Praxis Precision Medicines (PRAX) 10-Q 16 Aug 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Aug. 06, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity File Number	001-39620
Entity Registrant Name	PRAXIS PRECISION MEDICINES, INC.
Entity Central Index Key	0001689548
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-5195942
Entity Address, Address Line One	One Broadway
Entity Address, Address Line Two	16th Floor
Entity Address, Postal Zip Code	02142
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
City Area Code	617
Local Phone Number	300-8460
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	PRAX
Security Exchange Name	NASDAQ
Amendment Flag	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		44,712,538

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 175,879	$ 296,608
Marketable securities	163,305	0
Prepaid expenses and other current assets	9,249	5,718
Total current assets	348,433	302,326
Property and equipment, net	182	82
Operating lease right-of-use assets	4,400	754
Other non-current assets	496	15
Total assets	353,511	303,177
Current liabilities:
Accounts payable	7,401	4,088
Accrued expenses	7,826	10,869
Operating lease liabilities	553	763
Total current liabilities	15,780	15,720
Long-term liabilities:
Non-current portion of operating lease liabilities	3,959	0
Total liabilities	19,739	15,720
Commitments and contingencies (Note 6)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding as of June 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; 150,000,000 shares authorized; 44,693,162 shares issued and outstanding as of June 30, 2021, and 38,268,543 shares issued and outstanding as of December 31, 2020	5	4
Additional paid-in capital	547,145	437,007
Accumulated other comprehensive loss	(50)	0
Accumulated deficit	(213,328)	(149,554)
Total stockholders’ equity	333,772	287,457
Total liabilities and stockholders’ equity	$ 353,511	$ 303,177

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	44,693,162	38,268,543
Common stock, outstanding (in shares)	44,693,162	38,268,543

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 25,678	$ 9,050	$ 43,607	$ 15,918
General and administrative	10,805	2,520	20,295	4,121
Total operating expenses	36,483	11,570	63,902	20,039
Loss from operations	(36,483)	(11,570)	(63,902)	(20,039)
Other income:
Other income, net	82	5	128	133
Total other income	82	5	128	133
Loss before income taxes	(36,401)	(11,565)	(63,774)	(19,906)
Benefit from (provision for) income taxes	0	(3)	0	8
Net loss	(36,401)	(11,568)	(63,774)	(19,898)
Accretion and cumulative dividends on redeemable convertible preferred stock	0	(2,039)	0	(4,103)
Gain on repurchase of redeemable convertible preferred stock	0	0	0	493
Net loss attributable to common stockholders	$ (36,401)	$ (13,607)	$ (63,774)	$ (23,508)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.88)	$ (8.28)	$ (1.59)	$ (14.37)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.88)	$ (8.28)	$ (1.59)	$ (14.37)
Weighted average common shares outstanding, basic (in shares)	41,569,782	1,642,484	40,028,807	1,635,913
Weighted average common shares outstanding, diluted (in shares)	41,569,782	1,642,484	40,028,807	1,635,913

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (36,401)	$ (11,568)	$ (63,774)	$ (19,898)
Unrealized gains (losses) on marketable securities, net of tax	36	0	(50)	0
Comprehensive loss	$ (36,365)	$ (11,568)	$ (63,824)	$ (19,898)

Condensed Consolidated Statem_3

Condensed Consolidated Statements Of Redeemable Convertible Preferred Stock And Stockholders’ Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series B-1 Redeemable Convertible Preferred Stock	Series C Redeemable Convertible Preferred Stock	Series C Redeemable Convertible Preferred StockAccumulated Deficit
Beginning balance, Shares at Dec. 31, 2019						8,075,799	14,913,704	2,666,666	9,805,827
Beginning balance at Dec. 31, 2019						$ 9,932	$ 49,969	$ 10,431	$ 50,789
Increase (Decrease) in Temporary Equity [Roll Forward]
Repurchase of Series C redeemable convertible preferred stock (in shares)									(5,825,243)
Repurchase of Series C redeemable convertible preferred stock									$ (30,493)
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)									4,563,108
Issuance of redeemable convertible preferred stock, net of issuance costs									$ 23,459
Accretion of redeemable convertible preferred stock to redemption value						$ 322	$ 1,780	$ 397	$ 1,604
Ending balance, shares at Jun. 30, 2020						8,075,799	14,913,704	2,666,666	8,543,692
Ending balance at Jun. 30, 2020						$ 10,254	$ 51,749	$ 10,828	$ 45,359
Beginning balance, Shares at Dec. 31, 2019		1,621,880
Beginning balance at Dec. 31, 2019	$ (81,008)	$ 1	$ 0	$ (81,009)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of Series C redeemable convertible preferred stock									$ 493	$ 493
Stock-based compensation expense	432		432
Change in unrealized loss on marketable securities, net of tax	0
Vesting of restricted stock awards (in shares)		26,285
Accretion of redeemable convertible preferred stock to redemption value	(4,103)		(432)	(3,671)
Net loss	(19,898)			(19,898)
Ending balance, shares at Jun. 30, 2020		1,648,165
Ending balance at Jun. 30, 2020	(104,084)	$ 1	0	(104,085)	0
Beginning balance, Shares at Mar. 31, 2020						8,075,799	14,913,704	2,666,666	3,980,584
Beginning balance at Mar. 31, 2020						$ 10,092	$ 50,859	$ 10,630	$ 21,074
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)									4,563,108
Issuance of redeemable convertible preferred stock, net of issuance costs									$ 23,496
Accretion of redeemable convertible preferred stock to redemption value						$ 162	$ 890	$ 198	$ 789
Ending balance, shares at Jun. 30, 2020						8,075,799	14,913,704	2,666,666	8,543,692
Ending balance at Jun. 30, 2020						$ 10,254	$ 51,749	$ 10,828	$ 45,359
Beginning balance, Shares at Mar. 31, 2020		1,635,023
Beginning balance at Mar. 31, 2020	(90,762)	$ 1	0	(90,763)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	285		285
Change in unrealized loss on marketable securities, net of tax	0
Vesting of restricted stock awards (in shares)		13,142
Accretion of redeemable convertible preferred stock to redemption value	(2,039)		(285)	(1,754)
Net loss	(11,568)			(11,568)
Ending balance, shares at Jun. 30, 2020		1,648,165
Ending balance at Jun. 30, 2020	$ (104,084)	$ 1	0	(104,085)	0
Beginning balance, Shares at Dec. 31, 2020						0	0	0	0
Beginning balance at Dec. 31, 2020						$ 0	$ 0	$ 0	$ 0
Ending balance, shares at Jun. 30, 2021						0	0	0	0
Ending balance at Jun. 30, 2021						$ 0	$ 0	$ 0	$ 0
Beginning balance, Shares at Dec. 31, 2020	38,268,543	38,268,543
Beginning balance at Dec. 31, 2020	$ 287,457	$ 4	437,007	(149,554)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	10,066		10,066
Issuance of common stock from follow-on public offering, net of offering costs of $229 (in shares)		5,750,000
Issuance of common stock from follow-on public offering, net of offering costs of $229	$ 98,413	$ 1	98,412
Issuance of common stock upon exercise of stock options (in shares)	674,619	674,619
Issuance of common stock upon exercise of stock options	$ 1,660		1,660
Change in unrealized loss on marketable securities, net of tax	(50)				(50)
Net loss	$ (63,774)			(63,774)
Ending balance, shares at Jun. 30, 2021	44,693,162	44,693,162
Ending balance at Jun. 30, 2021	$ 333,772	$ 5	547,145	(213,328)	(50)
Beginning balance, Shares at Mar. 31, 2021						0	0	0	0
Beginning balance at Mar. 31, 2021						$ 0	$ 0	$ 0	$ 0
Ending balance, shares at Jun. 30, 2021						0	0	0	0
Ending balance at Jun. 30, 2021						$ 0	$ 0	$ 0	$ 0
Beginning balance, Shares at Mar. 31, 2021		38,621,049
Beginning balance at Mar. 31, 2021	265,515	$ 4	442,524	(176,927)	(86)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	5,400		5,400
Issuance of common stock from follow-on public offering, net of offering costs of $229 (in shares)		5,750,000
Issuance of common stock from follow-on public offering, net of offering costs of $229	98,413	$ 1	98,412
Issuance of common stock upon exercise of stock options (in shares)		322,113
Issuance of common stock upon exercise of stock options	809		809
Change in unrealized loss on marketable securities, net of tax	36				36
Net loss	$ (36,401)			(36,401)
Ending balance, shares at Jun. 30, 2021	44,693,162	44,693,162
Ending balance at Jun. 30, 2021	$ 333,772	$ 5	$ 547,145	$ (213,328)	$ (50)

Condensed Consolidated Statem_4

Condensed Consolidated Statements Of Redeemable Convertible Preferred Stock And Stockholders’ Equity (Deficit) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock issuance costs	$ 229		$ 229
Series C Redeemable Convertible Preferred Stock
Stock issuance costs		$ 4		$ 41

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (63,774)	$ (19,898)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	50	20
Stock-based compensation expense	10,066	432
Non-cash operating lease expense	475	341
Amortization of premiums and discounts on marketable securities, net	815	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,531)	(11)
Accounts payable	3,708	912
Accrued expenses	(3,106)	22
Operating lease liabilities	(373)	(340)
Other	(65)	9
Net cash used in operating activities	(55,735)	(18,513)
Cash flows from investing activities:
Purchases of property and equipment	(69)	0
Purchases of marketable securities	(164,170)	0
Net cash used in investing activities	(164,239)	0
Cash flows from financing activities:
Proceeds from follow-on public offering, net of issuance costs	98,576	0
Payment of issuance costs for initial public offering and issuance of redeemable convertible preferred stock	(575)	(13)
Proceeds from exercise of options to purchase common stock	1,660	0
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	23,459
Repurchase of Series C redeemable convertible preferred stock	0	(30,000)
Net cash provided by (used in) financing activities	99,661	(6,554)
Decrease in cash, cash equivalents and restricted cash	(120,313)	(25,067)
Cash, cash equivalents and restricted cash, beginning of period	297,208	45,415
Cash, cash equivalents and restricted cash, end of period	176,895	20,348
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	175,879	19,748
Restricted cash	1,016	600
Total cash, cash equivalents and restricted cash	176,895	20,348
Supplemental disclosures of non-cash activities:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	4,086	0
Deferred offering costs included in accounts payable and accrued expenses	163	372
Purchases of property and equipment included in accounts payable	83	0
Accretion of redeemable convertible preferred stock to redemption value	$ 0	$ 4,103

Nature of the Business

Nature of the Business	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Praxis Precision Medicines, Inc. (“Praxis” or the “Company”) is a clinical-stage biopharmaceutical company translating genetic insights into the development of therapies for central nervous system (“CNS”) disorders characterized by neuronal imbalance. The Company has established a broad portfolio, including multiple disclosed programs across CNS disorders, including depression, epilepsy, movement disorders and pain syndromes, with three clinical-stage product candidates. The Company intends to develop differentiated therapies that can deliver long-term benefits to human health by meaningfully impacting patients and society. The Company’s most advanced programs, PRAX-114 and PRAX-944, are currently in Phase 2/3 and Phase 2 development, respectively. PRAX-114 is an extrasynaptic GABA A receptor preferring positive allosteric modulator currently being developed for the treatment of major depressive disorder and perimenopausal depression. The Company plans to initiate Phase 2 trials of PRAX-114 in post-traumatic stress disorder and essential tremor ("ET") in the second half of 2021 and intends to disclose plans for a Phase 2b trial in women with menopausal and mood symptoms in the second half of 2021. PRAX-944 is a selective small molecule inhibitor of T-type calcium channels currently being developed for the treatment of ET. The Company plans to initiate a Phase 2 trial of PRAX-944 in Parkinson's disease in the first half of 2022. Praxis was incorporated in 2015 and commenced operations in 2016. The Company has funded its operations primarily with proceeds from the issuance of convertible debt and redeemable convertible preferred stock, and from the sale of common stock through an initial public offering and a follow-on public offering. From inception through June 30, 2021, the Company raised $509.4 million in aggregate cash proceeds from these transactions, net of issuance costs. In May 2021, the Company completed a follow-on public offering in which the Company issued and sold 5,750,000 shares of its common stock at a public offering price of $18.25 per share, including 750,000 shares of common stock issued and sold pursuant to the underwriters' exercise, in full, of their option to purchase additional shares of common stock, for aggregate gross proceeds of $104.9 million. The Company received approximately $98.4 million in net proceeds after deducting discounts, commissions and offering expenses payable by the Company. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including but not limited to, risks associated with completing preclinical studies and clinical trials, receiving regulatory approvals for product candidates, development by competitors of new biopharmaceutical products, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. Liquidity In accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) , the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that these condensed consolidated financial statements are issued. The Company has incurred recurring losses since its inception, including net losses of $63.8 million for the six months ended June 30, 2021. In addition, as of June 30, 2021, the Company had an accumulated deficit of $213.3 million. The Company expects to continue to generate operating losses for the foreseeable future.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and ASUs of the FASB. The significant accounting policies used in preparation of these condensed consolidated financial statements for the three and six months ended June 30, 2021 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company's 2020 Annual Report on Form 10-K, other than as noted below. Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2021, the condensed consolidated statements of operations for the three and six months ended June 30, 2021 and 2020, the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2021 and 2020, the condensed consolidated statements of cash flows for the six months ended June 30, 2021 and 2020 and the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ equity (deficit) for the three and six months ended June 30, 2021 and 2020 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of June 30, 2021, the results of its operations for the three and six months ended June 30, 2021 and 2020 and its cash flows for the six months ended June 30, 2021 and 2020. Financial statement disclosures for the three and six months ended June 30, 2021 and 2020 are condensed and do not include all disclosures required for an annual set of financial statements in accordance with GAAP. The results for the three and six months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ended December 31, 2021, any other interim periods, or any future year or period. Use of Estimates The preparation of condensed consolidated 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual for research and development expenses, stock-based compensation expense, and the valuation of equity awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates. Marketable Securities The Company invests its excess cash in money market funds and debt instruments of the U.S. Treasury, financial institutions, corporations and U.S. government agencies with strong credit ratings and an investment grade rating at or above A-1 or P-1 by two of the three nationally recognized statistical rating organizations. The Company does not believe that it is exposed to more than a nominal amount of credit risk in its marketable securities. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity, and periodically reviews and modifies these guidelines to maximize trends in yields and interest rates without compromising safety and liquidity. The Company classifies its investments in debt instruments as available-for-sale. Available-for-sale investments are reported at fair value at each balance sheet date, and include any unrealized holding gains and losses in accumulated other comprehensive gain (loss), a component of stockholders’ equity. Realized gains and losses are included in the Company's condensed consolidated statements of operations. All of the Company's available-for-sale securities are available for use in its current operations. As a result, the Company has categorized all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The Company evaluates securities for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the issuer, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit- related is recognized in other comprehensive (loss) income, net of applicable taxes. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes ("ASU 2019-12"). The ASU simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in ASC 740, Income Taxes, related to the approach for allocating income tax expense or benefit for the year to continuing operations, discontinued operations, other comprehensive income, and other charges or credits recorded directly to shareholders’ equity; the methodology for calculating income taxes in an interim period; and the recognition of deferred tax liabilities for outside basis differences. On January 1, 2021, the Company early adopted ASU 2019-12 on a prospective basis, with no material impact on its condensed consolidated financial statements and related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments, which has been subsequently amended by ASU No. 2018-19, ASU No. 2019-04, ASU No. 2019-05, ASU No. 2019-10, ASU No. 2019-11 and ASU No. 2020-03 (“ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for the Company on January 1, 2023, with early adoption permitted. The Company is currently evaluating the timing of its adoption of this standard, as well as the potential impact that this standard may have on its financial position and results of operations, but does not expect the impact to be significant.

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable SecuritiesThe following is a summary of the Company's investment portfolio at June 30, 2021 (in thousands). The Company did not have any marketable securities as of December 31, 2020. Gross Unrealized Estimated Cost Gains Losses Fair Value Available-for-sale securities: Corporate debt securities $ 58,511 $ 7 $ (6) $ 58,512 Commercial paper 55,952 — — 55,952 Total securities with a maturity of one year or less $ 114,463 $ 7 $ (6) $ 114,464 Corporate debt securities 36,692 — (55) 36,637 Debt securities issued by U.S. government agencies 12,200 4 — 12,204 Total securities with a maturity of one to two years $ 48,892 $ 4 $ (55) $ 48,841 Total available-for-sale securities $ 163,355 $ 11 $ (61) $ 163,305 As of June 30, 2021, the Company had 12 securities with a total fair market value of $73.8 million in an unrealized loss position. The Company believes that any unrealized losses associated with the decline in value of its securities is temporary and primarily related to the change in market interest rates since purchase, and believes that it is more likely than not that it will be able to hold its debt securities to maturity. Therefore, the Company anticipates a full recovery of the amortized cost basis of its debt securities at maturity.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset in an orderly transaction between market participants at the measurement date. The Company categorizes financial assets measured at fair value based on a fair value hierarchy. The following fair value hierarchy is used to classify financial assets based on observable inputs and unobservable inputs used to value the financial assets: • Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical assets; • Level 2: Quoted prices for similar assets in active markets, quoted prices in markets that are not active, or inputs which are unobservable, either directly or indirectly, for substantially the full term of the asset; or • Level 3: Prices or valuation techniques that require inputs that are both significant to the valuation of the asset and unobservable. The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): As of June 30, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 172,274 $ — $ — $ 172,274 Marketable securities: Corporate debt securities — 95,149 — 95,149 Commercial paper — 55,952 — 55,952 Debt securities issued by U.S. government agencies 12,204 — — 12,204 $ 184,478 $ 151,101 $ — $ 335,579 As of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 290,931 $ — $ — $ 290,931 $ 290,931 $ — $ — $ 290,931

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2021
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following (in thousands): June 30, 2021 December 31, 2020 Accrued external research and development expenses $ 4,848 $ 4,206 Accrued personnel-related expenses 2,179 5,516 Accrued other 799 1,147 Total accrued expenses $ 7,826 $ 10,869

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In May 2021, the Company entered into a sublease agreement for office space located in Boston, Massachusetts to be used as the Company's corporate headquarters. The sublease expires on January 31, 2026, with no option to renew or terminate early. The base rent increases by approximately 2% annually. The Company issued a letter of credit to the landlord for $0.4 million related to the security deposit, secured by restricted cash, which is reflected within other non-current assets on the accompanying condensed consolidated balance sheet as of June 30, 2021. This lease qualifies as an operating lease. At inception, the Company recorded an operating lease right-of-use asset and operating lease liability of $4.1 million. As of June 30, 2021, the Company had an operating lease right-of-use asset of $4.0 million, current operating lease liability of approximately $0.2 million, and non-current operating lease liability of approximately $4.0 million included in the condensed consolidated balance sheet. Future lease payments under the non-cancellable sublease agreement as of June 30, 2021 were as follows (in thousands): Year Ended December 31, Future Lease Payments 2021 $ — 2022 1,160 2023 1,270 2024 1,296 2025 1,321 2026 110 Total future lease payments $ 5,157 Less: interest (1,035) Present value of operating lease liabilities $ 4,122 As of June 30, 2021, the remaining lease term and discount rate of the sublease agreement was 4.6 years and 9.0%, respectively. In October 2018, the Company entered into a sublease agreement for office space located in Cambridge, Massachusetts that expires on December 31, 2021, with no option to renew or terminate early. The base rent increases by approximately 1% annually. The Company issued a letter of credit to the landlord for $0.6 million related to the security deposit, secured by restricted cash, which is reflected within prepaid expenses and other current assets on the accompanying condensed consolidated balance sheets as of June 30, 2021 and December 31, 2020, as the lease term expires less than twelve months from the condensed consolidated balance sheet dates. This lease qualifies as an operating lease.

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Common Stock As of June 30, 2021 and December 31, 2020, the authorized capital stock of the Company included 150,000,000 shares of common stock, $0.0001 par value. As of June 30, 2021 and December 31, 2020, the Company did not hold any treasury shares. Shares Reserved for Future Issuance The Company has reserved the following shares of common stock for future issuance: June 30, December 31, Shares reserved for exercise of outstanding stock options 6,608,072 5,944,546 Shares reserved for future awards under the 2020 Stock Option and Incentive Plan 3,138,096 3,036,776 Shares reserved for future awards under the 2020 Employee Stock Purchase Plan 654,204 327,102 Shares reserved for vesting of restricted stock units 340,563 — Total shares of authorized common stock reserved for future issuance 10,740,935 9,308,424 Preferred Stock As of June 30, 2021 and December 31, 2020, the authorized capital stock of the Company included 10,000,000 shares of undesignated preferred stock, $0.0001 par value.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation 2020 Stock Option and Incentive Plan The total number of shares of common stock authorized for issuance under the 2020 Stock Option Incentive Plan (the "2020 Plan”) as of June 30, 2021 and December 31, 2020 was 5,184,455 shares and 3,271,028 shares, respectively. 2017 Stock Incentive Plan The total number of shares of common stock authorized for issuance under the 2017 Stock Incentive Plan (the "2017 Plan”) as of June 30, 2021 and December 31, 2020 was 5,937,763 shares. Any authorization to issue new options under the 2017 Plan was cancelled upon the effectiveness of the 2020 Plan and no further awards will be granted under the 2017 Plan. 2020 Employee Stock Purchase Plan The total number of shares of common stock authorized for issuance under the 2020 Employee Stock Purchase Plan (the "2020 ESPP”) as of June 30, 2021 and December 31, 2020 was 654,204 shares and 327,102 shares, respectively. Restricted Stock Units The following table summarizes the Company’s restricted stock unit activity: Shares Weighted Unvested as of December 31, 2020 — $ — Issued 352,663 50.52 Vested — — Forfeited (12,100) 52.53 Unvested as of June 30, 2021 340,563 $ 50.45 Stock Options The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2020 5,944,546 $ 7.47 Granted 1,548,403 44.78 Exercised (674,619) 2.46 $ 17,696 Cancelled or Forfeited (210,258) 20.58 Outstanding as of June 30, 2021 6,608,072 $ 16.30 8.98 $ 56,586 Exercisable as of June 30, 2021 971,361 $ 3.97 7.86 $ 13,958 Vested and expected to vest as of June 30, 2021 6,458,407 $ 18.15 9.05 $ 54,961 The aggregate intrinsic value of stock options outstanding, exercisable, and vested and expected to vest is calculated as the difference between the exercise price of the underlying stock options and the estimated fair value of the Company’s common stock for those stock options that had exercise prices lower than the estimated fair value of the Company’s common stock at June 30, 2021. The aggregate intrinsic value of stock options exercised is calculated as the difference between the exercise price of the underlying stock options and the estimated fair value of the Company’s common stock on the date of exercise for those stock options that had exercise prices lower than the estimated fair value of the Company’s common stock on the exercise date. Stock Option Valuation The weighted-average assumptions that the Company used in the Black-Scholes option pricing model to determine the grant-date fair value of stock options granted to employees and non-employees on the date of grant were as follows for the three and six months ended June 30, 2021: Three Months Ended Six Months Ended June 30, 2021 2021 Risk-free interest rate 1.05 % 0.76 % Expected term (in years) 6.00 6.11 Expected volatility 86.42 % 85.58 % Expected dividend yield — % — % The weighted-average grant-date fair value of the Company’s stock options granted during the three and six months ended June 30, 2021 was $16.52 per share and $31.99 per share, respectively. Stock-Based Compensation Stock-based compensation expense was allocated as follows (in thousands): Three Months Ended Six Months Ended 2021 2020 2021 2020 Research and development $ 2,031 $ 153 $ 4,349 $ 255 General and administrative 3,369 132 5,717 177 Total stock-based compensation expense $ 5,400 $ 285 $ 10,066 $ 432 As of June 30, 2021, total unrecognized compensation expense related to unvested stock-based awards was $80.2 million, which is expected to be recognized over a weighted-average period of 3.06 years.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended Six Months Ended 2021 2020 2021 2020 Numerator: Net loss $ (36,401) $ (11,568) $ (63,774) $ (19,898) Accretion and cumulative dividends on redeemable convertible preferred stock — (2,039) — (4,103) Gain on repurchase of redeemable convertible preferred stock — — — 493 Net loss attributable to common stockholders $ (36,401) $ (13,607) $ (63,774) $ (23,508) Denominator: Weighted average common shares outstanding, basic and diluted 41,569,782 1,642,484 40,028,807 1,635,913 Net loss per share attributable to common stockholders, basic and diluted $ (0.88) $ (8.28) $ (1.59) $ (14.37) The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive: Three Months Ended Six Months Ended 2021 2020 2021 2020 Outstanding stock options 6,608,072 3,220,201 6,608,072 3,220,201 Unvested restricted common stock and restricted stock units 340,563 21,905 340,563 21,905 Series A redeemable convertible preferred stock — 3,773,820 — 3,773,820 Series B redeemable convertible preferred stock — 6,969,173 — 6,969,173 Series B-1 redeemable convertible preferred stock — 1,246,133 — 1,246,133 Series C redeemable convertible preferred stock — 3,992,463 — 3,992,463 6,948,635 19,223,695 6,948,635 19,223,695 The shares of common stock issuable upon conversion of the redeemable convertible preferred stock for the three and six months ended June 30, 2020 assumed automatic conversion in the event of a qualified public offering.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsOn September 11, 2019, the Company entered into a Cooperation and License Agreement (the “License Agreement”) with RogCon Inc. (“RogCon”). Under the License Agreement, RogCon granted to the Company an exclusive, worldwide license under RogCon’s intellectual property to research, develop and commercialize products for the treatment of all forms of epilepsy and/or neurodevelopmental disorders in each case caused by any mutation of the SCN2A gene. Pursuant to the terms of the License Agreement, the Company will conduct, at its own cost and expense, the research and development activities assigned to it under the associated research plan. In addition, the Company is responsible for reimbursing RogCon for any costs associated with research and development activities RogCon performs at the request of the Company. One of the founders of RogCon became the Company’s General Counsel in June 2020. The Company continues to reimburse RogCon for its out-of-pocket costs incurred for activities performed under the License Agreement. Expenses incurred during all periods presented were not material. As of June 30, 2021, the Company had accrued expenses of $0.3 million due to RogCon under the License Agreement.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the condensed consolidated financial statements to provide additional evidence for certain estimates or to identify matters that require additional disclosure. The Company has concluded that no subsequent events have occurred that require disclosure.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and ASUs of the FASB. The significant accounting policies used in preparation of these condensed consolidated financial statements for the three and six months ended June 30, 2021 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company's 2020 Annual Report on Form 10-K, other than as noted below.
Unaudited Interim Condensed Consolidated Financial Information	Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2021, the condensed consolidated statements of operations for the three and six months ended June 30, 2021 and 2020, the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2021 and 2020, the condensed consolidated statements of cash flows for the six months ended June 30, 2021 and 2020 and the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ equity (deficit) for the three and six months ended June 30, 2021 and 2020 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of June 30, 2021, the results of its operations for the three and six months ended June 30, 2021 and 2020 and its cash flows for the six months ended June 30, 2021 and 2020. Financial statement disclosures for the three and six months ended June 30, 2021 and 2020 are condensed and do not include all disclosures required for an annual set of financial statements in accordance with GAAP. The results for the three and six months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ended December 31, 2021, any other interim periods, or any future year or period.
Use of Estimates	Use of Estimates The preparation of condensed consolidated 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 condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual for research and development expenses, stock-based compensation expense, and the valuation of equity awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates.
Marketable Securities	Marketable Securities The Company invests its excess cash in money market funds and debt instruments of the U.S. Treasury, financial institutions, corporations and U.S. government agencies with strong credit ratings and an investment grade rating at or above A-1 or P-1 by two of the three nationally recognized statistical rating organizations. The Company does not believe that it is exposed to more than a nominal amount of credit risk in its marketable securities. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity, and periodically reviews and modifies these guidelines to maximize trends in yields and interest rates without compromising safety and liquidity. The Company classifies its investments in debt instruments as available-for-sale. Available-for-sale investments are reported at fair value at each balance sheet date, and include any unrealized holding gains and losses in accumulated other comprehensive gain (loss), a component of stockholders’ equity. Realized gains and losses are included in the Company's condensed consolidated statements of operations. All of the Company's available-for-sale securities are available for use in its current operations. As a result, the Company has categorized all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The Company evaluates securities for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the issuer, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit- related is recognized in other comprehensive (loss) income, net of applicable taxes.
Recently Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes ("ASU 2019-12"). The ASU simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in ASC 740, Income Taxes, related to the approach for allocating income tax expense or benefit for the year to continuing operations, discontinued operations, other comprehensive income, and other charges or credits recorded directly to shareholders’ equity; the methodology for calculating income taxes in an interim period; and the recognition of deferred tax liabilities for outside basis differences. On January 1, 2021, the Company early adopted ASU 2019-12 on a prospective basis, with no material impact on its condensed consolidated financial statements and related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments, which has been subsequently amended by ASU No. 2018-19, ASU No. 2019-04, ASU No. 2019-05, ASU No. 2019-10, ASU No. 2019-11 and ASU No. 2020-03 (“ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for the Company on January 1, 2023, with early adoption permitted. The Company is currently evaluating the timing of its adoption of this standard, as well as the potential impact that this standard may have on its financial position and results of operations, but does not expect the impact to be significant.

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale	The following is a summary of the Company's investment portfolio at June 30, 2021 (in thousands). The Company did not have any marketable securities as of December 31, 2020. Gross Unrealized Estimated Cost Gains Losses Fair Value Available-for-sale securities: Corporate debt securities $ 58,511 $ 7 $ (6) $ 58,512 Commercial paper 55,952 — — 55,952 Total securities with a maturity of one year or less $ 114,463 $ 7 $ (6) $ 114,464 Corporate debt securities 36,692 — (55) 36,637 Debt securities issued by U.S. government agencies 12,200 4 — 12,204 Total securities with a maturity of one to two years $ 48,892 $ 4 $ (55) $ 48,841 Total available-for-sale securities $ 163,355 $ 11 $ (61) $ 163,305

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Summary of financial assets measured at fair value on a recurring basis	The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): As of June 30, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 172,274 $ — $ — $ 172,274 Marketable securities: Corporate debt securities — 95,149 — 95,149 Commercial paper — 55,952 — 55,952 Debt securities issued by U.S. government agencies 12,204 — — 12,204 $ 184,478 $ 151,101 $ — $ 335,579 As of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 290,931 $ — $ — $ 290,931 $ 290,931 $ — $ — $ 290,931

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consisted of the following (in thousands): June 30, 2021 December 31, 2020 Accrued external research and development expenses $ 4,848 $ 4,206 Accrued personnel-related expenses 2,179 5,516 Accrued other 799 1,147 Total accrued expenses $ 7,826 $ 10,869

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Lessee, Operating Lease, Liability, Maturity	Future lease payments under the non-cancellable sublease agreement as of June 30, 2021 were as follows (in thousands): Year Ended December 31, Future Lease Payments 2021 $ — 2022 1,160 2023 1,270 2024 1,296 2025 1,321 2026 110 Total future lease payments $ 5,157 Less: interest (1,035) Present value of operating lease liabilities $ 4,122

Common Stock and Preferred St_2

Common Stock and Preferred Stock (Tables)	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Summary of common stock reserved for future issuance	The Company has reserved the following shares of common stock for future issuance: June 30, December 31, Shares reserved for exercise of outstanding stock options 6,608,072 5,944,546 Shares reserved for future awards under the 2020 Stock Option and Incentive Plan 3,138,096 3,036,776 Shares reserved for future awards under the 2020 Employee Stock Purchase Plan 654,204 327,102 Shares reserved for vesting of restricted stock units 340,563 — Total shares of authorized common stock reserved for future issuance 10,740,935 9,308,424

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of restricted stock activity	The following table summarizes the Company’s restricted stock unit activity: Shares Weighted Unvested as of December 31, 2020 — $ — Issued 352,663 50.52 Vested — — Forfeited (12,100) 52.53 Unvested as of June 30, 2021 340,563 $ 50.45
Summary of stock option activity	The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2020 5,944,546 $ 7.47 Granted 1,548,403 44.78 Exercised (674,619) 2.46 $ 17,696 Cancelled or Forfeited (210,258) 20.58 Outstanding as of June 30, 2021 6,608,072 $ 16.30 8.98 $ 56,586 Exercisable as of June 30, 2021 971,361 $ 3.97 7.86 $ 13,958 Vested and expected to vest as of June 30, 2021 6,458,407 $ 18.15 9.05 $ 54,961
Schedule of fair value of stock option awards on the grant date using the Black-Scholes option valuation model	The weighted-average assumptions that the Company used in the Black-Scholes option pricing model to determine the grant-date fair value of stock options granted to employees and non-employees on the date of grant were as follows for the three and six months ended June 30, 2021: Three Months Ended Six Months Ended June 30, 2021 2021 Risk-free interest rate 1.05 % 0.76 % Expected term (in years) 6.00 6.11 Expected volatility 86.42 % 85.58 % Expected dividend yield — % — %
Summary of stock-based compensation expense	Stock-based compensation expense was allocated as follows (in thousands): Three Months Ended Six Months Ended 2021 2020 2021 2020 Research and development $ 2,031 $ 153 $ 4,349 $ 255 General and administrative 3,369 132 5,717 177 Total stock-based compensation expense $ 5,400 $ 285 $ 10,066 $ 432

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Summary of basic and diluted net loss per share attributable to common stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended Six Months Ended 2021 2020 2021 2020 Numerator: Net loss $ (36,401) $ (11,568) $ (63,774) $ (19,898) Accretion and cumulative dividends on redeemable convertible preferred stock — (2,039) — (4,103) Gain on repurchase of redeemable convertible preferred stock — — — 493 Net loss attributable to common stockholders $ (36,401) $ (13,607) $ (63,774) $ (23,508) Denominator: Weighted average common shares outstanding, basic and diluted 41,569,782 1,642,484 40,028,807 1,635,913 Net loss per share attributable to common stockholders, basic and diluted $ (0.88) $ (8.28) $ (1.59) $ (14.37)
Summary of antidilutive securities excluded from computation of earnings per share	The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive: Three Months Ended Six Months Ended 2021 2020 2021 2020 Outstanding stock options 6,608,072 3,220,201 6,608,072 3,220,201 Unvested restricted common stock and restricted stock units 340,563 21,905 340,563 21,905 Series A redeemable convertible preferred stock — 3,773,820 — 3,773,820 Series B redeemable convertible preferred stock — 6,969,173 — 6,969,173 Series B-1 redeemable convertible preferred stock — 1,246,133 — 1,246,133 Series C redeemable convertible preferred stock — 3,992,463 — 3,992,463 6,948,635 19,223,695 6,948,635 19,223,695

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2021USD ($)$ / sharesshares	Jun. 30, 2021USD ($)candidate	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)candidate	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Class of Stock [Line Items]
Number of product candidates | candidate		3		3
Proceeds from issuance or sale of equity				$ 509,400
Net loss		$ 36,401	$ 11,568	63,774	$ 19,898
Accumulated deficit		213,328		213,328		$ 149,554
Cash, cash equivalents, and short-term investments		$ 339,200		$ 339,200
Follow-On Public Offering | Common Stock
Class of Stock [Line Items]
Number of shares issued in transaction | shares	5,750,000
Sale of stock, price per share | $ / shares	$ 18.25
Consideration received, gross amount	$ 104,900
Consideration received on transaction of sale of stock	$ 98,400
Over-Allotment Option | Common Stock
Class of Stock [Line Items]
Number of shares issued in transaction | shares	750,000

Marketable Securities - Investm

Marketable Securities - Investment Profile (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost, Maturity of one year or less	$ 114,463
Available-for-Sale, Cost, Maturity of one to two years	48,892
Available-for-sale, Cost	163,355
Available-for-Sale, Gross Unrealized Gain, Maturity of one year or less	7
Available-for-Sale, Gross Unrealized Gain, Maturity of one to two years	4
Available-for-sale, Gross Unrealized Gain	11
Available-for-Sale, Gross Unrealized Loss, Maturity of one year or less	(6)
Available-for-Sale, Gross Unrealized Loss, Maturity of one to two years	(55)
Available-for-sale, Gross Unrealized Loss	(61)
Available-for-Sale, Estimated Fair Value, Maturity of one year or less	114,464
Available-for-Sale, Estimated Fair Value, Maturity of one to two years	48,841
Available-for-sale, Estimated Fair Value	163,305	$ 0
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost, Maturity of one year or less	58,511
Available-for-Sale, Cost, Maturity of one to two years	36,692
Available-for-Sale, Gross Unrealized Gain, Maturity of one year or less	7
Available-for-Sale, Gross Unrealized Gain, Maturity of one to two years	0
Available-for-Sale, Gross Unrealized Loss, Maturity of one year or less	(6)
Available-for-Sale, Gross Unrealized Loss, Maturity of one to two years	(55)
Available-for-Sale, Estimated Fair Value, Maturity of one year or less	58,512
Available-for-Sale, Estimated Fair Value, Maturity of one to two years	36,637
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, Cost, Maturity of one year or less	55,952
Available-for-Sale, Gross Unrealized Gain, Maturity of one year or less	0
Available-for-Sale, Gross Unrealized Loss, Maturity of one year or less	0
Available-for-Sale, Estimated Fair Value, Maturity of one year or less	55,952
Debt securities issued by U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-Sale, Cost, Maturity of one to two years	12,200
Available-for-Sale, Gross Unrealized Gain, Maturity of one to two years	4
Available-for-Sale, Gross Unrealized Loss, Maturity of one to two years	0
Available-for-Sale, Estimated Fair Value, Maturity of one to two years	$ 12,204

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) $ in Millions	Jun. 30, 2021USD ($)security
Investments, Debt and Equity Securities [Abstract]
Number of securities | security	12
Securities, unrealized loss position, fair value | $	$ 73.8

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 335,579	$ 290,931
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	184,478	290,931
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	151,101	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	172,274	290,931
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	172,274	290,931
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	$ 0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	95,149
Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	95,149
Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	55,952
Commercial paper | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Commercial paper | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	55,952
Commercial paper | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Debt securities issued by U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	12,204
Debt securities issued by U.S. government agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	12,204
Debt securities issued by U.S. government agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Debt securities issued by U.S. government agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued external research and development expenses	$ 4,848	$ 4,206
Accrued personnel-related expenses	2,179	5,516
Accrued other	799	1,147
Total accrued expenses	$ 7,826	$ 10,869

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2021	May 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Operating lease right-of-use assets	$ 4,400		$ 754
Operating lease, liability	4,122
Operating lease liabilities	553		763
Non-current portion of operating lease liabilities	$ 3,959		0
Remaining lease term	4 years 7 months 6 days
Discount rate	9.00%
Office Space in Boston Massachusetts
Loss Contingencies [Line Items]
Percentage increase in annual base rent	2.00%
Restricted cash, noncurrent	$ 400
Operating lease right-of-use assets	4,000	$ 4,100
Operating lease, liability		$ 4,100
Operating lease liabilities	200
Non-current portion of operating lease liabilities	$ 4,000
Office Space in Cambridge Massachusetts
Loss Contingencies [Line Items]
Percentage increase in annual base rent	1.00%
Restricted cash, current	$ 600		$ 600

Commitments and Contingencies_2

Commitments and Contingencies - Future Lease Payments (Details) $ in Thousands	Jun. 30, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021	$ 0
2022	1,160
2023	1,270
2024	1,296
2025	1,321
2026	110
Total future lease payments	5,157
Less: interest	(1,035)
Present value of operating lease liabilities	$ 4,122

Common Stock and Preferred St_3

Common Stock and Preferred Stock - Additional Information (Details) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Schedule Of Common Stock Reserved For Future Issuance [Abstract]
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Treasury shares	0	0
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001

Common Stock and Preferred St_4

Common Stock and Preferred Stock - Summary of Common Stock Reserved For Future Issuance (Details) - shares	Jun. 30, 2021	Dec. 31, 2020
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	10,740,935	9,308,424
Share-based payment arrangement, option
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	6,608,072	5,944,546
Share-based payment arrangement | Shares reserved for future awards under the 2020 Stock Option and Incentive Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	3,138,096	3,036,776
Share-based payment arrangement | Shares reserved for future awards under the 2020 Employee Stock Purchase Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	654,204	327,102
Restricted Stock
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	340,563	0

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value of stock options granted, Per share	$ 16,520,000	$ 31.99
Unrecognized compensation expense related to unvested stock based awards	$ 80.2	$ 80.2
Unrecognized compensation expense expected to be recognised		3 years 21 days
2020 Employee Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	5,184,455	5,184,455	3,271,028
2017 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	5,937,763	5,937,763	5,937,763
2020 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	654,204	654,204	327,102

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Shares
Beginning balance (in shares) | shares	0
Issued (in shares) | shares	352,663
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(12,100)
Ending balance (in shares) | shares	340,563
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) | $ / shares	$ 0
Issued (in dollars per share) | $ / shares	50.52
Vested (in dollars per share) | $ / shares	0
Forfeitures (in dollars per shares) | $ / shares	52.53
Unvested ending balance (in dollars per share) | $ / shares	$ 50.45

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021
Number of Shares
Beginning balance (in shares)	5,944,546
Granted (in shares)	1,548,403
Exercised (in shares)	(674,619)
Canceled or forfeited (in shares)	(210,258)
Ending balance (in shares)	6,608,072
Number of shares exercisable (in shares)	971,361
Vested and expected to vest (in shares)	6,458,407
Weighted Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 7.47
Granted (in dollars per share)	44.78
Exercised (in dollars per share)	2.46
Cancelled or forfeited (in dollars per share)	20.58
Ending balance (in dollars per share)	16.30
Exercisable (in dollars per share)	3.97
Vested and expected to vest (in dollars per share)	$ 18.15
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term outstanding	8 years 11 months 23 days
Weighted average remaining contractual term exercisable	7 years 10 months 9 days
Weighted average remaining contractual term vested and expected to vest	9 years 18 days
Aggregate intrinsic value exercised	$ 17,696
Aggregate intrinsic value outstanding	56,586
Aggregate intrinsic value exercisable	13,958
Aggregate intrinsic value vested and expected to vest	$ 54,961

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	1.05%	0.76%
Expected term (in years)	6 years	6 years 1 month 9 days
Expected volatility	86.42%	85.58%
Expected dividend yield	0.00%	0.00%

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 5,400	$ 285	$ 10,066	$ 432
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	2,031	153	4,349	255
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 3,369	$ 132	$ 5,717	$ 177

Net Loss per Share - Summary of

Net Loss per Share - Summary of basic and diluted net loss per share attributable to common stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net loss	$ (36,401)	$ (11,568)	$ (63,774)	$ (19,898)
Accretion and cumulative dividends on redeemable convertible preferred stock	0	(2,039)	0	(4,103)
Gain on repurchase of redeemable convertible preferred stock	0	0	0	493
Net loss attributable to common stockholders	$ (36,401)	$ (13,607)	$ (63,774)	$ (23,508)
Denominator:
Weighted average common shares outstanding, basic (in shares)	41,569,782	1,642,484	40,028,807	1,635,913
Weighted average common shares outstanding, diluted (in shares)	41,569,782	1,642,484	40,028,807	1,635,913
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.88)	$ (8.28)	$ (1.59)	$ (14.37)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.88)	$ (8.28)	$ (1.59)	$ (14.37)

Net Loss per Share - Summary _2

Net Loss per Share - Summary of antidilutive securities excluded from computation of earnings per share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	6,948,635	19,223,695	6,948,635	19,223,695
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	6,608,072	3,220,201	6,608,072	3,220,201
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	340,563	21,905	340,563	21,905
Series A Preferred Stock | Convertible Preferred Stocks
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	3,773,820	0	3,773,820
Series B Preferred Stock | Convertible Preferred Stocks
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	6,969,173	0	6,969,173
Series B-1 Preferred Stock | Convertible Preferred Stocks
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,246,133	0	1,246,133
Series C Preferred Stock | Convertible Preferred Stocks
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	3,992,463	0	3,992,463

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) $ in Millions	Jun. 30, 2021USD ($)
RogCon Inc.
Related Party Transaction [Line Items]
Due to related parties	$ 0.3