0001564590-21-013330 | 10-K | XBRL Viewer

Document and Entity Information - shares	12 Months Ended
Document and Entity Information - shares	Dec. 31, 2020	Mar. 12, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-39527
Entity Interactive Data Current	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
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 Shell Company	true
Entity Ex Transition Period	false
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
Entity Common Stock, Shares Outstanding		46,585,860
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s Definitive Proxy Statement (“Proxy Statement”) relating to the 2021 Annual Meeting of Stockholders will be filed with the Commission within 120 days after the end of the Registrant’s 2020 fiscal year pursuant to Regulation 14A and is incorporated by reference into Part III of this Report.

STATEMENT OF BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 218,309	$ 18,879
Prepaid expenses and other current assets	2,500	1,345
Total current assets	220,809	20,224
Property and equipment, net	2,480	1,647
Deferred offering costs	301
Total assets	223,590	21,871
Current liabilities:
Capital lease obligation		258
Accounts payable	3,920	1,974
Accrued expenses and other current liabilities	7,455	2,603
Total current liabilities	11,375	4,835
Other liabilities	32	5
Total liabilities	11,407	4,840
Total convertible preferred stock		66,443
Commitments (note 7)
Stockholders’ equity:
Additional paid-in capital	319,605	1,085
Accumulated deficit	(107,426)	(50,497)
Total stockholders’ equity (deficit)	212,183	(49,412)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	223,590	21,871
Series A Convertible Preferred Stock
Current liabilities:
Total convertible preferred stock		36,595
Series B Convertible Preferred Stock
Current liabilities:
Total convertible preferred stock		$ 29,848
Voting Common Stock
Stockholders’ equity:
Common stock	3
Total stockholders’ equity (deficit)	3
Non-voting Common Stock
Stockholders’ equity:
Common stock	1
Total stockholders’ equity (deficit)	$ 1

STATEMENT OF BALANCE SHEETS (PARENTHETICAL) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Series A Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	13,574,008
Convertible preferred stock, shares issued	0	11,736,119
Convertible preferred stock, shares outstanding	0	11,736,119
Series B Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	18,500,000
Convertible preferred stock, shares issued	0	7,628,846
Convertible preferred stock, shares outstanding	0	7,628,846
Series C Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	0
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0
Voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	487,149,741	42,000,000
Common stock, shares, issued	32,595,301	3,161,653
Common stock, shares, outstanding	32,595,301	3,161,653
Non-voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	12,850,259	0
Common stock, shares, issued	11,110,371	0
Common stock, shares, outstanding	11,110,371	0

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 48,177	$ 24,279
General and administrative	10,586	3,830
Total operating expenses	58,763	28,109
Loss from operations	(58,763)	(28,109)
Other income, net	1,834	539
Net loss	$ (56,929)	$ (27,570)
Per share information:
Net loss per share of common stock, basic and diluted	$ (4.56)	$ (16.52)
Weighted average common shares outstanding, basic and diluted	12,478,463	1,668,549

STATEMENTS OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Voting Common Stock	Non-voting Common Stock	Additional Paid-in Capital	Accumulated Deficit
Convertible preferred stock, Beginning balance at Dec. 31, 2018		$ 36,595
Convertible preferred stock, Beginning balance (shares) at Dec. 31, 2018		11,736,119
Beginning balance at Dec. 31, 2018	$ (22,693)						$ 234	$ (22,927)
Beginning balance (shares) at Dec. 31, 2018					2,380,270
Exercise of stock options	$ 5						5
Exercise of stock options (shares)	19,669				3,242
Sale of convertible preferred stock, net of issuance costs			$ 29,848
Sale of convertible preferred stock, net of issuance costs (shares)			7,628,846
Stock-based compensation expense, including issuance of restricted stock awards	$ 846						846
Stock-based compensation expense, including issuance of restricted stock awards (shares)					778,141
Net loss	(27,570)							(27,570)
Convertible preferred stock, Ending balance at Dec. 31, 2019	66,443	$ 36,595	$ 29,848
Convertible preferred stock, Ending balance (shares) at Dec. 31, 2019		11,736,119	7,628,846	0
Ending balance at Dec. 31, 2019	(49,412)						1,085	(50,497)
Ending balance (shares) at Dec. 31, 2019					3,161,653
Exercise of stock options	$ 100						100
Exercise of stock options (shares)	100,545				100,545
Sale of convertible preferred stock, net of issuance costs			$ 29,942	$ 49,826
Sale of convertible preferred stock, net of issuance costs (shares)			7,628,846	3,443,612
Conversion of convertible preferred stock upon initial public offering	$ 146,211				$ 2	$ 1	146,208
Conversion of convertible preferred stock upon initial public offering (shares)		(11,736,119)	(15,257,692)	(3,443,612)
Conversion of convertible preferred stock upon initial public offering		$ (36,595)	$ (59,790)	$ (49,826)
Conversion of convertible preferred stock upon initial public offering (shares)					19,327,052	11,110,371
Sale of common stock in initial public offering, net of issuance costs of $2,538	166,630				$ 1		166,629
Sale of common stock in initial public offering, net of issuance costs of $2,538 (shares)					9,573,750
Stock-based compensation expense, including issuance of restricted stock awards	5,583						5,583
Stock-based compensation expense, including issuance of restricted stock awards (shares)					432,301
Net loss	(56,929)							(56,929)
Convertible preferred stock, Ending balance (shares) at Dec. 31, 2020		0	0	0
Ending balance at Dec. 31, 2020	$ 212,183				$ 3	$ 1	$ 319,605	$ (107,426)
Ending balance (shares) at Dec. 31, 2020					32,595,301	11,110,371

STATEMENTS OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Sale of convertible preferred stock, issuance costs	$ 12
Sale of common stock, issuance costs	2,538
Series B Convertible Preferred Stock
Sale of convertible preferred stock, issuance costs	58	$ 152
Series C Convertible Preferred Stock
Sale of convertible preferred stock, issuance costs	$ 174

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash flows used in operating activities:
Net loss	$ (56,929)	$ (27,570)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	542	382
Loss on disposal of property and equipment	11	10
Stock-based compensation	5,583	846
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,155)	(1,345)
Accounts payable	1,157	546
Accrued expenses and other liabilities	4,614	1,466
Net cash used in operating activities	(46,177)	(25,665)
Cash flows used in investing activities:
Purchases of property and equipment	(621)	(780)
Net cash used in investing activities	(621)	(780)
Cash flows provided by financing activities:
Proceeds from the issuance of common stock upon initial public offering, net of offering costs	166,630
Payment of offering costs associated with January 2021 offering	(12)
Payment of capital lease obligation	(258)	(124)
Proceeds from the exercise of stock options	100	5
Net cash provided by financing activities	246,228	29,729
Net increase in cash and cash equivalents	199,430	3,284
Cash and cash equivalents at beginning of year	18,879	15,595
Cash and cash equivalents at end of year	218,309	18,879
Supplemental disclosures:
Property and equipment in accounts payable	765	66
Offering costs in accrued expenses	265
Offering costs in accounts payable	24
Issuance of capital lease obligation in connection with purchase of property and equipment		382
Series C Convertible Preferred Stock
Cash flows provided by financing activities:
Proceeds from the sale of convertible preferred stock, net of offering costs	49,826
Payment of offering costs associated with January 2021 offering	(174)
Series B Convertible Preferred Stock
Cash flows provided by financing activities:
Proceeds from the sale of convertible preferred stock, net of offering costs	29,942	29,848
Payment of offering costs associated with January 2021 offering	$ (58)	$ (152)

Nature of Operations

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Operations

1. Nature of Operations

Prelude Therapeutics Incorporated (the “Company”) was incorporated in Delaware on February 5, 2016 and is a clinical-stage biotechnology company focused on discovering and developing new medicines targeting chromatin function to treat cancer and rare diseases. Since beginning operations, 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

12 Months Ended

Dec. 31, 2020

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 pre-clinical 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 has an accumulated deficit of $107.4 million at December 31, 2020. 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 existing cash and cash equivalents, together with the net proceeds of $161.4 million from the sale of common stock in January 2021 (see Note 11), will be sufficient to fund its operating expenses and capital expenditure requirements into 2023.

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.

On March 10, 2020, the World Health Organization characterized the novel COVID-19 virus as a global pandemic. There is significant uncertainty as to the likely effects of this disease which may, among other things, materially impact the Company’s planned clinical trials. This pandemic or outbreak could result in difficulty securing clinical trial site locations, CROs, and/or trial monitors and other critical vendors and consultants supporting the trial. In addition, outbreaks or the perception of an outbreak near a clinical trial site location could impact the Company’s ability to enroll patients. These situations, or others associated with COVID-19, could cause delays in the Company’s clinical trial plans and could increase expected costs, all of which could have a material adverse effect on the Company’s business and its financial condition. At the current time, the Company is unable to quantify the potential effects of this pandemic on its future financial statements.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). 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”) promulgated by the Financial Accounting Standards Board (“FASB”).

On September 18, 2020, in connection with the Company’s initial public offering (IPO) of common stock, the Company’s board of directors and stockholders approved a 1.1566-to-one reverse stock split of the Company’s issued and outstanding shares of common stock and convertible preferred stock. All share and per share amounts in the financial statements and notes hereto have been retrospectively adjusted for all periods presented to give effect to the reverse stock split.

The completion of the IPO, as described above, impacts the comparability of certain amounts to the corresponding prior year period, including earnings per share.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the 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 financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include the fair value of the Company’s common stock prior to the IPO, stock-based compensation assumptions, and accrued clinical trial expenses.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant credit risk beyond the normal credit risk associated with commercial banking relationships.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views and manages its operations as a single operating segment.

Fair Value of Financial Instruments

Management believes that the carrying amounts of the Company’s financial instruments, including cash, accounts payable, accrued expenses and a capital lease obligation, approximate fair value due to the short-term nature of these instruments.

Cash Equivalents

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.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation expense is recognized using the straight-line method over the estimated useful life of the asset, ranging from 5-7 years as follows:

Fixed Asset Type		Estimated useful life
Lab equipment		5 years
Computers		5 years
Furniture and fixtures		7 years

Leasehold improvements are amortized over the shorter of the estimated useful life of the assets or the remaining lease term. Assets under capital leases are recorded in property and equipment, net on the balance sheets and depreciated in a manner similar to other property and equipment.

Expenditures for repairs and maintenance of assets are charged to expense as incurred, while major betterments are capitalized. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in the statements of operations.

The Company reviews long-lived assets, such as property and equipment, for impairment when events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. If indicators of impairment are present, the assets are tested for recoverability by comparing the carrying amount of the assets to the related estimated future undiscounted cash flows that the assets are expected to generate. If the expected cash flows are less than the carrying value of the asset, then the asset is considered to be impaired and its carrying value is written down to fair value, based on the related estimated discounted future cash flows.

Deferred offering costs

The Company capitalizes costs that are directly associated with in-process equity financings until such financings are consummated, at which time such costs are recorded against the gross proceeds from the applicable financing. If a financing is abandoned, deferred offering costs are expensed. Deferred offering costs were $0.3 million at December 31, 2020.

Comprehensive loss

Comprehensive loss includes net loss and certain changes in stockholders’ equity (deficit) that are excluded from net loss. The Company’s comprehensive loss was equal to net loss for the years ended December 31, 2020 and 2019.

Stock-Based Compensation

The Company measures share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards.

Estimating the fair value of share-based awards requires the input of subjective assumptions, including, prior to the IPO, the estimated fair value of the Company’s common stock, and, for stock options, the expected life of the options and stock price volatility. The Company accounts for forfeitures for stock option awards as they occur. The Company uses the Black-Scholes option pricing model to value its stock option awards. The assumptions used in estimating the fair value of share-based awards represent management’s estimate and involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, share-based compensation expense could be materially different for future awards.

The expected life of the stock options is estimated using the "simplified method," as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For stock price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option.

Grant Income and Research and Development Tax Credits

The Company recognizes grant income and Delaware research and development tax credits, which are refundable irrespective of taxable income, in other income, net in the statements of operations when it is probable that the amounts will be received and the necessary qualifying conditions, as stated in the agreements, are met.

Research and Development

Research and development costs are expensed as incurred. Research and development expenses consist principally of personnel costs, including salaries, stock-based compensation, and benefits of employees, and other operational costs related to the Company’s research and development activities, including allocated facility-related expenses and external costs of outside vendors, such as clinical research organizations and clinical manufacturing organizations, and other direct and indirect costs.

Management makes estimates of the Company’s accrued research and development expenses as of each balance sheet date in the Company’s financial statements based on facts and circumstances known to the Company at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Nonrefundable advance payments for goods and services, including fees for process development or manufacturing and distribution of clinical supplies that will be used in future research and development activities, are deferred and recognized as expense in the period that the related goods are consumed or services are performed.

Income Taxes

Income taxes are accounted for under the asset-and-liability method as required by FASB ASC Topic 740, Income Taxes (“ASC 740”). Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period corresponding to the enactment date. Under ASC 740, a valuation allowance is required when it is more likely than not all or some portion of the deferred tax assets will not be realized through generating sufficient future taxable income.

FASB ASC Subtopic 740-10, Accounting for Uncertainty of Income Taxes, (“ASC 740-10”) defines the criterion an individual tax position must meet for any part of the benefit of the tax position to be recognized in financial statements prepared in conformity with GAAP. The Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not such tax position will be sustained on examination by the taxing authorities, based solely on the technical merits of the respective tax position. The tax benefits recognized in the financial statements from such a tax position should be measured based on the largest benefit having a greater than 50% likelihood of being realized upon ultimate settlement with the tax authority. In accordance with the disclosure requirements of ASC 740-10, the Company’s policy on income statement classification of interest and penalties related to income tax obligations is to include such items as part of total interest expense and other expense, respectively.

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. 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 or conversion of securities, such as convertible preferred stock and stock options, 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 convertible preferred stock and unvested restricted stock entitles 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 convertible preferred stock and unvested restricted stock 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:

	December 31,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,214,767		1,335,349
Stock options		6,839,091		2,269,742
		8,053,858		22,970,056

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 financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recent Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASC 842”), which requires a lessee to record a right-of-use asset and a corresponding lease liability on the balance sheet for most leases including operating leases. Lessees will classify leases as either finance or operating leases and lessors classify all leases as sales-type, direct financing or operating leases. The statement of operations presentation and expense recognition for lessees for finance leases is similar to that of capital leases under ASC 840 with separate interest and amortization expense with higher periodic expense in the earlier periods of a lease. For operating leases, the statement of operations presentation and expense recognition is similar to that of operating leases under ASC 840 with single lease cost recognized on a straight-line basis. The standard is effective for the Company beginning January 1, 2022, with early adoption permitted, using a modified retrospective approach. While the Company continues to evaluate the provisions of ASC 842 to determine how it will be impacted, the primary effect of adopting the new standard will be to record a right-of-use asset and a lease liability on the balance sheet for all leases with a term of greater than twelve months regardless of their classification. The adoption of ASC 842 is not expected to have a material impact on the Company's results of operations or cash flows.

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

4. 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, 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 in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
December 31, 2020:
Assets:
Cash equivalents (Money Market Funds)	$	217,072	$	—	$	—
December 31, 2019:
Assets:	$	18,779	$	—	$	—
Cash equivalents (Money Market Funds)

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property and Equipment

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Property and Equipment

5. Property and Equipment

Property and equipment consisted of the following:

	December 31,
(in thousands)	2020			2019
Lab equipment	$	3,010		$	1,842
Leasehold improvements		448			312
Computers		—			10
Furniture and fixtures		105			39
		3,563			2,203
Less accumulated depreciation		(1,083	)		(556	)
Property and equipment, net	$	2,480		$	1,647

Depreciation and amortization expense was $0.5 million and $0.4 million for the years ended December 31, 2020 and 2019, respectively.

In September 2019, the Company signed a 12-month capital lease for $0.4 million of lab equipment with an effective interest rate of 9.67%. At December 31, 2020, the Company had $0.1 million of accumulated amortization related to the capital lease. At December 31, 2020, the Company has no further lease payments under the capital lease.

Accrued Expenses

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses consisted of the following:

	December 31,
(in thousands)	2020		2019
Compensation and related benefits	$	3,614	$	1,631
Research and development		3,421		658
Other		420		314
	$	7,455	$	2,603

Commitments

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments

7. Commitments

Operating Leases

The Company leases office and laboratory space in Wilmington, Delaware under two separate noncancelable leases, which expire in December 2022 and March 2021, respectively. The Company has an option to renew both leases for additional 1-year and 6-months periods, respectively. The leases are classified as operating leases and the Company recognizes rent expense on a straight-line basis over the lease terms. The Company recognized rent expense of $1.2 million and $0.9 million during the years ended December 31, 2020 and 2019, respectively, related to these leases.

The future minimum lease payments under the Company’s operating lease agreements as of December 31, 2020 are $1.4 million for both 2021 and for 2022, with no commitments thereafter.

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 safe harbor match with a maximum amount of 4% of the participant’s compensation. The Company has not yet made any matching contributions since inception.

Other Research and Development Arrangements

The Company enters into agreements with contract 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.

Convertible Preferred Stock and Common Stock

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Convertible Preferred Stock and Common Stock

8. Convertible Preferred Stock and Common Stock

Preferred Stock Financings

In May 2019, the Company issued an aggregate of 7,628,846 shares of Series B convertible preferred stock (“Series B”) to existing investors at $3.9325 per share for aggregate net proceeds of $29.8 million.

Pursuant to the Series B Stock Purchase Agreement, the Series B investors could elect to purchase an aggregate of 7,628,846 additional shares of the Company’s Series B at a fixed purchase price of $3.9325 per share (the “Series B Future Tranche Right”). The Company determined that the Series B Future Tranche Right did not meet the definition of a freestanding financial instrument as it was not legally detachable. The Series B Future Tranche Right was also evaluated as an embedded derivative and the Company determined it did not meet the definition of a derivative instrument for which bifurcation would be required. In March 2020, the Company’s Series B investors exercised their Future Tranche Right and purchased 7,628,846 shares of Series B for net proceeds of approximately $29.9 million.

In August 2020, the Company’s existing Convertible Preferred Stock investors as well as a new investor purchased 3,443,612 shares of Series C at a price of $14.5197 per share for net proceeds of approximately $49.8 million.

Initial Public Offering

In September 2020, the Company completed its IPO in which the Company sold 9,573,750 shares of its common stock at a public offering price of $19.00 per share. The Company received net proceeds of $166.6 million after deducting underwriting discounts, commissions, and other offering expenses paid by the Company. In addition, immediately prior to the closing of the IPO on September 29, 2020, (i) all of the Company’s outstanding shares of convertible preferred stock converted into an aggregate of 30,437,423 shares of common stock (of which, 11,110,371 shares are non-voting common stock) and (ii) the Company filed an amended and restated certificate of incorporation to, among other things, increase the number of authorized shares of common stock to 500,000,000.

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.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

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”). The total number of shares initially authorized under the Plan was 4,680,000. Of this amount, 4,485,907 shares were available for future grants as of December 31, 2020. 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, commencing on January 1, 2021 and continuing for ten years, 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. As such, on January 1, 2021, 2,185,283 shares were added to the Plan. The Plan provides for the granting of common stock, incentive stock options, nonqualified stock options, restricted stock awards, 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 1 year and then monthly thereafter, and have a term of ten years. In September 2020, the Company also adopted the 2020 Employee Stock Purchase Plan (the “ESPP”), which includes 520,000 shares of common stock reserved for future issuance. No shares have been issued from the ESPP as of December 31, 2020. 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, commencing on January 1, 2021 and continuing for ten years, in an amount equal to one 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. As such, on January 1, 2021, 437,056 shares were added to the ESPP.

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:

	Year Ended December 31,
(in thousands)	2020		2019
Research and development	$	2,585	$	437
General and administrative		2,998		409
	$	5,583	$	846

Stock Options

The following table summarizes stock option activity for the Plan in the years indicated:

	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)
Outstanding at January 1, 2019		588,961		$	1.11		9.35
Granted		1,703,692		$	1.84
Exercised		(19,669	)	$	1.16
Forfeited		(3,242	)	$	1.02
Outstanding at December 31, 2019		2,269,742		$	1.66		9.20
Granted		4,785,630		$	11.35
Exercised		(100,545	)	$	0.99
Forfeited		(115,736	)	$	1.37
Outstanding at December 31, 2020		6,839,091		$	8.46		9.17
Exercisable at December 31, 2020		951,669		$	1.85		8.22

At December 31, 2020, the aggregate intrinsic value of outstanding options and exercisable options was $431.5 million and $66.3 million, respectively.

The following table summarizes information about stock options outstanding and exercisable at December 31, 2020 under the Plan:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$0.31 - $1.66		555,852		7.62	$	1.23		327,859	$	1.18
$1.67 - $7.37		2,954,883		8.88		1.89		606,757		1.89
$7.38 - $15.93		3,129,940		9.67		12.85		16,477		12.85
$15.94 - $69.92		198,416		9.90		57.25		576		19.00
		6,839,091						951,669

The weighted-average grant date fair value of options granted was $10.12 and $1.41 per share for the years ended December 31, 2020 and 2019, respectively. The aggregate intrinsic value of options exercised was $0.4 million and for the year ended December 31, 2020. The Company recorded stock-based compensation expense of $ 4.8 million and $0.4 million for the years ended December 31, 2020 and 2019, respectively, related to stock options. As of December 31, 2020, the total unrecognized compensation expense related to unvested stock option awards was $45.8 million, which the Company expects to recognize over a weighted-average period of 3.54 years.

The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below:

	Year Ended December 31,
	2020			2019
Expected volatility		115.17	%		91.60	%
Risk-free interest rate		0.43	%		1.87	%
Expected life (in years)		6.25			6.25
Expected dividend yield		—			—

Restricted Stock Awards

The Company issues restricted stock awards (“RSA”) to employees that generally vest over a four-year period with 25% of awards vesting after 1 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 amortized straight-line over the vesting period.

The following table summarizes activity related to RSA stock-based payment awards:

	Number of shares			Weighted- average grant date fair value
Unvested balance at January 1, 2019		856,438		$	0.74
Granted		778,141		$	1.89
Vested		(299,230	)	$	0.68
Unvested balance at December 31, 2019		1,335,349		$	1.42
Granted		432,301		$	3.26
Vested		(552,883	)	$	1.37
Unvested balance at December 31, 2020		1,214,767		$	2.09

The Company recorded stock-based compensation expense of $0.8 million and $0.4 million for the years ended December 31, 2020 and 2019, respectively, related to RSAs. As of December 31, 2020, the total unrecognized expense related to all RSAs was $2.2 million, which the Company expects to recognize over a weighted-average period of 2.71 years.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities were as follows:

	December 31,
(in thousands)	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	28,283		$	13,659
Research and development credits		4,753			2,216
Stock-based compensation		33			—
Gross deferred tax assets		33,069			15,875
Less: valuation allowance		(32,899	)		(15,409	)
Total deferred tax asset		170			466
Deferred tax liability
Stock-based compensation		—			(399	)
Depreciation		(170	)		(67	)
Total deferred tax liabilities		(170	)		(466	)
	$	—		$	—

In assessing the need for a valuation allowance, management must determine that there will be sufficient taxable income to allow for the realization of deferred tax assets. Based upon the historical and anticipated future losses, management has determined that the deferred tax assets 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 December 31, 2020 and 2019. The valuation allowance increased by $17.5 million and $9.2 million during the years ended December 31, 2020 and 2019, respectively.

A reconciliation of the federal income tax rate to the Company’s effective tax rate is as follows:

	Year ended December 31,
	2020			2019
Federal tax benefit at statutory rate		(21.0	)%		(21.0	)%
State tax, net of federal benefit		(6.5	)		(6.9	)
Return to provision		—			(0.7	)
Permanent differences		1.2			0.4
Research and development		(4.4	)		(5.4	)
Change in valuation allowance		30.7			33.6
		—	%		—	%

The following table summarizes carryforwards of federal, state and local net operating losses (“NOL”) and research tax credits:

	December 31,
(in thousands)	2020		2019
NOL carryforwards - Federal	$	101,471	$	49,005
NOL carryforwards - State		101,471		49,005
Research tax credits - Federal		4,720		2,182
Research tax credits - State		43		43

The NOL carryforwards begin expiring in 2036 for federal and Delaware state income tax purposes, however; all federal and Delaware state NOL carryforwards generated subsequent to January 1, 2018, are able to be carried forward indefinitely. As of December 31, 2020, the Company also had federal and Delaware research and development tax credit carryforwards of $4.7 million and $43,000, respectively that will begin to expire in 2036, unless previously utilized.

The NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. To date, the Company has not performed an analysis to determine whether or not ownership changes have occurred since inception. Delaware state NOLs may also be limited.

As of December 31, 2020, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s statement of operations. Due to NOL and tax credit carry forwards that remain unutilized, income tax returns for tax years from 2016, 2017, 2018 and 2019 remain subject to examination by the taxing jurisdictions. The NOL carryforwards remain subject to review until utilized.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Subsequent Event

12 Months Ended

Dec. 31, 2020

Subsequent Events [Abstract]

Subsequent Event

11. Subsequent Event

In January 2021, the Company sold 2,875,000 shares of its common stock at a public offering price of $60.00 per share. The Company received net proceeds of $161.4 million after deducting underwriting discounts, commissions, and other offering expenses paid by the Company.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of presentation

Basis of Presentation

The completion of the IPO, as described above, impacts the comparability of certain amounts to the corresponding prior year period, including earnings per share.

Use of estimates

Use of Estimates

Concentration of Credit Risk

Segment Information

Fair Value of Financial Instruments

Cash Equivalents

Property and Equipment

Fixed Asset Type		Estimated useful life
Lab equipment		5 years
Computers		5 years
Furniture and fixtures		7 years

Deferred Offering Costs

Deferred offering costs

Comprehensive Loss

Comprehensive loss

Stock-Based Compensation

The Company measures share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards.

Grant Income and Research and Development Tax Credits

Research and Development

Income taxes

Income Taxes

Net Loss Per Share

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:

	December 31,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,214,767		1,335,349
Stock options		6,839,091		2,269,742
		8,053,858		22,970,056

Amounts in the above table reflect the common stock equivalents.

Recently Issued Accounting Pronouncements

Emerging Growth Company Status

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Property Plant and Equipment Useful Life

Fixed Asset Type		Estimated useful life
Lab equipment		5 years
Computers		5 years
Furniture and fixtures		7 years

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:

	December 31,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,214,767		1,335,349
Stock options		6,839,091		2,269,742
		8,053,858		22,970,056

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2020

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 in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
December 31, 2020:
Assets:
Cash equivalents (Money Market Funds)	$	217,072	$	—	$	—
December 31, 2019:
Assets:	$	18,779	$	—	$	—
Cash equivalents (Money Market Funds)

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consisted of the following:

	December 31,
(in thousands)	2020			2019
Lab equipment	$	3,010		$	1,842
Leasehold improvements		448			312
Computers		—			10
Furniture and fixtures		105			39
		3,563			2,203
Less accumulated depreciation		(1,083	)		(556	)
Property and equipment, net	$	2,480		$	1,647

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Summary of Accrued Expenses

Accrued expenses consisted of the following:

	December 31,
(in thousands)	2020		2019
Compensation and related benefits	$	3,614	$	1,631
Research and development		3,421		658
Other		420		314
	$	7,455	$	2,603

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

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:

	Year Ended December 31,
(in thousands)	2020		2019
Research and development	$	2,585	$	437
General and administrative		2,998		409
	$	5,583	$	846

Summary of Stock Option Activity

The following table summarizes stock option activity for the Plan in the years indicated:

	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)
Outstanding at January 1, 2019		588,961		$	1.11		9.35
Granted		1,703,692		$	1.84
Exercised		(19,669	)	$	1.16
Forfeited		(3,242	)	$	1.02
Outstanding at December 31, 2019		2,269,742		$	1.66		9.20
Granted		4,785,630		$	11.35
Exercised		(100,545	)	$	0.99
Forfeited		(115,736	)	$	1.37
Outstanding at December 31, 2020		6,839,091		$	8.46		9.17
Exercisable at December 31, 2020		951,669		$	1.85		8.22

Summary of Information about Stock Options Outstanding

The following table summarizes information about stock options outstanding and exercisable at December 31, 2020 under the Plan:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$0.31 - $1.66		555,852		7.62	$	1.23		327,859	$	1.18
$1.67 - $7.37		2,954,883		8.88		1.89		606,757		1.89
$7.38 - $15.93		3,129,940		9.67		12.85		16,477		12.85
$15.94 - $69.92		198,416		9.90		57.25		576		19.00
		6,839,091						951,669

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 the date of grant using the weighted average assumptions in the table below:

	Year Ended December 31,
	2020			2019
Expected volatility		115.17	%		91.60	%
Risk-free interest rate		0.43	%		1.87	%
Expected life (in years)		6.25			6.25
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 shares			Weighted- average grant date fair value
Unvested balance at January 1, 2019		856,438		$	0.74
Granted		778,141		$	1.89
Vested		(299,230	)	$	0.68
Unvested balance at December 31, 2019		1,335,349		$	1.42
Granted		432,301		$	3.26
Vested		(552,883	)	$	1.37
Unvested balance at December 31, 2020		1,214,767		$	2.09

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities were as follows:

	December 31,
(in thousands)	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	28,283		$	13,659
Research and development credits		4,753			2,216
Stock-based compensation		33			—
Gross deferred tax assets		33,069			15,875
Less: valuation allowance		(32,899	)		(15,409	)
Total deferred tax asset		170			466
Deferred tax liability
Stock-based compensation		—			(399	)
Depreciation		(170	)		(67	)
Total deferred tax liabilities		(170	)		(466	)
	$	—		$	—

Schedule of Reconciliation of the Federal Income tax Rate to Effective Tax Rate

A reconciliation of the federal income tax rate to the Company’s effective tax rate is as follows:

	Year ended December 31,
	2020			2019
Federal tax benefit at statutory rate		(21.0	)%		(21.0	)%
State tax, net of federal benefit		(6.5	)		(6.9	)
Return to provision		—			(0.7	)
Permanent differences		1.2			0.4
Research and development		(4.4	)		(5.4	)
Change in valuation allowance		30.7			33.6
		—	%		—	%

Schedule of Federal State and Local Net Operating Losses and Research Tax Credits

The following table summarizes carryforwards of federal, state and local net operating losses (“NOL”) and research tax credits:

	December 31,
(in thousands)	2020		2019
NOL carryforwards - Federal	$	101,471	$	49,005
NOL carryforwards - State		101,471		49,005
Research tax credits - Federal		4,720		2,182
Research tax credits - State		43		43

Risks and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Risks And Liquidity [Line Items]
Accumulated deficit	$ (107,426)	$ (50,497)
IPO
Risks And Liquidity [Line Items]
Net proceeds from issuance of common stock	$ 161,400

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions		12 Months Ended
	Sep. 18, 2020	Dec. 31, 2020 USD ($)
Summary of Significant Accounting Policies [Line Items]
Reverse stock split	0.8646
Depreciation expense description		Depreciation expense is recognized using the straight-line method over the estimated useful life of the asset, ranging from 5-7 years
Deferred offering costs		$ 0.3
Minimum
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		5 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		7 years
Percentage of tax benefit recognized upon settlement		50.00%

Summary of Significant Accounting Policies - Schedule of Property Plant and Equipment Useful Life (Details)	12 Months Ended
	Dec. 31, 2020
Lab equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Computers
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	7 years

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	8,053,858	22,970,056
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		11,736,119
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		7,628,846
Unvested Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,214,767	1,335,349
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	6,839,091	2,269,742

Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
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, recurring basis, assets	$ 217,072	$ 18,779

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,563	$ 2,203
Less accumulated depreciation	(1,083)	(556)
Property and equipment, net	2,480	1,647
Lab equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,010	1,842
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	448	312
Computers
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		10
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 105	$ 39

Property and Equipment - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 500,000	$ 400,000
Lab equipment
Property, Plant and Equipment [Line Items]
Lease term	12 months
Capital lease	$ 400,000
Effective interest percentage	9.67%
Accumulated amortization related to the capital lease	$ 100,000
Lease payments under capital lease	$ 0

Accrued Expenses - Summary of Accrued Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Compensation and related benefits	$ 3,614	$ 1,631
Research and development	3,421	658
Other	420	314
Accrued expenses and other current liabilities	$ 7,455	$ 2,603

Commitments - Additional Information (Details)	12 Months Ended
Commitments - Additional Information (Details)	Dec. 31, 2020 USD ($) Lease	Dec. 31, 2019 USD ($) Lease
Other Commitments [Line Items]
Number of noncancelable leases \| Lease	2	2
Rent expense	$ 1,200,000	$ 900,000
Future minimum lease payments for 2021	1,400,000
Future minimum lease payments for 2022	1,400,000
Future minimum lease payments thereafter	$ 0
Defined contribution plan, maximum annual contributions per employee, percent	100.00%
Defined contribution plan, employer matching contribution, percent of employee's gross pay	4.00%
Operating Lease Expiring December 2022
Other Commitments [Line Items]
Lease renewal period	1 year
Operating Lease Expiring March 2021
Other Commitments [Line Items]
Lease renewal period	6 months

Convertible Preferred Stock and Common Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Sep. 30, 2020	Aug. 31, 2020	Mar. 31, 2020	May 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Proceeds from the issuance of common stock upon initial public offering, net of offering costs					$ 166,630
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
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%
IPO
Class Of Stock [Line Items]
Sale of common stock in initial public offering, net of offering costs of $2,538, (shares)	9,573,750
Proceeds from the issuance of common stock upon initial public offering, net of offering costs	$ 166,600
Convertible preferred stock converted into common stock	30,437,423
Common stock, shares authorized	500,000,000
IPO \| Common Stock
Class Of Stock [Line Items]
Public offering price	$ 19.00
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares issued			7,628,846	7,628,846	0	7,628,846
Convertible preferred stock, price per share				$ 3.9325
Net proceeds from issuance of preferred stock			$ 29,900	$ 29,800	$ 29,942	$ 29,848
Additional shares issuable				7,628,846
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares issued		3,443,612			0	0
Convertible preferred stock, price per share		$ 14.5197
Net proceeds from issuance of preferred stock		$ 49,800			$ 49,826
Non-voting Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized					12,850,259	0
Non-voting Common Stock \| IPO
Class Of Stock [Line Items]
Convertible preferred stock converted into common stock	11,110,371

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) Plan $ / shares shares	Dec. 31, 2019 USD ($) $ / shares	Jan. 01, 2021 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	$ 431,500
Aggregate intrinsic value of exercisable options	66,300
Stock-based compensation expense	$ 5,583	$ 846
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of options granted \| $ / shares	$ 10.12	$ 1.41
Aggregate intrinsic value of options exercised	$ 400
Stock-based compensation expense	4,800	$ 400
Total unrecognized compensation expense related to unvested stock option awards	$ 45,800
Total unrecognized compensation expense, weighted-average period	3 years 6 months 14 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
Percentage of stock options vested	25.00%
Stock-based compensation expense	$ 800	$ 400
Total unrecognized compensation expense, weighted-average period	2 years 8 months 15 days
Share-based payment arrangement, nonvested award, unrecognized expense	$ 2,200
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized \| shares	4,680,000
Number of shares available for future grants \| shares	4,485,907
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, commencing on January 1, 2021 and continuing for ten years, 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	5.00%
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	520,000
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, commencing on January 1, 2021 and continuing for ten years, in an amount equal to one 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	1.00%
Shares issued \| shares	0
Maximum \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
Minimum \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	1 year
Vesting After One Year \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested	25.00%
Subsequent Event \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized \| shares			2,185,283
Subsequent Event \| 2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized \| shares			437,056

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 5,583	$ 846
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	2,585	437
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 2,998	$ 409

Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares, Outstanding at beginning of period	2,269,742	588,961
Number of shares, Granted	4,785,630	1,703,692
Number of shares, Exercised	(100,545)	(19,669)
Number of shares, Forfeited	(115,736)	(3,242)
Number of shares, Outstanding at end of period	6,839,091	2,269,742	588,961
Number of shares, Exercisable at December 31, 2020	951,669
Weighted average exercise price per share, Outstanding at beginning of period	$ 1.66	$ 1.11
Weighted average exercise price per share, Granted	11.35	1.84
Weighted average exercise price per share, Exercised	0.99	1.16
Weighted average exercise price per share, Forfeited	1.37	1.02
Weighted average exercise price per share, Outstanding at end of period	8.46	$ 1.66	$ 1.11
Weighted average exercise price per share, Exercisable at December 31, 2020	$ 1.85
Weighted average remaining contractual term (years), Outstanding	9 years 2 months 1 day	9 years 2 months 12 days	9 years 4 months 6 days
Weighted average remaining contractual term (years), Exercisable	8 years 2 months 19 days

Stock-Based Compensation - Summary of Information about Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding, Number \| shares	6,839,091
Options Exercisable, Number Exercisable \| shares	951,669
$0.31 - $1.66
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 0.31
Range of Exercise Prices, Maximum	$ 1.66
Options Outstanding, Number \| shares	555,852
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 7 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 1.23
Options Exercisable, Number Exercisable \| shares	327,859
Options Exercisable, Weighted Average Exercise Price	$ 1.18
$1.67 - $7.37
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	1.67
Range of Exercise Prices, Maximum	$ 7.37
Options Outstanding, Number \| shares	2,954,883
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	8 years 10 months 17 days
Options Outstanding, Weighted Average Exercise Price	$ 1.89
Options Exercisable, Number Exercisable \| shares	606,757
Options Exercisable, Weighted Average Exercise Price	$ 1.89
$7.38 - $15.93
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	7.38
Range of Exercise Prices, Maximum	$ 15.93
Options Outstanding, Number \| shares	3,129,940
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 8 months 1 day
Options Outstanding, Weighted Average Exercise Price	$ 12.85
Options Exercisable, Number Exercisable \| shares	16,477
Options Exercisable, Weighted Average Exercise Price	$ 12.85
$15.94 - $69.92
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	15.94
Range of Exercise Prices, Maximum	$ 69.92
Options Outstanding, Number \| shares	198,416
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 57.25
Options Exercisable, Number Exercisable \| shares	576
Options Exercisable, Weighted Average Exercise Price	$ 19.00

Stock-Based Compensation - Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	115.17%	91.60%
Risk-free interest rate	0.43%	1.87%
Expected life (in years)	6 years 3 months	6 years 3 months

Stock-Based Compensation - Summary of Activity related to RSA Stock-Based Payment Awards (Details) - Restricted Stock Awards - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at beginning of period	1,335,349	856,438
Number of shares, Granted	432,301	778,141
Number of shares, Vested	(552,883)	(299,230)
Number of shares, Unvested balance at end of period	1,214,767	1,335,349
Weighted-average grant date fair value, Unvested balance	$ 1.42	$ 0.74
Weighted-average grant date fair value, Granted	3.26	1.89
Weighted-average grant date fair value, Vested	1.37	0.68
Weighted-average grant date fair value, Unvested balance	$ 2.09	$ 1.42

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 28,283	$ 13,659
Research and development credits	4,753	2,216
Stock-based compensation	33
Gross deferred tax assets	33,069	15,875
Less: valuation allowance	(32,899)	(15,409)
Total deferred tax asset	170	466
Deferred tax liability
Stock-based compensation		(399)
Depreciation	(170)	(67)
Total deferred tax liabilities	(170)	(466)
Net deferred income tax assets liabilities	$ 0	$ 0

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance increase	$ 17,500,000	$ 9,200,000
Research and development tax credits	$ 4,753,000	$ 2,216,000
NOL and tax credit carryforwards	The NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions.
Accrued interest related to uncertain tax positions	$ 0
Accrued penalties related to uncertain tax positions	0
Interest related to uncertain tax positions	0
Penalties related to uncertain tax positions	$ 0
Income tax examination, year under examination	2016 2017 2018 2019
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Research and development tax credits	$ 4,700,000
Tax credits expiration year	2036
Delaware
Income Tax Disclosure [Line Items]
Research and development tax credits	$ 43,000
Tax credits expiration year	2036

Income Taxes - Schedule of Reconciliation of the Federal Income tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal tax benefit at statutory rate	(21.00%)	(21.00%)
State tax, net of federal benefit	(6.50%)	(6.90%)
Return to provision		(0.70%)
Permanent differences	1.20%	0.40%
Research and development	(4.40%)	(5.40%)
Change in valuation allowance	30.70%	33.60%
Effective tax rate	0.00%	0.00%

Income Taxes - Schedule of Federal State and Local Net Operating Losses and Research Tax Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 28,283	$ 13,659
Federal
Operating Loss Carryforwards [Line Items]
NOL carryforwards	101,471	49,005
Research tax credits	4,720	2,182
State
Operating Loss Carryforwards [Line Items]
NOL carryforwards	101,471	49,005
Research tax credits	$ 43	$ 43

Subsequent Event - Additional Information (Details) - IPO - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Sep. 30, 2020
Subsequent Event [Line Items]
Net proceeds from issuance of common stock		$ 161.4
Common Stock
Subsequent Event [Line Items]
Public offering price			$ 19.00
Common Stock \| Subsequent Event
Subsequent Event [Line Items]
Number of shares sold	2,875,000
Public offering price	$ 60.00
Net proceeds from issuance of common stock	$ 161.4