Prelude Therapeutics (PRLD) 10-Q3 Aug 232023 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2023	Aug. 01, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Trading Symbol	PRLD
Entity Registrant Name	PRELUDE THERAPEUTICS INC
Entity Central Index Key	0001678660
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		54,808,715
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity File Number	001-39527
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1384762
Entity Address, Address Line One	200 Powder Mill Road
Entity Address, City or Town	Wilmington
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19803
City Area Code	302
Local Phone Number	467-1280
Document Quarterly Report	true
Document Transition Report	false

BALANCE SHEETS (UNAUDITED)

BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 26,446	$ 30,605
Marketable securities	228,543	171,123
Prepaid expenses and other current assets	5,221	2,652
Total current assets	260,210	204,380
Restricted cash	4,044	4,044
Property and equipment, net	6,082	4,908
Right-of-use asset	918	1,792
Prepaid expenses and other non-current assets	9,357	5,376
Total assets	280,611	220,500
Current liabilities:
Accounts payable	5,585	6,777
Accrued expenses and other current liabilities	8,667	13,093
Operating lease liability	938	1,832
Total current liabilities	15,190	21,702
Other liabilities	3,361	3,361
Total liabilities	18,551	25,063
Commitments (Note 8)
Stockholders’ equity:
Additional paid-in capital	655,473	531,682
Accumulated other comprehensive (loss)	(711)	(1,692)
Accumulated deficit	(392,707)	(334,558)
Total stockholders’ equity	262,060	195,437
Total liabilities and stockholders’ equity	280,611	220,500
Voting Common Stock
Stockholders’ equity:
Common stock	4	4
Non-voting Common Stock
Stockholders’ equity:
Common stock	$ 1	$ 1

BALANCE SHEETS (PARENTHETICAL)

BALANCE SHEETS (PARENTHETICAL) (UNAUDITED) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	487,149,741	487,149,741
Common stock, shares, issued	41,958,456	36,496,994
Common stock, shares, outstanding	41,958,456	36,496,994
Non-voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	12,850,259	12,850,259
Common stock, shares, issued	12,850,259	11,402,037
Common stock, shares, outstanding	12,850,259	11,402,037

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating expenses:
Research and development	$ 24,966	$ 21,310	$ 46,800	$ 44,131
General and administrative	7,432	8,151	14,713	15,618
Total operating expenses	32,398	29,461	61,513	59,749
Loss from operations	(32,398)	(29,461)	(61,513)	(59,749)
Other income, net	1,967	2,087	3,364	2,910
Net loss	$ (30,431)	$ (27,374)	$ (58,149)	$ (56,839)
Per share information:
Net loss per share of common stock, basic	$ (0.54)	$ (0.58)	$ (1.12)	$ (1.20)
Net loss per share of common stock, diluted	$ (0.54)	$ (0.58)	$ (1.12)	$ (1.20)
Weighted average common shares outstanding, basic	56,240,491	47,276,684	52,012,330	47,172,136
Weighted average common shares outstanding, diluted	56,240,491	47,276,684	52,012,330	47,172,136
Comprehensive loss
Net loss	$ (30,431)	$ (27,374)	$ (58,149)	$ (56,839)
Unrealized (loss) gain on marketable securities, net of tax	(313)	19	981	(1,583)
Comprehensive loss	$ (30,744)	$ (27,355)	$ (57,168)	$ (58,422)

STATEMENTS OF CHANGES IN STOCKH

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock Voting Common Stock	Common Stock Non-voting Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2021	$ 285,897	$ 4	$ 1	$ 505,723	$ (711)	$ (219,120)
Beginning balance (shares) at Dec. 31, 2021		36,200,299	11,402,037
Issuance of common stock upon exercise of stock options & vesting of RSU's	153			153
Issuance of common stock upon exercise of stock options & vesting of RSU's, (shares)		93,032
Unrealized gain (loss) on marketable securities, net of tax	(1,602)				(1,602)
Stock-based compensation expense	6,829			6,829
Net loss	(29,465)					(29,465)
Ending balance at Mar. 31, 2022	261,812	$ 4	$ 1	512,705	(2,313)	(248,585)
Ending balance (shares) at Mar. 31, 2022		36,293,331	11,402,037
Beginning balance at Dec. 31, 2021	285,897	$ 4	$ 1	505,723	(711)	(219,120)
Beginning balance (shares) at Dec. 31, 2021		36,200,299	11,402,037
Net loss	(56,839)
Ending balance at Jun. 30, 2022	240,844	$ 4	$ 1	519,092	(2,294)	(275,959)
Ending balance (shares) at Jun. 30, 2022		36,369,248	11,402,037
Beginning balance at Mar. 31, 2022	261,812	$ 4	$ 1	512,705	(2,313)	(248,585)
Beginning balance (shares) at Mar. 31, 2022		36,293,331	11,402,037
Issuance of common stock upon exercise of stock options & vesting of RSU's	59			59
Issuance of common stock upon exercise of stock options & vesting of RSU's, (shares)		31,253
Issuance of common stock under ESPP, (shares)		68,080
Issuance of common stock under ESPP	300			300
Unrealized gain (loss) on marketable securities, net of tax	19				19
Stock-based compensation expense	6,028			6,028
Stock-based compensation expense (shares)		(23,416)
Net loss	(27,374)					(27,374)
Ending balance at Jun. 30, 2022	240,844	$ 4	$ 1	519,092	(2,294)	(275,959)
Ending balance (shares) at Jun. 30, 2022		36,369,248	11,402,037
Beginning balance at Dec. 31, 2022	195,437	$ 4	$ 1	531,682	(1,692)	(334,558)
Beginning balance (shares) at Dec. 31, 2022		36,496,994	11,402,037
Issuance of common stock upon exercise of stock options & vesting of RSUs	28			28
Issuance of common stock upon exercise of stock options & vesting of RSUs, (shares)		17,224
Unrealized gain (loss) on marketable securities, net of tax	1,294				1,294
Stock-based compensation expense	6,256			6,256
Net loss	(27,718)					(27,718)
Ending balance at Mar. 31, 2023	175,297	$ 4	$ 1	537,966	(398)	(362,276)
Ending balance (shares) at Mar. 31, 2023		36,514,218	11,402,037
Beginning balance at Dec. 31, 2022	$ 195,437	$ 4	$ 1	531,682	(1,692)	(334,558)
Beginning balance (shares) at Dec. 31, 2022		36,496,994	11,402,037
Issuance of common stock and prefunded warrants, net of issuance costs of $2,599, shares		2,264,456
Issuance of common stock upon exercise of stock options & vesting of RSU's, (shares)	17,685
Net loss	$ (58,149)
Ending balance at Jun. 30, 2023	262,060	$ 4	$ 1	655,473	(711)	(392,707)
Ending balance (shares) at Jun. 30, 2023		41,958,456	12,850,259
Beginning balance at Mar. 31, 2023	175,297	$ 4	$ 1	537,966	(398)	(362,276)
Beginning balance (shares) at Mar. 31, 2023		36,514,218	11,402,037
Issuance of common stock upon exercise of stock options & vesting of RSUs	3			3
Issuance of common stock upon exercise of stock options & vesting of RSUs, (shares)		40,461
Issuance of common stock and prefunded warrants, net of issuance costs of $2,599, shares		5,312,978	1,448,222
Issuance of common stock and prefunded warrants, net of issuance costs of $2,599	110,423			110,423
Issuance of common stock under ESPP, (shares)		90,799
Issuance of common stock under ESPP	348			348
Unrealized gain (loss) on marketable securities, net of tax	(313)				(313)
Stock-based compensation expense	6,733			6,733
Net loss	(30,431)					(30,431)
Ending balance at Jun. 30, 2023	$ 262,060	$ 4	$ 1	$ 655,473	$ (711)	$ (392,707)
Ending balance (shares) at Jun. 30, 2023		41,958,456	12,850,259

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) (PARENTHETICAL) $ in Millions	3 Months Ended
	Jun. 30, 2023 USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance costs	$ 2.6

STATEMENTS OF CASH FLOWS (UNAUD

STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows used in operating activities:
Net loss	$ (58,149)	$ (56,839)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	559	625
Noncash lease expense	874	842
Stock-based compensation	12,989	12,857
Amortization of premium and discount on marketable securities, net	(805)	1,784
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,540)	1,557
Accounts payable	(1,333)	(838)
Accrued expenses and other liabilities	(4,493)	495
Long-term prepaid expenses and other long-term assets	(4,010)
Operating lease liabilities	(894)	(846)
Net cash used in operating activities	(57,802)	(40,363)
Cash flows (used in) provided by investing activities:
Purchases of marketable securities	(128,134)	(27,140)
Proceeds from maturities of marketable securities	72,500	87,579
Purchases of property and equipment	(1,793)	(1,710)
Net cash (used in) provided by investing activities	(57,427)	58,729
Cash flows provided by financing activities:
Proceeds from issuance of common stock and pre-funded warrants, net of offering costs	110,691
Proceeds from the issuance of common stock under ESPP	348	300
Proceeds from the issuance of common stock in connection with the exercise of stock options	31	212
Net cash provided by financing activities	111,070	512
Net (decrease) increase in cash, cash equivalents and restricted cash	(4,159)	18,878
Cash, cash equivalents, and restricted cash at beginning of period	34,649	35,872
Cash, cash equivalents, and restricted cash at end of period	30,490	54,750
Supplemental disclosures:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities		928
Property and equipment in accounts payable	30	77
Offering costs in accrued expenses and other current liabilities	67
Offering costs in accounts payable	201
Unrealized gain(loss) on marketable securities	$ 981	$ (1,583)

Background

Background	6 Months Ended
Background	Jun. 30, 2023
Background [Abstract]
Background	1. Background Prelude Therapeutics Incorporated (the “Company”) is a clinical-stage fully integrated oncology company built on a foundation of drug discovery excellence to deliver novel precision cancer medicines to underserved patients. Since beginning operations in 2016, the Company has devoted substantially all its efforts to research and development, conducting preclinical and clinical studies, recruiting management and technical staff, administration, and raising capital.

Risks and Liquidity

Risks and Liquidity	6 Months Ended
Risks and Liquidity	Jun. 30, 2023
Risks And Liquidity [Abstract]
Risks and Liquidity	2. Risks and liquidity The Company is subject to a number of risks common to early-stage companies in the biotechnology industry. Principal among these risks are the uncertainties in the development process, development of the same or similar technological innovations by competitors, protection of proprietary technology, dependence on key personnel, compliance with government regulations and approval requirements, and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance-reporting capabilities. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval, or that any approved products will be commercially viable. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and contractors. Since its inception, the Company has incurred operating losses and had an accumulated deficit of $ 392.7 million at June 30, 2023. The Company has no revenue to date and devotes its efforts to research and development. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its product candidates currently in development. The Company believes that its cash, cash equivalents, and marketable securities as of June 30, 2023 will be sufficient to fund its operating expenses and capital expenditure requirements for at least the next twelve months. To fund its operating expenses and capital expenditure requirements after that date, the Company plans to seek additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into strategic alliances or other arrangements on favorable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be required to delay, reduce or eliminate research and development programs, product portfolio expansion or future commercialization efforts, which could adversely affect its business prospects. Inflation has the potential to adversely affect the Company's liquidity, business, financial condition and results of operations by increasing the Company's overall cost structure. The existence of inflation in the economy has resulted in, and may continue to result in, higher interest rates and capital costs, supply shortages, increased costs of labor, components, manufacturing and shipping, as well as weakening exchange rates and other similar effects. As a result of inflation, the Company has experienced, and may continue to experience cost increases. Although the Company may take measures to mitigate the effects of inflation, if these measures are not effective, the Company's business, financial condition, results of operations and liquidity could be materially adversely affected. Even if such measures are effective, there could be a difference between the timing of when these beneficial actions impact the Company's results of operations and when the costs of inflation are incurred.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of significant accounting policies The summary of significant accounting policies included in the Company’s financial statements for the year ended December 31, 2022 can be found in “Note 3. Summary of significant accounting policies” of the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 15, 2023. Those policies have not materially changed. Basis of presentation The accompanying unaudited interim financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three and six months ended June 30, 2023 are not necessarily indicative of the results that may be expected for the year ending December 31, 2023. The accompanying unaudited interim financial statements should be read in conjunction with the annual audited financial statements and related notes as of and for the year ended December 31, 2022 found in the Company's Annual Report on Form 10-K filed with the SEC on March 15, 2023. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of estimates The preparation of the unaudited interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the unaudited interim financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed and the effects of the revisions are reflected in the accompanying unaudited interim financial statements in the period they are determined to be necessary. The most significant estimate relates to accrued clinical trial expenses. Income taxes Based upon the historical and anticipated future losses, management has determined that the deferred tax assets generated by net operating losses and research and development credits do not meet the more likely than not threshold for realizability. Accordingly, a full valuation allowance has been recorded against the Company’s net deferred tax assets as of June 30, 2023 and December 31, 2022. Cash, Cash Equivalents and Restricted cash The Company’s cash equivalents include short-term highly liquid investments with an original maturity of 90 days or less when purchased and are carried at fair value in the accompanying balance sheets. Restricted cash consists of a letter of credit with Silicon Valley Bank, a division of First Citizens Bank, for the benefit of the landlord in connection with the Company’s Chestnut Run Lease. See Note 8 for further details. The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) June 30, December 31, Cash and cash equivalents $ 26,446 $ 30,605 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 30,490 $ 34,649 Marketable Securities The Company’s marketable securities consist of investments in corporate debt securities, United States (“U.S.”) government debt securities, and agency securities that are classified as available-for-sale. The securities are carried at fair value with the unrealized gains and losses, net of tax, included in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses as well as credit losses, if any, on marketable securities are included in the Company’s statements of operations. The Company classifies marketable securities that are available for use in current operations as current assets on the balance sheets. Net Loss Per Share Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period, including pre-funded warrants to purchase shares of common stock that were issued in a financing transaction in May 2023 (Note 7). The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted stock awards as these instruments are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise of securities, such as stock options, and the effect from unvested restricted stock awards and restricted stock units which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The Company’s unvested restricted stock awards entitle the holder to participate in dividends and earnings of the Company, and, if the Company were to recognize net income, it would have to use the two-class method to calculate earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the unvested restricted stock awards have no obligation to fund losses. The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: June 30, 2023 2022 Unvested restricted stock awards 81,044 356,432 Unvested restricted stock units 125,000 170,000 Stock options 12,083,788 8,915,289 12,289,832 9,441,721 Amounts in the above table reflect the common stock equivalents. Recently Issued Accounting Pronouncements Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these unaudited interim financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued ASU Update No. 2020-06, Debt — Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging — Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (ASU 2020-06) (“ ASU 2020-06 ”). ASU 2020-06 eliminated the beneficial conversion and cash conversion accounting models in ASC 470-20 which required separate accounting for embedded conversion features and simplified the settlement assessment to determine whether an instrument qualifies for equity classification. The Company early adopted the new standard on January 1, 2023 .

Marketable Securities

Marketable Securities	6 Months Ended
Marketable Securities	Jun. 30, 2023
Investments Debt And Equity Securities [Abstract]
Marketable Securities	4. Marketable Securities The following is a summary of the Company’s marketable securities. (in thousands) Amortized Cost Gross unrealized gain Gross unrealized loss Fair Value June 30, 2023 Marketable securities: Agency securities $ 8,381 $ — $ ( 47 ) $ 8,334 Corporate debt securities 123,789 14 ( 385 ) 123,418 U.S. government securities 97,084 3 ( 296 ) 96,791 Total $ 229,254 $ 17 $ ( 728 ) $ 228,543 December 31, 2022 Marketable securities: Corporate debt securities $ 163,208 $ 7 $ ( 1,672 ) $ 161,543 U.S. government securities 9,607 — ( 27 ) 9,580 Total $ 172,815 $ 7 $ ( 1,699 ) $ 171,123 The Company’s marketable securities generally have contractual maturity dates of 13 months or less. As of June 30, 2023 , the Company had 39 securities with a total fair market value of $ 199.1 million in an unrealized loss position. The Company believes that any unrealized losses associated with the decline in value of its securities is temporary, is primarily related to market factors 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 and an allowance for credit losses was not recognized.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
Fair Value of Financial Instruments	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The Company follows the provisions of ASC 820, Fair Value Measurement, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories: • Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. • Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities. • Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis: Fair value measurement at reporting date using (in thousands) Quoted prices Significant Significant June 30, 2023 Assets: Cash equivalents (Money Market Funds) $ 25,435 $ — $ — Marketable securities: Agency securities — 8,334 — Corporate debt securities — 123,418 — U.S. government securities — 96,791 — Total $ 25,435 $ 228,543 $ — December 31, 2022 Assets: Cash equivalents (Money Market Funds) $ 25,996 $ — $ — Marketable securities: Corporate debt securities — 161,543 — U.S. government securities — 9,580 — Total $ 25,996 $ 171,123 $ —

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
Accrued Expenses and Other Current Liabilities	Jun. 30, 2023
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: (in thousands) June 30, December 31, Compensation and related benefits $ 5,043 $ 5,682 Research and development 2,815 6,887 Other 809 524 $ 8,667 $ 13,093

Common Stock

Common Stock	6 Months Ended
Common Stock	Jun. 30, 2023
Equity [Abstract]
Common Stock	7. Common Stock The Company has two classes of common stock; “voting common stock” and “non-voting common stock.” The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders . Except as otherwise required by law, the holders of non-voting common stock shall not be entitled to vote at any meetings of stockholders (or written actions in lieu of meetings) and the shares of non-voting common stock shall not be included in determining the number of shares voting or entitled to vote on any matter. Unless required by law, there shall be no cumulative voting. Any holder of non-voting common stock may elect to convert each share of non-voting common stock into one fully paid and non-assessable share of voting common stock at any time by providing written notice to the Company; provided that as a result of such conversion, such holder, together with its affiliates and any members of a Schedule 13(d) group with such holder, would not beneficially own in excess of 9.99 % of the Company’s common stock immediately prior to and following such conversion, unless otherwise as expressly provided for in the Company’s restated certificate of incorporation. However, this ownership limitation may be increased (not to exceed 19.99 %) or decreased to any other percentage designated by such holder of non-voting common stock upon 61 days’ notice to the Company. Second quarter 2023 financing During the second quarter of 2023, the Company sold 6,761,200 shares of its common stock which comprised of (i) 5,312,978 shares of its voting common stock and (ii) 1,448,222 shares of its non-voting common stock at a price of $ 5.75 per share and to certain investors in lieu of common stock, the Company sold pre-funded warrants to purchase 12,895,256 shares of voting common stock at a price of $ 5.7499 per pre-funded warrant, resulting in gross proceeds of $ 113.0 million. Offering costs of $ 2.6 million, of which $ 0.3 million were previously paid and deferred, were recorded to additional paid-in capital in the accompanying balance sheets, resulting in net proceeds of $ 110.4 million. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $ 0.0001 per share exercise price of such pre-funded warrant. As of June 30, 2023, no pre-funded warrants had been exercised. Of the voting common stock issued, 2,264,456 shares were purchased by the Company’s underwriters in connection with a 30-day option at a price of $ 5.75 per share. The pre-funded warrants were classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company’s common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return.

Commitments

Commitments	6 Months Ended
Commitments	Jun. 30, 2023
Commitments And Contingencies Disclosure [Abstract]
Commitments	8. Commitments Leases The Company leases office and laboratory space in Wilmington, Delaware under a noncancelable lease (the “Lease”). Future minimum annual lease payments under the Lease at June 30, 2023 are as follows: (in thousands) 2023 (remaining) $ 964 Total undiscounted lease payments 964 Less imputed interest ( 26 ) Current lease liability $ 938 In August 2022, we entered into an amendment (the “Lease Amendment”) to the lease agreement for office and lab space at Chestnut Run Plaza in Wilmington, Delaware (the “Chestnut Run Lease”). The Chestnut Run Lease has a commencement date of the earlier of (i) the Landlord Work Substantial Completion Date (as such term is defined in the Chestnut Run Lease), or (ii) the date the Company takes possession of the premises for the conduct of the Company’s business (the “Commencement Date”). The Chestnut Run Lease premises includes approximately 81,000 rentable square feet, located at Chestnut Run Plaza in Wilmington, Delaware (the "Premises"). Under the terms of the Chestnut Run Lease, the landlord has provided an allowance towards the cost of completing tenant improvements for the Premises and improvements resulting from both the landlord's build-out and the Company's improvements are the landlord's assets for accounting purposes. Costs incurred by the Company related to the tenant improvements in excess of the landlord's allowance will be treated as prepaid rent and will increase the right-of-use asset once the accounting commencement date occurs. As of June 30, 2023 , the Company recorded $ 9.0 million of prepaid rent. Upon the Commencement Date, which is expected to happen in the third quarter of 2023, the Company will recognize a right-of-use asset and operating lease liability in accordance with ASC 842, Leases. The Chestnut Run Lease has an initial term of 162 months with 3 five-year extension options and certain expansion rights. The estimated rent payments related to the Chestnut Run Lease are as follows: (in thousands) 2023 (remaining) $ — 2024 1,299 2025 2,784 2026 2,986 2027 3,060 2028 3,137 Thereafter 29,371 The Company paid a security deposit for the Chestnut Run Lease in the form of a letter of credit with Silicon Valley Bank, a division of First Citizens Bank, of $ 4.0 million, which is included in the balance sheet as restricted cash as of June 30, 2023 . The security deposit may be reduced to $ 0.5 million over time in accordance with the terms of the Chestnut Run Lease. In connection with the Company’s expansion of operations in the State of Delaware, the Company was approved for a grant from the State of Delaware in 2021 that will provide up to $ 5.5 million in reimbursements over three years for the development of lab space in addition to increasing jobs in Delaware to meet specific targeted levels through 2023 . During the third quarter of 2022, the Company was approved for an additional grant from the State of Delaware for the development of lab space in the amount of $ 1.0 million. In 2022, the Company received cash of $ 3.4 million from the grants for the development of lab space. The Company has deferred the recognition of these grant funds as they relate to capitalized costs and has classified them as long-term liabilities on the balance sheet. The Company will recognize the grant funds in other income as grant income over the useful life of the related assets. If, after two years from the disbursement date, the incurred costs for lab space are less than the $ 3.4 million received, the Company is required to pay back the difference between total funds received and allowable costs incurred. Additionally, if the Company leaves the State of Delaware within five years of the disbursement, the Company is required to return an amount equal to the amount of grant funds disbursed on a pro-rated basis. Rent expense was $ 0.6 million for both the three months ended June 30, 2023 and 2022 . Rent expense was $ 1.1 million for both the six months ended June 30, 2023 and 2022. Employment Agreements The Company entered into employment agreements with key personnel providing for compensation and severance in certain circumstances, as defined in the respective employment agreements. 401(k) Defined Contribution Plan The Company sponsors a 401(k) defined‑contribution plan covering all employees. Participants are permitted to contribute up to 100 % of their eligible annual pretax compensation up to an established federal limit on aggregate participant contributions. The Company provides a match of a maximum amount of 3 % of the participant’s compensation. For the three months ended June 30, 2023 and 2022 , the Company made matching contributions of $ 0.2 million and $ 0.1 million, res pectively. For the six months ended June 30, 2023 and 2022 , the Company made matching contributions of $ 0.4 million and $ 0.3 million, respectively. Other Research and Development Arrangements The Company enters into agreements with clinical research organizations ("CROs") to assist in the performance of research and development activities. Expenditures to CROs will represent a significant cost in clinical development for the Company.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
Stock-Based Compensation	Jun. 30, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation The Company has two equity incentive plans: the 2016 Equity Incentive Plan, as amended, and the 2020 Equity Incentive Plan. New awards can only be granted under the 2020 Equity Incentive Plan (the “Plan”) and as of June 30, 2023 , 4,823,436 shares were available for future grants. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year and continuing for ten years beginning on January 1, 2021, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year. The Plan provides for the granting of common stock, incentive stock options, nonqualified stock options, restricted stock awards, restricted stock units and/or stock appreciation rights to employees, directors, and other persons, as determined by the Company’s board of directors. The Company’s stock options vest based on the terms in each award agreement, generally over four-year periods with 25 % of options vesting after one year and then monthly thereafter, and have a term of ten years . The Company measures stock-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations: Three Months Ended Six Months Ended (in thousands) 2023 2022 2023 2022 Research and development $ 3,234 $ 2,472 $ 6,225 $ 5,672 General and administrative 3,499 3,556 6,764 7,185 $ 6,733 $ 6,028 $ 12,989 $ 12,857 Stock Options The following table summarizes stock option activity for the periods indicated: Number Weighted Weighted Outstanding at January 1, 2023 9,390,930 $ 12.08 8.31 Granted 2,977,898 $ 6.91 Exercised ( 17,685 ) $ 1.77 Forfeited ( 267,355 ) $ 17.72 Outstanding at June 30, 2023 12,083,788 $ 10.70 8.25 Exercisable at June 30, 2023 4,941,993 $ 11.56 7.28 At June 30, 2023 , the aggregate intrinsic value of outstanding options and exercisable options was $ 5.4 million and $ 4.8 million, respectively. The following table summarizes information about stock options outstanding at June 30, 2023 under the Plan: Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted Average Weighted Number Weighted $ 0.31 - $ 4.88 2,925,468 7.12 $ 2.74 2,188,856 $ 2.34 $ 4.89 - $ 7.50 4,100,967 9.49 6.57 35,665 6.03 $ 7.51 - $ 13.04 3,218,825 7.80 11.85 1,755,910 12.28 $ 13.05 - $ 88.98 1,838,528 8.06 30.53 961,562 31.44 12,083,788 4,941,993 The weighted-average grant date fair value of options granted was $ 5.04 and $ 6.00 per option for the six months ended June 30, 2023 and 2022 , respectively. The aggregate intrinsic value of options exercised was $ 80 thousand for the six months ended June 30, 2023 . The Company recorded stock-based compensation expense of $ 6.5 million and $ 5.7 million for the three months ended June 30, 2023 and 2022 , respectively, related to stock options. The Company recorded stock-based compensation expense of $ 12.4 million and $ 12.2 million for the six months ended June 30, 2023 and 2022, respectively, related to stock options. As of June 30, 2023 , the total unrecognized compensation expense related to unvested stock option awards was $ 50.5 million, which the Company expects to recognize over a weighted-average period of 2.37 years. The fair value of each option was estimated on th e date of grant using the weighted average assumptions in the table below: Six months ended 2023 2022 Expected volatility 83.51 % 84.82 % Risk-free interest rate 3.80 % 2.39 % Expected life (in years) 6.02 6.01 Expected dividend yield — — Restricted Stock Awards and Units The Company issues restricted stock awards (“RSA”) to employees that generally vest over a four-year period with 25 % of awards vesting after one year and then monthly thereafter. Any unvested shares will be forfeited upon termination of services. The fair value of an RSA is equal to the fair market value price of the Company’s common stock on the date of grant. RSA expense is recorded on a straight-line basis over the vesting period. The following table summarizes activity related to RSA stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2023 201,716 $ 2.81 Vested ( 120,672 ) $ 2.50 Unvested balance at June 30, 2023 81,044 $ 3.26 The Company recorded stock-based compensation expense of $ 0.1 million and $ 0.2 million for the three months ended June 30, 2023 and 2022 , respectively, related to RSAs. The Company recorded stock-based compensation expense of $ 0.3 million and $ 0.4 million for the six months ended June 30, 2023 and 2022, respectively, related to RSAs. As of June 30, 2023 , the total unrecognized expense related to all RSAs was $ 0.3 million, which the Company expects to recognize over a weighted-average period of 0.74 years. The Company granted restricted stock units (“RSU”) to employees that generally vest over a four-year period with 25 % of awards vesting after one year and then quarterly thereafter. Any unvested units will be forfeited upon termination of services. The following table summarizes activity related to RSU stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2023 165,000 $ 6.08 Vested ( 40,000 ) $ 5.70 Unvested balance at June 30, 2023 125,000 $ 6.21 The Company recorded stock-based compensation expense of $ 0.1 million for both the three and six months ended June 30, 2023 and 2022, related to RSUs. At June 30, 2023 , the total unrecognized expense related to the RSUs was $ 0.7 million, which the Company expects to recognize over 2.61 years. Employee Stock Purchase Plan The Company has an Employee Stock Purchase Plan (the “ESPP”), which, as of June 30, 2023 , had 1,698,350 shares of common stock reserved for future issuance. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the ESPP shall automatically increase on January 1st of each year and continuing for ten years beginning in 2021, in an amount equal to one percent of the total number of shares of all classes of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year. On January 1, 2023, 478,990 shares were added to the ESPP. Under the ESPP, eligible employees can purchase the Company’s common stock through accumulated payroll deductions at such times as are established by the compensation committee. Eligible employees may purchase the Company’s common stock at 85 % of the lower of the fair market value of the Company’s common stock on the first day of the offering period or on the last day of the offering period. Eligible employees may contribute up to 15 % of their eligible compensation. Under the ESPP, a participant may not accrue rights to purchase more than $ 25,000 worth of the Company’s common stock for each calendar year in which such right is outstanding. The ESPP is considered compensatory under the FASB stock compensation rules. Accordingly, share-based compensation expense is determined based on the option’s grant-date fair value as estimated by applying the Black Scholes option-pricing model and is recognized over the withholding period. The Company recognized share-based compensation expense of $ 0.1 million for both the three months ended June 30, 2023 and 2022 , related to the ESPP. The Company recognized share-based compensation expense of $ 0.2 million and $ 0.1 million for the six months ended June 30, 2023 and 2022 , respectively, related to the ESPP.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying unaudited interim financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three and six months ended June 30, 2023 are not necessarily indicative of the results that may be expected for the year ending December 31, 2023. The accompanying unaudited interim financial statements should be read in conjunction with the annual audited financial statements and related notes as of and for the year ended December 31, 2022 found in the Company's Annual Report on Form 10-K filed with the SEC on March 15, 2023. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Use of estimates	Use of estimates The preparation of the unaudited interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the unaudited interim financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed and the effects of the revisions are reflected in the accompanying unaudited interim financial statements in the period they are determined to be necessary. The most significant estimate relates to accrued clinical trial expenses.
Income taxes	Income taxes Based upon the historical and anticipated future losses, management has determined that the deferred tax assets generated by net operating losses and research and development credits do not meet the more likely than not threshold for realizability. Accordingly, a full valuation allowance has been recorded against the Company’s net deferred tax assets as of June 30, 2023 and December 31, 2022.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted cash The Company’s cash equivalents include short-term highly liquid investments with an original maturity of 90 days or less when purchased and are carried at fair value in the accompanying balance sheets. Restricted cash consists of a letter of credit with Silicon Valley Bank, a division of First Citizens Bank, for the benefit of the landlord in connection with the Company’s Chestnut Run Lease. See Note 8 for further details. The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) June 30, December 31, Cash and cash equivalents $ 26,446 $ 30,605 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 30,490 $ 34,649
Marketable Securities	Marketable Securities The Company’s marketable securities consist of investments in corporate debt securities, United States (“U.S.”) government debt securities, and agency securities that are classified as available-for-sale. The securities are carried at fair value with the unrealized gains and losses, net of tax, included in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses as well as credit losses, if any, on marketable securities are included in the Company’s statements of operations. The Company classifies marketable securities that are available for use in current operations as current assets on the balance sheets.
Net Loss Per Share	Net Loss Per Share Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period, including pre-funded warrants to purchase shares of common stock that were issued in a financing transaction in May 2023 (Note 7). The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted stock awards as these instruments are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise of securities, such as stock options, and the effect from unvested restricted stock awards and restricted stock units which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The Company’s unvested restricted stock awards entitle the holder to participate in dividends and earnings of the Company, and, if the Company were to recognize net income, it would have to use the two-class method to calculate earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the unvested restricted stock awards have no obligation to fund losses. The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: June 30, 2023 2022 Unvested restricted stock awards 81,044 356,432 Unvested restricted stock units 125,000 170,000 Stock options 12,083,788 8,915,289 12,289,832 9,441,721 Amounts in the above table reflect the common stock equivalents.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these unaudited interim financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued ASU Update No. 2020-06, Debt — Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging — Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (ASU 2020-06) (“ ASU 2020-06 ”). ASU 2020-06 eliminated the beneficial conversion and cash conversion accounting models in ASC 470-20 which required separate accounting for embedded conversion features and simplified the settlement assessment to determine whether an instrument qualifies for equity classification. The Company early adopted the new standard on January 1, 2023 .

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
Summary of Significant Accounting Policies (Tables)	Jun. 30, 2023
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) June 30, December 31, Cash and cash equivalents $ 26,446 $ 30,605 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 30,490 $ 34,649
Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding	The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: June 30, 2023 2022 Unvested restricted stock awards 81,044 356,432 Unvested restricted stock units 125,000 170,000 Stock options 12,083,788 8,915,289 12,289,832 9,441,721

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
Marketable Securities (Tables)	Jun. 30, 2023
Investments Debt And Equity Securities [Abstract]
Schedule of Marketable Securities	The following is a summary of the Company’s marketable securities. (in thousands) Amortized Cost Gross unrealized gain Gross unrealized loss Fair Value June 30, 2023 Marketable securities: Agency securities $ 8,381 $ — $ ( 47 ) $ 8,334 Corporate debt securities 123,789 14 ( 385 ) 123,418 U.S. government securities 97,084 3 ( 296 ) 96,791 Total $ 229,254 $ 17 $ ( 728 ) $ 228,543 December 31, 2022 Marketable securities: Corporate debt securities $ 163,208 $ 7 $ ( 1,672 ) $ 161,543 U.S. government securities 9,607 — ( 27 ) 9,580 Total $ 172,815 $ 7 $ ( 1,699 ) $ 171,123

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
Fair Value of Financial Instruments (Tables)	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis: Fair value measurement at reporting date using (in thousands) Quoted prices Significant Significant June 30, 2023 Assets: Cash equivalents (Money Market Funds) $ 25,435 $ — $ — Marketable securities: Agency securities — 8,334 — Corporate debt securities — 123,418 — U.S. government securities — 96,791 — Total $ 25,435 $ 228,543 $ — December 31, 2022 Assets: Cash equivalents (Money Market Funds) $ 25,996 $ — $ — Marketable securities: Corporate debt securities — 161,543 — U.S. government securities — 9,580 — Total $ 25,996 $ 171,123 $ —

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
Accrued Expenses and Other Current Liabilities (Tables)	Jun. 30, 2023
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: (in thousands) June 30, December 31, Compensation and related benefits $ 5,043 $ 5,682 Research and development 2,815 6,887 Other 809 524 $ 8,667 $ 13,093

Commitments (Tables)

Commitments (Tables)	6 Months Ended
Commitments (Tables)	Jun. 30, 2023
Operating Lease, until December 31,2023
Schedule of Future Minimum Annual Lease Payments Under Lease	Future minimum annual lease payments under the Lease at June 30, 2023 are as follows: (in thousands) 2023 (remaining) $ 964 Total undiscounted lease payments 964 Less imputed interest ( 26 ) Current lease liability $ 938
Chestnut Run Lease
Schedule of Future Minimum Annual Lease Payments Under Lease	The estimated rent payments related to the Chestnut Run Lease are as follows: (in thousands) 2023 (remaining) $ — 2024 1,299 2025 2,784 2026 2,986 2027 3,060 2028 3,137 Thereafter 29,371

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
Stock-Based Compensation (Tables)	Jun. 30, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations	The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations: Three Months Ended Six Months Ended (in thousands) 2023 2022 2023 2022 Research and development $ 3,234 $ 2,472 $ 6,225 $ 5,672 General and administrative 3,499 3,556 6,764 7,185 $ 6,733 $ 6,028 $ 12,989 $ 12,857
Summary of Stock Option Activity	The following table summarizes stock option activity for the periods indicated: Number Weighted Weighted Outstanding at January 1, 2023 9,390,930 $ 12.08 8.31 Granted 2,977,898 $ 6.91 Exercised ( 17,685 ) $ 1.77 Forfeited ( 267,355 ) $ 17.72 Outstanding at June 30, 2023 12,083,788 $ 10.70 8.25 Exercisable at June 30, 2023 4,941,993 $ 11.56 7.28
Summary of Information about Stock Options Outstanding	The following table summarizes information about stock options outstanding at June 30, 2023 under the Plan: Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted Average Weighted Number Weighted $ 0.31 - $ 4.88 2,925,468 7.12 $ 2.74 2,188,856 $ 2.34 $ 4.89 - $ 7.50 4,100,967 9.49 6.57 35,665 6.03 $ 7.51 - $ 13.04 3,218,825 7.80 11.85 1,755,910 12.28 $ 13.05 - $ 88.98 1,838,528 8.06 30.53 961,562 31.44 12,083,788 4,941,993
Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions	The fair value of each option was estimated on th e date of grant using the weighted average assumptions in the table below: Six months ended 2023 2022 Expected volatility 83.51 % 84.82 % Risk-free interest rate 3.80 % 2.39 % Expected life (in years) 6.02 6.01 Expected dividend yield — —
Summary of Activity related to RSA Stock-Based Payment Awards	The following table summarizes activity related to RSA stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2023 201,716 $ 2.81 Vested ( 120,672 ) $ 2.50 Unvested balance at June 30, 2023 81,044 $ 3.26
Summary of Activity related to RSU Stock-Based Payment Awards	The following table summarizes activity related to RSU stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2023 165,000 $ 6.08 Vested ( 40,000 ) $ 5.70 Unvested balance at June 30, 2023 125,000 $ 6.21

Risks and Liquidity - Additiona

Risks and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Risks And Liquidity [Abstract]
Accumulated deficit	$ (392,707)	$ (334,558)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 26,446	$ 30,605
Restricted cash	4,044	4,044
Total cash, cash equivalents, and restricted cash shown in statement of cash flows	$ 30,490	$ 34,649

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding (Details) - shares	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	12,289,832	9,441,721
Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	81,044	356,432
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	125,000	170,000
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	12,083,788	8,915,289

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2023
Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, ASU, adopted	true
Change in accounting principle, ASU, adoption date	Jan. 01, 2023
New accounting pronouncement or change in accounting principle, update	ASU 2020-06

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Marketable securities, Amortized cost	$ 229,254	$ 172,815
Marketable securities, Gross unrealized gain	17	7
Marketable securities, Gross unrealized loss	(728)	(1,699)
Marketable securities, Fair value	228,543	171,123
Agency Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	8,381
Marketable securities, Gross unrealized loss	(47)
Marketable securities, Fair value	8,334
Corporate Debt Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	123,789	163,208
Marketable securities, Gross unrealized gain	14	7
Marketable securities, Gross unrealized loss	(385)	(1,672)
Marketable securities, Fair value	123,418	161,543
U.S. Government Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	97,084	9,607
Marketable securities, Gross unrealized gain	3
Marketable securities, Gross unrealized loss	(296)	(27)
Marketable securities, Fair value	$ 96,791	$ 9,580

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) $ in Millions	Jun. 30, 2023 USD ($) Security
Investments Debt And Equity Securities [Abstract]
Number of marketable securities \| Security	39
Securities fair market value unrealized loss position \| $	$ 199.1

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	$ 228,543	$ 171,123
Agency Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	8,334
Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	123,418	161,543
U.S. Government Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	96,791	9,580
Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	25,435	25,996
Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	25,435	25,996
Recurring Basis \| Significant other observable inputs (Level 2)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	228,543	171,123
Recurring Basis \| Significant other observable inputs (Level 2) \| Agency Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	8,334
Recurring Basis \| Significant other observable inputs (Level 2) \| Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	123,418	161,543
Recurring Basis \| Significant other observable inputs (Level 2) \| U.S. Government Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	$ 96,791	$ 9,580

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Payables And Accruals [Abstract]
Compensation and related benefits	$ 5,043	$ 5,682
Research and development	2,815	6,887
Other	809	524
Accrued expenses and other current liabilities	$ 8,667	$ 13,093

Common Stock - Additional Infor

Common Stock - Additional Information (Details) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) $ / shares shares
Class Of Stock [Line Items]
Gross proceeds from issuance of common stock and prefunded warrants \| $	$ 113
Offering costs \| $	2.6	$ 2.6
Offering costs previously paid and deferred \| $	$ 0.3	0.3
Net proceeds from issuance \| $		$ 110.4
Pre-Funded Warrants
Class Of Stock [Line Items]
Warrants exercise price per share \| $ / shares	$ 0.0001	$ 0.0001
Warrants exercised	0	0
Pre-Funded Warrants \| Voting Common Stock
Class Of Stock [Line Items]
Shares issued price per share \| $ / shares	$ 5.7499	$ 5.7499
Warrants to purchase common stock	12,895,256	12,895,256
Common Stock
Class Of Stock [Line Items]
Common stock, voting rights		The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders
Number of shares sold	6,761,200
Shares issued price per share \| $ / shares	$ 5.75	$ 5.75
Common Stock \| Minimum
Class Of Stock [Line Items]
Beneficial ownership percentage		9.99%
Common Stock \| Maximum
Class Of Stock [Line Items]
Beneficial ownership percentage		19.99%
Common Stock \| Voting Common Stock
Class Of Stock [Line Items]
Number of shares sold	5,312,978
Shares issued during period	5,312,978	2,264,456
Common Stock \| Non-voting Common Stock
Class Of Stock [Line Items]
Number of shares sold	1,448,222
Shares issued during period	1,448,222

Commitments - Additional Inform

Commitments - Additional Information (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Aug. 31, 2022 ft² Extension	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)
Other Commitments [Line Items]
Prepaid rent		$ 9		$ 9
Rent expense		0.6	$ 0.6	1.1	$ 1.1
Reimbursements for development of lab space				$ 5.5
Reimbursements for development of lab space period				3 years
Reimbursements for development of lab space expiration year				2023
Additional grant for development of lab space				$ 1
Grant for development of lab space				$ 3.4
Defined contribution plan, maximum annual contributions per employee, percent				100%
Defined contribution plan, employer matching contribution, percent of employee's gross pay				3%
Defined contribution plan, employer discretionary contribution amount		0.2	$ 0.1	$ 0.4	$ 0.3
Maximum
Other Commitments [Line Items]
Disbursement incurred costs for lab space				3.4
Chestnut Run Lease
Other Commitments [Line Items]
Lease renewal period	5 years
Area of lease premises \| ft²	81,000
Initial term of lease	162 months
Number of lease extensions \| Extension	3
Chestnut Run Lease \| Letter of Credit \| Silicon Valley Bank
Other Commitments [Line Items]
Security deposit		4		4
Chestnut Run Lease \| Letter of Credit \| Pro Forma
Other Commitments [Line Items]
Security deposit		$ 0.5		$ 0.5

Commitments - Schedule of Futur

Commitments - Schedule of Future Minimum Annual Lease Payments Under Lease (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Lease Liability [Line Items]
Current lease liability	$ 938	$ 1,832
Operating Lease Until December 30 2023
Lease Liability [Line Items]
2023 (remaining)	964
Total undiscounted lease payments	964
Less imputed interest	(26)
Chestnut Run Lease
Lease Liability [Line Items]
2024	1,299
2025	2,784
2026	2,986
2027	3,060
2028	3,137
Thereafter	$ 29,371

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details)	3 Months Ended		6 Months Ended
Stock-Based Compensation - Additional Information (Details)	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Plan $ / shares shares	Jun. 30, 2022 USD ($) $ / shares	Jan. 01, 2023 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of equity incentive plans \| Plan			2
Aggregate intrinsic value of outstanding options	$ 5,400,000		$ 5,400,000
Aggregate intrinsic value of exercisable options	4,800,000		4,800,000
Stock-based compensation expense	6,733,000	$ 6,028,000	$ 12,989,000	$ 12,857,000
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of options granted \| $ / shares			$ 5.04	$ 6
Aggregate intrinsic value of options exercised			$ 80,000
Stock-based compensation expense	6,500,000	5,700,000	12,400,000	$ 12,200,000
Total unrecognized compensation expense related to unvested stock option awards	50,500,000		$ 50,500,000
Total unrecognized compensation expense, weighted-average period			2 years 4 months 13 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
Stock-based compensation expense	100,000	200,000	$ 300,000	400,000
Total unrecognized compensation expense, weighted-average period			8 months 26 days
Share-based payment arrangement, nonvested award, unrecognized expense	300,000		$ 300,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
Stock-based compensation expense	100,000	100,000	$ 100,000	100,000
Total unrecognized compensation expense, weighted-average period			2 years 7 months 9 days
Share-based payment arrangement, nonvested award, unrecognized expense	$ 700,000		$ 700,000
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	4,823,436		4,823,436
Terms of award			The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year and continuing for ten years beginning on January 1, 2021, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year.
Award term			10 years
Percentage of shares outstanding used to calculate annual increase in number of shares that can be issued			5%
2020 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
2020 Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			1 year
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	1,698,350		1,698,350
Terms of award			The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the ESPP shall automatically increase on January 1st of each year and continuing for ten years beginning in 2021, in an amount equal to one percent of the total number of shares of all classes of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year.
Award term			10 years
Percentage of shares outstanding used to calculate annual increase in number of shares that can be issued			1%
Stock-based compensation expense	$ 100,000	$ 100,000	$ 200,000	$ 100,000
Common stock additional capital shares reserved for future issuance \| shares					478,990
Eligible employees purchase common stock percentage of lower of fair market value			85%
Participants accrue rights to purchase maximum common stock amount			$ 25,000
2020 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Eligible employees contribution percentage			15%
Vesting After One Year \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested			25%
Vesting After One Year \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested			25%
Vesting After One Year \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested			25%

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 6,733	$ 6,028	$ 12,989	$ 12,857
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	3,234	2,472	6,225	5,672
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 3,499	$ 3,556	$ 6,764	$ 7,185

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares, Outstanding at beginning of period	9,390,930
Number of shares, Granted	2,977,898
Number of shares, Exercised	(17,685)
Number of shares, Forfeited	(267,355)
Number of shares, Outstanding at end of period	12,083,788	9,390,930
Number of shares, Exercisable at June 30, 2023	4,941,993
Weighted average exercise price per share, Outstanding at beginning of period	$ 12.08
Weighted average exercise price per share, Granted	6.91
Weighted average exercise price per share, Exercised	1.77
Weighted average exercise price per share, Forfeited	17.72
Weighted average exercise price per share, Outstanding at end of period	10.70	$ 12.08
Weighted average exercise price per share, Exercisable at June 30,2023	$ 11.56
Weighted average remaining contractual term (years), Outstanding	8 years 3 months	8 years 3 months 21 days
Weighted average remaining contractual term (years), Exercisable	7 years 3 months 10 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Information about Stock Options Outstanding (Details)	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding, Number \| shares	12,083,788
Options Exercisable, Number Exercisable \| shares	4,941,993
$0.31 - $4.88
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 0.31
Range of Exercise Prices, Maximum	$ 4.88
Options Outstanding, Number \| shares	2,925,468
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 1 month 13 days
Options Outstanding, Weighted Average Exercise Price	$ 2.74
Options Exercisable, Number Exercisable \| shares	2,188,856
Options Exercisable, Weighted Average Exercise Price	$ 2.34
$4.89 - $7.50
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	4.89
Range of Exercise Prices, Maximum	$ 7.50
Options Outstanding, Number \| shares	4,100,967
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 5 months 26 days
Options Outstanding, Weighted Average Exercise Price	$ 6.57
Options Exercisable, Number Exercisable \| shares	35,665
Options Exercisable, Weighted Average Exercise Price	$ 6.03
$7.51 - $13.04
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	7.51
Range of Exercise Prices, Maximum	$ 13.04
Options Outstanding, Number \| shares	3,218,825
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 11.85
Options Exercisable, Number Exercisable \| shares	1,755,910
Options Exercisable, Weighted Average Exercise Price	$ 12.28
$13.05 - $88.98
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	13.05
Range of Exercise Prices, Maximum	$ 88.98
Options Outstanding, Number \| shares	1,838,528
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	8 years 21 days
Options Outstanding, Weighted Average Exercise Price	$ 30.53
Options Exercisable, Number Exercisable \| shares	961,562
Options Exercisable, Weighted Average Exercise Price	$ 31.44

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions (Details) - Stock Options	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	83.51%	84.82%
Risk-free interest rate	3.80%	2.39%
Expected life (in years)	6 years 7 days	6 years 3 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Activity related to RSA Stock-Based Payment Awards (Details) - Restricted Stock Awards	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at beginning of period \| shares	201,716
Number of shares, Vested \| shares	(120,672)
Number of shares, Unvested balance at end of period \| shares	81,044
Weighted-average grant date fair value, Unvested balance at beginning of period \| $ / shares	$ 2.81
Weighted-average grant date fair value, Vested \| $ / shares	2.50
Weighted-average grant date fair value, Unvested balance at end of period \| $ / shares	$ 3.26

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Activity related to RSU Stock-Based Payment Awards (Details) - Restricted Stock Units	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at beginning of period \| shares	165,000
Number of shares, Vested \| shares	(40,000)
Number of shares, Unvested balance at end of period \| shares	125,000
Weighted-average grant date fair value, Unvested balance at beginning of period \| $ / shares	$ 6.08
Weighted-average grant date fair value, Vested \| $ / shares	5.70
Weighted-average grant date fair value, Unvested balance at end of period \| $ / shares	$ 6.21