Inozyme Pharma (INZY) 10-Q 12 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 07, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	Inozyme Pharma, Inc.
Entity Central Index Key	0001693011
Entity Incorporation, State or Country Code	DE
Entity File Number	001-39397
Entity Tax Identification Number	38-4024528
Entity Address, Address Line One	321 Summer Street
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02210
City Area Code	857
Local Phone Number	330-4340
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	INZY
Security Exchange Name	NASDAQ
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		23,483,093

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 16,486	$ 28,040
Short-term investments	128,600	119,657
Prepaid expenses and other current assets	2,955	3,282
Total current assets	148,041	150,979
Property and equipment, net	2,688	2,648
Right-of-use assets	2,341
Restricted cash	354	354
Long-term investments	2,548	12,199
Prepaid expenses, net of current portion	2,943	3,183
Total assets	158,915	169,363
Current liabilities:
Accounts payable	1,709	3,069
Accrued expenses	4,451	6,904
Operating lease liabilities	672
Total current liabilities	6,832	9,973
Operating lease liabilities, net of current portion	3,194	1,287
Total liabilities	10,026	11,260
Stockholders’ equity:
Preferred Stock, $0.0001 par value – 5,000,000 shares authorized at March 31, 2021 and December 31, 2020; No shares issued and outstanding at March 31, 2021 or December 31, 2020
Common Stock, $0.0001 par value – 200,000,000 shares authorized at March 31, 2021 and December 31, 2020; 23,473,703 shares issued and outstanding at March 31, 2021 and 23,384,969 shares issued and outstanding at December 31, 2020	2	2
Additional paid in-capital	251,001	249,175
Accumulated other comprehensive income	12	2
Accumulated deficit	(102,126)	(91,076)
Total stockholders’ equity	148,889	158,103
Total liabilities and stockholders’ equity	$ 158,915	$ 169,363

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	23,473,703	23,384,969
Common stock, shares outstanding	23,473,703	23,384,969

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses:
Research and development	$ 6,603	$ 6,406
General and administrative	4,369	1,500
Total operating expenses	10,972	7,906
Loss from operations	(10,972)	(7,906)
Other income (expense):
Interest income	63	171
Other expenses	(141)	(3)
Other income (expense), net	(78)	168
Net loss	(11,050)	(7,738)
Other comprehensive income:
Unrealized gains on available-for-sale securities	10	23
Total other comprehensive income	10	23
Comprehensive loss	(11,040)	(7,715)
Net loss attributable to common stockholders—basic and diluted	$ (11,050)	$ (7,738)
Net loss per share attributable to common stockholders—basic and diluted	$ (0.47)	$ (6.42)
Weighted-average common shares outstanding—basic and diluted	23,429,507	1,205,346

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance at Dec. 31, 2019	$ (33,219)				$ 1,428	$ 5	$ (34,652)
Temporary equity, shares at Dec. 31, 2019		48,850,000	23,566,431
Temporary equity, balance at Dec. 31, 2019		$ 44,657	$ 33,270
Balance, shares at Dec. 31, 2019				1,204,630
Stock-based compensation	129				129
Exercise of stock options	5				5
Exercise of stock options, shares				2,677
Comprehensive income:
Unrealized gain on investments	23					23
Net loss	(7,738)						(7,738)
Balance at Mar. 31, 2020	(40,800)				1,562	28	(42,390)
Temporary equity, shares at Mar. 31, 2020		48,850,000	23,566,431
Temporary equity, balance at Mar. 31, 2020		$ 44,657	$ 33,270
Balance, shares at Mar. 31, 2020				1,207,307
Balance at Dec. 31, 2019	(33,219)				1,428	5	(34,652)
Temporary equity, shares at Dec. 31, 2019		48,850,000	23,566,431
Temporary equity, balance at Dec. 31, 2019		$ 44,657	$ 33,270
Balance, shares at Dec. 31, 2019				1,204,630
Comprehensive income:
Net loss	(56,400)
Balance at Dec. 31, 2020	158,103			$ 2	249,175	2	(91,076)
Balance, shares at Dec. 31, 2020				23,384,969
Stock-based compensation	1,577				1,577
Exercise of stock options	$ 249				249
Exercise of stock options, shares	88,734			88,734
Comprehensive income:
Unrealized gain on investments	$ 10					10
Net loss	(11,050)						(11,050)
Balance at Mar. 31, 2021	$ 148,889			$ 2	$ 251,001	$ 12	$ (102,126)
Balance, shares at Mar. 31, 2021				23,473,703

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net loss	$ (11,050)	$ (7,738)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	158	25
Stock-based compensation expense	1,577	129
Amortization of premiums and discounts on marketable securities	68	(46)
Reduction in the carrying value of right-of-use assets	90
Unrealized gains on available for sale securities	(10)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	327	(95)
Accounts payable	(1,373)	668
Accrued expenses	(2,272)	814
Operating lease liabilities	(131)
Prepaid expenses - noncurrent	240
Other assets		(22)
Net cash used in operating activities	(12,376)	(6,265)
Investing activities
Purchases of marketable securities	(38,549)	(13,408)
Maturities of marketable securities	39,210	10,101
Purchases of property and equipment	(88)	(101)
Net cash provided by (used in) investing activities	573	(3,408)
Financing activities
Proceeds from exercise of stock options	249	5
Net cash provided by financing activities	249	5
Net decrease in cash, cash equivalents and restricted cash	(11,554)	(9,668)
Cash, cash equivalents and restricted cash at beginning of period	28,394	31,735
Cash, cash equivalents and restricted cash at end of period	16,840	22,067
Supplemental cash flow information:
Cash and cash equivalents	16,486	21,937
Restricted cash	354	130
Cash, cash equivalents and restricted cash at end of period	16,840	22,067
Property and equipment unpaid at end of period	110
Right-of-use asset at adoption of ASC 842	2,431
Operating lease liabilities at adoption of ASC 842	$ 3,997
Deferred offering costs unpaid at end of period		$ 191

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Inozyme Pharma, Inc. (the “Company”) is a clinical-stage rare disease biopharmaceutical company developing novel therapeutics for the treatment of diseases of abnormal mineralization impacting the vasculature, soft tissue and skeleton. The Company is pursuing the development of therapeutics to address the underlying causes of these debilitating diseases. It is well established that two genes, ENPP1 and ABCC6, play key roles in a critical mineralization pathway and that defects in these genes lead to abnormal mineralization. The Company is initially focused on developing a novel therapy to treat rare genetic diseases of ENPP1 and ABCC6 Deficiencies. The Company’s lead product candidate, INZ-701, is a soluble, recombinant, or genetically engineered, fusion protein that is designed to correct a defect in the mineralization pathway caused by ENPP1 and ABCC6 Deficiencies. This pathway is central to the regulation of calcium deposition throughout the body and is further associated with neointimal proliferation, or the overgrowth of smooth muscle cells inside blood vessels. Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). All adjustments considered necessary for a fair presentation have been included. The accompanying consolidated financial statements and footnotes to the financial statements have been prepared on the same basis as the most recently audited annual financial statements, except for disclosures related to the Company’s adoption of ASU 2016-02, Leases (“Topic 842”) included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 25, 2021 (the “Annual Report on Form 10-K”). Liquidity Since the Company’s incorporation in 2017 and through March 31, 2021, the Company has devoted substantially all of its efforts to raising capital, building infrastructure, developing intellectual property and conducting research and development. The Company incurred net losses of $11.1 million in the three months ended March 31, 2021 and $56.4 million in the year ended December 31, 2020 and had an accumulated deficit of $102.1 million as of March 31, 2021. The Company had cash, cash equivalents, and short-term and long-term investments of $147.6 million as of March 31, 2021. The accompanying condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has incurred recurring losses and negative cash flows from operations since inception and has primarily funded its operations with proceeds from the issuance of convertible preferred stock, and the Company’s initial public offering (“IPO”) completed on July 28, 2020. The Company expects its operating losses and negative operating cash flows to continue into the foreseeable future as it continues to expand its research and development efforts. The Company believes that its cash, cash equivalents, and short-term and long-term investments as of March 31, 2021 will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the date of filing this Quarterly Report on Form 10-Q. The Company will need additional funding to support its planned operating activities. If the Company is unable to obtain additional funding, it would be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion, or commercialization efforts, which could adversely affect its business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated. Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the accompanying consolidated financial statements are described in the Company’s audited consolidated financial statements for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 25, 2021. Apart from the Company’s adoption of Topic 842, there have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2021. Use of Estimates The preparation of the Company’s financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Estimates and judgments are based on historical information and other market-specific or various relevant assumptions, including, in certain circumstances, future projections that management believes to be reasonable under the circumstances. Actual results could differ materially from estimates. Significant estimates and assumptions are used for, but not limited to, the accruals for research and development expenses and, for equity instruments issued prior to the completion of the Company’s IPO, stock-based compensation expense, inclusive of the measurement of fair value of equity instruments. For equity instruments issued prior to the completion of the Company’s IPO, the Company utilized various valuation methodologies in accordance with the framework of the 2013 American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation Accrued Research and Development Costs The Company records accrued liabilities for estimated costs of research and development activities conducted by service providers for sponsored research, preclinical studies, clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued expenses in the accompanying consolidated balance sheets and within research and development expense in the accompanying consolidated statements of operations and comprehensive loss. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception. Research and Development Costs Research and development costs are expensed as incurred. Research and development costs consist of direct and indirect internal costs related to specific projects as well as fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Research and development costs also include the write-off of acquired in-process research and development assets with no alternative future use. Net Loss Per Share The Company follows the two-class method when computing net loss allocable to common securities per share as the Company had previously issued shares that meet the definition of participating securities, which include shares of: (i) Series A Convertible Preferred Stock; and (ii) Series A-2 Convertible Preferred Stock. The two-class method requires a portion of net income to be allocated to the participating securities to determine net income allocable to the common securities. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding during the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, diluted net loss per share attributable to common stockholders is calculated by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding after giving consideration to the dilutive effect of convertible preferred stock, restricted common stock, and stock options that are outstanding during the period. The Company has generated a net loss in all periods presented, therefore the basic and diluted net loss per share attributable to common stockholders are the same as the inclusion of the potentially dilutive securities would be anti-dilutive. Fair Value Measurements The Company categorizes its assets and liabilities measured at fair value in accordance with the authoritative accounting guidance that establishes a consistent framework for measuring fair value and expands disclosures for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as the exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: • Level 1- Unadjusted quoted prices in active markets that are accessible at the measurement date for identical assets or liabilities; • Level 2- Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; or • 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). Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term and long-term investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits and limits its exposure to credit risk by placing its cash with high credit quality financial institutions. The Company’s investments are comprised of U.S. Treasury and U.S. government agency debt securities and commercial paper of corporations. The Company mitigates credit risk by maintaining a diversified portfolio and limiting the amount of investment exposure as to institution, maturity and investment type. The Company has no significant off-balance sheet risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2021
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	3. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. Recently Issued and Adopted Accounting Standards In February 2016, the FASB issued Topic 842. The new standard, as amended, establishes a right-of-use model and requires a lessee to recognize on the balance sheet a right-of-use asset and corresponding lease liability for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the consolidated statements of operations and comprehensive loss. As a result of the FASB’s issuance of ASU No. 2020-05, “Revenue From Contracts With Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities”, In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract Recently Issued Accounting Standards Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses : Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU 2019-12, Income Taxes – Simplifying the Accounting for Income Taxes

Balance Sheet Details

Balance Sheet Details	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Details	4. Balance Sheet Details Short-term investments consisted of the following (dollar amounts in thousands): March 31, 2021 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 1 year or less $ 101,881 $ 8 $ (4 ) $ 101,885 U.S. Treasury securities 1 year or less 12,626 3 — 12,629 U.S. government agency debt securities 1 year or less 14,082 4 — 14,086 $ 128,589 $ 15 $ (4 ) $ 128,600 December 31, 2020 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 1 year or less $ 94,873 $ 5 $ (6 ) $ 94,872 U.S. Treasury securities 1 year or less 11,614 2 (1 ) 11,615 U.S. government debt securities 1 year or less 13,169 1 — 13,170 $ 119,656 $ 8 $ (7 ) $ 119,657 Long-term investments consisted of the following (dollar amounts in thousands): March 31, 2021 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities After 1 year through 5 years $ 2,547 $ 1 $ — $ 2,548 $ 2,547 $ 1 $ — $ 2,548 December 31, 2020 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities After 1 year through 5 years $ 5,126 $ — $ — $ 5,126 U.S. government agency debt securities After 1 year through 5 years 7,072 1 — 7,073 $ 12,198 $ 1 $ — $ 12,199 The Company concluded that the net declines in market value of available-for-sale securities were temporary in nature and did not consider any of the investments to be other-than-temporarily impaired. In accordance with its investment policy, the Company invests in investment grade securities with high credit quality issuers, and generally limits the amount of credit exposure to any one issuer. The Company evaluates securities for other-than-temporary impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the issuer, and the Company’s intent and ability to hold the investment to allow for an anticipated recovery in fair value. Furthermore, the aggregate of individual unrealized losses that had been outstanding for 12 months or less was not significant as of March 31, 2021 and December 31, 2020. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell the investments before a recovery of their amortized cost bases, which may be maturity. The Company also believes that it will be able to collect both principal and interest amounts due at maturity. Prepaid expenses and other current assets consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Interest receivable $ 122 $ 155 Prepaid insurance 1,034 1,723 Prepaid research studies 1,260 804 Prepaid other 539 600 Total $ 2,955 $ 3,282 Prepaid expenses, net of current portion consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Prepaid clinical trial and other $ 2,943 $ 3,183 $ 2,943 $ 3,183 Property and equipment consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Laboratory equipment and manufacturing equipment $ 522 $ 339 Furniture and fixtures 254 254 Computer equipment and software 302 287 Leasehold improvements 2,095 2,095 3,173 2,975 Less accumulated depreciation (485 ) (327 ) Total $ 2,688 $ 2,648 Depreciation expense for the three months ended March 31, 2021 and 2020 was $158 thousand and $25 thousand, respectively. Accrued expenses consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Payroll and related liabilities $ 1,123 $ 2,296 Professional fees 418 454 Research and development costs 2,259 2,997 Deferred rent — 279 Other 651 878 Total $ 4,451 $ 6,904

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement	5. Fair Value Measurement The following table represents the Company’s financial assets measured at fair value on a recurring basis and indicate the level of fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurements at Reporting Date Using Description March 31, 2021 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (included in cash and cash equivalents) $ 1,524 $ 1,524 $ — $ — Commercial paper 101,884 — 101,884 — U.S. Treasury securities 15,177 15,177 — — U.S. government agency debt securities 14,086 — 14,086 — Total assets $ 132,671 $ 16,701 $ 115,970 $ — Fair Value Measurements at Reporting Date Using Description December 31, 2020 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (included in cash and cash equivalents) $ 15,739 $ 15,739 $ — $ — Commercial paper 94,872 — 94,872 — U.S. Treasury securities 16,741 16,741 — — U.S. government agency debt securities 20,243 — 20,243 — Total assets $ 147,595 $ 32,480 $ 115,115 $ — There have been no transfers between fair value levels during the three months ended March 31, 2021.

License and Sponsored Research

License and Sponsored Research Agreements	3 Months Ended
	Mar. 31, 2021
Research And Development [Abstract]
License and Sponsored Research Agreements	6. License and Sponsored Research Agreements In January 2017, the Company entered into a license agreement with Yale University (“Yale”), which was amended in May 2020 and July 2020, under which the Company licensed certain intellectual property related to ectonucleotide pyrophosphatase/phosphodiesterase enzymes, that is the basis for the Company’s INZ-701 development program. Pursuant to the license agreement, as partial upfront consideration, the Company made a payment of approximately $60,000 to Yale, which amount reflected unreimbursed patent expenses incurred by Yale prior to the date of the license agreement. The Company is responsible for paying Yale an annual license maintenance fee in varying amounts throughout the term ranging from the low tens of thousands of dollars to the high tens of thousands of dollars. As of March 31, 2021, the Company incurred a total of $99,000 in license maintenance fees to Yale. The Company is required to pay Yale $3.0 million, based on the achievement of a specified net product sales milestone or specified development and commercialization milestones, for each therapeutic and prophylactic licensed product developed. In addition, the Company is required to pay Yale an amount in the several hundreds of thousands of dollars, based on the achievement of a specified net product sales milestone or specified development and commercialization milestones, for each diagnostic licensed product developed. While the agreement remains in effect, the Company is required to pay Yale low single-digit percentage royalties on aggregate worldwide net sales of certain licensed products. Yale is guaranteed a minimum royalty payment amount (ranging in dollar amounts from the mid six figures to low seven figures) for each year after the first sale of a therapeutic or prophylactic licensed product that results in net sales. Yale is guaranteed a minimum royalty payment amount (ranging from the low tens of thousands of dollars to the mid tens of thousands of dollars) for each year after the first sale of a diagnostic licensed product that results in net sales. The Company must also pay Yale a percentage in the twenties of certain types of income it receives from sublicensees. The Company is also responsible for costs relating to the prosecution and maintenance of the licensed patents. Finally, subject to certain conditions, all payments due by the Company to Yale will be tripled following any patent challenge or challenge to a claim by Yale that a product is a licensed product under the agreement made by the Company against Yale if Yale prevails in such challenge. The Company is not aware of any currently ongoing patent challenges. In January 2017, the Company also entered into a corporate sponsored research agreement with Yale (the “Sponsored Research Agreement”), which was amended in February 2019, under which the Company agreed to provide research support funding in the aggregate amount of $2.4 million over the five year period from contract inception through 2021. The Company recorded research and development expenses associated with this arrangement of $0.1 million and $0.2 million in the three months ended March 31, 2021 and 2020, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Operating Leases The Company adopted Topic 84 2 on January 1, 2021. Topic 842 allows the Company to elect a package of practical expedients, which provide that an entity need not reassess: (i) whether any expired or existing contracts are or contain leases; (ii) the lease classification for any expired or existing leases; and (iii) any initial direct costs for any existing leases. Another practical expedient allows the Company to use hindsight in determining the lease term when considering lessee options to extend or terminate the lease and to purchase the underlying asset. The Company has elected to utilize this package of practical expedients and has not elected the hindsight methodology in its implementation of Topic 842. The Company elected to adopt this standard using the optional modified retrospective approach and recognized a cumulative-effect adjustment to the condensed consolidated balance sheet on the date of adoption. Comparative periods have not been restated. With the adoption of Topic 842, the Company’s condensed consolidated balance sheet now contains the following line items: Right-of-use assets, Operating lease liabilities and Operating lease liabilities, net of current portion. The Company determined that it held the following significant operating leases of office and laboratory space as of January 1, 2021: • An operating lease for 8,499 square feet of office space in Boston, Massachusetts that expires in 2025, with an option to extend the term for five years; and • An operating lease for 6,244 square feet of laboratory space in Boston, Massachusetts that expires in 2025. In connection with the Company’s lease of office space, the Company provided a security deposit to the landlord in the form of a letter of credit totaling $130 thousand. The cash collateralizing the letter of credit is included in restricted cash in the accompanying balance sheets as of March 31, 2021 and December 31, 2020. The Company has elected to not recognize right-of-use assets and lease liabilities arising from short-term leases, which are leases that, at the commencement date, have a lease term of 12 months or less and do not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise. As all the existing leases subject to Topic 842 were previously classified as operating leases by the Company, they were similarly classified as operating leases under Topic 842. The Company has determined that the identified leases did not contain non-lease components and require no further allocation of the total lease cost. Additionally, the agreements in place did not contain information to determine the rate implicit in the lease. As such, the Company calculated the incremental borrowing rate based on the remaining lease terms as of January 1, 2021. At January 1, 2021 and March 31, 2021, the weighted average incremental borrowing rate and the weighted average remaining lease term for the operating leases held by the Company were 8.0% and 5.0 years, respectively. As of March 31, 2021, right-of-use assets and liabilities arising from operating leases were $2.3 million and $3.9 million, respectively. During the three months ended March 31, 2021, cash paid for amounts included for the measurement of lease liabilities was $0.2 million and the Company recorded operating lease expense of $0.2 million. Future lease payments under non-cancelable leases as of March 31, 2021 are as follows (dollar amounts in thousands): Year Ending December 31, 2021 (remaining 9 months) $ 709 2022 968 2023 992 2024 1,016 2025 944 Thereafter — $ 4,629 Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters arising out of the relationship between such parties and the Company. In addition, the Company has entered into indemnification agreements with members of its board of directors and senior management that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements, and it has not accrued any liabilities related to such obligations as of March 31, 2021 or December 31, 2020. Legal Proceedings The Company is not currently a party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses the costs related to its legal proceedings as they are incurred. No such costs have been incurred during the three months ended March 31, 2021 and 2020.

Convertible Preferred Stock and

Convertible Preferred Stock and Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Convertible Preferred Stock And Stockholders Equity [Abstract]
Convertible Preferred Stock and Stockholders' Equity	8. Convertible Preferred Stock and Stockholders’ Equity Convertible Preferred Stock In November 2018, the Company entered into a Series A-2 Convertible Preferred Stock Purchase Agreement, which was amended in March 2019 (as so amended, the “Series A-2 Agreement”) under which it agreed to issue up to 47,132,862 shares of Series A-2 Convertible Preferred Stock. Under the Series A-2 Agreement, the Company initially issued 7,482,515 shares at a price of $1.43 per share for net proceeds of $10.4 million in November 2018 and 16,083,916 shares at a price of $1.43 per share for net proceeds of $22.9 million in March 2019. The Series A-2 Agreement provided for a second tranche closing, pursuant to which the investors were required to purchase, and the Company to sell, an additional 23,566,431 shares of Series A-2 Convertible Preferred Stock at $1.43 per share upon the achievement of the defined milestone, or earlier upon board of directors and requisite stockholder approval to waive such requirement. In June 2020, the board of directors and requisite stockholders approved such waiver and the Company issued 23,566,431 shares of Series A-2 Convertible Preferred Stock at a price of $1.43 per share for net proceeds of $33.6 million. In July 2020, the Company increased the number of authorized shares of Series A-2 Convertible Preferred Stock from 47,132,862 to 55,427,222. In July 2020, the Company issued 8,294,360 shares of Series A-2 Convertible Preferred Stock to Alexion Pharmaceuticals, Inc. (“Alexion”) in consideration for the sale and assignment to the Company of specified patent rights and other specified assets related to ENPP1. In July 2020, the Company eliminated the per share and gross proceeds thresholds for a firm-commitment underwritten public offering that triggers the automatic conversion of all outstanding shares of preferred stock into common stock. On July 28, 2020, upon the closing of the Company’s IPO, all 104,277,222 shares of then outstanding preferred stock automatically converted into 13,953,850 shares of common stock. In addition, on July 28, 2020, the Company amended and restated its certificate of incorporation to authorize 200,000,000 shares of common stock and 5,000,000 shares of preferred stock, which shares of preferred stock are currently undesignated. The Company does not have any outstanding preferred stock as of March 31, 2021. There have been no dividends declared on preferred stock or common stock by the Company’s board of directors as of March 31, 2021. Equity Incentive Plans In January 2017, the Company’s board of directors and stockholders adopted the 2017 Equity Incentive Plan, which was amended and restated in July 2017, (as so amended and restated, the “2017 Plan”), which provided for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards and other stock awards. The maximum number of shares of common stock that were authorized for issuance under the 2017 Plan was 2,730,496. On July 17, 2020, the Company’s stockholders approved the 2020 Stock Incentive Plan (the “2020 Plan”), which became effective on July 23, 2020. The 2020 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares of the Company’s common stock reserved for issuance under the 2020 Plan is 1,588,315 shares, plus the 426,065 shares of common stock remaining available for issuance under the 2017 Plan as of July 23, 2020. The number of shares reserved under the 2020 Plan will be annually increased on each January 1 through January 1, 2030 by the lower of (i) 4% of the number of shares of common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors. The number of shares available for grant under the 2020 Plan increased by 935,398 on January 1, 2021 due to this provision. As of the effective date of the 2020 Plan, no further awards will be made under the 2017 Plan. Any options or awards outstanding under the 2017 Plan remain outstanding and effective and are governed by their existing terms. The shares of the Company’s common stock subject to outstanding awards under the 2017 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right will be added back to the shares of common stock available for issuance under the 2020 Plan. No more than 1,588,315 shares of the Company’s common stock may be granted subject to incentive stock options under the 2020 Plan. As of March 31, 2021, 819,406 shares of common stock remain available for future issuance under the 2020 Plan. For financial reporting purposes, the Company performed common stock valuations with the assistance of a third-party valuation specialist as of March 31, 2020, May 31, 2019, November 30, 2018, December 31, 2017 and April 30, 2017 to determine stock-based compensation expense for the stock options issued under the 2017 Plan prior to the IPO. Following the completion of the IPO, the fair value of the common stock underlying option grants is determined based on the closing price of the Company’s common stock on the Nasdaq Global Select Market on the date of grant. The following table summarizes stock option activity under the Company’s equity incentive plans since December 31, 2020: Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in years) (in thousands) Outstanding at December 31, 2020 3,064,457 $ 7.28 8.76 $ 41,680 Granted 746,185 20.47 Exercised (88,734 ) 2.80 Forfeited (198,322 ) 7.56 Outstanding at March 31, 2021 3,523,586 $ 10.17 8.79 $ 35,270 Exercisable at March 31, 2021 1,001,661 $ 3.31 7.64 $ 16,522 Vested and expected to vest at March 31, 2021 3,523,586 $ 10.17 8.79 $ 35,270 (1) The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The weighted-average grant date fair value of options granted during the three months ended March 31, 2021 was $17.01 per share. For purposes of calculating stock-based compensation expense, the Company estimates the fair value of stock options using the Black-Scholes option-pricing model. This model incorporates various assumptions, including the expected volatility, expected term, and interest rates. The underlying assumptions used to value stock options granted to participants using the Black-Scholes option-pricing were as follows: For the Three Months Ended March 31, 2021 2020 Risk-free interest rate range 0.48% to 1.05% N/A Dividend yield 0% N/A Expected term of options (years) 6.08 to 6.48 N/A Volatility rate range 88.70% to 90.53% N/A The total compensation cost recognized in the statements of operations associated with all the stock-based compensation awards granted by the Company is as follows (in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 641 $ 85 General and administrative 936 44 Total $ 1,577 $ 129 The total unrecognized compensation cost related to outstanding employee awards as of March 31, 2021 was $23.8 million, and is expected to be recognized over a weighted-average period of 2.6 years. Employee Stock Purchase Plan On July 17, 2020, the Company’s stockholders approved the 2020 Employee Stock Purchase Plan (the “ESPP”), which became effective on July 23, 2020. The ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 198,539 shares of the Company’s common stock. The number of shares of common stock reserved for issuance under the ESPP will automatically increase on each January 1 through January 1, 2031, in an amount equal to the lowest of (1) 397,079 shares of the Company’s common stock, (2) 1% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (3) an amount determined by the Company’s board of directors. The number of shares available for grant under this plan increased by 233,849 on January 1, 2021 due to this provision. As of March 31, 2021, no shares have been purchased by employees under the ESPP.

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss per Share	9. Net Loss per Share Net Loss per Share Attributable to Common Stockholders For purposes of the diluted net loss per share calculation, stock options, and convertible preferred stock are considered to be common stock equivalents but have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential dilutive securities from the computation of diluted net loss per share attributable to common stockholders because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2021 2020 Series A Convertible Preferred Stock (as converted to common stock) — 6,536,856 Series A-2 Convertible Preferred Stock (as converted to common stock) — 3,153,537 Options to purchase common stock 3,523,586 1,623,911 3,523,586 11,314,304

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2021
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	10. Employee Benefit Plans The Company established a defined contribution savings plan in 2018 for all eligible U.S. employees under Section 401(k) of the Internal Revenue Code. Employees can designate the investment of their 401(k) accounts into several mutual funds. Effective January 1, 2021, the Company implemented a matching policy under which the Company matches 50% of an employee’s contributions to the 401(k) plan, up to a maximum of 6% of the employee’s base salary and bonus paid during the year.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). All adjustments considered necessary for a fair presentation have been included. The accompanying consolidated financial statements and footnotes to the financial statements have been prepared on the same basis as the most recently audited annual financial statements, except for disclosures related to the Company’s adoption of ASU 2016-02, Leases (“Topic 842”) included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on March 25, 2021 (the “Annual Report on Form 10-K”).
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated. Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the accompanying consolidated financial statements are described in the Company’s audited consolidated financial statements for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 25, 2021. Apart from the Company’s adoption of Topic 842, there have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2021.
Use of Estimates	Use of Estimates The preparation of the Company’s financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Estimates and judgments are based on historical information and other market-specific or various relevant assumptions, including, in certain circumstances, future projections that management believes to be reasonable under the circumstances. Actual results could differ materially from estimates. Significant estimates and assumptions are used for, but not limited to, the accruals for research and development expenses and, for equity instruments issued prior to the completion of the Company’s IPO, stock-based compensation expense, inclusive of the measurement of fair value of equity instruments. For equity instruments issued prior to the completion of the Company’s IPO, the Company utilized various valuation methodologies in accordance with the framework of the 2013 American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation
Accrued Research and Development Costs	Accrued Research and Development Costs The Company records accrued liabilities for estimated costs of research and development activities conducted by service providers for sponsored research, preclinical studies, clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued expenses in the accompanying consolidated balance sheets and within research and development expense in the accompanying consolidated statements of operations and comprehensive loss. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with service providers. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development costs consist of direct and indirect internal costs related to specific projects as well as fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Research and development costs also include the write-off of acquired in-process research and development assets with no alternative future use.
Net Loss Per Share	Net Loss Per Share The Company follows the two-class method when computing net loss allocable to common securities per share as the Company had previously issued shares that meet the definition of participating securities, which include shares of: (i) Series A Convertible Preferred Stock; and (ii) Series A-2 Convertible Preferred Stock. The two-class method requires a portion of net income to be allocated to the participating securities to determine net income allocable to the common securities. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding during the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, diluted net loss per share attributable to common stockholders is calculated by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding after giving consideration to the dilutive effect of convertible preferred stock, restricted common stock, and stock options that are outstanding during the period. The Company has generated a net loss in all periods presented, therefore the basic and diluted net loss per share attributable to common stockholders are the same as the inclusion of the potentially dilutive securities would be anti-dilutive.
Fair Value Measurements	Fair Value Measurements The Company categorizes its assets and liabilities measured at fair value in accordance with the authoritative accounting guidance that establishes a consistent framework for measuring fair value and expands disclosures for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as the exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: • Level 1- Unadjusted quoted prices in active markets that are accessible at the measurement date for identical assets or liabilities; • Level 2- Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; or • 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).
Concentration of Credit Risk and Off-Balance Sheet Risk	Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term and long-term investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits and limits its exposure to credit risk by placing its cash with high credit quality financial institutions. The Company’s investments are comprised of U.S. Treasury and U.S. government agency debt securities and commercial paper of corporations. The Company mitigates credit risk by maintaining a diversified portfolio and limiting the amount of investment exposure as to institution, maturity and investment type. The Company has no significant off-balance sheet risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements.
Recently Issued and Adopted Accounting Standards	Recently Issued and Adopted Accounting Standards In February 2016, the FASB issued Topic 842. The new standard, as amended, establishes a right-of-use model and requires a lessee to recognize on the balance sheet a right-of-use asset and corresponding lease liability for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the consolidated statements of operations and comprehensive loss. As a result of the FASB’s issuance of ASU No. 2020-05, “Revenue From Contracts With Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities”, In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract
Recently Issued Accounting Standards Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses : Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU 2019-12, Income Taxes – Simplifying the Accounting for Income Taxes

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Short-Term Investments	Short-term investments consisted of the following (dollar amounts in thousands): March 31, 2021 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 1 year or less $ 101,881 $ 8 $ (4 ) $ 101,885 U.S. Treasury securities 1 year or less 12,626 3 — 12,629 U.S. government agency debt securities 1 year or less 14,082 4 — 14,086 $ 128,589 $ 15 $ (4 ) $ 128,600 December 31, 2020 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 1 year or less $ 94,873 $ 5 $ (6 ) $ 94,872 U.S. Treasury securities 1 year or less 11,614 2 (1 ) 11,615 U.S. government debt securities 1 year or less 13,169 1 — 13,170 $ 119,656 $ 8 $ (7 ) $ 119,657
Schedule of Long-Term Investments	Long-term investments consisted of the following (dollar amounts in thousands): March 31, 2021 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities After 1 year through 5 years $ 2,547 $ 1 $ — $ 2,548 $ 2,547 $ 1 $ — $ 2,548 December 31, 2020 Description Maturity Amortized Costs Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value U.S. Treasury securities After 1 year through 5 years $ 5,126 $ — $ — $ 5,126 U.S. government agency debt securities After 1 year through 5 years 7,072 1 — 7,073 $ 12,198 $ 1 $ — $ 12,199
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Interest receivable $ 122 $ 155 Prepaid insurance 1,034 1,723 Prepaid research studies 1,260 804 Prepaid other 539 600 Total $ 2,955 $ 3,282
Schedule of Prepaid Expenses, Net of Current Portion	Prepaid expenses, net of current portion consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Prepaid clinical trial and other $ 2,943 $ 3,183 $ 2,943 $ 3,183
Schedule of Property and Equipment	Property and equipment consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Laboratory equipment and manufacturing equipment $ 522 $ 339 Furniture and fixtures 254 254 Computer equipment and software 302 287 Leasehold improvements 2,095 2,095 3,173 2,975 Less accumulated depreciation (485 ) (327 ) Total $ 2,688 $ 2,648
Schedule of Accrued Expenses	Accrued expenses consisted of the following (dollar amounts in thousands): At March 31, 2021 At December 31, 2020 Payroll and related liabilities $ 1,123 $ 2,296 Professional fees 418 454 Research and development costs 2,259 2,997 Deferred rent — 279 Other 651 878 Total $ 4,451 $ 6,904

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured at Fair Value	The following table represents the Company’s financial assets measured at fair value on a recurring basis and indicate the level of fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurements at Reporting Date Using Description March 31, 2021 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (included in cash and cash equivalents) $ 1,524 $ 1,524 $ — $ — Commercial paper 101,884 — 101,884 — U.S. Treasury securities 15,177 15,177 — — U.S. government agency debt securities 14,086 — 14,086 — Total assets $ 132,671 $ 16,701 $ 115,970 $ — Fair Value Measurements at Reporting Date Using Description December 31, 2020 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds (included in cash and cash equivalents) $ 15,739 $ 15,739 $ — $ — Commercial paper 94,872 — 94,872 — U.S. Treasury securities 16,741 16,741 — — U.S. government agency debt securities 20,243 — 20,243 — Total assets $ 147,595 $ 32,480 $ 115,115 $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Lease Payments Under Non-Cancelable Leases	Future lease payments under non-cancelable leases as of March 31, 2021 are as follows (dollar amounts in thousands): Year Ending December 31, 2021 (remaining 9 months) $ 709 2022 968 2023 992 2024 1,016 2025 944 Thereafter — $ 4,629

Convertible Preferred Stock a_2

Convertible Preferred Stock and Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Summary of Stock Option Activity Under Equity Incentive Plans	The following table summarizes stock option activity under the Company’s equity incentive plans since December 31, 2020: Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in years) (in thousands) Outstanding at December 31, 2020 3,064,457 $ 7.28 8.76 $ 41,680 Granted 746,185 20.47 Exercised (88,734 ) 2.80 Forfeited (198,322 ) 7.56 Outstanding at March 31, 2021 3,523,586 $ 10.17 8.79 $ 35,270 Exercisable at March 31, 2021 1,001,661 $ 3.31 7.64 $ 16,522 Vested and expected to vest at March 31, 2021 3,523,586 $ 10.17 8.79 $ 35,270 (1) The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock.
Summary of Total Compensation Cost Recognized in Statements of Operations	The total compensation cost recognized in the statements of operations associated with all the stock-based compensation awards granted by the Company is as follows (in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 641 $ 85 General and administrative 936 44 Total $ 1,577 $ 129
Employees
Summary of Assumptions Used to Value Stock Options Granted Using Black-Scholes Option-Pricing	For purposes of calculating stock-based compensation expense, the Company estimates the fair value of stock options using the Black-Scholes option-pricing model. This model incorporates various assumptions, including the expected volatility, expected term, and interest rates. The underlying assumptions used to value stock options granted to participants using the Black-Scholes option-pricing were as follows: For the Three Months Ended March 31, 2021 2020 Risk-free interest rate range 0.48% to 1.05% N/A Dividend yield 0% N/A Expected term of options (years) 6.08 to 6.48 N/A Volatility rate range 88.70% to 90.53% N/A

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Potential Dilutive Securities from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The Company excluded the following potential dilutive securities from the computation of diluted net loss per share attributable to common stockholders because including them would have had an anti-dilutive effect: Three Months Ended March 31, 2021 2020 Series A Convertible Preferred Stock (as converted to common stock) — 6,536,856 Series A-2 Convertible Preferred Stock (as converted to common stock) — 3,153,537 Options to purchase common stock 3,523,586 1,623,911 3,523,586 11,314,304

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ 11,050	$ 7,738	$ 56,400
Accumulated deficit	102,126		$ 91,076
Cash and cash equivalents and short term and long term investments	$ 147,600

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)
Accounting Policies [Abstract]
Off-balance sheet concentrations of credit risk description	The Company has no significant off-balance sheet risk such as foreign exchange contracts, option contracts, or other foreign hedging arrangements.
Off-balance sheet concentrations of credit risk	$ 0

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements - Additional Information (Details) - USD ($)	Mar. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Right-of-use assets	$ 2,341,000
Operating lease liabilities	3,900,000
Accumulated deficit	$ (102,126,000)		$ (91,076,000)
ASU 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2021
Change in accounting principle, accounting standards update, adopted	true
Right-of-use assets		$ 2,400,000
Operating lease liabilities		4,000,000
Operating lease, reversed lease liability		1,600,000
ASU 2016-02 | Revision of Prior Period, Accounting Standards Update, Adjustment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accumulated deficit		$ 0
ASU 2018-15
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2021
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true

Balance Sheet Details - Schedul

Balance Sheet Details - Schedule of Short-Term Investments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Costs	$ 128,589	$ 119,656
Gross Unrealized Gains	15	8
Gross Unrealized Losses	(4)	(7)
Estimated Fair Value	$ 128,600	$ 119,657
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year or less	1 year or less
Amortized Costs	$ 101,881	$ 94,873
Gross Unrealized Gains	8	5
Gross Unrealized Losses	(4)	(6)
Estimated Fair Value	$ 101,885	$ 94,872
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year or less	1 year or less
Amortized Costs	$ 12,626	$ 11,614
Gross Unrealized Gains	3	2
Gross Unrealized Losses		(1)
Estimated Fair Value	$ 12,629	$ 11,615
U.S. Government Agency Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year or less	1 year or less
Amortized Costs	$ 14,082	$ 13,169
Gross Unrealized Gains	4	1
Estimated Fair Value	$ 14,086	$ 13,170

Balance Sheet Details - Sched_2

Balance Sheet Details - Schedule of Long-Term Investments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Costs	$ 128,589	$ 119,656
Gross Unrealized Gains	15	8
Gross Unrealized Losses	(4)	(7)
Estimated Fair Value	$ 128,600	$ 119,657
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year or less	1 year or less
Amortized Costs	$ 12,626	$ 11,614
Gross Unrealized Gains	3	2
Gross Unrealized Losses		(1)
Estimated Fair Value	$ 12,629	$ 11,615
U.S. Government Agency Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity	1 year or less	1 year or less
Amortized Costs	$ 14,082	$ 13,169
Gross Unrealized Gains	4	1
Estimated Fair Value	14,086	13,170
Long Term Investments
Schedule Of Available For Sale Securities [Line Items]
Amortized Costs	2,547	12,198
Gross Unrealized Gains	1	1
Estimated Fair Value	$ 2,548	$ 12,199
Long Term Investments | U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity	After 1 year through 5 years	After 1 year through 5 years
Amortized Costs	$ 2,547	$ 5,126
Gross Unrealized Gains	1
Estimated Fair Value	$ 2,548	$ 5,126
Long Term Investments | U.S. Government Agency Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Maturity		After 1 year through 5 years
Amortized Costs		$ 7,072
Gross Unrealized Gains		1
Estimated Fair Value		$ 7,073

Balance Sheet Details - Sched_3

Balance Sheet Details - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Interest receivable	$ 122	$ 155
Prepaid insurance	1,034	1,723
Prepaid research studies	1,260	804
Prepaid other	539	600
Total	$ 2,955	$ 3,282

Balance Sheet Details - Sched_4

Balance Sheet Details - Schedule of Prepaid Expenses, Net of Current Portion (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Prepaid clinical trial and other	$ 2,943	$ 3,183
Prepaid expenses, net of current portion	$ 2,943	$ 3,183

Balance Sheet Details - Sched_5

Balance Sheet Details - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 3,173	$ 2,975
Less accumulated depreciation	(485)	(327)
Total	2,688	2,648
Laboratory Equipment and Manufacturing Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	522	339
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	254	254
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	302	287
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,095	$ 2,095

Balance Sheet Details - Additio

Balance Sheet Details - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Depreciation expense	$ 158	$ 25

Balance Sheet Details - Sched_6

Balance Sheet Details - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Payroll and related liabilities	$ 1,123	$ 2,296
Professional fees	418	454
Research and development costs	2,259	2,997
Deferred rent		279
Other	651	878
Total	$ 4,451	$ 6,904

Fair Value Measurement - Summar

Fair Value Measurement - Summary of Financial Assets Measured at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	$ 132,671	$ 147,595
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents fair value disclosure	1,524	15,739
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	101,884	94,872
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	16,701	32,480
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents fair value disclosure	1,524	15,739
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	115,970	115,115
Significant Other Observable Inputs (Level 2) | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	101,884	94,872
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	15,177	16,741
U.S. Treasury Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	15,177	16,741
U.S. Government Agency Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	14,086	20,243
U.S. Government Agency Debt Securities | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	$ 14,086	$ 20,243

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value Disclosures [Abstract]
Fair value assets level 1 to level 2 transfers amount	$ 0
Fair value assets level 2 to level 1 transfers amount	0
Fair value measurement with unobservable inputs reconciliation recurring basis asset transfers into level 3	0
Fair value measurement with unobservable inputs reconciliation recurring basis asset transfers out of level 3	$ 0

License and Sponsored Researc_2

License and Sponsored Research Agreements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Feb. 28, 2019	Mar. 31, 2021	Mar. 31, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expenses		$ 6,603,000	$ 6,406,000
Yale
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Partial upfront consideration payment under license agreement		60,000
Milestone payment upon achievement of certain milestones		3,000,000
Yale | Sponsored Research Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research support funding amount	$ 2,400,000
Research support funding period	5 years
Research support funding expiration year	2021
Research and development expenses		100,000	$ 200,000
Yale | License
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maintenance fees		$ 99,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Jan. 01, 2021USD ($)ft²	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Lessee Lease Description [Line Items]
Weighted average incremental borrowing rate for operating leases	8.00%	8.00%
Weighted average remaining lease term for operating leases	5 years	5 years
Right-of-use assets		$ 2,341,000
Operating lease liabilities		3,900,000
Cash paid for amounts included for measurement of lease liabilities		200,000
Operating lease expense		200,000
Costs related to legal proceedings		0	$ 0
Restricted Cash | Letter of Credit
Lessee Lease Description [Line Items]
Security deposits		$ 130,000		$ 130,000
Office Space | Boston, Massachusetts
Lessee Lease Description [Line Items]
Area of leased space | ft²	8,499
Lessee operating lease expiration year	2025
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Lessee operating lease option to extend description		option to extend the term for five years
Operating lease renewal term	5 years
Laboratory Space | Boston, Massachusetts
Lessee Lease Description [Line Items]
Area of leased space | ft²	6,244
Lessee operating lease expiration year	2025
ASU 2016-02
Lessee Lease Description [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2021
Right-of-use assets	$ 2,400,000
Operating lease liabilities	$ 4,000,000

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Lease Payments Under Non-Cancelable Leases (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021 (remaining 9 months)	$ 709
2022	968
2023	992
2024	1,016
2025	944
Operating lease liability	$ 4,629

Convertible Preferred Stock a_3

Convertible Preferred Stock and Stockholders' Equity - Additional Information (Details) - USD ($)	Jul. 23, 2020	Jun. 30, 2020	Mar. 31, 2019	Nov. 30, 2018	Mar. 31, 2021	Mar. 31, 2020	Jan. 01, 2021	Dec. 31, 2020	Jul. 31, 2020	Jul. 28, 2020	Jul. 17, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, shares outstanding					0			0
Number of outstanding preferred stock converted into common stock										13,953,850
Common stock, shares authorized					200,000,000			200,000,000		200,000,000
Preferred stock, shares authorized					5,000,000			5,000,000		5,000,000
Dividends declared on preferred stock or common stock					$ 0
Plan description					On July 17, 2020, the Company’s stockholders approved the 2020 Stock Incentive Plan (the “2020 Plan”), which became effective on July 23, 2020. The 2020 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares of the Company’s common stock reserved for issuance under the 2020 Plan is 1,588,315 shares, plus the 426,065 shares of common stock remaining available for issuance under the 2017 Plan as of July 23, 2020. The number of shares reserved under the 2020 Plan will be annually increased on each January 1 through January 1, 2030 by the lower of (i) 4% of the number of shares of common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors. The number of shares available for grant under the 2020 Plan increased by 935,398 on January 1, 2021 due to this provision. As of the effective date of the 2020 Plan, no further awards will be made under the 2017 Plan. Any options or awards outstanding under the 2017 Plan remain outstanding and effective and are governed by their existing terms. The shares of the Company’s common stock subject to outstanding awards under the 2017 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right will be added back to the shares of common stock available for issuance under the 2020 Plan. No more than 1,588,315 shares of the Company’s common stock may be granted subject to incentive stock options under the 2020 Plan. As of March 31, 2021, 819,406 shares of common stock remain available for future issuance under the 2020 Plan.
Granted options					746,185
Weighted-average exercise price of options granted					$ 20.47
Weighted-average grant date fair value of options granted					$ 17.01
Aggregate intrinsic value of stock options exercised					$ 200,000
Total unrecognized compensation cost related to outstanding employee awards					$ 23,800,000
Total unrecognized compensation cost related to outstanding employee awards, expected to be recognized over a weighted-average period					2 years 7 months 6 days
Share based compensation options to purchase number of common stock					3,523,586			3,064,457
2020 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	1,588,315				819,406		935,398
Number of common stock reserved for issuance increase percentage on stock outstanding	4.00%
2017 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	426,065
2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance									2,730,496
Number of awards available for issuance											0
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance							233,849
Number of common stock reserved for issuance increase percentage on stock outstanding	1.00%
Plan description					The number of shares of common stock reserved for issuance under the ESPP will automatically increase on each January 1 through January 1, 2031, in an amount equal to the lowest of (1) 397,079 shares of the Company’s common stock, (2) 1% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (3) an amount determined by the Company’s board of directors.
Share based compensation options to purchase number of common stock	198,539
Increase in additional number of shares to be issued	397,079
Number of shares purchased						0
IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, shares outstanding										104,277,222
Maximum | 2020 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of awards available for issuance					1,588,315
Series A-2 Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued			16,083,916	7,482,515
Shares issued, price per share		$ 1.43	$ 1.43	$ 1.43
Net proceeds from issuance of shares		$ 33,600,000	$ 22,900,000	$ 10,400,000
Shares available for issuance to investors			23,566,431
Shares available for issuance, price per share			$ 1.43
Additional shares issued		23,566,431
Series A-2 Convertible Preferred Stock | Alexion Pharmaceuticals, Inc
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued									8,294,360
Series A-2 Convertible Preferred Stock | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued				47,132,862
Convertible preferred stock, shares authorized									55,427,222
Series A-2 Convertible Preferred Stock | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Convertible preferred stock, shares authorized				47,132,862

Convertible Preferred Stock a_4

Convertible Preferred Stock and Stockholders' Equity - Summary of Stock Option Activity Under Equity Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Convertible Preferred Stock And Stockholders Equity [Abstract]
Options Outstanding, Beginning Balance	3,064,457
Options Outstanding, Granted	746,185
Options Outstanding, Exercised	(88,734)
Options Outstanding, Forfeited	(198,322)
Options Outstanding, Ending Balance	3,523,586	3,064,457
Options Outstanding, Exercisable	1,001,661
Options Outstanding, Vested and expected to vest	3,523,586
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 7.28
Weighted Average Exercise Price, Granted	20.47
Weighted Average Exercise Price, Exercised	2.80
Weighted Average Exercise Price, Forfeited	7.56
Weighted Average Exercise Price, Outstanding, Ending Balance	10.17	$ 7.28
Weighted Average Exercise Price, Exercisable	3.31
Weighted Average Exercise Price, Vested and expected to vest	$ 10.17
Weighted Average Remaining Contractual Term (in years), Outstanding	8 years 9 months 14 days	8 years 9 months 3 days
Weighted Average Remaining Contractual Term (in years), Exercisable	7 years 7 months 20 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest	8 years 9 months 14 days
Aggregate Intrinsic Value, Outstanding	$ 35,270	$ 41,680
Aggregate Intrinsic Value, Exercisable	16,522
Aggregate Intrinsic Value, Vested and expected to vest	$ 35,270

Convertible Preferred Stock a_5

Convertible Preferred Stock and Stockholders' Equity - Summary of Assumptions Used to Value Stock Options Granted to Employees using Black-Scholes Option-Pricing (Details)	3 Months Ended
	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate range, minimum	0.48%
Risk-free interest rate range, maximum	1.05%
Dividend yield	0.00%
Volatility rate range, minimum	88.70%
Volatility rate range, maximum	90.53%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of options (years)	6 years 29 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of options (years)	6 years 5 months 23 days

Convertible Preferred Stock a_6

Convertible Preferred Stock and Stockholders' Equity - Summary of Total Compensation Cost Recognized in Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 1,577	$ 129
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	641	85
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 936	$ 44

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Potential Dilutive Securities from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	3,523,586	11,314,304
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share		6,536,856
Series A-2 Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share		3,153,537
Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share	3,523,586	1,623,911

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	Jan. 01, 2021	Mar. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percentage of match	50.00%
Employer contribution amount		$ 58
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percentage of employees base salary and bonus paid	6.00%