0000950170-23-002830 | 10-K | XBRL Viewer

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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2022	Feb. 09, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Trading Symbol	ALVR
Entity Registrant Name	ALLOVIR, INC.
Entity Central Index Key	0001754068
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Document Annual Report	true
Document Transition Report	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 143.5
Entity Common Stock, Shares Outstanding		93,463,200
Security12b Title	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-39409
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	83-1971007
Entity Address Address Line1	1100 Winter Street
Entity Address City Or Town	Waltham
Entity Address State Or Province	MA
Entity Address Postal Zip Code	02451
City Area Code	617
Local Phone Number	433-2605
Documents Incorporated by Reference	Portions of the Proxy Statement for the registrant’s 2023 Annual Meeting of Stockholders, or the Proxy Statement, which the Registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the Registrant’s fiscal year end of December 31, 2022, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, MA, USA

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 106,092	$ 201,661
Short-term investments	127,703	46,459
Interest receivable	157	50
Prepaid expenses and other current assets	7,100	5,178
Prepaid expenses to related party	2,000
Total current assets	243,052	253,348
Restricted cash	852	852
Other assets	612	1,102
Property and equipment, net	930	1,549
Operating lease right-of-use assets	31,633	29,743
Total assets	277,079	286,594
Current liabilities:
Accounts payable	3,004	8,361
Accrued expenses	13,985	20,152
Income tax payable	128	1,007
Operating lease liability, current	7,165	6,591
Amount due to related party	56	1,742
Total current liabilities	24,338	37,853
Operating lease liability, long term	28,222	23,475
Total liabilities	52,560	61,328
Stockholders' equity:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized at December 31, 2022 and December 31, 2021, respectively; 0 shares issued and outstanding at December 31, 2022 and December 31, 2021, respectively;
Common stock, $0.0001 par value: 150,000,000 shares authorized at December 31, 2022 and December 31, 2021, respectively; 93,268,069 and 65,170,332 shares issued at December 31, 2022 and December 31, 2021, respectively; and 93,093,243 and 63,565,886 shares outstanding at December 31, 2022 and December 31, 2021, respectively	9	7
Additional paid-in capital	690,753	522,479
Accumulated other comprehensive loss	(468)	(155)
Accumulated deficit	(465,775)	(297,065)
Total stockholders' equity	224,519	225,266
Total liabilities and stockholders' equity	$ 277,079	$ 286,594

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par or stated value per share	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	93,268,069	65,170,332
Common stock, shares outstanding	93,093,243	63,565,886

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 118,870	$ 120,735
General and administrative	52,332	49,083
Total operating expenses	171,202	169,818
Loss from operations	(171,202)	(169,818)
Total other income (loss), net:
Interest income	1,876	1,315
Other income (loss), net	351	(2,452)
Loss before income taxes	(168,975)	(170,955)
Income tax (benefit) expense	(265)	1,007
Net loss	$ (168,710)	$ (171,962)
Net loss per share - basic	$ (2.20)	$ (2.74)
Net loss per share - diluted	$ (2.20)	$ (2.74)
Weighted-average common shares outstanding - basic	76,654,856	62,782,126
Weighted-average common shares outstanding - diluted	76,654,856	62,782,126
Comprehensive loss:
Net loss	$ (168,710)	$ (171,962)
Other comprehensive income (loss), net of tax:
Unrealized (loss) gain on available-for-sale securities	(313)	1
Foreign currency translation adjustment		(44)
Total other comprehensive loss	(313)	(43)
Comprehensive loss	$ (169,023)	$ (172,005)

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Balance at Dec. 31, 2020	$ 353,064	$ 7	$ 478,272	$ (112)	$ (125,103)
Balance, Shares at Dec. 31, 2020		61,931,255
Stock-based compensation	43,975		43,975
Issuance of common stock, upon vesting of restricted stock, Shares		1,609,479
Issuance of common stock, upon exercise of common stock	232		232
Issuance of common stock, upon exercise of common stock, Shares		25,152
Unrealized (loss) gain on available-for-sale securities	1			1
Foreign currency translation adjustment	(44)			(44)
Net loss	(171,962)				(171,962)
Balance at Dec. 31, 2021	225,266	$ 7	522,479	(155)	(297,065)
Balance, Shares at Dec. 31, 2021		63,565,886
Stock-based compensation	41,315		41,315
Issuance of common stock, upon vesting of restricted stock, Shares		1,912,210
Purchase of common stock under the 2020 Employee Stock Purchase Plan	536		536
Purchase of common stock under the 2020 employee stock purchase plan, Shares		157,052
Issuance of common stock in registered direct offering, net of issuance costs	126,425	$ 2	126,423
Issuance of common stock in registered direct offering, net of issuance costs, Shares		27,458,095
Unrealized (loss) gain on available-for-sale securities	(313)			(313)
Net loss	(168,710)				(168,710)
Balance at Dec. 31, 2022	$ 224,519	$ 9	$ 690,753	$ (468)	$ (465,775)
Balance, Shares at Dec. 31, 2022		93,093,243

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Issuance costs	$ 0.2

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net loss	$ (168,710)	$ (171,962)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	723	189
Non-cash lease expense	1,842	928
(Accretion) amortization of short-term investment (premiums) discounts	(1,076)	1,197
Stock-based compensation expense	41,315	43,975
Changes in operating assets and liabilities:
Interest receivable	(107)	400
Prepaid expenses and other current assets and prepaid expenses to related party	(3,028)	(1,241)
Other assets	490	(1,102)
Income tax payable	(879)	1,007
Accounts payable, accrued expenses and amount due to related party	(12,622)	20,290
Net cash used in operating activities	(142,052)	(106,319)
Cash flows from investing activities
Purchase of property and equipment		(26)
Purchase of short-term investments	(228,806)	(76,591)
Maturities of short-term investments	148,328	262,600
Net cash (used in) provided by investing activities	(80,478)	185,983
Cash flows from financing activities
Proceeds from issuance of common stock in registered direct offering, net of issuance costs	126,425
Proceeds from issuance of stock under the 2020 Employee Stock Purchase Plan	536
Proceeds from exercise of stock options		232
Net cash provided by financing activities	126,961	232
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		(44)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(95,569)	79,852
Cash, cash equivalents, and restricted cash at beginning of period	202,513	122,661
Cash, cash equivalents, and restricted cash at end of period	106,944	202,513
Non-cash investing and financing activities
Unrealized (loss) gain on available-for-sale securities	(313)	1
Right-of-use assets obtained in exchange for operating lease liability	14,717	26,386
Reduction of right-of-use asset due to modification	(5,506)
Purchase of property and equipment included in AP and accrued expenses	104	899
Supplemental disclosure of cash flows
Income taxes paid, net of refunds	613
Cash and cash equivalents	106,092	201,661
Restricted Cash	852	852
Total cash, cash equivalents, and restricted cash	$ 106,944	$ 202,513

Nature of the Business

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business

1. Nature of the Business

AlloVir, Inc. (“AlloVir” or “the Company”, formerly known as ViraCyte, Inc.) is a leading late clinical-stage cell therapy company developing highly innovative allogeneic T cell therapies to treat and prevent devastating viral diseases. The Company’s innovative and proprietary virus-specific T cell, or VST, therapy platform allows AlloVir to generate off-the-shelf VSTs designed to restore immunity in patients with T cell deficiencies who are at risk from the life-threatening consequences of viral diseases. There is an urgent medical need for therapies to treat a large number of patients suffering from viral diseases who currently have limited or no treatment options. The Company is developing three innovative, allogeneic, off-the-shelf VST therapy candidates targeting 11 different devastating viruses. The Company's lead product, posoleucel (previously referred to as Viralym-M or ALVR105), is a multi-VST therapy that targets six viruses: adenovirus, or AdV, BK virus, or BKV, cytomegalovirus, or CMV, Epstein-Barr virus, or EBV, human herpesvirus 6, or HHV-6 and JC virus, or JCV. The Company believes that posoleucel has the potential to fundamentally transform the treatment landscape for transplant patients by substantially reducing or preventing disease morbidity and mortality, thereby dramatically improving patient outcomes.

Posoleucel is being studied in three ongoing Phase 3 registrational trials for 3 distinct indications - the prevention of clinically significant infections from multiple viruses, the treatment of virus-associated hemorrhagic cystitis, or HC, and the treatment of AdV infections – all in allogeneic hematopoietic cell transplant, or HCT, patients who are at high risk for life-threatening viral infections from the six viruses targeted by posoleucel. We have successfully accelerated the multi-prevention study in recognition of the fact that prevention best addresses patients’ unmet medical needs. The three Phase 3 studies are expected to complete enrollment by the end of 2023, enabling potential data readouts from all three trials in 2024. In addition to the ongoing Phase 3 registrational studies, posoleucel has been studied in a Phase 2 proof-of-concept study for the treatment of BK viremia in kidney transplant patients. Positive topline results of this study were released in February 2023. This is the first study of posoleucel in SOT patients, and the results of this trial will inform next steps for this potential indication as well as the company’s broader SOT strategy.

The Company’s pipeline includes additional investigational VST therapies that may benefit high-risk individuals. ALVR106 is the Company’s second off-the-shelf, multi-VST product candidate targeting devastating respiratory diseases caused by human metapneumovirus, or hMPV, influenza, parainfluenza virus, or PIV and respiratory syncytial virus, or RSV. A Phase 1b/2 POC clinical study of ALVR106 is enrolling patients in the U.S. In the preclinical space, the Company is developing ALVR107 to treat hepatitis B, or HBV, infected cells and with the aim of curing chronic HBV infection. Preclinical and IND-enabling studies of ALVR107 to treat and cure HBV were completed in 2022 to support advancement into a POC study after completion of the posoleucel Phase 3 registrational studies. ALVR109 is an allogeneic, off-the-shelf, single virus-targeted cell therapy designed to target SARS-CoV-2, the virus that causes the severe and life-threatening viral disease, COVID-19. Data from the POC clinical trial of ALVR109 were reported in 2021, and positive reports of ALVR109 compassionate use in immune-compromised patients also have been published and presented, including poster presentations at the 2022 American Transplant Congress.

The Company was formed on August 16, 2013 as a Delaware limited liability company (“LLC”), under the name AdCyte LLC and on July 29, 2014 the Company changed its name to ViraCyte LLC. On September 17, 2018, the Company converted from a Delaware LLC to a Delaware corporation (“LLC Conversion”) and changed its name to ViraCyte, Inc. On May 22, 2019, the Company changed its name to AlloVir, Inc. The Company has principal offices in Waltham, Massachusetts, Houston, Texas and Dublin, Ireland.

On August 8, 2019, AlloVir formed AlloVir International Designated Activity Company (“AlloVir International”), a wholly-owned subsidiary established in Ireland.

On October 9, 2019, AlloVir Securities Corporation was incorporated as a Massachusetts Security Corporation, a wholly-owned subsidiary of AlloVir.

On November 10, 2019, AlloVir International formed AlloVir Italia S.R.L., a wholly-owned subsidiary in Italy.

On July 20, 2021, AlloVir Inc. formed AlloVir U.S., Inc., a wholly-owned subsidiary of AlloVir.

On August 3, 2020, the Company completed an initial public offering (“IPO”) in which the Company issued and sold 18,687,500 shares of its common stock, at a public offering price of $17.00 per share, resulting in gross proceeds of $317.7 million. The Company received $292.0 million in net proceeds after deducting underwriting discounts and commissions and offering costs.

Upon the closing of the IPO, all of the then-outstanding shares of convertible preferred stock automatically converted into 39,859,139 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of convertible preferred stock outstanding.

On July 26, 2022, the Company entered into a Securities Purchase Agreement (the "Securities Purchase Agreement") with certain investors for the issuance and sale of 27,458,095 shares of its common stock for aggregate net proceeds of $126.4 million.

ElevateBio, LLC

On September 17, 2018, the Company executed a Series A2 Preferred Stock Purchase Agreement ("Series A2 Agreement"), with ElevateBio, LLC ("ElevateBio") and ElevateBio was a purchaser in our registered direct offering in July 2022. ElevateBio, through its diverse platform of technologies to support cell and gene therapy products and expertise, provides drug development and manufacturing services. As a result of ElevateBio’s purchase of our Series A2 Preferred Stock, which converted to common stock upon completion of our IPO, and as a result of ElevateBio’s participation in the July 2022 registered direct offering, ElevateBio acquired an ownership interest in the Company. The Chief Financial Officer of ElevateBio currently serves in a similar management role with AlloVir. In May 2021, Diana M. Brainard M.D. succeeded David Hallal, ElevateBio’s Chief Executive Officer, as the Company’s Chief Executive Officer. Mr. Hallal currently serves as Executive Chairman of the Company's board of directors. In addition to Mr. Hallal and Mr. Sinha, two other members of the Company's board of directors, Morana Jovan-Embiricos and Ansbert Gadicke, also serve as directors of the board of directors of ElevateBio.

Going Concern

In accordance with Accounting Standards Update (“ASU”) 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the consolidated financial statements are issued.

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance and reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

The accompanying 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. Through December 31, 2022, the Company has funded its operations primarily with proceeds received from the sale of common stock, research grants, and from the sale of preferred stock. The Company has incurred recurring losses since its inception, including net losses attributable to common stockholders of $168.7 million for the year ended December 31, 2022 and $172.0 million for the year ended December 31, 2021. In addition, at December 31, 2022, the Company had an accumulated deficit of $465.8 million. The Company expects to continue to generate operating losses for the foreseeable future.

The Company believes that its $233.8 million of cash, cash equivalents and short-term investments held at December 31, 2022, is sufficient to fund planned operations for at least twelve months from the date that these consolidated financial statements are available to be issued.

COVID-19 Considerations

The development of product candidates could be disrupted and materially adversely affected in the future by a pandemic, epidemic or outbreak of an infectious disease, such as the recent COVID-19 pandemic. The spread of COVID-19 has impacted the global economy and has impacted the Company’s operations, including the interruption of preclinical and clinical trial activities and potential interruption to the Company’s supply chain. For example, the COVID-19 pandemic has delayed clinical trials. If the disruption due to the COVID-19 pandemic continues, planned pivotal clinical trials also could be delayed due to government orders and site policies on account of the pandemic, and some patients may be unwilling or unable to travel to study sites, enroll in trials or be unable to comply with clinical trial protocols if quarantines impede patient movement or interrupt healthcare services, which would delay the Company’s ability to conduct preclinical studies and clinical trials or release clinical trial results and could delay the Company’s ability to obtain regulatory approval and commercialize product candidates. Furthermore, COVID-19 could affect the Company’s employees or the employees of research sites and service providers on whom the Company relies on as well as those of companies with which the Company does business, including suppliers and CMOs, thereby disrupting business operations. Quarantines and travel restrictions imposed by governments in the jurisdictions in which the Company and the companies with which it does business operate could materially impact

the ability of employees to access preclinical and clinical sites, laboratories, manufacturing sites and offices. For the health and safety of our employees, the Company has implemented work-at-home policies and we have generally restricted on site staff to only those employees who are fully vaccinated or essential to the development and research of product candidates; accordingly, the Company may experience limitations in employee resources. The outbreak and any other preventative or protective actions that the Company, its suppliers or other third parties with which it has business relationships, or governments may take in respect of the COVID-19 pandemic, could disrupt, delay or otherwise adversely impact the business.

The Company is still assessing business plans and the impact the COVID-19 pandemic may have on its ability to advance the testing, development and manufacturing of drug candidates, including as a result of adverse impacts on the research sites, service providers, vendors, or suppliers on whom the Company relies on, or to raise financing to support the development of our drug candidates. No assurances can be given that this analysis will enable the Company to avoid part or all of any impact from the spread of COVID-19 or its consequences, including downturns in business sentiment generally or this sector in particular. The Company cannot presently predict the scope and severity of any potential business shutdowns or disruptions, but if the Company or any of the third parties on whom it relies on or with whom it conducts business, were to experience shutdowns or other business disruptions, the Company’s ability to conduct business in the manner and on the timelines presently planned could be materially and adversely impacted.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation and Consolidation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). The consolidated financial statements include the Company’s accounts and those of its wholly-owned subsidiaries. All intercompany accounts, transactions and balances have been eliminated in consolidation.

Segment Information

Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s singular focus is the research, development and commercialization of off-the-shelf VST therapies to prevent and treat severe viral-associated diseases. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. All of the Company’s long-lived assets are held in the United States.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP 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. Changes in estimates and assumptions are reflected in reported results in the period in which they become known. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash and cash equivalents are short-term, highly liquid investments with original maturities of three months or less at the date of purchase. Investments qualifying as cash equivalents primarily consist of money market funds, corporate bonds and commercial paper.

Short-Term Investments

Short-term investments consist of U.S. treasury securities, corporate bonds and commercial paper classified as available-for-sale that have maturities of less than one year. Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in other comprehensive income (loss). The amortized cost of debt securities in this category is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization or accretion is included in "other income (loss), net".

The cost of securities sold is based on the specific identification method. Interest on debt securities classified as available-for-sale are included in interest income. To determine whether an other-than-temporary impairment exists, the Company considers whether it has the ability and intent to hold the investment until a market price recovery, and whether evidence indicating the recoverability of the cost of the investment outweighs evidence to the contrary. There were no individual securities with impairments at December 31, 2022 and 2021.

Restricted Cash

Cash accounts with any type of restriction are classified as restricted cash. The Company has restricted cash deposits with a bank, which serve as collateral for a letter of credit issued to the landlord of the Company’s leased Waltham facility for a security deposit. The Company classified this amount as non-current restricted cash in the accompanying condensed consolidated balance sheet at December 31, 2022 and 2021.

Property and Equipment, Net

The Company records property and equipment at cost and recognizes depreciation using the straight-line method over the estimated useful lives of the respective assets, as follows:


Asset category		Estimated useful life
Computer equipment		3 years
Laboratory equipment		5 years

The Company periodically evaluates whether events and circumstances have occurred that may warrant revision of the estimated useful life of property and equipment. Expenditures for repairs and maintenance of assets are expensed as incurred. Upon retirement or sale, the cost of assets disposed and the corresponding accumulated depreciation are removed from the related accounts and any resulting gain or loss is reflected in the results of operations. Construction in progress is not depreciated until it is placed in service. Property and equipment to be disposed of are carried at fair value less costs to sell.

Impairment of Long-Lived Assets

The Company accounts for long-lived assets in accordance with ASC Topic 360, Property, Plant, and Equipment (“ASC 360”). ASC 360 requires companies to: (i) recognize an impairment loss only if the carrying amount of a long-lived asset is not recoverable based on its undiscounted future cash flows and (ii) measure an impairment loss as the difference between the carrying amount and the fair value of the asset.

The Company tests long-lived assets to be held and used, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of assets or asset groups may not be fully recoverable. Determination of recoverability is based on an estimate of undiscounted future cash flows resulting from the use of the asset and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their fair values. The Company has not recognized any impairment losses during the years ended December 31, 2022 and 2021.

Fair Value Measurements

ASC Topic 820, Fair Value Measurement (“ASC 820”), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances.

ASC 820 identifies fair value as the exchange price, or 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 a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes among the following:

•

Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

•

Level 2 – Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly.

•

Level 3 – Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

The Company’s financial instruments include cash equivalents, short-term investments, accounts payable, amount due to related party and accrued expenses. Certain of the Company’s financial assets, including cash equivalents and short-term investments, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services or other observable market data. The pricing services utilize industry standard valuation models and observable market inputs to determine value.

Other financial instruments, including accounts payable, amount due to related party and accrued expenses, are carried at cost, which approximate fair value due to the short duration and term to maturity.

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the equity financing, these costs are presented in the consolidated balance sheets as a direct reduction from the carrying amount of the respective equity instrument issued. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive loss. At December 31, 2022 and 2021, the Company had no deferred offering costs.

Cloud Computing Arrangements

The Company capitalizes certain implementation costs for internal-use software incurred in a cloud computing agreement that is a service contract. Eligible costs associated with cloud computing arrangements, such as the implementation costs incurred to develop or obtain software business applications used in the normal course of business, are capitalized in accordance with ASC 350. Capitalization ceases at the point the software is substantially complete and ready for its intended use, and after all substantial testing is completed. Amortization is recorded on a straight-line basis over the expected useful life of three years of the internal-use software cost in the same line item in the statement of operations and comprehensive loss as the expense for fees for the associated cloud computing arrangement. Amortization expense associated with the Company's cloud computing arrangements has been recognized in the amount of $0.5 million and $0.1 during the years ended December 31, 2022 and 2021.

Other Income (Loss), Net

The Company records interest expense, investment amortization and accretion of discounts and premiums on short-term investments and foreign exchange gains and losses in “other income (loss), net” over the same period in which the qualifying costs are incurred.

Research and Development Costs

Research and development costs are charged to expense as incurred. Research and development expenses are comprised of costs incurred in performing research and development activities, including personnel-related costs, stock-based compensation, facilities, research-related overhead, clinical trial costs, contracted services, research-related manufacturing, license fees and other external costs. The Company accounts for nonrefundable advance payments for goods and services that will be used in future research and development activities as expenses when the services have been performed or when the goods have been received.

Accrued Research and Development Expenses

The Company has entered into various research and development contracts. The payments under these contracts are recorded as research and development expenses as incurred. The Company records accrued liabilities for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Judgements and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.

Stock-Based Compensation Expense

The Company grants restricted stock and stock options to employees, consultants and directors. The Company recognizes stock-based compensation cost for awards with performance conditions if and when it concludes that it is probable that the performance conditions will be achieved. For awards with only a service condition, the Company expenses stock-based compensation on a straight-line basis over the requisite employee service period or for grants issued with performance conditions, on a graded-vesting basis over the requisite employee service period. Awards for employees and non-employees are accounted for similarly. The Company records stock-based compensation expense associated with grants of restricted stock and stock options in the consolidated statements of operations and comprehensive loss based on their estimated fair value at the date of the grant. The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the grantee’s payroll costs are classified or in which the grantee’s service payments are classified. Forfeitures are accounted for as they occur.

The fair value of each stock option grant is estimated on the date of grant using the Black‑Scholes option pricing model. As there was no public market for the Company’s common stock prior to the initial public offering of its common stock in August 2020, the estimated fair value of common stock was determined by the Company’s board of directors as of the date of each option grant, with input from management, considering third-party valuations of its common stock, as well as the Company’s board of directors’ assessment of additional objective and subjective factors that it believed were relevant, and which may have changed from the date of the most recent third-party valuation through the date of the grant. These third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately Held Company Equity Securities Issued as Compensation. Following the closing of the initial public offering, the fair value of the Company’s common stock is determined based on the quoted market price of common stock. The Company also lacks company‑specific historical and implied volatility information for its stock. The Company estimates its expected stock price volatility based on the historical volatility of publicly traded peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method. The “simplified” method estimates the expected term of stock options as the mid‑point between the weighted average time to vesting and the contractual maturity. The risk‑free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. There is no expected dividend yield since the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future.

Net Loss per Share

Basic and diluted net loss per share is determined by dividing net loss by the weighted‑average common stock outstanding during the period. Since we have incurred operating losses for all periods presented, outstanding stock options and unvested restricted common stock have been excluded from the calculation because their effects would be anti‑dilutive. Therefore, the weighted‑average shares used to calculate both basic and diluted loss per share are the same.

Income Taxes

The Company accounts for income taxes under the asset and liability method in accordance with ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted rates in effect for the year in which these temporary differences are expected to be recovered or settled. Valuation allowances are provided if based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management believes that it is more likely than not that all deferred tax assets will not be realized.

The Company recognizes liabilities for potential tax payments to various tax authorities related to uncertain tax positions. The liabilities are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filing is more likely

than not to be realized following resolution of any potential contingencies present related to the tax benefit. Potential interest and penalties associated with such uncertain tax positions, if any, are recorded as components of income tax expense.

The Company assesses its income tax positions and records tax benefits for all years subject to examination based upon management’s evaluation of the facts, circumstances and information available as of the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company records the largest amount of tax benefit with a greater than 50 percent likelihood of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, the Company does not recognize a tax benefit in the consolidated financial statements.

Concentration of Credit Risk and Off-Balance Sheet Risk

Financial instruments that subject the Company to credit risk consist primarily of cash, cash equivalents, restricted cash and short-term investments. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company deposits its cash in financial institutions that it believes have high credit quality and have not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Such deposits have and will continue to exceed federally insured limits. The Company has not experienced any losses on its cash deposits.

At December 31, 2022 and 2021, the Company had no off-balance sheet risk.

Foreign Exchange

As a result of certain intercompany transactions in September 2021, the Company determined that the functional currency for AlloVir International and AlloVir Italia is the U.S. Dollar (“USD”) during the year ended December 31, 2021. Prior to this determination, the functional currency of AlloVir International and Allovir Italia was the Euro; however, due to the immateriality of the transactions that occurred at AlloVir International and AlloVir Italia previously, the impact of the determination for the transition from Euro to USD is not material and is not considered a change in accounting principle for reporting purposes. Reporting currency has been and remains the USD.

Prior to the change in functional currency for AlloVir International and AlloVir Italia, assets and liabilities were translated into USD at the exchange rate in effect on the balance sheet date. Equity balances, other than retained earnings, were translated at historical exchange rates. Income items and expenses were translated at the average exchange rate in effect during the period. Unrealized translation gains and losses were recorded as a cumulative translation adjustment in the consolidated balance sheets.

Transactions in foreign currencies are remeasured into the functional currency of the relevant subsidiaries at the exchange rate in effect at the date of the transaction. Any monetary assets and liabilities arising from these transactions are translated into the functional currency at exchange rates in effect at the balance sheet date or on settlement. Resulting gains and losses are recorded in "other income (loss), net" within the consolidated statements of operations and comprehensive loss.

Comprehensive Loss

Comprehensive loss is defined as a change in equity of a business enterprise during a period, resulting from transactions from non-owner sources. Comprehensive loss includes net loss and certain changes in stockholder’s deficit that are excluded from net loss. The Company's comprehensive loss includes unrealized gains (losses) on available-for-sale securities during the year ended December 31, 2022 and 2021 and foreign currency translation adjustments from foreign subsidiaries prior to the change in functional currency for AlloVir International and AlloVir Italia during the year ended December 31, 2021.

Leases

In accordance with ASC Topic 842, Lease Accounting, at the inception of an arrangement, the Company determines whether the arrangement is or contains a lease. Leases with a term greater than one year are recognized on the consolidated balance sheet as a right-of-use (“ROU”) asset and current and non-current lease liabilities, as applicable. The Company has made an accounting policy election, known as the short-term lease recognition exemption, which allows the Company to not recognize ROU assets and lease liabilities that arise from short-term leases (12 months or less) for any class of underlying asset. Options to renew or options to cancel a lease are not included in the Company’s assessment unless there is reasonable certainty that the Company will renew or will not cancel, respectively.

Operating lease liabilities and their corresponding ROU assets are recorded based on the present value of future lease payments over the expected remaining lease term. Lease cost for operating leases is recognized on a straight-line basis over the lease term as an operating expense. Certain adjustments to the ROU asset may be required for items such as lease prepayments or incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate, which reflects the fixed rate at which the Company could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment.

The Company has elected to account for the lease and non-lease components together for all existing classes of underlying assets.

Subsequent Events

The Company evaluates events occurring after the date of our accompanying consolidated balance sheets for potential recognition or disclosure in our consolidated financial statements. The Company did not identify any material subsequent events requiring adjustment to our accompanying consolidated financial statements (recognized subsequent events). Those items requiring disclosure (unrecognized subsequent events) in the consolidated financial statements have been disclosed accordingly. Refer to Note 16 for further details.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s consolidated financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with certain new or revised accounting standards pursuant to Section 107(b) of the JOBS Act.

Recently Adopted Accounting Pronouncements

None.

Recently Issued Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 significantly changes the impairment model for most financial assets and certain other instruments. ASU 2016-13 will require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, which will generally result in earlier recognition of allowances for credit losses on loans and other financial instruments. ASU 2016-13 is effective for the Company’s fiscal year beginning after December 15, 2022 and subsequent interim periods. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements and related disclosures.

Short-Term Investments

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

3. Short-Term Investments

The following tables summarize the amortized cost and estimated fair value of the Company’s U.S. government treasury securities and marketable securities, which are considered to be available-for-sale investments and are included in short-term investments on the consolidated balance sheets:


	December 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	99,288	$	1	$	(253	)	$	99,036
Marketable securities:
Corporate and agency bonds		28,748		3		(84	)		28,667
Totals	$	128,036	$	4	$	(337	)	$	127,703

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	25,092	$	—	$	(20	)	$	25,072
Marketable securities:
Commercial paper		11,568		1		—			11,569
Corporate and agency bonds		9,821		—		(3	)		9,818
Totals	$	46,481	$	1	$	(23	)	$	46,459

Certain short-term debt securities with original maturities of less than three months are included in cash and cash equivalents on the consolidated balance sheets and are not included in the tables above. At December 31, 2022 and 2021, all investments had contractual maturities within one year.

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The following tables present information about the Company’s financial assets measured at fair value on a recurring basis:


	December 31, 2022
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	32,641	$	—	$	—	$	32,641
Totals	$	32,641	$	—	$	—	$	32,641
Short-term investments:
U.S. government treasury securities	$	99,036	$	—	$	—	$	99,036
Marketable securities:
Corporate and agency bonds		—		28,667		—		28,667
Totals	$	99,036	$	28,667	$	—	$	127,703


	December 31, 2021
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	141,378	$	—	$	—	$	141,378
Marketable securities:
Commercial paper		—		7,998		—		7,998
Corporate and agency bonds		—		753		—		753
Totals	$	141,378	$	8,751	$	—	$	150,129
Short-term investments:
U.S. government treasury securities	$	25,072	$	—	$	—	$	25,072
Marketable securities:
Commercial paper		—		11,569	$	—		11,569
Corporate and agency bonds		—		9,818		—		9,818
Totals	$	25,072	$	21,387	$	—	$	46,459

During the years ended December 31, 2022 and 2021, there were no transfers between levels. The Company classifies its money market fund and U.S. government treasury securities as Level 1 assets under the fair value hierarchy, as these assets have been valued using quoted market prices in active markets without any valuation adjustment. The Company classifies its marketable securities (corporate and agency bonds and commercial paper) as Level 2 assets under the fair value hierarchy, as these assets have pricing inputs that are other than quoted prices in active markets, which are either directly or indirectly observable as of the reporting date, and fair value is determined using models or other valuation methodologies.

The carrying amounts of prepaid expenses and other current assets, prepaid expenses to related party, accounts payable, amount due to related party and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities.

- 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

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Leases

5. Leases

Operating leases

Operating lease liabilities and their corresponding ROU assets are recorded based on the present value of future lease payments over the expected remaining lease term. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term. The Company uses an incremental borrowing rate based on information available at the commencement date in determining the present value of lease payments. The incremental borrowing rate represents the rate of interest that a lessee would have to pay to borrow on a collateralized basis over a similar term at an amount equal to the lease payments in a similar economic environment. The Company estimates this rate based on prevailing market conditions, comparable company and credit analysis, the impact of collateralization, and the term of each of the Company’s lease agreements.

DMS Agreement with Third-Party Supplier

In March 2019, the Company entered into an interim services agreement which ultimately led to a Development and Manufacturing Services Agreement ("DMS Agreement") with a third-party supplier in July 2019. The DMS Agreement specifies a dedicated manufacturing suite for the manufacture of AlloVir’s products at the facility. The DMS Agreement initially expired upon the later of (1) July 2021 and (2) the completion of services under all statements of work (“SOWs”). Effective June 2022, the Company entered into a First Amendment to the DMS Agreement to extend the expiration date to June 2024 provided that the terms and conditions of the DMS Agreement will continue to apply to any active SOW's. The DMS Agreement (or any individual SOW) may be terminated earlier by AlloVir at any time by providing 190 days’ notice. In March 2019, at the inception of this lease, the Company recorded a ROU asset and lease liability of $6.9 million over a total estimated lease term of approximately 4.25 years, expiring in July 2023. In September 2019, the Company executed a SOW for another dedicated manufacturing suite under the DMS Agreement with substantially the same terms as the original SOW. In September 2019, at the inception of this lease, the Company recorded a ROU asset and lease liability of $6.3 million over a total estimated lease term of approximately 3.75 years, expiring in July 2023. The SOW calls for a fixed monthly payment through July 2023, with additional two-year renewal options. The use of these manufacturing suites qualifies as a lease under ASC 842, as it includes an identified asset for exclusive use by the Company at its direction.

In February 2022, the Company entered into amendments to both SOWs under the DMS Agreement. The original SOW under the DMS Agreement (beginning March 2019) was modified to add a new termination clause whereby the Company can terminate the lease upon entering into a contract for another suite at the facility. Management concluded that the SOW amendment constituted a lease modification under ASC 842 and recorded a $1.4 million reduction to the related ROU asset and lease liability in February 2022. The original SOW under the DMS Agreement was terminated in October 2022 upon execution of the new 2022 SOW under the DMS Agreement. The second SOW under the DMS agreement (beginning September 2019) was terminated as of the effective date of the amendment in February 2022. As a result of the amendment, which also represented a lease modification under ASC 842, the Company recorded a $2.6 million reduction to the related ROU asset and lease liability.

In October 2022, the Company entered into a new SOW under the DMS Agreement ("2022 SOW under the DMS Agreement") with a third-party supplier. The 2022 SOW under the DMS Agreement contained an embedded lease for a dedicated manufacturing suite for the manufacture of AlloVir’s products at the facility because the Company directs how and for what purpose the suite is used and obtains substantially all of the economic benefit of the suite. At inception of the lease, it was determined that, in exchange for this dedicated manufacturing suite, AlloVir will pay the supplier a monthly fixed suite utilization fee, fixed batch payments and other related fixed costs, totaling $16.3 million over the 2.25 year lease term ending in December 2024. As part of the arrangement, there were also variable costs for materials, non-fixed batch payments, testing, storage, knowledge and tech transfer and other common area maintenance fees that were not included in the measurement of the lease. The lease of the facility was determined to be classified as an operating

lease and commenced in October 2022, the point at which the suite was substantially complete and available for use by the Company. Accordingly, at inception, the Company recorded a ROU asset and lease liability of $14.7 million.

2020 DMS Agreement with BaseCamp

In May 2020, the Company entered into a new Development and Manufacturing Services Agreement (“2020 DMS Agreement”) with ElevateBio BaseCamp, Inc. ("BaseCamp") and signed a SOW in November 2020. The 2020 DMS Agreement and related SOW contained an embedded lease for a dedicated manufacturing suite for the manufacture of AlloVir’s products at the facility because the Company directs how and for what purpose the suite is used and obtains substantially all of the economic benefit of the suite. At inception of the lease, it was determined that, in exchange for this dedicated manufacturing suite, AlloVir will pay the supplier a monthly fixed suite utilization fee, and other related fixed costs, totaling $3.2 million over the two-year lease term (one year lease with a one-year renewal option), that covers costs associated with reserving capacity for AlloVir, as well as cleaning services, utilities, handling and maintenance of the manufacturing suite. At inception of the lease, the Company estimated that the exercise of the one-year renewal option was reasonably certain to occur, and the Company was reasonably certain that it would not exercise its early termination right, providing for a total estimated lease term of two years expiring in January 2023. As part of the arrangement, there were also variable costs for materials, non-fixed batch payments, storage, knowledge and tech transfer and other common area maintenance fees that were not included in the measurement of the lease. The lease of the facility was determined to be classified as an operating lease and commenced in February 2021, the point at which the new facility area was substantially complete and available for use by the Company. Accordingly, at inception, the Company recorded a ROU asset of $3.1 million and a lease liability of $2.5 million. The Company prepaid $0.6 million of the suite utilization fee, which was reclassified from prepaid expense to the ROU asset upon lease commencement.

In February 2022, the Company decided not to exercise the one-year renewal option and subsequently executed a Change Order to modify the terms of the SOW under the 2020 DMS Agreement. Management concluded that the amendments laid out in the change order collectively constituted a lease remeasurement under ASC 842 and recorded a $1.3 million reduction to the related lease liability and a $1.5 million reduction to the related ROU asset.

Waltham Leases

In September 2021, the Company entered into a new lease agreement with BP Bay Colony LLC and a sublease with AMAG Pharmaceuticals Inc. for the lease of property in Waltham, Massachusetts (collectively, the "Waltham leases"). The space identified under the Waltham leases is intended for general office space, research and development, laboratory use, and light manufacturing. The Waltham leases have been classified as operating leases and commenced in September 2021. At the inception date, the Company has recorded an ROU asset and lease liability of $6.0 million for the lease and a ROU asset and lease liability of $17.3 million for the sublease based on a July 30, 2030 end date for the Waltham leases. As part of the arrangement, there were also variable costs for common area maintenance fees that were not included in the measurement of the lease. The agreement also provides a $3.1 million tenant improvement allowance which is to be reimbursed by the landlord over the duration of the first two years of the Waltham leases. As of December 31, 2022 $0.9 million of the tenant improvement allowance has been used. The Company has the option to renew the leased space for an additional one time period of five years with written notice from the Company. As of December 31, 2022, the Company has no reasonable certainty that this option to extend will be exercised.

Maturities of operating lease liabilities at December 31, 2022 are as follows (in thousands):


2023		9,074
2024		12,525
2025		3,229
2026		3,308
2027		3,386
Thereafter		9,683
Total lease payments		41,205
Less: interest		5,818
Total lease liability	$	35,387
Lease liability – current	$	7,165
Lease liability – long-term	$	28,222

Total lease costs were $6.6 million and $6.2 million for the years ended December 31, 2022 and 2021, respectively. Cash paid for operating leases was $4.8 million and $5.2 million for the year ended December 31, 2022 and 2021, respectively. The Company’s total variable lease costs, such as materials, non-fixed batch payments, testing, storage, knowledge and tech transfer, and other common area

maintenance fees, related to the operating leases was $3.7 million and $14.5 million for the years ended December 31, 2022 and 2021, respectively. The weighted average remaining lease term is 6.93 years at December 31, 2022. The weighted average discount rate is 6.23%.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

6. Property and Equipment, Net

Property and equipment, net consisted of the following:


	December 31,
(in thousands)	2022			2021
Laboratory equipment	$	1,395		$	1,395
Computer equipment		435			435
Construction-in-progress		104			—
Total property and equipment		1,934			1,830
Less: accumulated depreciation		(1,004	)		(281	)
Property and equipment, net	$	930		$	1,549

Depreciation expense was $0.7 million and $0.2 million for the years ended December 31, 2022 and 2021, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Accrued Expenses

7. Accrued Expenses

Accrued expenses consisted of the following:


	December 31,
(in thousands)	2022		2021
Employee compensation and benefits	$	6,416	$	6,867
Professional fees		559		738
Research and development		5,678		3,573
Process development and manufacturing costs		504		7,685
Other		828		1,289
Total accrued expenses	$	13,985	$	20,152

Sponsored Research, Collaboration and License Agreements

12 Months Ended

Dec. 31, 2022

Research and Development [Abstract]

Sponsored Research, Collaboration and License Agreements

8. Sponsored Research, Collaboration and License Agreements

Amended and Restated Exclusive License Agreement with BCM

In June 2017, the Company signed a License Agreement (the “License Agreement”) with BCM, whereby the Company acquired a royalty-bearing, worldwide, exclusive license to BCM’s rights in Subject Technology and related patent rights in the field of viral infection. In May 2020, the Company amended and restated the License Agreement (the “A&R License Agreement”), pursuant to which the Company obtained (a) an exclusive worldwide license, with the right to sublicense, under certain patent rights and other intellectual property rights of BCM, to make, have made, use, market, sell, offer to sell, lease, import and export products in a particular field, except that such license is non-exclusive within a particular subfield, and in addition with respect to certain patent rights such license is limited to two particular subfields, and (b) an exclusive, worldwide sublicense, with the right to further sublicense, under all patent rights and other intellectual property rights that are exclusively licensed to BCM by a certain third party licensor, to make, have made, use, market, sell, offer to sell, lease, import and export products in the same field. The Company’s rights are subject to the rights of the U.S. government and certain rights retained by BCM.

Unless earlier terminated, the A&R License Agreement will expire on a country-by-country basis with respect to a product upon the later of (a) the expiration of the last to expire valid claim of a patent or patent application covering such product in such country or (b) 10 years after the first commercial sale of such product in such country. The Company may terminate the A&R License Agreement in its entirety at any time for convenience upon a certain number of days’ written notice. BCM may terminate the A&R License Agreement in its entirety for the Company’s uncured material default.

BCM maintains control of all filing, prosecution and maintenance of its patent rights licensed by the Company, and the Company is responsible for all related costs and expenses during the term of the agreement. The Company also reimbursed BCM for costs and expenses (including reasonable legal fees and expenses) incurred prior to the effective date of the agreement with respect to the filing,

prosecution and maintenance of the patent rights licensed by the Company. If BCM licenses the patent rights licensed by the Company to third parties for additional fields of use, the Company’s responsibility for patent related costs and expenses will be reduced on a pro-rata basis.

Under the A&R License Agreement, the Company must use commercially reasonable efforts to develop and commercialize one or more products in certain countries. As partial consideration for the rights conveyed by BCM under the original agreement executed in June 2017, the Company paid BCM a non-refundable license fee of $250,000. During the term of the A&R License Agreement, the Company is obligated to pay BCM a non-refundable annual license maintenance fee, but beginning with the fifth year after the original agreement date, license maintenance fees are fully creditable against royalty revenue due in the applicable year. The Company is required to pay certain milestone payments upon the achievement of specified clinical, regulatory, and sales milestones. In the event that the Company is able to successfully develop, launch and commercialize a product under the A&R License Agreement, total milestone payments could exceed $40.0 million. BCM is also eligible to receive tiered royalties at percentage rates ranging from less than 1% to the low single-digits, on net sales of any products that are commercialized by the Company or its sublicensees that incorporate, utilize or are made with the use of, the intellectual property licensed by the Company. To the extent the Company sublicenses its license rights under the A&R License Agreement, BCM would be eligible to receive tiered sublicense income at percentage rates in the mid-single to low double-digits.

In November 2020, the Company also entered into the First Amendment (the “License Amendment”) to the A&R License Agreement. Under the License Amendment, the Company assumed responsibility from BCM for the filing, prosecution and maintenance of the patent rights licensed by the Company from BCM under the A&R License Agreement that are in common with the License Agreement. Further, BCM also transferred to the Company the right of enforcement against third parties for any suspected infringement of any claims in such patent rights or misuse, misappropriation, theft or breach of confidence of other proprietary rights.

Exclusive License Agreement with BCM

In November 2020, the Company signed a second License Agreement (the “Second License Agreement) with BCM, whereby the Company acquired a royalty-bearing, worldwide, exclusive license to BCM’s rights in Subject Technology and related patent rights outside the field of viral infection (all fields other than those covered by the A&R License Agreement).

Unless earlier terminated, the Second License Agreement will expire on a country-by-country basis with respect to a product upon the later of (a) the expiration of the last to expire valid claim of a patent or patent application covering such product in such country or (b) 10 years after the first commercial sale of such product in such country, provided that the Second License Agreement shall not expire later than March 25, 2040. The Company may terminate the Second License Agreement in its entirety at any time for convenience upon a certain number of days’ written notice. BCM may terminate the Second License Agreement in its entirety for the Company’s uncured material default.

Under the Second License Agreement, BCM transferred to the Company control of all filing, prosecution and maintenance of the patent rights licensed by the Company, and the Company is responsible for all related costs and expenses during the term of the Second License Agreement. BCM also transferred to the Company the right of enforcement against third parties for any suspected infringement of any claims in the patent rights or misuse, misappropriation, theft or breach of confidence of other proprietary rights. The Company also reimbursed BCM for costs and expenses (including reasonable legal fees and expenses) incurred prior to the effective date of the Second License Agreement with respect to the filing, prosecution and maintenance of the patent rights licensed by the Company, to the extent not already paid by the Company under the A&R License Agreement.

Under the Second License Agreement, the Company must use commercially reasonable efforts to develop and commercialize one or more products in certain countries. As partial consideration for the rights conveyed by BCM under the Second License Agreement, the Company paid BCM a non-refundable license fee of $125,000. During the term of the Second License Agreement, the Company is obligated to pay BCM a non-refundable annual license maintenance fee of (a) $20,000 for the first through fourth anniversary of the effective date of the Second License Agreement, and (b) $40,000 for the fifth anniversary of the effective date and continuing thereafter, but beginning with the fifth year, license maintenance fees are fully creditable against royalty revenue due in the applicable year. The Company is required to pay certain milestone payments upon the achievement of specified clinical, regulatory, and sales milestones. In the event that the Company is able to successfully develop, launch and commercialize multiple products under the Second License Agreement, total milestone payments could exceed $30.0 million. BCM is also eligible to receive tiered royalties at percentage rates ranging from less than 1% to the low single-digits, on net sales of any products that are commercialized by the Company or its sublicensees that incorporate, utilize or are made with the use of, the intellectual property licensed by the Company. To the extent the Company sublicenses its license rights under the Second License Agreement, BCM would be eligible to receive tiered sublicense income at percentage rates in the mid-single to low double-digits.

Collaboration Agreement with BCM

In November 2020, the Company entered into a Research Collaboration Agreement (the “Research Agreement”) with BCM, under which the Company agreed to pay BCM for performing certain research activities under the direction of Dr. Ann Leen commencing on January 1, 2021 and continuing for a three-year period thereafter. The Research Agreement requires the Company to make payments to BCM totaling approximately $2.0 million per year, for a total of approximately $6.0 million over the term of the Research Agreement.

Collectively under the agreements above and for services provided by BCM the Company paid $2.5 million and $3.3 million during the years ended December 31, 2022 and 2021, respectively, and the payments were classified in research and development expense in the consolidated statements of operations and comprehensive loss. As of December 31, 2022, and 2021 $0 and $0.2 million in accrued milestone expenses are recorded under accrued expenses in the consolidated balance sheet.

CPRIT Grant

In August 2017, the Company was awarded a grant (the “CPRIT Grant”) from the Cancer Prevention and Research Institute of Texas (“CPRIT”). The CPRIT Grant required that the Company grant CPRIT a non-commercial license to technology developed under the grant and pay CPRIT a share of revenue on sales of commercial products developed using CPRIT funds equal to low single digits of revenue until such time as CPRIT has been paid an aggregate amount equal to 400% of the grant award proceeds. No royalty payments were made under this license agreement during the years ended December 31, 2022 and 2021, respectively.

Redeemable Preferred Stock Redemption Agreement

In September 2018, the Company entered into a redeemable preferred stock redemption agreement, or Redemption Agreement, to redeem shares of our Series A1 convertible preferred stock held by certain investors, including executive officer Ann Leen, director and former executive officer Juan Vera and entities affiliated with director, Malcolm Brenner and former director, John Wilson (or their affiliates). Pursuant to the Redemption Agreement, for a period of 20 years from the date of the first commercial sale of Viralym-M, the Company is obligated to make earnout payments to such investors on at least an annual basis. The earnout payments will be 10% of net sales of Viralym-M, which number will be reduced to a high single-digit percentage if certain events occur. Specifically, royalties due to third parties for the sale of Viralym-M are subtracted from the earnout payments due to the investors. Further, if the investors receive at least $50,000,000 in earnout payments from AlloVir during the three-year period after the first commercial sale of Viralym-M, the earnout payment percentage will be reduced.

Stockholder's Equity

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Stockholder's Equity

. Stockholder’s Equity

On August 3, 2020, in connection with the closing of the Company’s IPO, the Company filed its amended and restated certificate of incorporation, which authorizes the Company to issue up to 10,000,000 shares of preferred stock, $0.0001 par value per share. There were no shares of preferred stock issued or outstanding at December 31, 2022 and 2021.

At December 31, 2022 and 2021, the Company’s amended and restated certificate of incorporation authorized the Company to issue 150,000,000 shares of common stock at a par value of $0.0001 per share.

On July 26, 2022, the Company entered into the Securities Purchase Agreement with certain investors for aggregate net proceeds of $126.4 million after deducting issuance costs of $0.2 million. Pursuant to the terms of the Securities Purchase Agreement, the Company agreed to issue and sell to the investors in a registered direct offering an aggregate of 27,458,095 shares of the Company's common stock, par value $0.0001 per share (the "Shares") at a purchase price of $4.61 per Share (the "Offering"). The Offering was made without an underwriter or a placement agent, and therefore, there were no underwriting discounts or commissions in connection with the offering.

The following is a summary of the rights and privileges of the holders of the Company’s common stock at December 31, 2022 and 2021:

Voting Rights

The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders (and written actions in lieu of meetings), and there are not any cumulative voting rights. The number of authorized shares of common stock may be increased or decreased by the affirmative vote of the holders of shares of capital stock of the Company; however, the issuance of common stock may be subject to the vote of the holders of one or more series of preferred stock that may be required by terms of the Third Amended and Restated Certificate of Incorporation.

Dividends

Subject to preferences that may be applicable to any then-outstanding preferred stock, holders of common stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by the Board out of legally available funds. At December 31, 2022, no cash dividends have been declared or paid.

Liquidation Preference

In the event of a liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all debts and other liabilities and the satisfaction of any liquidation preference granted to the then-outstanding shares of preferred stock.

Rights and Preferences

Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock that the Company may designate in the future.

The Company has reserved shares of common stock for issuance as follows:


	December 31,
	2022		2021
Unvested restricted stock		2,239,106		2,866,909
Options to purchase common stock		7,922,797		6,155,055
Stock available for grant under the 2020 Stock Option and Grant Plan		4,253,680		3,812,396
Stock available for issuance under the 2020 Employee Stock Purchase Plan		454,302		611,354
Total		14,869,885		13,445,714

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

10. Stock-Based Compensation

Stock-Based Compensation Expense

Stock-based compensation expense was as follows:


	Years Ended December 31,
(in thousands)	2022		2021
Research and development	$	14,014	$	20,632
General and administrative		27,301		23,343
Total stock-based compensation expense	$	41,315	$	43,975

2018 Equity Incentive Plan

The Company’s 2018 Plan provided for the Company to issue restricted stock, restricted stock units, incentive stock options, and non-statutory stock options and other stock-based awards to employees, officers, members of the Board, consultants and advisors of the Company. The 2018 Plan was most recently amended in July 2020. The awards granted under this plan generally vest over a four-year period and have a 10-year contractual term.

At December 31, 2022, the Company had granted 6,715,415 shares of common stock under the 2018 Plan. At December 31, 2022, there was an aggregate of 64,042 shares of common stock issuable upon the exercise of outstanding options under the 2018 Plan and 6,616,772 shares of restricted common stock granted under the 2018 plan. No shares remain available for future issuance under the 2018 Plan. Any options or awards outstanding under the 2018 Plan remain outstanding and effective.

2020 Stock Option and Grant Plan

On July 2, 2020, the Company’s Board of Directors adopted and in July 2020 the stockholders approved the 2020 Stock Option and Grant Plan (the “2020 Plan”) which became effective on July 28, 2020, the date immediately prior to the date on which the registration statement related to the IPO was declared effective, and as a result no further awards were made under the 2018 Plan thereafter. Initially, the aggregate number of shares of our common stock that may be issued pursuant to stock awards under the 2020

Plan was 8,008,734 shares. The number of shares of our common stock reserved for issuance under the 2020 Plan shall be cumulatively increased on January 1, 2021 and each January 1 thereafter by 5% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year or a lesser number of shares determined by our board of directors. Unless our board of directors elects not to increase the number of shares available for future grant each year, our stockholders may experience additional dilution, which could cause our stock price to fall. Accordingly, on January 1, 2022, 3,528,817 shares were added to the number of available shares under the 2020 Plan. The awards granted under this plan generally vest over a four-year period and have a 10-year contractual term.

At December 31, 2022, there were an aggregate of 7,858,755 shares of common stock issuable upon the exercise of outstanding options under the 2020 Plan and 3,076,516 shares of restricted common stock granted under the 2020 Plan. There is an aggregate of 4,253,680 shares reserved for future issuance under the 2020 Plan.

Restricted Common Stock

The following table summarizes restricted common stock activity for the year ended December 31, 2022:


	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2022		2,866,909		$	15.45
Granted		1,632,996			7.70
Forfeited		(348,589	)		17.74
Vested		(1,912,210	)		10.40
Unvested at December 31, 2022		2,239,106		$	13.75

At December 31, 2022, there was $27.4 million of unrecognized stock-based compensation cost related to the restricted stock, which is expected to be recognized over a weighted average period of 2.54 years.

Stock Options

The following table summarizes stock option activity (in thousands, except share and per share data):


	Shares			Weighted Average Exercise Price		Weighted Average Contractual Life		Aggregate Intrinsic Value
Options outstanding at January 1, 2022		6,155,055		$	23.42	8.8		$	480
Granted		3,051,906			7.48		—		—
Exercised		—			—		—		—
Forfeited		(1,284,164	)		20.13		—		—
Options outstanding at December 31, 2022		7,922,797		$	17.81		8.3	$	786
Options vested and exercisable at December 31, 2022		2,945,832		$	22.10		7.8	$	88

The aggregate intrinsic value of 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 common stock as of the end of the period. The aggregate intrinsic value of options exercised were $0 and $0.3 million during the year ended December 31, 2022 and 2021, respectively.

The weighted average grant-date fair value of stock options granted during the year ended December 31, 2022 and 2021 was $5.61 per share and $24.76 per share, respectively. The weighted average grant date fair value of options vested was $19.16 and $13.61 per share for the year ended December 31, 2022 and 2021, respectively. At December 31, 2022, there was $50.5 million of unrecognized stock-based compensation expense related to unvested stock options, which is being recognized over a period of 2.20 years.

The fair value was estimated on the date of grant using the Black-Scholes option-pricing model, with the following weighted-average assumptions:


	Years Ended December 31,
	2022			2021
Expected term (in years)		6.07			6.06
Expected volatility		90	%		95	%
Risk-free interest rate		2.00	%		0.87	%
Expected dividend yield		—			—
Fair value of common stock	$	7.48		$	32.41

2020 Employee Stock Purchase Plan

In July 2020, the 2020 Employee Stock Purchase Plan (the “2020 ESPP”) was adopted by the Board of Directors and approved by the stockholders. The purpose of the 2020 ESPP is to provide eligible employees of the Company and other designated companies, with opportunities to purchase shares of the Company’s common stock, par value $0.0001 per share.

Initially, 611,354 shares of common stock in the aggregate were approved and reserved for this purpose. The number of shares of common stock reserved and available for issuance under the 2020 ESPP shall be cumulatively increased on January 1, 2021 and each January 1 thereafter by the least of (i) 1,222,707 shares of common stock, (ii) 1% of the number of shares of common stock issued and outstanding on the immediately preceding December 31, and (iii) such number of shares of common stock as determined by the Administrator. The Board of Directors elected not to increase the number of available shares as of January 1, 2021 and 2022. At December 31, 2022, there was an aggregate of 454,302 shares reserved for future issuance under the ESPP.

The ESPP allows eligible employees to authorize payroll deductions of up to 15% of their base salary or wages up to $25,000 annually to be applied toward the purchase of shares of the Company's common stock on the last trading day of the offering period. Participating employees will purchase shares of the Company's common stock at a discount of up to 15% on the lesser of the closing price of the Company's common stock on the NASDAQ Global Market (i) on the first trading day of the offering period or (ii) the last day of any offering period. The Company utilizes the Black Scholes option pricing model to compute the fair market value of the shares and compensation expense is recognized over the offering period. The first ESPP offering period was shortened in duration to three months and commenced on April 1, 2022 and ended on June 30, 2022. New six-month offering periods will commence each January 1 and July 1 thereafter during the term of the plan, with the administrator having the right to establish different offering periods.

Participation in the ESPP is voluntary. Eligible employees become participants in the ESPP by enrolling in the plan and authorizing payroll deductions. At the end of each offering period, accumulated payroll deductions are used to purchase the Company’s shares at the discounted price. The Company makes no contributions to the ESPP. A participant may withdraw from the ESPP or suspend contributions to the ESPP. If the participant elects to withdraw during an offering period, all contributions are refunded as soon as administratively practicable. If a participant elects to withdraw or suspend contributions, they will not be able to re-enroll in the current offering but may elect to participate in future offerings. The ESPP purchases only whole shares of the Company’s common stock.

The Company issued 157,052 common shares under the ESPP during the year ended December 31, 2022, at an average price per share of $3.42. Cash received from purchases under the ESPP for the year ended December 31, 2022 was $0.5 million. The Company recognized $0.2 million of compensation expense for the ESPP during the year ended December 31, 2022.

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

11. Income Taxes

The Company accounts for income taxes under the asset and liability method in accordance with ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted rates in effect for the year in which these temporary differences are expected to be recovered or settled. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. Management believes that it is more likely than not that all deferred tax assets will not be realized.

Income (loss) before provision for income taxes consisted of the following:


	Years Ended December 31,
(in thousands)	2022			2021
Federal		(113,389	)		49,045
Foreign		(55,586	)		(220,000	)
Loss before provision for income taxes	$	(168,975	)	$	(170,955	)

The provision for income taxes for the years ended December 31, 2022 and 2021 consisted of the following:


	Years Ended December 31,
(in thousands)	2022			2021
Current income tax (benefit) expense:
Federal	$	(246	)		987
State		(19	)		20
Foreign		—			—
Total current income tax (benefit) expense		(265	)		1,007
Deferred income tax (benefit) expense:
Federal		—			—
State		—			—
Foreign		—			—
Total deferred income tax (benefit) expense		—			—
Total income tax (benefit) expense	$	(265	)	$	1,007

The Company’s income tax (benefit) expense for the years ended December 31, 2022 and 2021 relating to federal, state and foreign tax jurisdictions differs from the amounts determined by applying the statutory federal income tax rate based on the following:


	Years Ended December 31,
(in thousands)	2022					2021
Benefit at the federal rate	$	(35,472	)	21.0	%	$	(35,901	)	21.0	%
Increase (decrease) resulting from:
Foreign tax rate differential		2,177		(1.3	)%		43,786		(25.6	)%
State taxes, net of federal benefit		(1,603	)	0.9	%		1,018		(0.6	)%
Change in valuation allowance		35,406		(21.0	)%		22,268		(13.0	)%
Intellectual property transfer		—		0.0	%		(25,538	)	14.9	%
Tax credits		(6,992	)	4.1	%		(5,540	)	3.3	%
Officer's compensation		695		(0.4	)%		2,648		(1.5	)%
Stock compensation		4,637		(2.7	)%		(2,464	)	1.4	%
Permanent differences		(182	)	0.1	%		—		—
Other		1,069		(0.6	)%		730		(0.5	)%
Total income tax (benefit) expense	$	(265	)	0.1	%	$	1,007		(0.6	)%

During the year ended December 31, 2022, the Company began applying the requirement to capitalize U.S. research and development expenses in the period incurred, as required by the Tax Cuts and Job Act of 2017. During the year ended December 31, 2021, the Company transferred intellectual property rights between tax jurisdictions, resulting in a deferred tax benefit on the basis

difference in our intangible assets. The additional deferred tax asset was offset by valuation allowance, resulting in no net impact to deferred tax expense (benefit). The transfer of intellectual property rights generated U.S. current income tax expense of $1.0 million after utilization of net operating loss and tax credit carryforwards.

Components of deferred income taxes consist of the following:


	December 31,
(in thousands)	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	9,374		$	5,460
Tax credit carryforwards		12,374			4,683
Intangible assets		25,537			25,538
Operating lease liabilities		8,074			6,865
Non-qualified stock compensation		12,017			8,028
Restricted stock compensation		235			1,778
Capitalization of R&D expenses		20,375			—
Other		1,661			1,646
Total deferred tax assets		89,647			53,998
Valuation allowance		(82,228	)		(46,823	)
Net deferred tax asset (liability)	$	7,419		$	7,175
Deferred tax liabilities:
Operating lease right-of-use assets		(7,218	)		(6,791	)
Restricted stock compensation		—			—
Depreciation		(186	)		(350	)
Other		(15	)		(34	)
Total deferred tax liabilities		(7,419	)		(7,175	)
Net deferred tax asset (liability)	$	—		$	—

The Company’s accounting for deferred taxes involves the evaluation of a number of factors concerning the realizability of its net deferred tax assets. The Company primarily considered such factors as its history of operating losses, the nature of the Company’s deferred tax assets, and the timing, likelihood and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible. At December 31, 2022 and 2021, the Company does not believe that it is more likely than not that the deferred tax assets will be realized; accordingly, a full valuation allowance has been established and no deferred tax asset is shown in the accompanying consolidated balance sheets. For the year ended December 31, 2022, the valuation allowance for deferred tax assets increased by $35.4 million, which was principally due to net operating losses, tax credits, tax basis generated from the intellectual property transfer, and U.S. research and development expense capitalization.

At December 31, 2022 and 2021, the Company had unused federal net operating loss carryforwards of $0 and $13.3 million, respectively. The federal net operating loss carryforwards have no expiration. The CARES Act temporarily allows the Company to carryback net operating losses arising in 2018, 2019 and 2020 to the five prior tax years. In addition, net operating losses generated in these years could fully offset prior year taxable income without the 80% of the taxable income limitation under the TCJA which was enacted on December 22, 2017. Given that the Company utilized a substantial portion of its net operating losses in 2021, is expected to utilize all remaining net operating losses in 2022, the net operating loss carryback provisions under the CARES Act are not applicable to the Company.

At December 31, 2022 and 2021, the Company had unused state net operating loss carryforwards of $3.6 million and $8.5 million, respectively. The state net operating loss carryforwards expire in 2035.

At December 31, 2022 and 2021, the Company had unused foreign net operating loss carryforwards of $72.9 million and $16.8 million, respectively. The foreign net operating loss carryforwards have no expiration.

At December 31, 2022 and 2021, the Company had $6.6 million and $2.8 million of research and development tax credit carryforwards that may be available to offset future federal income taxes through 2040. Additionally, at December 31, 2022, the Company had a federal orphan drug credit (ODC) carryforward related to qualifying research of $4.8 million that will begin to expire

in 2041. At December 31, 2022 and 2021, the Company also had $1.3 million and $0.8 million of research and development tax credit carryforwards that may be available to offset future state income taxes in the state of Massachusetts through 2035.

Utilization of net operating loss and research and development tax credit carryforwards may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986, as amended, due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of net operating loss and research and development tax credit carryforwards that can be utilized annually to offset future taxable income and tax expense, respectively. The Company has completed several financings since its inception which may result in a change of control as defined in Section 382 of the Internal Revenue Code or could result in a change in control in the future.

The Company complies with the provisions of ASC 740 in accounting for its uncertain tax positions. ASC 740 addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the consolidated financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely that not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. At December 31, 2022 and 2021, the Company had no uncertain tax positions.

The Company recognizes interest accrued related to unrecognized tax benefits and penalties in income tax expense. The Company had no accruals for interest and penalties at December 31, 2022 and 2021.

The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. The statute of limitations for assessment by the Internal Revenue Service and state tax authorities remains open for the tax years December 31, 2019 through December 31, 2022 as the Company was incorporated in September 2018. There are currently no federal, state or foreign income tax audits in progress. The resolution of tax matters is not expected to have a material effect on the Company's consolidated financial statements.

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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+ Details

Net Loss per Share

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss per Share

12. Net Loss per Share

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company:


	Years Ended December 31,
(in thousands, except share and per share data)	2022			2021
Numerator:
Net loss – basic and diluted	$	(168,710	)	$	(171,962	)
Denominator:
Weighted-average common shares outstanding – basic and diluted		76,654,856			62,782,126
Net loss per share – basic and diluted	$	(2.20	)	$	(2.74	)

Based on the amounts outstanding at December 31, 2022 and 2021, the Company excluded the following potential shares of common stock from the computation of diluted net loss per share attributable to common stockholders for the years ended December 31, 2022 and 2021, because including them would have had an anti-dilutive effect. 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.


	Years Ended December 31,
	2022		2021
Options to purchase common stock		7,922,797		6,155,055
Unvested restricted stock		2,239,106		2,866,909

Commitments and Contingencies

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13. Commitments and Contingencies

Leases

The Company entered into a lease agreement and a sublease agreement for the lease of property in Waltham, Massachusetts (see Note 5). The Company also leases an office space in Houston, Texas under an operating lease which will be terminated effective March 31, 2023 and an office space in Dublin, Ireland under an operating lease that expires on December 31, 2023.

Legal Proceedings

From time to time, in the ordinary course of business, the Company is subject to litigation and regulatory examinations as well as information gathering requests, inquiries and investigations. At December 31, 2022, there were no matters which would have a material impact on the Company’s financial results.

Purchase and Other Obligations

We enter into contracts in the normal course of business with CROs and other third-party vendors for clinical trials and testing and manufacturing services, which can contain purchase commitments or other noncancelable obligations. Most contracts do not contain minimum purchase commitments and are cancellable by us upon written notice. Payments due upon cancellation consist of payments for services provided or expenses incurred, including non-cancelable obligations of services provided up to one year after the date of cancellation. The amount and timing of such payments are not known.

We may incur potential contingent payments upon our achievement of clinical, regulatory and commercial milestones, as applicable, or we may be required to make royalty payments under license and grant agreements we have entered into with various entities pursuant to which we have in-licensed certain intellectual property. Due to the uncertainty of the achievement and timing of the events requiring payment under these agreements, the amounts to be paid by us are not fixed or determinable at this time (see Note 8).

Related Party Transactions

12 Months Ended

Dec. 31, 2022

Related Party Transactions

14. Related Party Transactions

In March 2020, the Company entered into a Management and Administrative Services Agreement with ElevateBio Technologies, Inc. that provides for ongoing services to the Company in areas such as information technology, human resources and administration management, and facilities. The Company is billed monthly for such services at cost, with mark-up for profit on specific services, but including reasonable allocations of employee benefits, facilities and other direct or fairly allocated indirect costs that relate to the associates providing the services.

In May 2020, the Company entered into the 2020 DMS Agreement with BaseCamp pursuant to which BaseCamp provides products and services that are used in the Company's laboratory operations, including consulting services, project management services, quality control services and cGMP drug product manufacturing (see Note 5).

In August 2022, the Company made a $2.0 million prepayment to BaseCamp for future services.

The Company incurred $3.5 million and $5.9 million during the year ended December 31, 2022 and 2021, respectively, related to services provided to the Company by ElevateBio and affiliates. At December 31, 2022 and 2021, the Company owed ElevateBio and affiliates $0.1 million and $1.7 million, respectively and had prepaid expenses with ElevateBio and affiliates of $2.0 million and $0, respectively.

Members of the Company’s management and board of directors received consulting fees totaling $0.5 million and $0.5 million during the years ended December 31, 2022 and 2021, respectively.

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Benefit Plans	15. Employee Benefit Plans Effective January 1, 2019, the Company adopted a 401(k) Plan for its employees, which is designed to be qualified under Section 401(k) of the Internal Revenue Code. Eligible employees are permitted to contribute to the 401(k) Plan within statutory and 401(k) Plan limits. The Company made matching contributions of $0.8 million and $0.5 million for the years ended December 31, 2022 and 2021, respectively.

Subsequent Events

12 Months Ended

Dec. 31, 2022

Subsequent Events [Abstract]

Subsequent Events

16. Subsequent Events

For the financial statements at December 31, 2022 and for the year then ended, the Company has evaluated all subsequent events through February 15, 2023, the date the consolidated financial statements were available to be issued, noting there were no events or matters identified that require additional disclosure.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation and Consolidation

Segment Information

Use of Estimates

Cash and Cash Equivalents

Short-Term Investments

Restricted Cash

Property and Equipment, Net

The Company records property and equipment at cost and recognizes depreciation using the straight-line method over the estimated useful lives of the respective assets, as follows:


Asset category		Estimated useful life
Computer equipment		3 years
Laboratory equipment		5 years

Impairment of Long-Lived Assets

Fair Value Measurements

•

Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

•

Level 3 – Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

Deferred Offering Costs

Cloud Computing Arrangements

Other Income (Loss), Net

Research and Development Costs

Accrued Research and Development Expenses

Stock-Based Compensation Expense

Net Loss Per Share

Net Loss per Share

Income Taxes

Concentration of Credit Risk and Off-Balance Sheet Risk

At December 31, 2022 and 2021, the Company had no off-balance sheet risk.

Foreign Exchange

Comprehensive Loss

Leases

The Company has elected to account for the lease and non-lease components together for all existing classes of underlying assets.

Subsequent Events

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

None.

Recently Issued Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Schedule of Estimated Useful Life

The Company records property and equipment at cost and recognizes depreciation using the straight-line method over the estimated useful lives of the respective assets, as follows:


Asset category		Estimated useful life
Computer equipment		3 years
Laboratory equipment		5 years

Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Estimated Fair Value of Marketable Securities


	December 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	99,288	$	1	$	(253	)	$	99,036
Marketable securities:
Corporate and agency bonds		28,748		3		(84	)		28,667
Totals	$	128,036	$	4	$	(337	)	$	127,703

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	25,092	$	—	$	(20	)	$	25,072
Marketable securities:
Commercial paper		11,568		1		—			11,569
Corporate and agency bonds		9,821		—		(3	)		9,818
Totals	$	46,481	$	1	$	(23	)	$	46,459

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following tables present information about the Company’s financial assets measured at fair value on a recurring basis:


	December 31, 2022
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	32,641	$	—	$	—	$	32,641
Totals	$	32,641	$	—	$	—	$	32,641
Short-term investments:
U.S. government treasury securities	$	99,036	$	—	$	—	$	99,036
Marketable securities:
Corporate and agency bonds		—		28,667		—		28,667
Totals	$	99,036	$	28,667	$	—	$	127,703


	December 31, 2021
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	141,378	$	—	$	—	$	141,378
Marketable securities:
Commercial paper		—		7,998		—		7,998
Corporate and agency bonds		—		753		—		753
Totals	$	141,378	$	8,751	$	—	$	150,129
Short-term investments:
U.S. government treasury securities	$	25,072	$	—	$	—	$	25,072
Marketable securities:
Commercial paper		—		11,569	$	—		11,569
Corporate and agency bonds		—		9,818		—		9,818
Totals	$	25,072	$	21,387	$	—	$	46,459

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Summary of Maturities Operating Leases Liabilities

Maturities of operating lease liabilities at December 31, 2022 are as follows (in thousands):


2023		9,074
2024		12,525
2025		3,229
2026		3,308
2027		3,386
Thereafter		9,683
Total lease payments		41,205
Less: interest		5,818
Total lease liability	$	35,387
Lease liability – current	$	7,165
Lease liability – long-term	$	28,222

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consisted of the following:


	December 31,
(in thousands)	2022			2021
Laboratory equipment	$	1,395		$	1,395
Computer equipment		435			435
Construction-in-progress		104			—
Total property and equipment		1,934			1,830
Less: accumulated depreciation		(1,004	)		(281	)
Property and equipment, net	$	930		$	1,549

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2022

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following:


	December 31,
(in thousands)	2022		2021
Employee compensation and benefits	$	6,416	$	6,867
Professional fees		559		738
Research and development		5,678		3,573
Process development and manufacturing costs		504		7,685
Other		828		1,289
Total accrued expenses	$	13,985	$	20,152

Stockholder's Equity (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Issuance

The Company has reserved shares of common stock for issuance as follows:


	December 31,
	2022		2021
Unvested restricted stock		2,239,106		2,866,909
Options to purchase common stock		7,922,797		6,155,055
Stock available for grant under the 2020 Stock Option and Grant Plan		4,253,680		3,812,396
Stock available for issuance under the 2020 Employee Stock Purchase Plan		454,302		611,354
Total		14,869,885		13,445,714

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was as follows:


	Years Ended December 31,
(in thousands)	2022		2021
Research and development	$	14,014	$	20,632
General and administrative		27,301		23,343
Total stock-based compensation expense	$	41,315	$	43,975

Summary of Restricted Common Stock Activity

The following table summarizes restricted common stock activity for the year ended December 31, 2022:


	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2022		2,866,909		$	15.45
Granted		1,632,996			7.70
Forfeited		(348,589	)		17.74
Vested		(1,912,210	)		10.40
Unvested at December 31, 2022		2,239,106		$	13.75

Summary of Stock Option Activity

The following table summarizes stock option activity (in thousands, except share and per share data):


	Shares			Weighted Average Exercise Price		Weighted Average Contractual Life		Aggregate Intrinsic Value
Options outstanding at January 1, 2022		6,155,055		$	23.42	8.8		$	480
Granted		3,051,906			7.48		—		—
Exercised		—			—		—		—
Forfeited		(1,284,164	)		20.13		—		—
Options outstanding at December 31, 2022		7,922,797		$	17.81		8.3	$	786
Options vested and exercisable at December 31, 2022		2,945,832		$	22.10		7.8	$	88

Schedule of Estimated Fair Value Weighted-Average Assumptions Using Black-Scholes Option-Pricing Model

The fair value was estimated on the date of grant using the Black-Scholes option-pricing model, with the following weighted-average assumptions:


	Years Ended December 31,
	2022			2021
Expected term (in years)		6.07			6.06
Expected volatility		90	%		95	%
Risk-free interest rate		2.00	%		0.87	%
Expected dividend yield		—			—
Fair value of common stock	$	7.48		$	32.41

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Summary of Income (Loss) Before Provision for Income Taxes

Income (loss) before provision for income taxes consisted of the following:


	Years Ended December 31,
(in thousands)	2022			2021
Federal		(113,389	)		49,045
Foreign		(55,586	)		(220,000	)
Loss before provision for income taxes	$	(168,975	)	$	(170,955	)

Schedule of Provision for Income Taxes

The provision for income taxes for the years ended December 31, 2022 and 2021 consisted of the following:


	Years Ended December 31,
(in thousands)	2022			2021
Current income tax (benefit) expense:
Federal	$	(246	)		987
State		(19	)		20
Foreign		—			—
Total current income tax (benefit) expense		(265	)		1,007
Deferred income tax (benefit) expense:
Federal		—			—
State		—			—
Foreign		—			—
Total deferred income tax (benefit) expense		—			—
Total income tax (benefit) expense	$	(265	)	$	1,007

Schedule of Income Tax (Benefit) Expense Reconciliation


	Years Ended December 31,
(in thousands)	2022					2021
Benefit at the federal rate	$	(35,472	)	21.0	%	$	(35,901	)	21.0	%
Increase (decrease) resulting from:
Foreign tax rate differential		2,177		(1.3	)%		43,786		(25.6	)%
State taxes, net of federal benefit		(1,603	)	0.9	%		1,018		(0.6	)%
Change in valuation allowance		35,406		(21.0	)%		22,268		(13.0	)%
Intellectual property transfer		—		0.0	%		(25,538	)	14.9	%
Tax credits		(6,992	)	4.1	%		(5,540	)	3.3	%
Officer's compensation		695		(0.4	)%		2,648		(1.5	)%
Stock compensation		4,637		(2.7	)%		(2,464	)	1.4	%
Permanent differences		(182	)	0.1	%		—		—
Other		1,069		(0.6	)%		730		(0.5	)%
Total income tax (benefit) expense	$	(265	)	0.1	%	$	1,007		(0.6	)%

Summary of Components of Deferred Income Taxes

Components of deferred income taxes consist of the following:


	December 31,
(in thousands)	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	9,374		$	5,460
Tax credit carryforwards		12,374			4,683
Intangible assets		25,537			25,538
Operating lease liabilities		8,074			6,865
Non-qualified stock compensation		12,017			8,028
Restricted stock compensation		235			1,778
Capitalization of R&D expenses		20,375			—
Other		1,661			1,646
Total deferred tax assets		89,647			53,998
Valuation allowance		(82,228	)		(46,823	)
Net deferred tax asset (liability)	$	7,419		$	7,175
Deferred tax liabilities:
Operating lease right-of-use assets		(7,218	)		(6,791	)
Restricted stock compensation		—			—
Depreciation		(186	)		(350	)
Other		(15	)		(34	)
Total deferred tax liabilities		(7,419	)		(7,175	)
Net deferred tax asset (liability)	$	—		$	—

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Computation Of Basic And Diluted Net Loss Per Share Attributable To Common Stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company:


	Years Ended December 31,
(in thousands, except share and per share data)	2022			2021
Numerator:
Net loss – basic and diluted	$	(168,710	)	$	(171,962	)
Denominator:
Weighted-average common shares outstanding – basic and diluted		76,654,856			62,782,126
Net loss per share – basic and diluted	$	(2.20	)	$	(2.74	)

Potential Dilutive Securities Excluded From Computation Of Diluted Net Loss Per Share Attributable To Common Stockholders


	Years Ended December 31,
	2022		2021
Options to purchase common stock		7,922,797		6,155,055
Unvested restricted stock		2,239,106		2,866,909

Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 26, 2022	Aug. 03, 2020	Dec. 31, 2022	Dec. 31, 2021	Aug. 04, 2020
Net proceeds from issuance initial public offering		$ 292,000
Net losses attributable to common stockholders			$ (168,710)	$ (171,962)
Accumulated deficit			(465,775)	$ (297,065)
Cash, cash equivalents and short-term investments			$ 233,800
Convertible Preferred Stock
Preferred stock, shares outstanding					0
Common Stock
Common stock issued and sold			27,458,095
IPO
Common stock issued and sold		18,687,500
Public offering price per share		$ 17.00
Gross proceeds from issuance of common stock		$ 317,700
IPO \| Common Stock
Stock issued upon conversion of preferred stock		39,859,139
Securities Purchase Agreement
Public offering price per share	$ 4.61
Share issued to investors	27,458,095
Net proceeds with certain investors	$ 126,400

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Security Segment	Dec. 31, 2021 USD ($) Security
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Cash and cash equivalents maturity period	3 months
Short-term investments maturity period	1 year
Number of individual securities with impairments \| Security	0	0
Property, plant and equipment, valuation basis	cost
Property, plant and equipment, depreciation methods	recognizes depreciation using the straight-line method over the estimated useful lives of the respective assets
Impairment losses on long-lived assets	$ 0	$ 0
Deferred offering costs	0	0
Amortization expense for cloud computing arrangements	$ 500,000	$ 0.1
Expected dividend yield	0.00%	0.00%
Off-balance sheet risk description	At December 31, 2022 and 2021, the Company had no off-balance sheet risk.
Internal-use Software
Summary Of Significant Accounting Policies [Line Items]
Expected useful life	3 years

Summary of Significant Accounting Policies - Schedule of Estimated Useful Life (Details)	12 Months Ended
	Dec. 31, 2022
Computer Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	3 years
Laboratory Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years

Short-Term Investments - Summary of Amortized Cost and Estimated Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 128,036	$ 46,481
Unrealized Gains	4	1
Unrealized Losses	(337)	(23)
Fair Value	127,703	46,459
U.S. Government Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	99,288	25,092
Unrealized Gains	1
Unrealized Losses	(253)	(20)
Fair Value	99,036	25,072
Corporate and Agency Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	28,748	9,821
Unrealized Gains	3
Unrealized Losses	(84)	(3)
Fair Value	$ 28,667	9,818
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		11,568
Unrealized Gains		1
Fair Value		$ 11,569

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Cash equivalents:
Cash equivalents	$ 32,641	$ 150,129
Short-term investments:
Short-term investments	127,703	46,459
Commercial Paper
Cash equivalents:
Cash equivalents		7,998
Short-term investments:
Short-term investments		11,569
Corporate and Agency Bonds
Cash equivalents:
Cash equivalents		753
Short-term investments:
Short-term investments	28,667	9,818
Money Market Fund
Cash equivalents:
Cash equivalents	32,641	141,378
U.S. Government Treasury Securities
Short-term investments:
Short-term investments	99,036	25,072
Level 1
Cash equivalents:
Cash equivalents	32,641	141,378
Short-term investments:
Short-term investments	99,036	25,072
Level 1 \| Money Market Fund
Cash equivalents:
Cash equivalents	32,641	141,378
Level 1 \| U.S. Government Treasury Securities
Short-term investments:
Short-term investments	99,036	25,072
Level 2
Cash equivalents:
Cash equivalents		8,751
Short-term investments:
Short-term investments	28,667	21,387
Level 2 \| Commercial Paper
Cash equivalents:
Cash equivalents		7,998
Short-term investments:
Short-term investments		11,569
Level 2 \| Corporate and Agency Bonds
Cash equivalents:
Cash equivalents		753
Short-term investments:
Short-term investments	$ 28,667	$ 9,818

Leases - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended							12 Months Ended
	Oct. 31, 2022	Feb. 28, 2022	Sep. 30, 2021	Feb. 28, 2021	Sep. 30, 2019	Jul. 31, 2019	Mar. 31, 2019	Dec. 31, 2022	Dec. 31, 2021
Leases [Line Items]
Expiration date								Dec. 31, 2023
ROU asset								$ 31,633	$ 29,743
Lease liability								35,387
Operating lease costs								6,600	6,200
Cash paid for operating lease								4,800	5,200
Variable lease costs								$ 3,700	$ 14,500
Operating lease, weighted average remaining lease term								6 years 11 months 4 days
Operating lease, weighted average discount rate, percent								6.23%
DMS Agreement
Leases [Line Items]
Lease expiration month and year						2021-07
Lease, option to extend								Effective June 2022, the Company entered into a First Amendment to the DMS Agreement to extend the expiration date to June 2024 provided that the terms and conditions of the DMS Agreement will continue to apply to any active SOW's. The DMS Agreement (or any individual SOW) may be terminated earlier by AlloVir at any time by providing 190 days’ notice.
Operating lease, existence of option to terminate						true
Lease, option to terminate								The DMS Agreement (or any individual SOW) may be terminated earlier by AlloVir at any time by providing 190 days’ notice.
Lease renewal term					2 years
Estimated lease term					3 years 9 months		4 years 3 months
Estimated lease expiring month and year					2023-07		2023-07
ROU asset					$ 6,300		$ 6,900
Lease liability					$ 6,300		$ 6,900
2020 DMS Agreement
Leases [Line Items]
Term of agreement				1 year
Lease renewal term				1 year
Estimated lease term				2 years
Estimated lease expiring month and year				2023-01
ROU asset				$ 3,100
Lease liability				2,500
Utilization fee				$ 3,200
Lessee operating lease, lease term including renewal option				2 years
Prepaid utilization fee				$ 600
Waltham Leases
Leases [Line Items]
Expiration date			Jul. 30, 2030
Operating lease, existence of option to extend			true
Lease, option to extend								The Company has the option to renew the leased space for an additional one time period of five years with written notice from the Company. As of December 31, 2022, the Company has no reasonable certainty that this option to extend will be exercised.
Lease commencement month and year			2021-09
Additional one time lease period			5 years
Tenant improvement allowance to be reimbursed			$ 3,100
Tenant improvement allowance, reimbursement period			2 years
Tenant improvement allowance								$ 900
New Lease Agreement with BP Bay Colony LLC
Leases [Line Items]
ROU asset			$ 6,000
Lease liability			6,000
Sublease with AMAG Pharmaceuticals
Leases [Line Items]
ROU asset			17,300
Lease liability			$ 17,300
Original SOW Amendment under DMS Agreement \| Lease Modification under ASC 842
Leases [Line Items]
ROU asset		$ (1,400)
Lease liability		$ (1,400)
Second SOW Amendment under DMS Agreement
Leases [Line Items]
Lease expiration month and year		2022-02
Second SOW Amendment under DMS Agreement \| Lease Modification under ASC 842
Leases [Line Items]
ROU asset		$ (2,600)
Lease liability		(2,600)
2022 SOW Under the DMS Agreement
Leases [Line Items]
Lease expiration month and year	2024-12
ROU asset	$ 14,700
Lease liability	14,700
Utilization fee	$ 16,300
Lessee operating lease, lease term including renewal option	2 years 3 months
Change Order to Modify Terms of SOW under 2020 DMS Agreement \| Lease Modification under ASC 842
Leases [Line Items]
ROU asset		(1,500)
Lease liability		$ (1,300)

Leases - Summary of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2023	$ 9,074
2024	12,525
2025	3,229
2026	3,308
2027	3,386
Thereafter	9,683
Total lease payments	41,205
Less: interest	5,818
Total lease liability	35,387
Lease liability – current	7,165	$ 6,591
Lease liability – long-term	$ 28,222	$ 23,475

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,934	$ 1,830
Less: accumulated depreciation	(1,004)	(281)
Property and equipment, net	930	1,549
Laboratory equipment
Property Plant And Equipment [Line Items]
Total property and equipment	1,395	1,395
Computer equipment
Property Plant And Equipment [Line Items]
Total property and equipment	435	$ 435
Construction-in-Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 104

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expenses	$ 0.7	$ 0.2

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 6,416	$ 6,867
Professional fees	559	738
Research and development	5,678	3,573
Process development and manufacturing costs	504	7,685
Other	828	1,289
Total accrued expenses	$ 13,985	$ 20,152

Sponsored Research, Collaboration and License Agreements - Additional Information (Details) - USD ($)	1 Months Ended			12 Months Ended
	Nov. 30, 2020	Sep. 30, 2018	Jun. 30, 2017	Dec. 31, 2022	Dec. 31, 2021
Sponsored Research, Collaboration and License Agreements [Line Items]
Research and development expense				$ 118,870,000	$ 120,735,000
CPRIT \| License agreement terms
Sponsored Research, Collaboration and License Agreements [Line Items]
Maximum paid percentage of grant award proceeds until which revenue share is payable				400.00%
Royalty payments				$ 0	0
A&R License Agreement \| BCM
Sponsored Research, Collaboration and License Agreements [Line Items]
Non-refundable license fee payments			$ 250,000
Milestone payments				$ 40,000,000.0
Minimum percentage of eligible to receive tiered royalties				1.00%
Second License Agreement \| BCM
Sponsored Research, Collaboration and License Agreements [Line Items]
Non-refundable license fee payments	$ 125,000
Milestone payments				$ 30,000,000.0
Minimum percentage of eligible to receive tiered royalties				1.00%
Non-refundable license fee payments, first year through fourth anniversary of effective date				$ 20,000
Non-refundable license fee payments fifth anniversary of effective date and continuing thereafter				40,000
Research Agreement \| BCM
Sponsored Research, Collaboration and License Agreements [Line Items]
Agreement for research activities, term	3 years
Research activities performing fees	$ 2,000,000.0
Total research activities performing fees, over the term	$ 6,000,000.0
Collective Agreements \| BCM
Sponsored Research, Collaboration and License Agreements [Line Items]
Research and development expense				2,500,000	3,300,000
Collective Agreements \| BCM \| Accured member
Sponsored Research, Collaboration and License Agreements [Line Items]
Accrued milestone expenses				$ 0	$ 200,000
Redumption Agreement
Sponsored Research, Collaboration and License Agreements [Line Items]
Earnout payment as percentage of net sales		10.00%
Earnout payment obligation for number of years from first commercial sale		20 years
Minimum earnout payments received by investors for reduction of earnout payment		$ 50,000,000
Period for reduction of earnout payment after first commercial sale		3 years

Stockholders Equity - Additional Information (Details)		12 Months Ended
Stockholders Equity - Additional Information (Details)	Jul. 26, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) Vote $ / shares shares	Dec. 31, 2021 $ / shares shares	Dec. 31, 2020 shares	Aug. 03, 2020 $ / shares shares
Class Of Stock [Line Items]
Preferred stock, par or stated value per share \| $ / shares		$ 0.0001	$ 0.0001
Preferred stock, shares authorized \| shares		10,000,000	10,000,000
Preferred stock, shares issued \| shares		0	0
Preferred stock, shares outstanding \| shares		0	0
Common stock, shares authorized \| shares		150,000,000	150,000,000	150,000,000
Common stock, par value \| $ / shares		$ 0.0001	$ 0.0001
Number of votes per share \| Vote		1
Common stock, voting rights		The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders (and written actions in lieu of meetings), and there are not any cumulative voting rights. The number of authorized shares of common stock may be increased or decreased by the affirmative vote of the holders of shares of capital stock of the Company; however, the issuance of common stock may be subject to the vote of the holders of one or more series of preferred stock that may be required by terms of the Third Amended and Restated Certificate of Incorporation.
Cash dividends declared or paid \| $		$ 0
IPO
Class Of Stock [Line Items]
Preferred stock, par or stated value per share \| $ / shares					$ 0.0001
Preferred stock, shares authorized \| shares					10,000,000
Offering price per share \| $ / shares					$ 17.00
Securities Purchase Agreement
Class Of Stock [Line Items]
Common stock, par value \| $ / shares	$ 0.0001
Net proceeds with certain investors \| $	$ 126,400,000
Offering costs \| $	$ 200,000
Share issued to investors \| shares	27,458,095
Underwriting Discounts Commissions \| $	$ 0
Offering price per share \| $ / shares	$ 4.61

Stockholders Equity - Schedule of Reserved Shares of Common Stock for Issuance (Details) - shares	Dec. 31, 2022	Dec. 31, 2021	Jul. 31, 2020
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	14,869,885	13,445,714
2020 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	454,302		611,354
Unvested Restricted Stock
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	2,239,106	2,866,909
Option To Purchase Common Stock
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	7,922,797	6,155,055
Stock Available For Grant \| 2020 Stock Option and Grant Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	4,253,680	3,812,396
Stock Available For Issuance \| 2020 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	454,302	611,354

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 41,315	$ 43,975
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	14,014	20,632
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 27,301	$ 23,343

Stock-Based Compensation - Additional Information (Details) - USD ($)			1 Months Ended	12 Months Ended
	Jan. 01, 2022	Jul. 02, 2020	Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reserved shares of common stock for issuance				14,869,885	13,445,714
Common stock, par value				$ 0.0001	$ 0.0001
Stock-based compensation expense				$ 41,315,000	$ 43,975,000
Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted				1,632,996
Unrecognized stock-based compensation cost				$ 27,400,000
Weighted average period of cost expected to be recognized				2 years 6 months 14 days
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period of cost expected to be recognized				2 years 2 months 12 days
Aggregate intrinsic value of options exercised				$ 0	$ 300,000
Weighted average grant-date fair value of stock options granted				$ 5.61	$ 24.76
Weighted average grant-date fair value of stock options vested				$ 19.16	$ 13.61
Unrecognized stock-based compensation expenses				$ 50,500,000
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period				4 years
Awards contractual term				10 years
Common stock shares granted				6,715,415
Number of shares of common stock issuable upon exercise of outstanding options				64,042
Reserved shares of common stock for issuance				0
2018 Equity Incentive Plan \| Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted				6,616,772
2020 Stock Option and Grant Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period		4 years
Awards contractual term		10 years
Common stock authorized for issuance		8,008,734
Cumulative increase in number shares reserved for issuance, percentage		5.00%
Shares added to number of available shares under plan	3,528,817
Common stock issuable upon exercise of outstanding options				7,858,755
2020 Stock Option and Grant Plan \| Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted				3,076,516
2020 Stock Option and Grant Plan \| Stock Available For Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reserved shares of common stock for issuance				4,253,680	3,812,396
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reserved shares of common stock for issuance			611,354	454,302
Percentage of payroll deductions of base salary or wages			15.00%
Percentage of maximum discount on purchase of shares of common stock			15.00%
Offering period, description				(i) on the first trading day of the offering period or (ii) the last day of any offering period. The Company utilizes the Black Scholes option pricing model to compute the fair market value of the shares and compensation expense is recognized over the offering period. The first ESPP offering period was shortened in duration to three months and commenced on April 1, 2022 and ended on June 30, 2022. New six-month offering periods will commence each January 1 and July 1 thereafter during the term of the plan, with the administrator having the right to establish different offering periods.
Cumulative increase in number shares reserved for issuance, percentage			1.00%
Common stock, par value			$ 0.0001
Annual increase in number of shares reserved for issuance			1,222,707
Purchase of common stock under the employee stock purchase plan				157,052
Share issued, average price per share				$ 3.42
Cash received from purchases under the ESPP				$ 500,000
Stock-based compensation expense				$ 200,000
2020 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Base salary or wages			$ 25,000

Stock-Based Compensation - Summary of Restricted Common Stock Activity (Details) - Restricted Common Stock	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Number of Shares
Number of Shares, Unvested at January 1, 2022 \| shares	2,866,909
Number of Shares, Granted \| shares	1,632,996
Number of Shares, Forfeited \| shares	(348,589)
Number of Shares, Vested \| shares	(1,912,210)
Number of Shares, Unvested at December 31, 2022 \| shares	2,239,106
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Unvested at January 1, 2022 \| $ / shares	$ 15.45
Weighted Average Grant Date Fair Value, Granted \| $ / shares	7.70
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	17.74
Weighted Average Grant Date Fair Value, Vested \| $ / shares	10.40
Weighted Average Grant Date Fair Value, Unvested at December 31, 2022 \| $ / shares	$ 13.75

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Number of Options Outstanding, Beginning Balance	6,155,055
Number of Options, Granted	3,051,906
Number of Options, Forfeited	(1,284,164)
Number of Options Outstanding, Ending Balance	7,922,797	6,155,055
Options vested and exercisable at December 31, 2022	2,945,832
Weighted Average Exercise Price, Options outstanding at January 1, 2022	$ 23.42
Weighted Average Exercise Price, Granted	7.48
Weighted Average Exercise Price, Forfeited	20.13
Weighted Average Exercise Price, Options outstanding at December 31, 2022	17.81	$ 23.42
Weighted Average Exercise Price, Options vested and exercisable at December 31, 2022	$ 22.10
Weighted Average Contractual Life, Options outstanding	8 years 3 months 18 days	8 years 9 months 18 days
Weighted Average Contractual Life, Options vested and exercisable at December 31, 2022	7 years 9 months 18 days
Aggregate Intrinsic Value, Options outstanding at January 1, 2022	$ 480
Aggregate Intrinsic Value, Options outstanding at December 31, 2022	786	$ 480
Aggregate Intrinsic Value, Options vested and exercisable at December 31, 2022	$ 88

Stock-Based Compensation - Schedule of Estimated Fair Value Weighted-Average Assumptions Using Black-Scholes Option-Pricing Model (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Expected term (in years)	6 years 25 days	6 years 21 days
Expected volatility	90.00%	95.00%
Risk-free interest rate	2.00%	0.87%
Expected dividend yield	0.00%	0.00%
Fair value of common stock	$ 7.48	$ 32.41

Income Taxes - Summary of Income (Loss) Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal	$ (113,389)	$ 49,045
Foreign	(55,586)	(220,000)
Loss before income taxes	$ (168,975)	$ (170,955)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

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+ Details

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current income tax (benefit) expense:
Federal	$ (246)	$ 987
State	(19)	20
Total current income tax (benefit) expense	(265)	1,007
Deferred income tax (benefit) expense:
Total income tax (benefit) expense	$ (265)	$ 1,007

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Schedule of Income Tax (Benefit) Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Benefit at the federal rate	$ (35,472)	$ (35,901)
Foreign tax rate differential	2,177	43,786
State taxes, net of federal benefit	(1,603)	1,018
Change in valuation allowance	35,406	22,268
Intellectual property transfer		(25,538)
Tax credits	(6,992)	(5,540)
Officer's compensation	695	2,648
Stock compensation	4,637	(2,464)
Permanent differences	(182)
Other	1,069	730
Total income tax (benefit) expense	$ (265)	$ 1,007
Benefit at the federal rate	21.00%	21.00%
Foreign tax rate differential	(1.30%)	(25.60%)
State taxes, net of federal benefit	0.90%	(0.60%)
Change in valuation allowance	(21.00%)	(13.00%)
Intellectual property transfer	0.00%	14.90%
Tax credits	4.10%	3.30%
Officer's compensation	(0.40%)	(1.50%)
Stock compensation	(2.70%)	1.40%
Permanent differences	0.10%
Other	(0.60%)	(0.50%)
Total income tax (benefit) expense	0.10%	(0.60%)

Income Taxes - Summary of Components of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 9,374	$ 5,460
Tax credit carryforwards	12,374	4,683
Intangible Assets	25,537	25,538
Operating lease liabilities	8,074	6,865
Non-qualified stock compensation	12,017	8,028
Restricted stock compensation	235	1,778
Capitalization of R&D expenses	20,375
Other	1,661	1,646
Total deferred tax assets	89,647	53,998
Valuation allowance	(82,228)	(46,823)
Net deferred tax asset (liability)	7,419	7,175
Deferred tax liabilities:
Operating lease right-of-use assets	(7,218)	(6,791)
Depreciation	(186)	(350)
Other	(15)	(34)
Total deferred tax liabilities	$ (7,419)	$ (7,175)

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
U.S. current income tax expense	$ (265,000)	$ 1,007,000
Increase in deferred tax assets valuation allowance	$ 35,406,000	22,268,000
Operating loss carryforwards carryback period	5 years
Percentage of TCJA limitations on net operating loss carryforwards to taxable income	80.00%
Uncertain tax positions	$ 0	0
Unrecognized tax benefits, interest and penalties accrued	$ 0	0
Earliest Tax Year
Income Taxes [Line Items]
Open tax year	2019
Latest Tax Year
Income Taxes [Line Items]
Open tax year	2022
Federal
Income Taxes [Line Items]
Operating loss carryforwards	$ 0	13,300,000
Federal \| Research and Development
Income Taxes [Line Items]
Tax credit carryforwards	$ 6,600,000	2,800,000
Tax credit carryforwards expiration year	2040
Federal \| Orphan Drug Credit (ODC)
Income Taxes [Line Items]
Tax credit carryforwards	$ 4,800,000
Tax credit carryforwards expiration year	2041
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 3,600,000	8,500,000
Operating loss carryforwards expiration year	2035
State \| Research and Development
Income Taxes [Line Items]
Tax credit carryforwards	$ 1,300,000	800,000
Tax credit carryforwards expiration year	2035
Foreign
Income Taxes [Line Items]
Operating loss carryforwards	$ 72,900,000	$ 16,800,000

Net Loss per Share - Computation Of Basic And Diluted Net Loss Per Share Attributable To Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss – basic and diluted	$ (168,710)	$ (171,962)
Denominator:
Weighted-average common shares outstanding - basic	76,654,856	62,782,126
Weighted-average common shares outstanding - diluted	76,654,856	62,782,126
Net loss per share - basic	$ (2.20)	$ (2.74)
Net loss per share - diluted	$ (2.20)	$ (2.74)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

+ References + Details

Net Loss per Share - Potential Dilutive Securities Excluded From Computation Of Diluted Net Loss Per Share Attributable To Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,922,797	6,155,055
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,239,106	2,866,909

Commitments and Contingencies- Additional Information (Details)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Lease termination effective date	Mar. 31, 2023
Expiration date	Dec. 31, 2023

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Amount due to related party	$ 56	$ 1,742
Consulting fees to members of management and board of directors	500	500
ElevateBio and Affiliates
Related Party Transaction [Line Items]
Prepaid expense	2,000	0
Expenses related to services with related party	3,500	5,900
Amount due to related party	100	$ 1,700
BaseCamp
Related Party Transaction [Line Items]
Prepaid expense	$ 2,000

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Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Matching contributions by employer	$ 0.8	$ 0.5