123,890
Automatic conversion of preferred stock, shares				16,833,790
Secondary public offering costs		$ (2,409)	(400)
Stock-based compensation expense	12,568						12,568
Exercise of common warrants	58						58
Exercise of common warrants, shares				19,986
Exercise of common options	4						4
Exercise of common options, shares				38,961
Vesting of restricted stock units, shares				105,163
Other comprehensive income	5										$ 5
Net loss	(43,957)									(43,957)
Temporary Equity, ending balance, shares at Dec. 31, 2019												0
Ending balance at Dec. 31, 2019	389,916			$ 3			465,420			(75,512)	5
Ending balance, shares at Dec. 31, 2019				26,012,754
Secondary public offering costs			$ (34)						$ (34)
Stock-based compensation expense	13,471						13,471
Exercise of common options	$ 4,098						4,098
Exercise of common options, shares	975,704			975,704
Other comprehensive income	$ 34										34
Net loss	(68,554)									(68,554)
Temporary Equity, ending balance, shares at Dec. 31, 2020												0
Ending balance at Dec. 31, 2020	$ 338,931			$ 3			$ 482,955			$ (144,066)	$ 39
Ending balance, shares at Dec. 31, 2020				26,988,458

CONSOLIDATED STATEMENTS OF RE_2

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Initial Public Offering
Underwriting discounts and commissions	$ 7,285
Offering cost	2,409
Secondary Public Offering
Underwriting discounts and commissions	14,976
Offering cost	400
Series A Redeemable Convertible Preferred Stock
Issuance of redeemable convertible preferred stock, net of issuance costs		$ 120
Series B Redeemable Convertible Preferred Stock
Issuance of redeemable convertible preferred stock, net of issuance costs	$ 175

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (68,554)	$ (43,957)	$ (17,512)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	13,471	12,568	958
Amortization of premiums and accretion of discounts on investment securities	642	(824)
Depreciation and amortization expense	145	58	6
Loss on disposal of assets	20
Accretion of debt discount (Note 5)		945	2,176
Change in fair value of derivative liability (Note 5)		135	444
Non-cash interest (income) expense, net (Note 5)		(11)	407
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(18,555)	(1,600)	(1,534)
Change in accrued interest on investment securities	(191)	(436)
Accrued expenses	2,791	1,815	105
Accounts payable	318	278	(529)
Right-of-use assets	631
Operating lease liability	(574)
Deferred lease obligation		106	102
Net cash used in operating activities	(69,856)	(30,923)	(15,377)
Cash flows from investing activities
Purchases of investment securities	(344,213)	(231,718)	(4,983)
Maturities of investment securities	254,982	50,000
Sales of investment securities		7,498
Acquisition of property and equipment	(419)	(115)	(132)
Net cash used in investing activities	(89,650)	(174,335)	(5,115)
Cash flows from financing activities
Proceeds from exercise of stock options	4,098	4
Payment of offering costs	(405)
Proceeds from secondary public offering, net of underwriting discounts and commissions		234,624
Proceeds from initial public offering, net of underwriting discounts and commissions		95,453
Proceeds from issuance of convertible notes		3,128	11,700
Proceeds from exercise of warrant		58
Net cash provided by financing activities	3,659	405,283	27,577
Net (decrease) increase in cash, cash equivalents and restricted cash	(155,847)	200,025	7,085
Cash, cash equivalents and restricted cash at beginning of period	209,052	9,027	1,942
Cash, cash equivalents and restricted cash at end of period	53,205	209,052	9,027
Supplemental disclosures of cash flows information
Lease liabilities arising from obtaining right-of-use assets	3,259
Conversion of redeemable convertible preferred stock into common stock		123,892
Conversion of convertible notes, accrued interest and discount upon conversion to preferred stock		7,102	26,087
Secondary Public Offering
Cash flows from financing activities
Payment of offering costs	$ (34)	(400)
Initial Public Offering
Cash flows from financing activities
Payment of offering costs		(2,409)
Series B Redeemable Convertible Preferred Stock
Cash flows from financing activities
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		$ 74,825
Series A Redeemable Convertible Preferred Stock
Cash flows from financing activities
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs			$ 15,877

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	Note 1. Nature of the Business Description of the Business Karuna Therapeutics, Inc. (the “Company”) was incorporated under the laws of the State of Delaware in July 2009 as Karuna Pharmaceuticals, Inc. and is headquartered in Boston, Massachusetts. In March 2019, the Company changed its name to Karuna Therapeutics, Inc. The Company is an innovative clinical-stage biopharmaceutical company driven to create and deliver transformative medicines for people living with psychiatric and neurological conditions. Since the Company’s inception, it has focused substantially all of its efforts and financial resources on organizing and staffing the Company, acquiring and developing its technology, raising capital, building its intellectual property portfolio, undertaking preclinical studies and clinical trials and providing general and administrative support for these activities. The Company has not generated any product revenue related to its primary business purpose to date and is subject to a number of risks similar to those of other early stage companies, including dependence on key individuals, regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability, the impact of the COVID-19 coronavirus pandemic, and the need to obtain adequate additional financing to fund the development of its product candidates. Forward Stock Split On June 14, 2019, the Company effected a one-for-1.2987 stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s redeemable convertible preferred stock (see Note 6). Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this stock split and adjustment of the redeemable convertible preferred stock conversion ratios. Initial Public Offering On June 27, 2019, the Company’s registration statement on Form S-1 relating to its initial public offering of its common stock (“IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). In the IPO, which closed on July 2, 2019, the Company issued and sold 6,414,842 shares of common stock, including full exercise of the underwriters’ over-allotment option to purchase an additional 836,718 shares, at a public offering price of $16.00 per share. The aggregate net proceeds to the Company from the IPO, inclusive of proceeds from the over-allotment exercise, were approximately $93.0 million after deducting underwriting discounts and commissions of $7.2 million and offering expenses of $2.4 million. Upon closing of the IPO, all 12,962,045 shares of the Company’s redeemable convertible preferred stock then outstanding converted into an aggregate of 16,833,790 shares of common stock. Secondary Public Offering On November 20, 2019, the Company’s registration statement on Form S-1 relating to its secondary public offering of its common stock was declared effective by the SEC. In this offering, which closed on November 25, 2019, the Company issued and sold 2,600,000 shares of common stock at a public offering price of $96.00 per share. The aggregate net proceeds were approximately $234.2 million after deducting underwriting discounts and commissions of $15.0 million and offering expenses of $0.4 million. Registration Statement and ATM Program On July 2, 2020, the Company filed an automatically effective registration statement on Form S-3 (the “Registration Statement”) with the SEC which registers the offering, issuance and sale of an unspecified amount of common stock, preferred stock, debt securities, warrants and/or units of any combination thereof. The Company simultaneously entered into an equity distribution agreement with Goldman Sachs & Co. LLC, as sales agent, to provide for the issuance and sale by the Company of up to $ 150.0 million of common stock from time to time in “at-the-market” offerings under the Registration Statement and related prospectus filed with the Registration Statement (the “ATM Program”). As of December 31 , 2020, no sales had been made pursuant to the ATM Program. Liquidity The Company’s financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. The Company experienced negative operating cash flows of $69.9 million for the year ended December 31, 2020 and had an accumulated deficit of $144.1 million as of December 31, 2020. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents and available-for-sale If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation and Use of Estimates The accompanying consolidated The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated The consolidated financial statements include the accounts of Karuna Therapeutics, Inc. and its wholly owned subsidiary, Karuna Securities Corporation. All inter-company transactions and balances have been eliminated in consolidation. Cash and Cash Equivalents The Company considers all short-term, highly liquid investments with maturities of 90 days or less at acquisition date to be cash equivalents. Investment Securities The Company’s investment securities are classified as available-for-sale and are carried at fair value with the unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. The cost of investment securities classified as available-for-sale is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. Realized gains and losses are included as a component of other income (expense), net based on the specific identification method. When the fair value of an available-for-sale debt security falls below the amortized cost basis it is evaluated to determine if any of the decline in value is attributable to credit loss. Decreases in fair value attributable to credit loss are recorded directly to earnings with a corresponding allowance for credit losses, limited to the amount that the fair value is less than the amortized cost basis. If the credit quality subsequently improves the allowance is reversed up to a maximum of the previously recorded credit losses. When the Company intends to sell an impaired available-for-sale debt security, or if it is more likely than not that the Company will be required to sell the security prior to recovering the amortized cost basis, the entire fair value adjustment will immediately be recognized in earnings with no corresponding allowance for credit losses. Concentration of Manufacturing Risk The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statement of operations. Deferred offering costs were approximately $0.4 million as of December 31, 2020. As of December 31, 2019 and 2018, there were no deferred offering costs outstanding. All deferred offering costs accumulated during 2019 and associated with the Company’s IPO and secondary public offering were recorded as a reduction of additional paid-in capital upon the close of the Company’s public offerings on July 2, 2019 and November 25, 2019, respectively. Fair Value of Financial Instruments The Company’s financial instruments consist of cash equivalents, investment securities, accounts payable, accrued expenses, convertible notes and derivatives embedded within the convertible notes. The carrying amount of accounts payable, accrued expenses and convertible notes are considered a reasonable estimate of their fair value, due to the short-term maturity of these instruments. The Company’s cash equivalents, investment securities and derivative liabilities are carried at fair value, determined according to the fair value hierarchy described below (see Note 10). The Company follows the guidance in FASB ASC 820, Fair Value Measurements and Disclosures Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Fair value is a market-based measure considered from the perspective of a market participant rather than an entity-specific measure. Therefore, even when market assumptions are not readily available, the Company’s own assumptions reflect those that market participants would use in pricing the asset or liability at the measurement date. The Company uses prices and inputs that are current as of the measurement date, including during periods of market dislocation. In periods of market dislocation, the observability of prices and inputs may be reduced for many instruments. This condition could cause an instrument to be reclassified from Level 1 to Level 2 or Level 2 to Level 3. Property and Equipment Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight-line method. Leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the lease by use of the straight-line method. Maintenance and repair costs are expensed as incurred. When assets are retired or sold, the assets and accumulated depreciation are removed from the respective accounts and any gain or loss is recognized. Convertible Notes and Derivative Liabilities In connection with the issuance of the Wellcome Trust Convertible Notes and the Convertible Notes (see Note 5), the Company had identified embedded derivatives, which were recorded as liabilities on the Company’s balance sheet and were remeasured to fair value at each reporting date until the derivative was settled. Changes in the fair value of the derivative liabilities were recognized as change in fair value of derivative in the statements of operations. The fair value of the derivative liabilities were determined at each period end using a with and without method, which assesses the likelihood and timing of events that would result in either a conversion or change-of-control feature being triggered, as well as changes in the market conditions. Upon issuance of the notes, each note was recorded at cost, net of the derivative liability. The discount on each note was amortized as interest expense to the date such note was expected to convert using the effective interest rate method and was reflected in the statements of operations as accretion of debt discount. The Company classified its derivative liabilities in the balance sheet as current or non-current based on its expectation of when the derivative will be settled, consistent with the assumptions used when determining the fair value of the derivative liabilities. In 2019, all notes were converted into redeemable convertible preferred stock and the associated derivative liabilities were settled in connection with the Company’s issuance of Series B redeemable convertible preferred stock. There were no convertible notes or derivative liabilities outstanding as of December 31, 2020 and 2019. Redeemable Convertible Preferred Stock Prior to the IPO, the Company recorded all shares of redeemable convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The redeemable convertible preferred stock was recorded outside of permanent equity because upon the occurrence of certain deemed liquidation events, the majority of the holders could opt to redeem the shares at the liquidation preference and these events, including a merger, acquisition or sale of substantially all of the assets, was considered not solely within the Company’s control. Prior to the IPO, the Company had not adjusted the carrying values of the redeemable convertible preferred stock to its redemption value because it was uncertain whether or when a deemed liquidation event would occur. Upon closing of the IPO, all 12,962,045 shares of the Company’s redeemable convertible preferred stock then outstanding converted into an aggregate of 16,833,790 shares of common stock. Leases Effective January 1, 2020, the Company adopted ASU Leases (Topic 842), Leases At the inception of an arrangement, we determine whether the arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement. Operating leases are recognized on the balance sheet as right-of-use (“ROU”) lease assets, current portion of operating lease liability, and operating lease liability, net of current portion. We do not have financing leases. Operating lease liabilities and their corresponding ROU lease assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the ROU lease asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, we utilize our incremental borrowing rate to discount lease payments, which reflects the fixed rate at which we could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate our incremental borrowing rate, a credit rating applicable to us is estimated using a synthetic credit rating analysis since we do not currently have a rating agency-based credit rating. Prospectively, we will adjust the ROU lease assets for straight-line rent expense or any incentives received and remeasure the lease liability at the net present value using the same incremental borrowing rate that was in effect as of the lease commencement or transition date. We have elected not to recognize leases with an original term of one year or less on the balance sheet. We typically only include an initial lease term in our assessment of a lease arrangement. Options to renew a lease are not included in our assessment unless there is reasonable certainty that we will renew. Assumptions that we made at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. Lease modifications are accounted for as a separate contract or are treated as a change in accounting for the existing lease. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs include salaries and bonuses, stock-based compensation, employee benefits, consulting costs and external contract research and development and manufacturing expenses. Upfront payments and milestone payments made for the licensing of technology are expensed as research and development in the period in which they are incurred. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed. Research and Development Contract Costs and Accruals The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of discovery and preclinical studies, clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided and includes these costs in accrued liabilities in the balance sheets and within research and development expense in the statements of operations. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the research studies or clinical trials and manufacturing activities, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Stock-Based Compensation The Company measures all stock options and other stock-based awards to employees, directors and non-employees based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. The Company has mainly issued stock options with service-based vesting conditions and records the expense for these awards using the straight-line method. The Company has also issued stock options with performance-based vesting conditions and records the expense for these awards at the time that the achievement of the performance becomes highly probable or complete. The Company recognizes adjustments to stock-based compensation expense for forfeitures as they occur. The Company classifies stock-based compensation expense in its statements of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company had historically been a private company and lacks company-specific historical and implied volatility information. Therefore, expected stock volatility has been calculated based on the historical volatility of a publicly traded set of peer companies. The Company expects to continue to use such methodology until such time as it has adequate historical data regarding the volatility of its own publicly traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The fair value for each restricted common stock award is estimated on the date of grant based on the fair value of the Company’s common stock on that same date. Net Loss Per Share In July 2019, upon closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted to common stock. Prior to this conversion, the Company followed the two-class method when computing net income (loss) per share, as the Company had issued shares that met the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net income (loss) per share attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) attributable to common stockholders is computed by adjusting income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including outstanding stock options. Diluted net income (loss) per share attributable to common stockholders is computed by dividing the diluted net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of outstanding stock options. Prior to the IPO, the Company’s outstanding redeemable convertible preferred stock contractually entitled the holders of such shares to participate in distributions but contractually did not require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2020, 2019 and 2018. Comprehensive Income (Loss) Comprehensive income (loss) includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2020 and 2019, the Company’s only element of other comprehensive income (loss) was unrealized gains on available-for-sale investments. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Leases (Topic 842): Targeted Improvements Leases (Topic 842): Codification Improvements In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Revenue from Contracts with Customers In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, Net	Note 3. Property and Equipment, Net Property and equipment, net, consisted of the following (in thousands): December 31, 2020 2019 Computer equipment $ 229 $ 87 Leasehold improvements 154 115 Software 154 38 Furniture and fixtures 85 10 Office equipment 29 2 Total property and equipment 651 252 Less: accumulated depreciation (202 ) (57 ) Property and equipment, net $ 449 $ 195 Depreciation expense was $0.1 million for the year ended December 31, 2020 and less than $0.1 million for the years ended December 31, 2019 and 2018.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets and Accrued Expenses	12 Months Ended
	Dec. 31, 2020
Prepaid Expenses And Other Current Assets And Accrued Expenses [Abstract]
Prepaid Expenses and Other Current Assets and Accrued Expenses	Note 4. Prepaid Expenses and Other Current Assets and Accrued Expenses Prepaid expenses and other current assets consisted of the following (in thousands): December 31, 2020 2019 Prepaid research and development expenses $ 18,660 $ 694 Prepaid insurance 2,116 2,130 Other 1,088 485 Total prepaid expenses and other current assets $ 21,864 $ 3,309 Accrued expenses consisted of the following (in thousands): December 31, 2020 2019 Accrued payroll and related expenses $ 2,654 $ 1,823 Accrued research and development expenses 1,829 344 Professional fees 458 142 Other 203 44 Total accrued expenses $ 5,144 $ 2,353

Convertible Notes Payable

Convertible Notes Payable	12 Months Ended
	Dec. 31, 2020
Convertible Debt Disclosure [Abstract]
Convertible Notes Payable	Note 5. Convertible Notes Payable Wellcome Trust Convertible Notes In July 2015, the Company entered into a Company Funding Agreement with The Wellcome Trust, Limited (“Wellcome Trust”), pursuant to which the Company was eligible to receive $3.8 million in gross proceeds upon the achievement of specified milestones (the “2015 Convertible Note”). As of December 31, 2017, the Company had received the full amount of gross proceeds under the 2015 Convertible Note. In June 2018, the Company entered into a second Company Funding Agreement with Wellcome Trust to receive up to $8.0 million in gross proceeds from the issuance of a convertible note (the “2018 Convertible Note,” and together with the 2015 Convertible Note, the “Wellcome Trust Notes”). The Company received $ 2.0 million of proceeds in July 2018 , $ 2.7 million in November 2018, $ 1.6 million in March 2019, and $ 1.6 million in April 2019. The Wellcome Trust Notes have a stated interest rate of 2% per annum above the three-month Dollar LIBOR rate, which was not payable until settlement of the principal. The notes were subject to redemption upon written demand by Wellcome Trust any time after the fifth anniversary of the effective date. The principal due under the Wellcome Trust Notes was convertible into the class of the Company’s stock issued in the Company’s next qualified financing or upon event of default at a discounted conversion price between 0% and 25% of the purchase price per share of such securities issued. The accrued interest in such a circumstance would be forgiven. At inception of each the 2015 Convertible Note and 2018 Convertible Note, the Company concluded that the each contained a conversion option at a significant discount that was deemed to be an embedded derivative, which was required to be bifurcated and accounted for separately from the debt host. There were no debt issuance costs associated with the 2018 Convertible Note. The Company recognized the following changes in the debt related to the Wellcome Trust Notes during the years ended December 31, 2019 and 2018 (in thousands): Financial statement impacted Balance, December 31, 2017 $ 3,985 Issuance of 2018 Convertible Note 2,000 Balance sheet Accretion to settlement value 51 Statement of operations Accrued interest 102 Statement of operations Interest forgiven upon conversion (289 ) Statement of operations Conversion of Wellcome Trust Notes to redeemable convertible preferred stock (5,849 ) Balance sheet Balance, August 1, 2018 (date of conversion) — Issuance of 2018 Convertible Note 2,700 Balance sheet Allocation of proceeds to derivative liability (375 ) Balance sheet Accretion to settlement value 180 Statement of operations Accrued interest 11 Statement of operations Balance, December 31, 2018 2,516 Issuance of 2018 Convertible Note 3,128 Balance sheet Allocation of proceeds to derivative liability (750 ) Balance sheet Accretion to settlement value 945 Statement of operations Accrued interest 29 Statement of operations Interest forgiven upon conversion (40 ) Statement of operations Conversion of Wellcome Trust Notes to redeemable convertible preferred stock (5,828 ) Balance sheet Balance, December 31, 2019 $ — There were no debt issuances outstanding under the Wellcome Trust Notes as of December 31, 2019 or issued during the year ended December 31, 2020. Convertible Notes Since inception, and excluding the Wellcome Trust Notes, the Company has issued $14.0 million of convertible notes (the “Convertible Notes”), of which $13.5 million were issued to PureTech Health LLC (“PureTech Health”), a related party (see Note 13). During the year ended December 31, 2018, the Company issued Convertible Notes to PureTech Health with principal totaling $7.0 million. There were no debt issuance costs associated with the Convertible Notes. The Convertible Notes had a stated interest rate of 10% per annum which is not payable until the settlement of the principal. The notes matured upon written demand by the majority note holders. In the event of a default, the interest rate was 15% per annum. Principal and unpaid interest due under the notes convert on demand of a majority of note holders into the class of the Company’s stock issued in the Company’s next qualified financing at a conversion price between 0% to 25% discount off of the purchase price per share of such securities issued. The Company concluded that the Convertible Notes contained a conversion option at a significant premium that was deemed to be an embedded derivative, which is required to be bifurcated and accounted for separately from the debt host. In August 2018, the outstanding Convertible Notes were converted into Series A Preferred Stock. The Company recognized the following changes in the debt related to the Convertible Notes during the year ended December 31, 2018 (in thousands): Financial statement impacted Balance, December 31, 2017 $ 7,674 Issuance of new notes 7,000 Balance sheet Allocation of proceeds to derivative liability (1,418 ) Balance sheet Accretion to settlement value 1,945 Statement of operations Accrued interest 630 Statement of operations Interest forgiven upon conversion (47 ) Statement of operations Conversion of Convertible Notes to redeemable convertible preferred stock (15,784 ) Balance sheet Balance, December 31, 2018 $ — There were no debt issuances outstanding under the Convertible Notes as of December 31, 2018 or issued during the years ended December 31, 2020 and 2019.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	Note 6. Redeemable Convertible Preferred Stock Series Seed Redeemable Convertible Preferred Stock Between 2009 and 2011, the Company authorized and issued 4,412,500 shares of Series Seed Preferred Stock at an issuance price of $0.0001 per share, for total proceeds of less than $0.1 million. There were no issuance costs in connection with the Series Seed Preferred Stock issuance. Series A Redeemable Convertible Preferred Stock In August 2018, the Company authorized 3,126,700 shares of Series A Preferred Stock. The Company then issued 1,188,707 shares of Series A Preferred Stock at an issuance price of $13.46 per share resulting in gross proceeds of approximately $16.0 million. There were $0.1 million of issuance costs associated with the Series A Preferred Stock. In conjunction with the August 2018 issuance of Series A Preferred Stock, all outstanding principal and accrued interest under the Wellcome Trust Notes and Convertible Notes converted into 1,937,993 shares of Series A Preferred Stock. Series B Redeemable Convertible Preferred Stock In March 2019, the Company authorized 5,422,845 shares of Series B Preferred Stock. The Company then issued 4,953,758 shares of Series B Preferred Stock at an issuance price of $15.14 per share resulting in gross proceeds of approximately $75.0 million. There were $0.2 million of issuance costs associated with the Series B Preferred Stock. In conjunction with the March 2019 issuance of Series B Preferred Stock, all outstanding principal and accrued interest under the Wellcome Trust Notes converted into 331,344 shares of Series B Preferred Stock. In April 2019, the Company received an additional $1.6 million pursuant to the 2018 Convertible Note which was subsequently converted into 137,743 shares of Series B Preferred Stock. Upon closing of the Company’s IPO, the then-outstanding shares of the Series Seed, Series A and Series B redeemable convertible preferred stock converted into common stock. As of December 31, 2020 and 2019, there were no shares of redeemable convertible preferred stock authorized, issued or outstanding.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	Note 7. Stockholders’ Equity Preferred Stock On July 2, 2019, in connection with the closing of the Company’s IPO, the Company filed its restated Certificate of Incorporation, which authorizes the Company to issue up to 10,000,000 shares of preferred stock, $0.0001 par value per share. There were no shares of preferred stock outstanding as of December 31, 2020 or 2019. Common Stock As of December 31, 2020, the Company’s Certificate of Incorporation authorized the Company to issue 150,000,000 shares of common stock, $0.0001 par value per share. Holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. The holders of common stock shall be entitled to receive dividends out of funds legally available, as declared by the board of directors. These dividends are subject to the preferential dividend rights of the holders of the Company’s preferred stock. Through December 31, 2020, no cash dividends have been declared or paid. Upon completion of the Company’s IPO on July 2, 2019, all outstanding shares of Series Seed, Series A, and Series B redeemable convertible preferred stock converted to common stock. As of December 31, 2020, there were 26,988,458 shares of common stock outstanding.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share	Note 8. Net Loss per Share Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share of common stock for the years ended December 31, 2020, 2019 and 2018 (in thousands, except share and per share data): Year Ended December 31, 2020 2019 2018 Net Loss $ (68,554 ) $ (43,957 ) $ (17,512 ) Weighted-average shares used in computing net loss per share 26,446,006 11,958,152 4 Net loss per share, basic and diluted $ (2.59 ) $ (3.68 ) $ (4,378,000 ) The Company’s potentially dilutive securities, which include stock options and convertible preferred stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. Prior to the IPO, the Company’s outstanding shares of preferred stock contractually entitled the holders of such shares to participate in distributions but contractually did not require the holders of such shares to participate in losses of the Company. Accordingly, these shares have not been included in the denominator used to calculate net loss per share. Common Stock Equivalents The following common stock equivalents presented based on amounts outstanding at each period end, have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact: December 31, 2020 2019 2018 Redeemable convertible preferred stock (as converted to common stock) — — 9,791,151 Stock options to purchase common stock 4,612,790 4,614,544 2,310,369 Warrants to purchase common stock — — 19,986 4,612,790 4,614,544 12,121,506

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	Note 9. Stock-based Compensation Stock Options In September 2009, the Company’s board of directors approved the 2009 Stock Incentive Plan (the “2009 Plan”) which provided for the grant of incentive In May 2019, the board of directors approved the 2019 Stock Option and Incentive Plan (the “2019 Plan”) which became effective on June 26, 2019, the date immediately prior to the date on which the registration statement related to the IPO was declared effective by the SEC. The 2019 Plan will expire in May 2029. Under the 2019 Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards, RSUs and other stock-based awards. There were 1,709,832 shares of the Company’s common stock initially reserved for issuance under the 2019 Plan. The number of shares of common stock underlying awards that expire, or are terminated, surrendered, canceled or forfeited without having been fully exercised under the 2009 Plan will be added to the shares of common stock available for issuance under the 2019 Plan. In addition, the number of shares available for issuance automatically increases on January 1 of each calendar year, commencing on January 1, 2020, by 4% of the number of shares of common stock outstanding on the immediately preceding December 31 or such lesser amount determined by the Company’s board of directors or the compensation committee of the board of directors. As of December 31, 2020, there were 934,730 common shares available for issuance and 1,951,974 options outstanding under the 2019 Plan. Options under the 2019 Plan generally vest based on the grantee’s continued service with the Company during a specified period following a grant as determined by the board of directors and expire ten years from the grant date. In general, awards typically vest in four years, but vesting conditions can vary based on the discretion of the Company’s board of directors. A summary of the Company’s stock option activity and related information is as follows: Number of Shares Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2019 4,614,544 $ 8.94 8.3 $ 306,395 Granted 1,029,950 93.33 Exercised (975,704 ) 4.20 Forfeited (56,000 ) 21.77 Outstanding as of December 31, 2020 4,612,790 $ 28.63 8.3 $ 336,740 Options vested and expected to vest as of December 31, 2020 4,612,790 $ 28.63 8.3 $ 336,740 Options exercisable as of December 31, 2020 2,858,905 $ 10.48 7.9 $ 260,485 The aggregate intrinsic values of options outstanding, exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the publicly traded stock price of the Company’s common stock as of December 31, 2020. As of December 31, 2020, there was $46.1 million of unrecognized compensation cost, which is expected to be recognized over a weighted-average period of 3.04 years. The fair value of all option activity was estimated at the date of grant using the Black-Scholes model with the following assumptions: Year Ended December 31, 2020 2019 2018 Fair value of options $ 35.17 - 59.72 $ 3.84 - 8.05 $ 4.49 - 5.49 Fair value of common stock $ 62.14 - 106.46 $ 9.20 - 20.02 $ 9.14 - 9.44 Expected term (in years) 5.50 - 7.00 5.02 - 6.16 5.65 - 9.34 Expected volatility 55.73% - 61.28% 43.54% - 48.22% 45.57% - 48.84% Risk-free interest rate 0.35% - 1.49% 1.59% - 2.44% 2.69% - 3.04% Expected dividend yield 0.00% 0.00% 0.00% On May 16, 2019, the Company issued 105,163 fully vested restricted common stock units. The average grant date fair value was $10.97 per share. As of December 31, 2020 and 2019, there was no unrecognized compensation expense related to unvested RSUs. Warrants In October 2016, PureTech Health, a related party, agreed to provide management services to the Company in exchange for a warrant to purchase up to 19,998 shares of the Company’s common stock. The warrant vested monthly as services were performed over a 24-month period and had a purchase price of $2.92 per share. The total expense for the year ended December 31, 2018 for the warrant was less than $0.1 million, and no expense was recognized in the years ended December 31, 2020 and 2019, as the warrant was fully vested as of October 2018. There was no unrecognized compensation cost related to the warrants as of December 31, 2020, 2019 and 2018. In August 2018, PureTech Health partially exercised the warrant to purchase 12 shares of the Company’s common stock, resulting in a nominal amount of proceeds to the Company. In March 2019, PureTech Health exercised the remaining portion of the warrant to purchase 19,986 shares of the Company’s common stock, resulting in proceeds to the Company of $ 0.1 million. There we re no outstanding warrants as of December 31, 2020 or 2019 . Stock-based Compensation Expense Stock-based compensation expense is classified in the statements of operations for the years ended December 31, 2020, 2019 and 2018 as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 3,767 $ 580 $ 107 General and administrative 9,704 11,988 851 Total stock-based compensation expense $ 13,471 $ 12,568 $ 958

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	12 Months Ended
	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Abstract]
Fair Value of Financial Assets and Liabilities	Note 10. Fair Value of Financial Assets and Liabilities The following table presents information about the Company’s assets as of December 31, 2020 and 2019 that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurement at December 31, 2020 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 50,141 $ — $ — $ 50,141 Investment securities: US Treasuries 172,295 — — 172,295 Corporate debt securities — 36,817 — 36,817 Commercial paper — 60,170 — 60,170 Total $ 222,436 $ 96,987 $ — $ 319,423 Fair Value Measurement at December 31, 2019 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 197,303 $ — $ — $ 197,303 Investment securities: US Treasuries 180,468 — — 180,468 Total $ 377,771 $ — $ — $ 377,771 The fair values of the Company’s commercial paper and corporate debt securities are based on prices obtained from independent pricing sources. Securities with validated quotes from pricing services are reflected within Level 2, as they are primarily based on observable pricing for similar assets or other market observable inputs. Typical inputs used by these pricing services include, but are not limited to, reported trades, benchmark yields, issuer spreads, bids, offers or estimates of cash flow, prepayment spreads and default rates. The Company does not hold any securities classified as Level 3, which are securities valued using unobservable inputs. The Company has not transferred any investment securities between the classification levels. The estimated fair value and amortized cost of the Company’s available-for-sale investments, by contractual maturity and security type, are summarized as follows (in thousands): December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value US Treasuries (due within one year) $ 172,265 $ 37 $ (7 ) $ 172,295 Corporate debt securities (due within one year) 36,823 3 (9 ) 36,817 Commercial paper (due within one year) 60,155 16 (1 ) 60,170 Total $ 269,243 $ 56 $ (17 ) $ 269,282 December 31, 2019 Amortized Cost Unrealized Gains Unrealized Losses Fair Value US Treasuries (due within one year) $ 180,463 $ 5 $ — $ 180,468 Total $ 180,463 $ 5 $ — $ 180,468 The Company classifies all of its available-for-sale investment securities, including those with maturities beyond one year, as current assets on its consolidated balance sheets based on the highly liquid nature of the investment securities and because these investment securities are considered available for use in current operations. As described under Recently Adopted Accounting Pronouncements (see Note 2) the Company adopted FASB ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) Unrealized losses on available-for-sale securities presented in the previous table have not been recognized in the consolidated statements of operations because the securities are high credit quality, investment grade securities that the Company does not intend to sell and will not be required to sell prior to their anticipated recovery, and the decline in fair value is attributable to factors other than credit losses. Based on its evaluation, the Company determined its year-to-date credit losses related to its available-for-sale securities were immaterial at December 31, 2020. The derivative liability was considered a Level 3 liability because its fair value measurement was based, in part, on significant inputs not observed in the market. The Company recognized the following changes in the fair value of derivative liabilities during the years ended December 31, 2019 and 2018 (in thousands): Balance, December 31, 2017 $ 2,606 Allocation of note issuance proceeds to derivative 1,418 Change in fair value of derivative 430 Conversion of convertible debt to Series A preferred stock (4,454 ) Balance, August 1, 2018 (date of conversion) — Allocation of note issuance proceeds to derivative 375 Change in fair value of derivative 14 Balance, December 31, 2018 389 Allocation of note issuance proceeds to derivative 750 Change in fair value of derivative 135 Conversion of convertible debt to Series B preferred stock (1,274 ) Balance, December 31, 2019 $ — There was no derivative liability recorded as of December 31, 2020 or 2019.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 11. Commitments and Contingencies Leases The Company entered into an agreement to lease approximately 7,050 square feet of office space in Boston, Massachusetts (“Original Premises”) that began in December 2018 and had an original expiry in February 2023. In January 2020, the Company entered into an amended agreement (“Amended Lease Agreement”) to gain access to approximately 4,175 square feet of additional office space (“Expansion Premises”) beginning in March 2020, and to extend the maturity of the agreement for the Original Premises to December 2023. The Amended Lease Agreement provides for future minimum annual rental payments as defined within the agreement. Under the terms of the amended agreement, the Company is required to maintain a cash balance of approximately $0.2 million to secure a letter of credit associated with this lease. The amount was classified as restricted cash in the consolidated balance sheets as of December 31, 2020 and 2019. The Amended Lease Agreement also provides for approximately $0.1 million in leasehold incentives which may be applied to base rent or improvements to the Expansion Premises, subject to limitations. The Company determined the Amended Lease Agreement represented a lease modification, and the Original Premises and Expansion Premises were identified as separate lease components. The extension of maturity with respect to the Original Premises was treated as a modification not accounted for as a separate contract, in which the lease classification was reassessed and the lease liability was remeasured. The effect of the remeasurement, in the amount of $0.4 million, was recorded as an adjustment to the right-of-use asset as of February 1, 2020, the effective date of the modification. The addition of the Expansion Premises was accounted for as a separate contract which granted the Company an additional right of use not included in the original lease, in which the lease payments increased commensurate with the standalone price for the additional right of use. As the leasehold incentives were not paid or payable at commencement, the Company will account for the incentives once the contingency is resolved. In February 2020, the Company entered into an agreement to lease approximately 5,050 square feet of office space, and furniture within the office space, in Carmel, Indiana (“Indiana Lease Agreement”), which began in June 2020 and expires in July 2023, with the option to renew for an additional three-year term. In addition, the agreement provides an option to purchase the office furniture at the expiration of the agreement. The office space and office furniture within the Indiana Lease Agreement were each determined to represent separate lease components. Consideration for the contract was allocated to each lease component based on their relative stand-alone selling price. The options to renew the lease for an additional three-year term as well as purchase the office furniture at the expiration of the agreement were excluded from the determination of lease liabilities arising from obtaining the ROU assets, as they were not considered probable of being exercised at commencement. For each of the lease agreements entered into or modified, the Company identified certain non-lease components. Lease and non-lease components were combined into a single lease component. In addition, all identified leases were assessed as operating leases. As the Company’s leases do not provide an implicit rate, the Company used its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a term equal to the lease payments in a similar economic environment in determining the present value of lease payments for each identified lease at the lease commencement date. In addition to the lease liabilities arising from ROU assets recognized upon adoption of ASC 842, Leases The components of lease cost were as follows (dollar amounts in thousands): Year Ended December 31, 2020 2019 2018 Lease Cost Operating lease cost $ 791 $ 441 $ 37 Short-term lease cost — — — Total lease cost $ 791 $ 441 $ 37 As the Company adopted ASC 842 effective January 1, 2020, prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historic accounting under Topic 840. Year Ended December 31, 2020 Other Information Cash paid for amounts included in the measurement of lease liabilities $ 733 Operating lease liabilities arising from obtaining right-of-use assets $ 3,259 Weighted-average remaining lease term 2.94 years Weighted-average discount rate 6.21 % The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities and a reconciliation to present value of lease liabilities as of December 31, 2020 (in thousands): Year ended: December 31, 2021 982 December 31, 2022 1,001 December 31, 2023 949 Total future minimum lease payments 2,932 Less imputed interest (246 ) Present value of lease liabilities $ 2,686 Future minimum lease payments under non-cancelable operating lease agreements as of December 31, 2019 (under ASC 840, prior to the adoption of ASC 842 effective January 1, 2020), were as follows (in thousands): Year ended: December 31, 2020 $ 499 December 31, 2021 506 December 31, 2022 514 December 31, 2023 86 December 31, 2024 and thereafter — $ 1,605 Intellectual Property License with Eli Lilly and Company In May 2012, the Company entered into an exclusive license agreement (the “Lilly License Agreement”) with Eli Lilly, pursuant to which Eli Lilly assigned to the Company all of its rights to certain patents (now expired), regulatory documentation, data records and materials related to xanomeline. The Company is also entitled to sublicense or otherwise transfer the rights granted in connection with the Lilly License Agreement. Under the Lilly License Agreement, the Company is obligated to use commercially reasonable efforts to develop, manufacture, commercialize and seek and maintain regulatory approval for xanomeline, in any formulation, for use in humans. The Company paid Eli Lilly an upfront payment of $0.1 million and has agreed to make milestone payments to Eli Lilly of up to an aggregate of $16 million upon the achievement of specified regulatory milestones and up to an aggregate of $54 million in commercial milestones. In addition, the Company is obligated to pay Eli Lilly tiered royalties, at rates in the low to mid single-digit percentages, on the worldwide net sales of any commercialized product on a country-by-country basis until the expiration of the applicable royalty term, which is the longer of six years from the date of first commercial sale of each licensed product within a country or data exclusivity in such country. During the royalty term, Eli Lilly is prohibited from granting any third-party rights to the patents, regulatory documentation, data records and materials that have been licensed to the Company under the Lilly License Agreement. The Lilly License Agreement will expire on the later of (i) the expiration of the last-to-expire royalty term on a licensed product-by-licensed product basis or (ii) the date on which the Company has made all milestone payments pursuant to the terms of the Lilly License Agreement, unless terminated earlier by the parties. In no event will the term of the Lilly License Agreement exceed 15 years past the anniversary of the first commercial sale of a xanomeline product. The Company may terminate the Lilly License Agreement for any reason with proper prior notice to Eli Lilly. Either party may terminate the Lilly License Agreement upon an uncured material breach by the other party. The initial upfront payment of $0.1 million was expensed when incurred in May 2012. As of December 31, 2020, no milestones have been reached, and accordingly, no milestone payments have been made. Intellectual Property License with PureTech Health In March 2011, the Company entered into an exclusive license agreement (the “Patent License Agreement”) with PureTech Health, pursuant to which PureTech Health granted the Company an exclusive license to patent rights relating to combinations of a muscarinic activator with a muscarinic inhibitor for the treatment of central nervous system disorders. In connection with the Patent License Agreement, the Company has agreed to make milestone payments to PureTech Health of up to an aggregate of $10 million upon the achievement of specified development and regulatory milestones. In addition, the Company is obligated to pay PureTech Health low single-digit royalties on the worldwide net sales of any commercialized product covered by the licenses granted under the Patent License Agreement. In the event that the Company sublicenses any of the patent rights granted under the Patent License Agreement, the Company will be obligated to pay PureTech Health royalties within the range of 15% to 25% on any income we receive from the sublicensee, excluding royalties. The Company may terminate the Patent License Agreement for any reason with proper prior notice to PureTech Health. Either party may terminate the Patent License Agreement upon an uncured material breach by the other party. In December 2020, the Company paid $2.0 million to PureTech Health, having reached the milestone of Phase 3 clinical trial commencement. The Company incurred no expenses related to the Patent License provided by PureTech Health during the years ended December 31, 2019 and 2018. The Company had no outstanding liabilities to PureTech Health related to the Patent License at December 31, 2020 or 2019. Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may incur charges in the future as a result of these indemnification obligations. Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. Litigation The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities as of December 31, 2020.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 12. Income Taxes During the years ended December 31, 2020, 2019 and 2018, the Company recorded income tax benefit (expense) of less than $(0.1) million, $0, and $0, respectively. The Company did not recognize any significant tax expense for the years ended December 31, 2020, 2019, or 2018 as the Company was subject to a full valuation allowance. A reconciliation of the differences between the effective tax rates of the Company and the U.S. federal statutory tax rate are as follows: Year Ended December 31, 2020 2019 2018 Statutory tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 10.3 % 6.7 % 5.0 % Share-based compensation 21.3 % 0.0 % -1.0 % Change in derivative liability 0.0 % -0.1 % -0.5 % Non-deductible interest expense 0.0 % -0.4 % -3.1 % Other -0.1 % 0.3 % 0.0 % Tax credits 3.2 % 4.9 % 3.0 % Change in valuation allowance -55.7 % -32.4 % -24.4 % Effective Income tax rate 0.0 % 0.0 % 0.0 % Significant components of the Company’s deferred tax assets and liabilities at December 31, 2020 and 2019 are as follows: December 31, 2020 2019 Deferred tax assets: Operating tax losses $ 47,349 $ 14,145 Tax Credit Carryforwards 5,613 3,028 Fixed Assets — — Accrued expenses 631 580 Lease liability 702 — Share-based compensation 5,923 3,613 Deferred tax assets 60,218 21,366 Valuation allowance (59,563 ) (21,339 ) Deferred tax liabilities: ROU assets (633 ) — Depreciation (22 ) (27 ) Deferred tax liabilities (655 ) (27 ) Net Deferred Tax Asset / (Liability) $ — $ — Deferred income taxes reflect the net tax effect of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amount used for income tax purposes. The Company applied the separate return method for allocation of current and deferred tax expense. As of August 1, 2018, PureTech no longer held 80% of the outstanding shares of the Company. Therefore, from that date onward, the Company was required to file a separate U.S. federal income tax return. As of July 2, 2019, PureTech no longer held 50% of the outstanding shares of the Company. As such, we have filed separate state income tax returns subsequent to this date. At December 31, 2020, on a separate return method, the Company has federal net operating loss carryforwards totaling $179.8 million of which $9.7 million begin to expire in 2029 and $170.1 million can be carried forward indefinitely. In addition, we had state net operating loss carryforwards totaling $151.7 million which begin to expire in 2030 ur net operating loss and tax credit carryforwards could, in whole or in part, expire unused and be unavailable to offset future income tax liabilities. Management has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are comprised principally of net operating loss carryforwards and tax credit carryforwards. Under the applicable accounting standards, management has considered the Company's history of losses and concluded that it is more likely than not that the Company will not recognize the benefits of deferred tax assets. Accordingly, a full valuation allowance has been established against the net deferred tax assets at December 31, 2020. The valuation allowance increased by $38.2 million during the year ended December 31, 2020 which primarily relates to the current year operating loss and tax credits generated. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year On March 27, 2020, the Coronavirus Aid, Relief and Economic Security (“CARES”) Act was enacted and signed into law. Among other things, the CARES Act allows for a five-year The Company accounts for uncertain tax positions pursuant to ASC 740 which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. As of December 31, 2020, the Company has not recorded any unrecognized tax benefits. The Company does not expect any material change in unrecognized tax benefits within the next twelve months. The Company’s policy is to record interest and penalties as a component of income tax expense. As of December 31, 2020, the Company has not accrued interest or penalties related to any uncertain tax positions. We are subject to taxation in the United States federal and certain state jurisdictions. The Company has incurred operating losses since inception, and therefore, the losses in all periods may be adjusted by taxing jurisdictions in future periods in which they are utilized.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Note 13. Related Party Transactions PureTech Health Management Consulting Services and Overhead Agreement The Company previously engaged PureTech Health, a related party, to provide, among other things, management expertise, strategic advice, administrative support, computer and telecommunications services and office infrastructure. In exchange for providing such services, the Company paid PureTech Health a monthly fee. In addition, PureTech Health periodically invoiced the Company for out-of-pocket expenses reasonably incurred in connection with providing such business services. The Company incurred general and administrative costs for management services provided by PureTech Health totaling less than $0.1 million and $0.2 million in the years ended December 31, 2019 and 2018, respectively. The Company had outstanding current liabilities to PureTech Health of less than $0.1 million at December 31, 2019, which were recorded as accounts payable in the consolidated balance sheets. As of and for the year ended December 31, 2020, the Company had no outstanding liabilities to PureTech Health and no general and administrative costs for management services were incurred.

401(k) Savings Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
401(k) Savings Plan	Note 14. 401(k) Savings Plan The Company has a 401(k) retirement plan in which substantially all U.S. employees are eligible to participate. Eligible employees may elect to contribute up to the maximum limits, as set by the Internal Revenue Service, of their eligible compensation. The total contribution expense for the Company was $0.2 million for the year ended December 31, 2020 and less than $0.1 million for each of the years ended December 31, 2019 and 2018.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The accompanying consolidated The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated The consolidated financial statements include the accounts of Karuna Therapeutics, Inc. and its wholly owned subsidiary, Karuna Securities Corporation. All inter-company transactions and balances have been eliminated in consolidation.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all short-term, highly liquid investments with maturities of 90 days or less at acquisition date to be cash equivalents.
Investment Securities	Investment Securities The Company’s investment securities are classified as available-for-sale and are carried at fair value with the unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. The cost of investment securities classified as available-for-sale is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. Realized gains and losses are included as a component of other income (expense), net based on the specific identification method. When the fair value of an available-for-sale debt security falls below the amortized cost basis it is evaluated to determine if any of the decline in value is attributable to credit loss. Decreases in fair value attributable to credit loss are recorded directly to earnings with a corresponding allowance for credit losses, limited to the amount that the fair value is less than the amortized cost basis. If the credit quality subsequently improves the allowance is reversed up to a maximum of the previously recorded credit losses. When the Company intends to sell an impaired available-for-sale debt security, or if it is more likely than not that the Company will be required to sell the security prior to recovering the amortized cost basis, the entire fair value adjustment will immediately be recognized in earnings with no corresponding allowance for credit losses.
Concentration of Manufacturing Risk	Concentration of Manufacturing Risk The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statement of operations. Deferred offering costs were approximately $0.4 million as of December 31, 2020. As of December 31, 2019 and 2018, there were no deferred offering costs outstanding. All deferred offering costs accumulated during 2019 and associated with the Company’s IPO and secondary public offering were recorded as a reduction of additional paid-in capital upon the close of the Company’s public offerings on July 2, 2019 and November 25, 2019, respectively.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments consist of cash equivalents, investment securities, accounts payable, accrued expenses, convertible notes and derivatives embedded within the convertible notes. The carrying amount of accounts payable, accrued expenses and convertible notes are considered a reasonable estimate of their fair value, due to the short-term maturity of these instruments. The Company’s cash equivalents, investment securities and derivative liabilities are carried at fair value, determined according to the fair value hierarchy described below (see Note 10). The Company follows the guidance in FASB ASC 820, Fair Value Measurements and Disclosures Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2: Valuations based on quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Fair value is a market-based measure considered from the perspective of a market participant rather than an entity-specific measure. Therefore, even when market assumptions are not readily available, the Company’s own assumptions reflect those that market participants would use in pricing the asset or liability at the measurement date. The Company uses prices and inputs that are current as of the measurement date, including during periods of market dislocation. In periods of market dislocation, the observability of prices and inputs may be reduced for many instruments. This condition could cause an instrument to be reclassified from Level 1 to Level 2 or Level 2 to Level 3.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight-line method. Leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the lease by use of the straight-line method. Maintenance and repair costs are expensed as incurred. When assets are retired or sold, the assets and accumulated depreciation are removed from the respective accounts and any gain or loss is recognized.
Convertible Notes and Derivative Liabilities	Convertible Notes and Derivative Liabilities In connection with the issuance of the Wellcome Trust Convertible Notes and the Convertible Notes (see Note 5), the Company had identified embedded derivatives, which were recorded as liabilities on the Company’s balance sheet and were remeasured to fair value at each reporting date until the derivative was settled. Changes in the fair value of the derivative liabilities were recognized as change in fair value of derivative in the statements of operations. The fair value of the derivative liabilities were determined at each period end using a with and without method, which assesses the likelihood and timing of events that would result in either a conversion or change-of-control feature being triggered, as well as changes in the market conditions. Upon issuance of the notes, each note was recorded at cost, net of the derivative liability. The discount on each note was amortized as interest expense to the date such note was expected to convert using the effective interest rate method and was reflected in the statements of operations as accretion of debt discount. The Company classified its derivative liabilities in the balance sheet as current or non-current based on its expectation of when the derivative will be settled, consistent with the assumptions used when determining the fair value of the derivative liabilities. In 2019, all notes were converted into redeemable convertible preferred stock and the associated derivative liabilities were settled in connection with the Company’s issuance of Series B redeemable convertible preferred stock. There were no convertible notes or derivative liabilities outstanding as of December 31, 2020 and 2019.
Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock Prior to the IPO, the Company recorded all shares of redeemable convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The redeemable convertible preferred stock was recorded outside of permanent equity because upon the occurrence of certain deemed liquidation events, the majority of the holders could opt to redeem the shares at the liquidation preference and these events, including a merger, acquisition or sale of substantially all of the assets, was considered not solely within the Company’s control. Prior to the IPO, the Company had not adjusted the carrying values of the redeemable convertible preferred stock to its redemption value because it was uncertain whether or when a deemed liquidation event would occur. Upon closing of the IPO, all 12,962,045 shares of the Company’s redeemable convertible preferred stock then outstanding converted into an aggregate of 16,833,790 shares of common stock.
Leases	Leases Effective January 1, 2020, the Company adopted ASU Leases (Topic 842), Leases At the inception of an arrangement, we determine whether the arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement. Operating leases are recognized on the balance sheet as right-of-use (“ROU”) lease assets, current portion of operating lease liability, and operating lease liability, net of current portion. We do not have financing leases. Operating lease liabilities and their corresponding ROU lease assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the ROU lease asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, we utilize our incremental borrowing rate to discount lease payments, which reflects the fixed rate at which we could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate our incremental borrowing rate, a credit rating applicable to us is estimated using a synthetic credit rating analysis since we do not currently have a rating agency-based credit rating. Prospectively, we will adjust the ROU lease assets for straight-line rent expense or any incentives received and remeasure the lease liability at the net present value using the same incremental borrowing rate that was in effect as of the lease commencement or transition date. We have elected not to recognize leases with an original term of one year or less on the balance sheet. We typically only include an initial lease term in our assessment of a lease arrangement. Options to renew a lease are not included in our assessment unless there is reasonable certainty that we will renew. Assumptions that we made at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. Lease modifications are accounted for as a separate contract or are treated as a change in accounting for the existing lease. A lease modification results in a separate contract when the modification grants the lessee an additional right of use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right of use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs include salaries and bonuses, stock-based compensation, employee benefits, consulting costs and external contract research and development and manufacturing expenses. Upfront payments and milestone payments made for the licensing of technology are expensed as research and development in the period in which they are incurred. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed.
Research and Development Contract Costs and Accruals	Research and Development Contract Costs and Accruals The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of discovery and preclinical studies, clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided and includes these costs in accrued liabilities in the balance sheets and within research and development expense in the statements of operations. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the research studies or clinical trials and manufacturing activities, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.
Share-Based Compensation	Stock-Based Compensation The Company measures all stock options and other stock-based awards to employees, directors and non-employees based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. The Company has mainly issued stock options with service-based vesting conditions and records the expense for these awards using the straight-line method. The Company has also issued stock options with performance-based vesting conditions and records the expense for these awards at the time that the achievement of the performance becomes highly probable or complete. The Company recognizes adjustments to stock-based compensation expense for forfeitures as they occur. The Company classifies stock-based compensation expense in its statements of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company had historically been a private company and lacks company-specific historical and implied volatility information. Therefore, expected stock volatility has been calculated based on the historical volatility of a publicly traded set of peer companies. The Company expects to continue to use such methodology until such time as it has adequate historical data regarding the volatility of its own publicly traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The fair value for each restricted common stock award is estimated on the date of grant based on the fair value of the Company’s common stock on that same date.
Net Loss Per Share	Net Loss Per Share In July 2019, upon closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted to common stock. Prior to this conversion, the Company followed the two-class method when computing net income (loss) per share, as the Company had issued shares that met the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net income (loss) per share attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) attributable to common stockholders is computed by adjusting income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including outstanding stock options. Diluted net income (loss) per share attributable to common stockholders is computed by dividing the diluted net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of outstanding stock options. Prior to the IPO, the Company’s outstanding redeemable convertible preferred stock contractually entitled the holders of such shares to participate in distributions but contractually did not require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2020, 2019 and 2018.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2020 and 2019, the Company’s only element of other comprehensive income (loss) was unrealized gains on available-for-sale investments.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) Leases (Topic 842): Targeted Improvements Leases (Topic 842): Codification Improvements In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Revenue from Contracts with Customers In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment	Property and equipment, net, consisted of the following (in thousands): December 31, 2020 2019 Computer equipment $ 229 $ 87 Leasehold improvements 154 115 Software 154 38 Furniture and fixtures 85 10 Office equipment 29 2 Total property and equipment 651 252 Less: accumulated depreciation (202 ) (57 ) Property and equipment, net $ 449 $ 195

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Prepaid Expenses And Other Current Assets And Accrued Expenses [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): December 31, 2020 2019 Prepaid research and development expenses $ 18,660 $ 694 Prepaid insurance 2,116 2,130 Other 1,088 485 Total prepaid expenses and other current assets $ 21,864 $ 3,309
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): December 31, 2020 2019 Accrued payroll and related expenses $ 2,654 $ 1,823 Accrued research and development expenses 1,829 344 Professional fees 458 142 Other 203 44 Total accrued expenses $ 5,144 $ 2,353

Convertible Notes Payable (Tabl

Convertible Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2020
Convertible Notes Payable [Line Items]
Schedule of Changes in Convertible Debt	The Company recognized the following changes in the debt related to the Convertible Notes during the year ended December 31, 2018 (in thousands): Financial statement impacted Balance, December 31, 2017 $ 7,674 Issuance of new notes 7,000 Balance sheet Allocation of proceeds to derivative liability (1,418 ) Balance sheet Accretion to settlement value 1,945 Statement of operations Accrued interest 630 Statement of operations Interest forgiven upon conversion (47 ) Statement of operations Conversion of Convertible Notes to redeemable convertible preferred stock (15,784 ) Balance sheet Balance, December 31, 2018 $ —
Wellcome Trust Notes
Convertible Notes Payable [Line Items]
Schedule of Changes in Convertible Debt	The Company recognized the following changes in the debt related to the Wellcome Trust Notes during the years ended December 31, 2019 and 2018 (in thousands): Financial statement impacted Balance, December 31, 2017 $ 3,985 Issuance of 2018 Convertible Note 2,000 Balance sheet Accretion to settlement value 51 Statement of operations Accrued interest 102 Statement of operations Interest forgiven upon conversion (289 ) Statement of operations Conversion of Wellcome Trust Notes to redeemable convertible preferred stock (5,849 ) Balance sheet Balance, August 1, 2018 (date of conversion) — Issuance of 2018 Convertible Note 2,700 Balance sheet Allocation of proceeds to derivative liability (375 ) Balance sheet Accretion to settlement value 180 Statement of operations Accrued interest 11 Statement of operations Balance, December 31, 2018 2,516 Issuance of 2018 Convertible Note 3,128 Balance sheet Allocation of proceeds to derivative liability (750 ) Balance sheet Accretion to settlement value 945 Statement of operations Accrued interest 29 Statement of operations Interest forgiven upon conversion (40 ) Statement of operations Conversion of Wellcome Trust Notes to redeemable convertible preferred stock (5,828 ) Balance sheet Balance, December 31, 2019 $ —

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Share of Common Stock	The following table sets forth the computation of basic and diluted net loss per share of common stock for the years ended December 31, 2020, 2019 and 2018 (in thousands, except share and per share data): Year Ended December 31, 2020 2019 2018 Net Loss $ (68,554 ) $ (43,957 ) $ (17,512 ) Weighted-average shares used in computing net loss per share 26,446,006 11,958,152 4 Net loss per share, basic and diluted $ (2.59 ) $ (3.68 ) $ (4,378,000 )
Schedule of Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following common stock equivalents presented based on amounts outstanding at each period end, have been excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact: December 31, 2020 2019 2018 Redeemable convertible preferred stock (as converted to common stock) — — 9,791,151 Stock options to purchase common stock 4,612,790 4,614,544 2,310,369 Warrants to purchase common stock — — 19,986 4,612,790 4,614,544 12,121,506

Stock-based Compensation (Tabl

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	A summary of the Company’s stock option activity and related information is as follows: Number of Shares Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2019 4,614,544 $ 8.94 8.3 $ 306,395 Granted 1,029,950 93.33 Exercised (975,704 ) 4.20 Forfeited (56,000 ) 21.77 Outstanding as of December 31, 2020 4,612,790 $ 28.63 8.3 $ 336,740 Options vested and expected to vest as of December 31, 2020 4,612,790 $ 28.63 8.3 $ 336,740 Options exercisable as of December 31, 2020 2,858,905 $ 10.48 7.9 $ 260,485
Summary of Fair Value of Option Activity Estimated at Date of Grant Using Black-Scholes Model	The fair value of all option activity was estimated at the date of grant using the Black-Scholes model with the following assumptions: Year Ended December 31, 2020 2019 2018 Fair value of options $ 35.17 - 59.72 $ 3.84 - 8.05 $ 4.49 - 5.49 Fair value of common stock $ 62.14 - 106.46 $ 9.20 - 20.02 $ 9.14 - 9.44 Expected term (in years) 5.50 - 7.00 5.02 - 6.16 5.65 - 9.34 Expected volatility 55.73% - 61.28% 43.54% - 48.22% 45.57% - 48.84% Risk-free interest rate 0.35% - 1.49% 1.59% - 2.44% 2.69% - 3.04% Expected dividend yield 0.00% 0.00% 0.00%
Summary of Stock-based Compensation Expense	Stock-based compensation expense is classified in the statements of operations for the years ended December 31, 2020, 2019 and 2018 as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 3,767 $ 580 $ 107 General and administrative 9,704 11,988 851 Total stock-based compensation expense $ 13,471 $ 12,568 $ 958

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Abstract]
Schedule of Fair Value Measurement on Recurring Basis and Indicates the level of Fair Value Hierarchy Utilized	The following table presents information about the Company’s assets as of December 31, 2020 and 2019 that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurement at December 31, 2020 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 50,141 $ — $ — $ 50,141 Investment securities: US Treasuries 172,295 — — 172,295 Corporate debt securities — 36,817 — 36,817 Commercial paper — 60,170 — 60,170 Total $ 222,436 $ 96,987 $ — $ 319,423 Fair Value Measurement at December 31, 2019 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 197,303 $ — $ — $ 197,303 Investment securities: US Treasuries 180,468 — — 180,468 Total $ 377,771 $ — $ — $ 377,771
Summary of Estimated Fair Value and Amortized Cost of Available-for-Sale Investments by Contractual Maturity	The estimated fair value and amortized cost of the Company’s available-for-sale investments, by contractual maturity and security type, are summarized as follows (in thousands): December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value US Treasuries (due within one year) $ 172,265 $ 37 $ (7 ) $ 172,295 Corporate debt securities (due within one year) 36,823 3 (9 ) 36,817 Commercial paper (due within one year) 60,155 16 (1 ) 60,170 Total $ 269,243 $ 56 $ (17 ) $ 269,282 December 31, 2019 Amortized Cost Unrealized Gains Unrealized Losses Fair Value US Treasuries (due within one year) $ 180,463 $ 5 $ — $ 180,468 Total $ 180,463 $ 5 $ — $ 180,468
Schedule of Changes in Fair Value Derivative Liabilities	The derivative liability was considered a Level 3 liability because its fair value measurement was based, in part, on significant inputs not observed in the market. The Company recognized the following changes in the fair value of derivative liabilities during the years ended December 31, 2019 and 2018 (in thousands): Balance, December 31, 2017 $ 2,606 Allocation of note issuance proceeds to derivative 1,418 Change in fair value of derivative 430 Conversion of convertible debt to Series A preferred stock (4,454 ) Balance, August 1, 2018 (date of conversion) — Allocation of note issuance proceeds to derivative 375 Change in fair value of derivative 14 Balance, December 31, 2018 389 Allocation of note issuance proceeds to derivative 750 Change in fair value of derivative 135 Conversion of convertible debt to Series B preferred stock (1,274 ) Balance, December 31, 2019 $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Components of Lease Cost	The components of lease cost were as follows (dollar amounts in thousands): Year Ended December 31, 2020 2019 2018 Lease Cost Operating lease cost $ 791 $ 441 $ 37 Short-term lease cost — — — Total lease cost $ 791 $ 441 $ 37 As the Company adopted ASC 842 effective January 1, 2020, prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historic accounting under Topic 840. Year Ended December 31, 2020 Other Information Cash paid for amounts included in the measurement of lease liabilities $ 733 Operating lease liabilities arising from obtaining right-of-use assets $ 3,259 Weighted-average remaining lease term 2.94 years Weighted-average discount rate 6.21 %
Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities and Reconciliation to Present Value of Lease Liabilities	The following is a maturity analysis of the annual undiscounted cash flows of the operating lease liabilities and a reconciliation to present value of lease liabilities as of December 31, 2020 (in thousands): Year ended: December 31, 2021 982 December 31, 2022 1,001 December 31, 2023 949 Total future minimum lease payments 2,932 Less imputed interest (246 ) Present value of lease liabilities $ 2,686
Schedule of Future Minimum Lease Payments Under Non-Cancelable Operating Lease Agreements	Future minimum lease payments under non-cancelable operating lease agreements as of December 31, 2019 (under ASC 840, prior to the adoption of ASC 842 effective January 1, 2020), were as follows (in thousands): Year ended: December 31, 2020 $ 499 December 31, 2021 506 December 31, 2022 514 December 31, 2023 86 December 31, 2024 and thereafter — $ 1,605

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Effective Tax Rate and Federal Statutory Tax Rate	A reconciliation of the differences between the effective tax rates of the Company and the U.S. federal statutory tax rate are as follows: Year Ended December 31, 2020 2019 2018 Statutory tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 10.3 % 6.7 % 5.0 % Share-based compensation 21.3 % 0.0 % -1.0 % Change in derivative liability 0.0 % -0.1 % -0.5 % Non-deductible interest expense 0.0 % -0.4 % -3.1 % Other -0.1 % 0.3 % 0.0 % Tax credits 3.2 % 4.9 % 3.0 % Change in valuation allowance -55.7 % -32.4 % -24.4 % Effective Income tax rate 0.0 % 0.0 % 0.0 %
Schedule of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities at December 31, 2020 and 2019 are as follows: December 31, 2020 2019 Deferred tax assets: Operating tax losses $ 47,349 $ 14,145 Tax Credit Carryforwards 5,613 3,028 Fixed Assets — — Accrued expenses 631 580 Lease liability 702 — Share-based compensation 5,923 3,613 Deferred tax assets 60,218 21,366 Valuation allowance (59,563 ) (21,339 ) Deferred tax liabilities: ROU assets (633 ) — Depreciation (22 ) (27 ) Deferred tax liabilities (655 ) (27 ) Net Deferred Tax Asset / (Liability) $ — $ —

Nature of the Business - Additi

Nature of the Business - Additional Information (Details)	Nov. 25, 2019USD ($)$ / sharesshares	Jul. 02, 2019USD ($)$ / sharesshares	Jun. 14, 2019	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)	Jul. 02, 2020USD ($)
Subsidiary Sale Of Stock [Line Items]
Stock split ratio, description				one-for-1.2987
Stock split, conversion ratio			1.2987
Payment of offering costs				$ 405,000
Common stock value				3,000	$ 3,000
Cash flows from operating activities				69,856,000	30,923,000	$ 15,377,000
Accumulated deficit				144,066,000	75,512,000
Cash and cash equivalents and available-for-sale investments				322,300,000
Redeemable Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Temporary Equity, shares outstanding | shares		12,962,045
Redeemable Convertible Preferred Stock | Common Stock
Subsidiary Sale Of Stock [Line Items]
Conversion of stock, shares issued | shares		16,833,790
Initial Public Offering
Subsidiary Sale Of Stock [Line Items]
Payment of offering costs					$ 2,409,000
Initial Public Offering | Common Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued and sold | shares		6,414,842			6,414,842
Public offering price pre share | $ / shares		$ 16
Net proceeds from initial public offering		$ 93,000,000
Underwriting discounts and commissions		7,200,000
Payment of offering costs		$ 2,400,000
Underwriters' Over-Allotment Option | Common Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued and sold | shares		836,718
Secondary Public Offering
Subsidiary Sale Of Stock [Line Items]
Payment of offering costs				34,000	$ 400,000
Secondary Public Offering | Common Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued and sold | shares	2,600,000				2,600,000
Public offering price pre share | $ / shares	$ 96
Underwriting discounts and commissions	$ 15,000,000
Net proceeds from secondary public offering	234,200,000
Offering expenses related to secondary public offering	$ 400,000
At-the-Market Offering Program
Subsidiary Sale Of Stock [Line Items]
Revenue				$ 0
At-the-Market Offering Program | Maximum
Subsidiary Sale Of Stock [Line Items]
Common stock value							$ 150,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jul. 02, 2019	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Deferred offering costs		$ 405,000
Convertible notes outstanding		0
Derivative liabilities outstanding		0
Total lease liabilities		2,686,000
Right-of-use lease assets - operating, net		$ 2,420,000
Deferred lease obligation outstanding				$ 200,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Total lease liabilities			$ 1,500,000
Right-of-use lease assets - operating, net			$ 1,200,000
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
ASU 2019-12
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
ASU 2018-18
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true
Redeemable Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Temporary Equity, shares outstanding	12,962,045
Redeemable Convertible Preferred Stock | Common Stock
Summary Of Significant Accounting Policies [Line Items]
Conversion of stock, shares issued	16,833,790
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of lease hold improvements		shorter of their estimated useful lives or the term of the lease

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 651	$ 252
Less: accumulated depreciation	(202)	(57)
Property and equipment, net	449	195
Computer Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	229	87
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	154	115
Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	154	38
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	85	10
Office Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 29	$ 2

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 100,000
Maximum
Property, Plant and Equipment [Line Items]
Depreciation expense		$ 100,000	$ 100,000

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets and Accrued Expenses - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid research and development expenses	$ 18,660	$ 694
Prepaid insurance	2,116	2,130
Other	1,088	485
Total prepaid expenses and other current assets	$ 21,864	$ 3,309

Prepaid Expenses and Other Cu_4

Prepaid Expenses and Other Current Assets and Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued payroll and related expenses	$ 2,654	$ 1,823
Accrued research and development expenses	1,829	344
Professional fees	458	142
Other	203	44
Total accrued expenses	$ 5,144	$ 2,353

Convertible Notes Payable - Add

Convertible Notes Payable - Additional Information (Details) - USD ($)

1 Months Ended

5 Months Ended

7 Months Ended

12 Months Ended

138 Months Ended

Apr. 30, 2019

Mar. 31, 2019

Nov. 30, 2018

Jul. 31, 2018

Jun. 30, 2018

Jul. 31, 2015

Dec. 31, 2018

Jul. 31, 2018

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2020

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

$ 3,128,000

$ 11,700,000

2015 Convertible Note | Wellcome Trust | Maximum

Debt Instrument [Line Items]

Gross proceeds from the issuance of a convertible note

$ 3,800,000

2018 Convertible Note

Debt Instrument [Line Items]

Debt issuance cost

$ 0

$ 0

2018 Convertible Note | Wellcome Trust

Debt Instrument [Line Items]

Gross proceeds from the issuance of a convertible note

$ 1,600,000

$ 1,600,000

$ 2,000,000

$ 2,700,000

2018 Convertible Note | Wellcome Trust | Maximum

Debt Instrument [Line Items]

Gross proceeds from the issuance of a convertible note

$ 8,000,000

Wellcome Trust Notes | Wellcome Trust

Debt Instrument [Line Items]

Gross proceeds from the issuance of a convertible note

$ 2,700,000

$ 2,000,000

3,128,000

Interest on unpaid principal balance of convertible notes

2.00%

2.00%

Wellcome Trust Notes | Wellcome Trust | Maximum

Debt Instrument [Line Items]

Percentage of debt discount conversion price

25.00%

Wellcome Trust Notes | Wellcome Trust | Minimum

Debt Instrument [Line Items]

Percentage of debt discount conversion price

0.00%

2018 Convertible Note | Wellcome Trust

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

$ 0

Notes outstanding

0

Convertible Notes

Debt Instrument [Line Items]

Interest on unpaid principal balance of convertible notes

10.00%

10.00%

Proceeds from issuance of convertible notes

$ 0

$ 0

$ 7,000,000

$ 14,000,000

Notes outstanding

0

0

Debt instrument interest rate percentage in event of default

15.00%

15.00%

Convertible Notes | Maximum

Debt Instrument [Line Items]

Percentage of debt discount conversion price

25.00%

Convertible Notes | Minimum

Debt Instrument [Line Items]

Percentage of debt discount conversion price

0.00%

Convertible Notes | PureTech Health

Debt Instrument [Line Items]

Debt issuance cost

$ 0

0

Proceeds from issuance of convertible notes

$ 7,000,000

$ 13,500,000

Convertible Notes Payable - Sch

Convertible Notes Payable - Schedule of Changes in Convertible Debt (Details) - USD ($)	5 Months Ended	7 Months Ended	12 Months Ended			138 Months Ended
	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Debt Instrument [Line Items]
Issuance of new notes				$ 3,128,000	$ 11,700,000
Conversion of Wellcome Trust Notes to redeemable convertible preferred stock				(7,102,000)	(26,087,000)
Ending balance			$ 0			$ 0
Convertible Notes
Debt Instrument [Line Items]
Beginning balance		$ 7,674,000			7,674,000
Issuance of new notes			$ 0	0	7,000,000	$ 14,000,000
Allocation of proceeds to derivative liability					(1,418,000)
Accretion to settlement value					1,945,000
Accrued interest					630,000
Interest forgiven upon conversion					(47,000)
Conversion of Wellcome Trust Notes to redeemable convertible preferred stock					(15,784,000)
Wellcome Trust | Wellcome Trust Notes
Debt Instrument [Line Items]
Beginning balance		3,985,000		2,516,000	3,985,000
Issuance of 2018 Convertible Note	$ 2,700,000	2,000,000		3,128,000
Allocation of proceeds to derivative liability	(375,000)			(750,000)
Accretion to settlement value	180,000	51,000		945,000
Accrued interest	11,000	102,000		29,000
Interest forgiven upon conversion		(289,000)		(40,000)
Conversion of Wellcome Trust Notes to redeemable convertible preferred stock		$ (5,849,000)		$ (5,828,000)
Ending balance	$ 2,516,000				$ 2,516,000

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($)	1 Months Ended			12 Months Ended			36 Months Ended
	Apr. 30, 2019	Mar. 31, 2019	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2011	Dec. 31, 2017
Temporary Equity [Line Items]
Payments of stock issuance costs				$ 405,000
Proceeds from issuance of convertible notes					$ 3,128,000	$ 11,700,000
Wellcome Trust Notes
Temporary Equity [Line Items]
Proceeds from issuance of convertible notes	$ 1,600,000
Series Seed Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized							4,412,500
Redeemable convertible preferred stock, shares issued							4,412,500
Stock issuance price per share							$ 0.0001
Payments of stock issuance costs							$ 0
Series Seed Redeemable Convertible Preferred Stock | Maximum
Temporary Equity [Line Items]
Proceeds from issuance of redeemable convertible preferred stock							$ 100,000
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized			3,126,700
Redeemable convertible preferred stock, shares issued			1,188,707
Stock issuance price per share			$ 13.46
Proceeds from issuance of redeemable convertible preferred stock			$ 16,000,000
Payments of stock issuance costs			$ 100,000
Number of shares issued upon conversion of debt			1,937,993
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		5,422,845
Redeemable convertible preferred stock, shares issued		4,953,758
Stock issuance price per share		$ 15.14
Proceeds from issuance of redeemable convertible preferred stock		$ 75,000,000
Payments of stock issuance costs		$ 200,000
Number of shares issued upon conversion of debt	137,743	331,344
Series Seed, A and B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized				0
Redeemable convertible preferred stock, shares issued				0
Redeemable convertible preferred stock, shares outstanding				0	0	7,539,200		4,412,500

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jul. 02, 2019
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	150,000,000	150,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Dividends declared	$ 0
Common stock, shares outstanding	26,988,458	26,012,754
Initial Public Offering
Class Of Stock [Line Items]
Preferred stock, shares authorized			10,000,000
Preferred stock, par value			$ 0.0001

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share Basic And Diluted [Abstract]
Net Loss	$ (68,554)	$ (43,957)	$ (17,512)
Weighted average common shares outstanding used in computing net loss per share, basic and diluted	26,446,006	11,958,152	4
Net loss per share, basic and diluted	$ (2.59)	$ (3.68)	$ (4,378,000)

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	4,612,790	4,614,544	12,121,506
Redeemable convertible preferred stock (as converted to common stock)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount			9,791,151
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	4,612,790	4,614,544	2,310,369
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	0	0	19,986

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($)	May 16, 2019	Mar. 31, 2019	Aug. 31, 2018	Oct. 31, 2016	Sep. 30, 2009	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding						4,612,790	4,614,544
Unrecognized compensation cost						$ 46,100,000
Unrecognized compensation costs, weighted average recognition period						3 years 14 days
Proceeds from exercise of warrant							$ 58,000
PureTech Health
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exchange for a warrant to purchase shares of common stock				19,998
Warrant vested monthly as service performance, period				24 months
Warrant purchase price, per share				$ 2.92
Total expense of warrant						$ 0	$ 0
Exercise of warrant to purchase shares of common stock		19,986	12
Proceeds from exercise of warrant		$ 100,000
Outstanding warrants						0	0
PureTech Health | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total expense of warrant								$ 100,000
PureTech Health | Warrants to Purchase Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense						$ 0	$ 0	$ 0
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Average grant date fair value, per share	$ 10.97
Unrecognized compensation expense related to unvested RSUs						$ 0	$ 0
Restricted Stock Units | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units, shares vested with respective common stock	105,163
2009 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate common shares issuable					3,911,138
Share based compensation arrangement by share based payment award termination date					Jul. 2, 2019
2009 Plan | Options and Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding						2,660,816
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate common shares issuable						934,730
Number of shares outstanding						1,951,974
Common stock reserved for future issuance									1,709,832
Automatic increase in stock issuance as percentage on outstanding stock						4.00%
Stock option and incentive plan expiration month and year						2029-05
Expiration period						10 years
Vesting period						4 years

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Compensation Related Costs [Abstract]
Number of Shares, Outstanding, beginning of period	4,614,544
Number of Shares, Granted	1,029,950
Number of Shares, Exercised	(975,704)
Number of Shares, Forfeited	(56,000)
Number of Shares, Outstanding, end of period	4,612,790
Number of Shares, Options vested and expected to vest	4,612,790
Number of Shares, Options exercisable	2,858,905
Weighted-Average Exercise Price Per Share, Outstanding, beginning of period	$ 8.94
Weighted-Average Exercise Price Per Share, Outstanding, Granted	93.33
Weighted-Average Exercise Price Per Share, Outstanding, Exercised	4.20
Weighted-Average Exercise Price Per Share, Outstanding, Forfeited	21.77
Weighted-Average Exercise Price Per Share, Outstanding, end of period	28.63
Weighted-Average Exercise Price Per Share, Options vested and expected to vest	28.63
Weighted-Average Exercise Price Per Share, Options exercisable	$ 10.48
Weighted-Average Remaining Contractual Term, Outstanding (Years)	8 years 3 months 18 days	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Options vested and expected to vest	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Options exercisable	7 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 336,740	$ 306,395
Aggregate Intrinsic Value, Options vested and expected to vest	336,740
Aggregate Intrinsic Value, Options exercisable	$ 260,485

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Fair Value of Option Activity Estimated at Date of Grant Using Black-Scholes Model (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	55.73%	43.54%	45.57%
Expected volatility, maximum	61.28%	48.22%	48.84%
Risk-free interest rate, minimum	0.35%	1.59%	2.69%
Risk-free interest rate, maximum	1.49%	2.44%	3.04%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of options	$ 35.17	$ 3.84	$ 4.49
Fair value of common stock	$ 62.14	$ 9.20	$ 9.14
Expected term (in years)	5 years 6 months	5 years 7 days	5 years 7 months 24 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of options	$ 59.72	$ 8.05	$ 5.49
Fair value of common stock	$ 106.46	$ 20.02	$ 9.44
Expected term (in years)	7 years	6 years 1 month 28 days	9 years 4 months 2 days

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	$ 13,471	$ 12,568	$ 958
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	3,767	580	107
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	$ 9,704	$ 11,988	$ 851

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Schedule of Fair Value Measurement on Recurring Basis and Indicates the level of Fair Value Hierarchy Utilized (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value assets	$ 319,423	$ 377,771
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	36,817
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	50,141	197,303
US Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	172,295	180,468
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	60,170
Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value assets	222,436	377,771
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	50,141	197,303
Fair Value, Inputs, Level 1 | US Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	172,295	$ 180,468
Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value assets	96,987
Fair Value, Inputs, Level 2 | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	36,817
Fair Value, Inputs, Level 2 | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 60,170

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Summary of Estimated Fair Value and Amortized Cost of Available-for-Sale Investments by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 269,243	$ 180,463
Unrealized Gains	56	5
Unrealized Losses	(17)
Fair Value	269,282	180,468
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Due within in one year, Amortized cost	36,823
Due within one year, Amortized cost, Unrealized gains	3
Due within one year , Amortized cost, Unrealized losses	(9)
Due in one year or less, Fair value	36,817
US Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Due within in one year, Amortized cost	172,265	180,463
Due within one year, Amortized cost, Unrealized gains	37	5
Due within one year , Amortized cost, Unrealized losses	(7)
Due in one year or less, Fair value	172,295	$ 180,468
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Due within in one year, Amortized cost	60,155
Due within one year, Amortized cost, Unrealized gains	16
Due within one year , Amortized cost, Unrealized losses	(1)
Due in one year or less, Fair value	$ 60,170

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Schedule of Changes in Fair Value Derivative Liabilities (Details) - Derivative Financial Instruments, Liabilities - USD ($) $ in Thousands	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Balance	$ 389		$ 0	$ 2,606
Allocation of note issuance proceeds to derivative	375	$ 1,418	750
Change in fair value of derivative	$ 14	430	135
Series A Preferred Stock
Derivatives Fair Value [Line Items]
Conversion of convertible debt		$ (4,454)
Series B Preferred Stock
Derivatives Fair Value [Line Items]
Conversion of convertible debt			$ (1,274)

Fair Value of Financial Asset_6

Fair Value of Financial Assets and Liabilities - Additional Information (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Derivative Liabilities [Abstract]
Derivative Liability	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Jan. 01, 2020USD ($)	Dec. 31, 2020USD ($)	Feb. 29, 2020ft²	Jan. 31, 2020ft²	May 31, 2012USD ($)	Mar. 31, 2011USD ($)	Dec. 31, 2020USD ($)ft²Milestone	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 01, 2020USD ($)
Commitments And Contingencies [Line Items]
Restricted cash		$ 157,000					$ 157,000	$ 123,000
Operating lease liability remeasurement amount										$ 400,000
Incremental lease liabilities arising from obtaining ROU assets							3,259,000
Contingency reserves for litigation		0					$ 0
PureTech Health | Phase III Clinical Trial
Commitments And Contingencies [Line Items]
Milestone payments		2,000,000
Intellectual Property License Agreement | Eli Lilly and Company
Commitments And Contingencies [Line Items]
Upfront payment					$ 100,000
Royalty expiration term					6 years
License agreement term							15 years
Number of milestones reached | Milestone							0
Milestone payments							$ 0
Intellectual Property License Agreement | Eli Lilly and Company | Maximum
Commitments And Contingencies [Line Items]
Contingent milestone payments payable					$ 16,000,000
Commercial milestone payments payable					$ 54,000,000
Patent License | PureTech Health
Commitments And Contingencies [Line Items]
Expenses incurred								0	$ 0
Outstanding liabilities		0					$ 0	$ 0
Patent License | Maximum | PureTech Health
Commitments And Contingencies [Line Items]
Contingent milestone payments payable						$ 10,000,000
Percentage of royalties payable on income from sublicensee, excluding royalties						25.00%
Patent License | Minimum | PureTech Health
Commitments And Contingencies [Line Items]
Percentage of royalties payable on income from sublicensee, excluding royalties						15.00%
ASU 2016-02
Commitments And Contingencies [Line Items]
Incremental lease liabilities arising from obtaining ROU assets	$ 1,800,000
Office Space | Massachusetts
Commitments And Contingencies [Line Items]
No. of square feet acquired | ft²				4,175			7,050
Lease commencement period				2020-03			2018-12
Lease expiration period							2023-12	2023-02
Restricted cash		200,000					$ 200,000	$ 200,000
Leasehold incentives		$ 100,000					$ 100,000
Office Space And Furniture | Carmel, Indiana
Commitments And Contingencies [Line Items]
No. of square feet acquired | ft²			5,050
Lease commencement period			2020-06
Lease expiration period			2023-07

Commitments and Contingencies_2

Commitments and Contingencies - Components of Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lease Cost
Operating lease cost	$ 791	$ 441	$ 37
Total lease cost	791	$ 441	$ 37
Cash paid for amounts included in the measurement of lease liabilities	733
Operating lease liabilities arising from obtaining right-of-use assets	$ 3,259
Weighted-average remaining lease term	2 years 11 months 8 days
Weighted-average discount rate	6.21%

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Maturity Analysis of Annual Undiscounted Cash Flows of Operating Lease Liabilities and Reconciliation to Present Value of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
December 31, 2021	$ 982
December 31, 2022	1,001
December 31, 2023	949
Total future minimum lease payments	2,932
Less imputed interest	(246)
Present value of lease liabilities	$ 2,686

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-Cancelable Operating Lease Agreements (Details) $ in Thousands	Dec. 31, 2019USD ($)
Commitments And Contingencies Disclosure [Abstract]
December 31, 2020	$ 499
December 31, 2021	506
December 31, 2022	514
December 31, 2023	86
Total	$ 1,605

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	Mar. 27, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jul. 02, 2019	Aug. 01, 2018
Income tax expense		$ 43,000	$ 0	$ 0
Valuation allowance increase related to current year operating loss and tax credits		$ 38,200,000
Period of cumulative changes in ownership interests		3 years
Unrecognized tax benefits		$ 0
Unrecognized tax benefits, income tax penalties and interest accrued		0
Domestic Tax Authority
Net operating loss carryforwards		179,800,000
Future offset taxable due		$ 4,900,000
Domestic Tax Authority | CARES Act
Net operating loss carryback period	5 years
Percentage of taxable income removed as limitation for net operating loss deductions	80.00%
Changes in net operating loss as per enactment		On March 27, 2020, the Coronavirus Aid, Relief and Economic Security (“CARES”) Act was enacted and signed into law.  Among other things, the CARES Act allows for a five-year carryback of Federal net operating losses generated in tax years beginning in 2018, 2019, or 2020 and removes the 80% taxable income limitation for net operating loss deductions for tax years beginning before January 1, 2021.  The Company has evaluated the income tax ramifications of the CARES Act and has determined that there is no material impact to its overall income tax position.
Domestic Tax Authority | Research Tax Credit Carryforward
Research credits carryforwards		$ 5,000,000
Research credits carryforwards, expiration year		2031
Domestic Tax Authority | Begin to expire in 2029
Net operating loss carryforwards		$ 9,700,000
Domestic Tax Authority | Indefinite Carryforward
Net operating loss carryforwards		170,100,000
State and Local Jurisdiction
Future offset taxable due		800,000
State and Local Jurisdiction | Research Tax Credit Carryforward
Research credits carryforwards		$ 800,000
Research credits carryforwards, expiration year		2031
State and Local Jurisdiction | Begin to expire in 2030
Net operating loss carryforwards		$ 151,700,000
PureTech Health
Percentage of outstanding shares, no longer held					50.00%	80.00%
PureTech Health | Domestic Tax Authority
Future offset taxable income		179,400,000
PureTech Health | State and Local Jurisdiction
Future offset taxable income		131,700,000
Maximum
Income tax expense		$ 100,000
Minimum
Ownership interest of significant shareholders		50.00%

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Tax Rate and Federal Statutory Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	10.30%	6.70%	5.00%
Share-based compensation	21.30%	0.00%	(1.00%)
Change in derivative liability	0.00%	(0.10%)	(0.50%)
Non-deductible interest expense	0.00%	(0.40%)	(3.10%)
Other	(0.10%)	0.30%	0.00%
Tax credits	3.20%	4.90%	3.00%
Change in valuation allowance	(55.70%)	(32.40%)	(24.40%)
Effective Income tax rate	0.00%	0.00%	0.00%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Operating tax losses	$ 47,349	$ 14,145
Tax Credit Carryforwards	5,613	3,028
Accrued expenses	631	580
Lease liability	702
Share-based compensation	5,923	3,613
Deferred tax assets	60,218	21,366
Valuation allowance	(59,563)	(21,339)
Deferred tax liabilities:
ROU assets	(633)
Depreciation	(22)	(27)
Deferred tax liabilities	$ (655)	$ (27)

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - PureTech Health - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
General and administrative expenses incurred	$ 0		$ 200,000
Outstanding current liabilities due to related party	$ 0
Maximum
Related Party Transaction [Line Items]
General and administrative expenses incurred		$ 100,000
Outstanding current liabilities due to related party		$ 100,000

401(k) Savings Plan - Additiona

401(k) Savings Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, plan name	401(k)
Total contribution expense	$ 200,000
Maximum
Defined Benefit Plan Disclosure [Line Items]
Total contribution expense		$ 100,000	$ 100,000