0000950170-22-007792 | 10-Q | XBRL Viewer

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2022

Accrued expenses consisted of the following:


(in thousands)	March 31, 2022		December 31, 2021
Employee compensation and benefits	$	2,099	$	6,867
Professional fees		642		738
Research and development		4,245		3,573
Process development and manufacturing costs		2,703		7,685
Other		394		1,289
Total accrued expenses	$	10,083	$	20,152

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 10,467	$ 8,103
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3,341	3,311
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,126	$ 4,792

Stock-Based Compensation - Additional Information (Details) - USD ($)			1 Months Ended	3 Months Ended
	Jan. 01, 2022	Jul. 02, 2020	Jul. 31, 2020	Mar. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reserved shares of common stock for issuance				15,664,936
Weighted average grant-date fair value of stock options granted				$ 6.89
Common stock, par value				$ 0.0001	$ 0.0001
Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards forfeited or cancelled				53,291
Number of shares granted				809,877
Unrecognized stock-based compensation cost				$ 36,700,000
Weighted average period of cost expected to be recognized				2 years 11 months 26 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 9 months 21 days
Unrecognized stock-based compensation expenses				$ 76,200,000
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
Awards forfeited or cancelled				0
Reserved shares of common stock for issuance				0
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				7,468,416
2020 Stock Option and Grant Plan \| Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted				2,253,397
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				5,232,376
2020 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reserved shares of common stock for issuance			611,354
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
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. Offering periods under the 2020 ESPP will generally be in six months increments, commencing on January 1 and July 1 of each calendar year with the administrator having the right to establish different offering periods. The first offering period was shortened in duration to three months and commenced on April 1, 2022.
2020 ESPP \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Base salary or wages			$ 25,000

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Amount due to related party	$ 1,220		$ 1,742
Consulting fees to members of management and board of directors	200	$ 200
ElevateBio and Affiliates
Related Party Transaction [Line Items]
Expenses related to services with related party	1,400	$ 2,000
Amount due to related party	$ 1,200		$ 1,700

- Definition

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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+ Details

Income Taxes

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

The Company’s income tax provision is computed based on the federal statutory rate, the average state statutory rates, net of the related federal benefit, and foreign statutory rates. For the three months ended March 31, 2022 and 2021, the Company did not record a current or deferred income tax expense or benefit due to current and historical losses incurred by the Company.

The Company’s estimate of the realizability of the deferred tax asset is dependent on estimates of projected future levels of taxable income. In analyzing future taxable income levels, the Company considered all evidence currently available, both positive and negative.

- 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.

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+ Details

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2022
Accounting Policies [Abstract]
Interim Financial Information	Interim Financial Information The accompanying condensed consolidated balance sheet at March 31, 2022, and the condensed consolidated statements of operations and comprehensive loss, statements of changes in stockholders’ equity for the three months ended March 31, 2022 and 2021 and condensed consolidated statements of cash flows for the three months ended March 31, 2022 and 2021 are unaudited. The condensed consolidated interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position at March 31, 2022 and the results of its operations for the three months ended March 31, 2022 and 2021 and its cash flows for the three months ended March 31, 2022 and 2021. The financial data and other information disclosed in these notes related to the three months ended March 31, 2022 and 2021 are also unaudited. The results for the three months ended March 31, 2022 are not necessarily indicative of results to be expected for the year ending December 31, 2022 or for any other subsequent interim period.
Recent Accounting Pronouncements	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. Since December 31, 2021, there have been no new accounting pronouncements adopted by the Company or issued by FASB that are applicable to the Company, except as noted below.
Recently Issued Accounting Pronouncements Not Yet Adopted	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.

Related Party Transactions

3 Months Ended

Mar. 31, 2022

Related Party Transactions

11. Related Party Transactions

The Company entered into an agreement with ElevateBio that provides for ongoing services to the Company in areas such as accounting operations, public relations, information technology, human resources and administration management, finance and risk management, marketing services, facilities, procurement and travel and corporate development and strategy (the “Shared Services Agreement”). The Company also entered into a Development and Manufacturing Services Agreement ("2020 DMS Agreement") with ElevateBio BaseCamp, Inc. (see "Note 5 - Leases"). The Company was billed quarterly 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. The Company incurred $1.4 million and $2.0 million during the three months ended March 31, 2022 and 2021, respectively, related to services provided to the Company by ElevateBio and affiliates. The Company owed ElevateBio $1.2 million and $1.7 million at March 31, 2022 and December 31, 2021, respectively, which is recorded in “Amount due to related party” on the condensed consolidated balance sheets.

Members of the Company’s management and board of directors received a total of $0.2 million and $0.2 million in consulting fees during the three months ended March 31, 2022 and 2021, respectively.

Stockholders Equity - Schedule of Reserved Shares of Common Stock for Issuance (Details)	Mar. 31, 2022 shares
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	15,664,936
Unvested Restricted Stock
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	2,925,254
Option To Purchase Common Stock
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	7,507,306
Stock Available For Grant \| 2020 Stock Option and Grant Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	5,232,376

Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Aug. 03, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Aug. 04, 2020
Net proceeds from issuance initial public offering	$ 292,000
Net losses attributable to common stockholders		$ (43,863)	$ (30,923)
Accumulated deficit		(340,928)		$ (297,065)
Cash, cash equivalents and short-term investments		$ 201,400
Convertible Preferred Stock
Preferred stock, shares outstanding					0
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

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 2,099	$ 6,867
Professional fees	642	738
Research and development	4,245	3,573
Process development and manufacturing costs	2,703	7,685
Other	394	1,289
Total accrued expenses	$ 10,083	$ 20,152

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Mar. 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	65,364,572	65,170,332
Common stock, shares outstanding	64,264,127	63,565,886

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net loss	$ (43,863)	$ (30,923)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	466	18
Non-cash lease expense	380	54
Amortization and accretion of discounts on short-term investments	76	456
Stock compensation expense	10,467	8,103
Changes in operating assets and liabilities:
Interest receivable	(122)	(19)
Prepaid expenses and other current assets	284	1,735
Other assets	122
Income tax payable	(500)
Accounts payable, accrued expenses and amount due to related party	(13,786)	1,650
Net cash used in operating activities	(46,476)	(18,926)
Cash flows from investing activities
Purchase of property and equipment		(75)
Purchase of short-term investments	(60,979)	(30,098)
Maturities of short-term investments	6,000	95,000
Net cash (used in) provided by investing activities	(54,979)	64,827
Cash flows from financing activities
Effect of exchange rate changes on cash, cash equivalents, and restricted cash		83
Net (decrease) increase in cash, cash equivalents, and restricted cash	(101,455)	45,984
Cash, cash equivalents, and restricted cash at beginning of period	202,513	122,661
Cash, cash equivalents, and restricted cash at end of period	101,058	168,645
Non-cash investing and financing activities
Unrealized (loss) gain on available-for-sale securities	(195)	42
Right-of-use assets obtained in exchange for operating lease liability		3,099
Reduction of right-of-use asset due to modification	(5,506)
Supplemental disclosure of cash flows
Cash paid for income taxes	500
Cash and cash equivalents	100,206	168,645
Restricted cash	852
Total cash, cash equivalents, and restricted cash	$ 101,058	$ 168,645

Net Loss per Share (Tables)

3 Months Ended

Mar. 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:


	Three Months Ended March 31,
(in thousands, except share and per share data)	2022			2021
Numerator:
Net loss – basic and diluted	$	(43,863	)	$	(30,923	)
Denominator:
Weighted-average common shares outstanding – basic and diluted		63,993,053			62,193,734
Net loss per share – basic and diluted	$	(0.69	)	$	(0.50	)

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

Based on the amounts outstanding at March 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 three months ended March 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.


	March 31,
	2022		2021
Options to purchase common stock		7,507,306		5,145,047
Unvested restricted stock		2,925,254		3,519,753

Short-Term Investments - Summary of Amortized Cost and Estimated Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 101,392	$ 46,481
Unrealized Gains		1
Unrealized Losses	(223)	(23)
Fair Value	101,169	46,459
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,573	11,568
Unrealized Gains		1
Unrealized Losses	(2)
Fair Value	5,571	11,569
Corporate bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	10,767	9,821
Unrealized Losses	(7)	(3)
Fair Value	10,760	9,818
U.S. Government Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	85,052	25,092
Unrealized Losses	(214)	(20)
Fair Value	$ 84,838	$ 25,072

Stockholder's Equity

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Stockholder's Equity

7. 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 March 31, 2022 and December 31, 2021.

At March 31, 2022 and December 31, 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.

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


	March 31, 2022
Unvested restricted stock		2,925,254
Options to purchase common stock		7,507,306
Stock available for grant under the 2020 Stock Option and Grant Plan		5,232,376
Total		15,664,936

- 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.

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-Paragraph 13
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 100,206	$ 201,661
Short-term investments	101,169	46,459
Interest receivable	172	50
Prepaid expenses and other current assets	4,894	5,178
Total current assets	206,441	253,348
Restricted cash	852	852
Other assets	979	1,102
Property and equipment, net	1,083	1,549
Operating lease right-of-use assets	21,735	29,743
Total assets	231,090	286,594
Current liabilities:
Accounts payable	4,473	8,361
Accrued expenses	10,083	20,152
Income tax payable	507	1,007
Operating lease liability, current	2,356	6,591
Amount due to related party	1,220	1,742
Total current liabilities	18,639	37,853
Operating lease liability, long term	20,776	23,475
Total liabilities	39,415	61,328
Commitments and contingencies (See Note 5, Leases)
Stockholders’ equity:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized at March 31, 2022 and December 31, 2021, respectively; 0 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively
Common stock, $0.0001 par value: 150,000,000 shares authorized at March 31, 2022 and December 31, 2021, respectively; 65,364,572 and 65,170,332 shares issued at March 31, 2022 and December 31, 2021, respectively; and 64,264,127 and 63,565,886 shares outstanding at March 31, 2022 and December 31, 2021, respectively	7	7
Additional paid-in capital	532,946	522,479
Accumulated other comprehensive loss	(350)	(155)
Accumulated deficit	(340,928)	(297,065)
Total stockholders’ equity	191,675	225,266
Total liabilities and stockholders’ equity	$ 231,090	$ 286,594

Leases - Summary of Operating Lease Liabilities (Details) (Parenthetical)	Mar. 31, 2022
Lessee, Lease, Description [Line Items]
Operating lease interest percentage	5.02%
Minimum
Lessee, Lease, Description [Line Items]
Operating lease interest percentage	3.40%
Maximum
Lessee, Lease, Description [Line Items]
Operating lease interest percentage	5.75%

Fair Value Measurements (Tables)

3 Months Ended

Mar. 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 and liabilities measured at fair value on a recurring basis:


	March 31, 2022
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	17,176	$	—	$	—	$	17,176
U.S. government treasury securities		23,998		—		—		23,998
Totals	$	41,174	$	—	$	—	$	41,174
Short-term investments:
U.S. government treasury securities	$	84,838	$	—	$	—	$	84,838
Marketable securities:
Commercial paper		—		5,571	$	—		5,571
Corporate bonds		—		10,760		—		10,760
Totals	$	84,838	$	16,331	$	—	$	101,169


	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 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 bonds		—		9,818		—		9,818
Totals	$	25,072	$	21,387	$	—	$	46,459

Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

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


	March 31, 2022
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market fund	$	17,176	$	—	$	—	$	17,176
U.S. government treasury securities		23,998		—		—		23,998
Totals	$	41,174	$	—	$	—	$	41,174
Short-term investments:
U.S. government treasury securities	$	84,838	$	—	$	—	$	84,838
Marketable securities:
Commercial paper		—		5,571	$	—		5,571
Corporate bonds		—		10,760		—		10,760
Totals	$	84,838	$	16,331	$	—	$	101,169


	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 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 bonds		—		9,818		—		9,818
Totals	$	25,072	$	21,387	$	—	$	46,459

During the three months ended March 31, 2022 and the year ended December 31, 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 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, 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

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 0	$ 0
Deferred income tax expense (benefit)	$ 0	$ 0

Accrued Expenses

3 Months Ended

Mar. 31, 2022

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses consisted of the following:


(in thousands)	March 31, 2022		December 31, 2021
Employee compensation and benefits	$	2,099	$	6,867
Professional fees		642		738
Research and development		4,245		3,573
Process development and manufacturing costs		2,703		7,685
Other		394		1,289
Total accrued expenses	$	10,083	$	20,152

Stockholder's Equity (Tables)

3 Months Ended

Mar. 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:


	March 31, 2022
Unvested restricted stock		2,925,254
Options to purchase common stock		7,507,306
Stock available for grant under the 2020 Stock Option and Grant Plan		5,232,376
Total		15,664,936

Nature of the Business

3 Months Ended

Mar. 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 four innovative, allogeneic, off-the-shelf VST therapy candidates targeting 12 different devastating viruses. The Company's lead product, posoleucel (previously referred to as Viralym-M or ALVR105), is a multi-VST-cell 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.

To fully explore the clinical benefit of posoleucel, the Company is conducting three Phase 3 pivotal and two Phase 2 proof-of-concept, or POC, trials in 2022 for the treatment and prevention of life-threatening viral diseases in pediatric and/or adult allogeneic hematopoietic cell transplant, or HCT, patients, each representing a potential meaningful commercial opportunity. The three ongoing pivotal trials evaluate the efficacy and safety of posoleucel for the treatment of virus-associated hemorrhagic cystitis, or HC, for the treatment of AdV infections and for the prevention of infections and disease caused by posoleucel’s six target viruses, respectively. A POC clinical trial for multi-virus prevention in HCT has completed enrollment and final data are expected by year-end. A second POC trial evaluating posoleucel for BKV treatment in kidney transplant is ongoing. The BKV trial is the first posoleucel study in solid organ transplant patients.

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 opened for enrollment at the end of 2021. In the preclinical space, the Company is advancing ALVR107 designed to target 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 are expected to be completed in 2022 to support advancement into a POC study. 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 the Company continues to make ALVR109 available to physicians in response to appropriate compassionate use requests.

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 and Houston, Texas.

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. (“AlloVir Italia”), a wholly-owned subsidiary in Italy.

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 20, 2021, AlloVir Inc. formed AlloVir U.S., Inc. (“AlloVir U.S.”), a wholly-owned subsidiary of AlloVir.

ElevateBio, LLC

On September 17, 2018, the Company executed a Series A2 Preferred Stock Purchase Agreement (“Series A2 Agreement”) with ElevateBio, LLC, a Delaware LLC (“ElevateBio”) concurrent with the LLC Conversion. ElevateBio was formed on November 29, 2017 and is headquartered in Waltham, Massachusetts with a focus on the development of a portfolio of novel cell therapy programs acquired through business development activities with biotechnology companies. ElevateBio is structured as a holding company, comprised of asset-specific subsidiaries focused on the development of pipeline assets, as well as a manufacturing subsidiary with the expertise to provide drug development and manufacturing services. As a result of the purchase of the Company’s Series A2 Preferred Stock, ElevateBio acquired an ownership interest in the Company. The Chief Executive Officer, Chief Financial Officer, and other executives of ElevateBio have previously or currently serve in similar management roles 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 and principal executive officer.

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 condensed 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 condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Through March 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 $43.9 million and $30.9 million for the three months ended March 31, 2022 and 2021, respectively. In addition, at March 31, 2022, the Company had an accumulated deficit of $340.9 million. The Company expects to continue to generate operating losses for the foreseeable future.

The Company believes that its $201.4 million of cash, cash equivalents and short-term investments held at March 31, 2022, are sufficient to fund planned operations for at least twelve months from the date that these condensed 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 contract manufacturing organizations or 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.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

8. Stock-Based Compensation

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 March 31, 2022, the Company had granted 6,715,415 shares of common stock under the 2018 Plan, including an aggregate of 64,042 shares of common stock issuable upon the exercise of outstanding options under the 2018 Plan. Of the awards granted, no awards have been forfeited or cancelled during the three months ended March 31, 2022. 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 March 31, 2022, there was an aggregate of 7,468,416 shares of common stock issuable upon the exercise of outstanding options under the 2020 Plan and 2,253,397 shares of restricted common stock granted under the 2020 Plan. Additionally, there were an aggregate of 5,232,376 shares reserved for future issuance under the 2020 Plan.

Restricted Common Stock

The following table summarizes restricted common stock activity for the three months ended March 31, 2022:


	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2022		2,866,909		$	15.45
Granted		809,877			9.20
Forfeited		(53,291	)		29.96
Vested		(698,241	)		12.83
Unvested at March 31, 2022		2,925,254		$	14.08

At March 31, 2022, there was $36.7 million of unrecognized stock-based compensation cost related to the restricted stock, which is expected to be recognized over a weighted average period of 2.99 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 (in years)		Aggregate Intrinsic Value
Options outstanding at January 1, 2022		6,155,055		$	23.42		8.80	$	480
Granted		1,764,190			9.19		—		—
Exercised		—			—		—		—
Forfeited		(411,939	)		25.10		—		—
Options outstanding at March 31, 2022		7,507,306		$	19.98		8.88	$	181
Options vested and exercisable at March 31, 2022		1,709,930		$	21.44		8.41	$	122

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 weighted-average grant date fair value of stock options granted during the three months ended March 31, 2022 was $6.89. At March 31, 2022, there was $76.2 million of unrecognized stock-based compensation expense related to unvested stock options, which is being recognized over a period of 2.81 years.

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


	Three Months Ended March 31, 2022
Expected term (in years)		6.11
Expected volatility		90.53	%
Risk-free interest rate		1.73	%
Expected dividend yield		—
Fair value of common stock	$	9.19

Stock-Based Compensation Expense

Stock-based compensation expense was as follows:


	Three Months Ended March 31,
(in thousands)	2022		2021
Research and development	$	3,341	$	3,311
General and administrative		7,126		4,792
Total stock-based compensation expense	$	10,467	$	8,103

2020 Employee Stock Purchase Plan

In July 2020, the 2020 Employee Stock Purchase Plan (the “2020 ESPP”) was also 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. The 2020 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. Offering periods under the 2020 ESPP will generally be in six months increments, commencing on January 1 and July 1 of each calendar year with the administrator having the right to establish different offering periods. The first offering period was shortened in duration to three months and commenced on April 1, 2022.

Net Loss per Share

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Net Loss per Share

10. 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:


	Three Months Ended March 31,
(in thousands, except share and per share data)	2022			2021
Numerator:
Net loss – basic and diluted	$	(43,863	)	$	(30,923	)
Denominator:
Weighted-average common shares outstanding – basic and diluted		63,993,053			62,193,734
Net loss per share – basic and diluted	$	(0.69	)	$	(0.50	)


	March 31,
	2022		2021
Options to purchase common stock		7,507,306		5,145,047
Unvested restricted stock		2,925,254		3,519,753

Leases

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Leases

5. Leases

Operating leases

Operating lease liabilities and their corresponding right-of-use (“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.

In March 2019, the Company entered into an interim services agreement which ultimately led to the 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 will expire upon the later of: 1) two years from the Effective Date, or July 2021, and 2) the completion of services under all SOWs. The term may be extended by agreement of the parties for additional two-year periods upon written notice to the supplier at least 30 days prior to expiration of the then-current term. The DMS Agreement (or any individual SOW) may be terminated earlier by AlloVir at any time by providing 190 days’ notice. The Company has extended the DMS Agreement, and estimates that early termination is not reasonably certain to occur. The total estimated lease term of approximately 4.25 years expires in July 2023. In March 2019, at the inception of this lease, the Company recorded a ROU asset and lease liability of $6.9 million. 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. The SOW calls for a fixed monthly payment through July 2023, with additional two-year renewal options. The total estimated lease term of approximately 3.75 years expires in July 2023. The use of these manufacturing suites qualify 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 (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, which is expected to occur in September 2022. 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 second SOW under the DMS agreement (beginning September 2019) was terminated as of the effective date 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 May 2020, the Company entered into a new Development and Manufacturing Services Agreement (“2020 DMS Agreement”) with ElevateBio BaseCamp, Inc. 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 for and obtains substantially all of the economic benefit of the suite. 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. The Company estimates that the exercise of the one-year renewal option is reasonably certain to occur, and the Company is reasonably certain that it will 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 modification 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.

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 March 31, 2022, no allowances have been used and therefore no reduction to the tenant improvement allowance has been made. The Company will monitor the timing of the reimbursements and adjust the ROU asset and lease liability at such time. 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 March 31, 2022, the Company has no reasonable certainty that this option to extend will be exercised.

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


2022 (remaining 9 months)	$	2,715
2023		3,049
2024		3,151
2025		3,229
2026		3,308
Thereafter		13,069
Total lease payments		28,521
Less: interest (3.40% - 5.75%)		(5,389	)
Total lease liability	$	23,132
Lease liability – current	$	2,356
Lease liability – long-term	$	20,776

Total lease costs were $1.6 million and $1.3 million for the three months ended March 31, 2022 and 2021, respectively. Cash paid for operating leases was $1.2 million and $1.1 million for the three months ended March 31, 2022 and 2021, respectively. The Company’s total variable lease costs, such as materials, batch payments, storage, knowledge and tech transfer, and other common area maintenance fees, related to the operating leases was $1.2 million and $0.9 million for the three months ended March 31, 2022 and 2021, respectively. The weighted average remaining lease term is 8.07 years at March 31, 2022. The weighted average discount rate is 5.02% at March 31, 2022.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Summary of Restricted Common Stock Activity

The following table summarizes restricted common stock activity for the three months ended March 31, 2022:


	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2022		2,866,909		$	15.45
Granted		809,877			9.20
Forfeited		(53,291	)		29.96
Vested		(698,241	)		12.83
Unvested at March 31, 2022		2,925,254		$	14.08

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 (in years)		Aggregate Intrinsic Value
Options outstanding at January 1, 2022		6,155,055		$	23.42		8.80	$	480
Granted		1,764,190			9.19		—		—
Exercised		—			—		—		—
Forfeited		(411,939	)		25.10		—		—
Options outstanding at March 31, 2022		7,507,306		$	19.98		8.88	$	181
Options vested and exercisable at March 31, 2022		1,709,930		$	21.44		8.41	$	122

Schedule of Estimated Fair Value 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:


	Three Months Ended March 31, 2022
Expected term (in years)		6.11
Expected volatility		90.53	%
Risk-free interest rate		1.73	%
Expected dividend yield		—
Fair value of common stock	$	9.19

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was as follows:


	Three Months Ended March 31,
(in thousands)	2022		2021
Research and development	$	3,341	$	3,311
General and administrative		7,126		4,792
Total stock-based compensation expense	$	10,467	$	8,103

Short-Term Investments (Tables)

3 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Estimated Fair Value of Marketable Securities

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


	March 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	85,052	$	—	$	(214	)	$	84,838
Marketable securities:
Commercial paper		5,573		—		(2	)		5,571
Corporate bonds		10,767		—		(7	)		10,760
Totals	$	101,392	$	—	$	(223	)	$	101,169


	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 bonds		9,821		—		(3	)		9,818
Totals	$	46,481	$	1	$	(23	)	$	46,459

Leases - Summary of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2022 (remaining 9 months)	$ 2,715
2023	3,049
2024	3,151
2025	3,229
2026	3,308
Thereafter	13,069
Total lease payments	28,521
Less: interest (3.40% - 5.75%)	(5,389)
Total lease liability	23,132
Lease liability - current	2,356	$ 6,591
Lease liability - long-term	$ 20,776	$ 23,475

Net Loss per Share - Computation Of Basic And Diluted Net Loss Per Share Attributable To Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss – basic and diluted	$ (43,863)	$ (30,923)
Denominator:
Weighted-average common shares outstanding — basic and diluted	63,993,053	62,193,734
Net loss per share – basic and diluted	$ (0.69)	$ (0.50)

- Definition

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

Short-Term Investments

3 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

3. Short-Term Investments


	March 31, 2022
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	85,052	$	—	$	(214	)	$	84,838
Marketable securities:
Commercial paper		5,573		—		(2	)		5,571
Corporate bonds		10,767		—		(7	)		10,760
Totals	$	101,392	$	—	$	(223	)	$	101,169


	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 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 condensed consolidated balance sheets and are not included in the tables above. At March 31, 2022 and December 31, 2021, all investments had contractual maturities within one year.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 29,067	$ 20,393
General and administrative	14,126	10,470
Total operating expenses	43,193	30,863
Loss from operations	(43,193)	(30,863)
Total other income (loss), net:
Interest income	148	505
Other (loss) income, net	(818)	(565)
Loss before income taxes	(43,863)
Income tax expense	0	0
Net loss	$ (43,863)	$ (30,923)
Net loss per share — basic and diluted	$ (0.69)	$ (0.50)
Weighted-average common shares outstanding — basic and diluted	63,993,053	62,193,734
Comprehensive loss:
Net loss	$ (43,863)	$ (30,923)
Other comprehensive income (loss), net of tax:
Unrealized (loss) gain on available-for-sale securities	(195)	42
Foreign currency translation adjustment	0	83
Total other comprehensive (loss) income	(195)	125
Comprehensive loss	$ (44,058)	$ (30,798)

Leases (Tables)

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Summary of Maturities Operating Leases Liabilities

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


2022 (remaining 9 months)	$	2,715
2023		3,049
2024		3,151
2025		3,229
2026		3,308
Thereafter		13,069
Total lease payments		28,521
Less: interest (3.40% - 5.75%)		(5,389	)
Total lease liability	$	23,132
Lease liability – current	$	2,356
Lease liability – long-term	$	20,776

Stockholders Equity - Additional Information (Details) - $ / shares	Mar. 31, 2022	Dec. 31, 2021	Aug. 03, 2020
Class Of Stock [Line Items]
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, shares authorized	150,000,000	150,000,000
Common stock, par value	$ 0.0001	$ 0.0001
IPO
Class Of Stock [Line Items]
Preferred stock, par or stated value per share			$ 0.0001
Preferred stock, shares authorized			10,000,000

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Number of Options Outstanding, Beginning Balance	6,155,055
Number of Options, Granted	1,764,190
Number of Options, Forfeited	(411,939)
Number of Options Outstanding, Ending Balance	7,507,306	6,155,055
Options vested and exercisable at March 31, 2022	1,709,930
Weighted Average Exercise Price, Options outstanding as of January 1, 2022	$ 23.42
Weighted Average Exercise Price, Granted	9.19
Weighted Average Exercise Price, Forfeited	25.10
Weighted Average Exercise Price, Options outstanding at March 31, 2022	19.98	$ 23.42
Weighted Average Exercise Price, Options vested and exercisable at March 31, 2022	$ 21.44
Weighted Average Contractual Life, Options outstanding	8 years 10 months 17 days	8 years 9 months 18 days
Weighted Average Contractual Life, Options vested and exercisable at March 31, 2022	8 years 4 months 28 days
Aggregate Intrinsic Value, Options outstanding at January 1, 2022	$ 480
Aggregate Intrinsic Value, Options outstanding at March 31, 2022	181	$ 480
Aggregate Intrinsic Value, Options vested and exercisable at March 31, 2022	$ 122

Net Loss per Share - Potential Dilutive Securities Excluded From Computation Of Diluted Net Loss Per Share Attributable To Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 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	7,507,306	5,145,047
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,925,254	3,519,753

Stock-Based Compensation - Schedule of Estimated Fair Value Assumptions Using Black Scholes Option-Pricing Model (Details)	3 Months Ended
	Mar. 31, 2022 $ / shares
Share-based Payment Arrangement [Abstract]
Expected term (in years)	6 years 1 month 9 days
Expected volatility	90.53%
Risk-free interest rate	1.73%
Fair value of common stock	$ 9.19

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Interim Financial Information

The accompanying condensed consolidated balance sheet at March 31, 2022, and the condensed consolidated statements of operations and comprehensive loss, statements of changes in stockholders’ equity for the three months ended March 31, 2022 and 2021 and condensed consolidated statements of cash flows for the three months ended March 31, 2022 and 2021 are unaudited. The condensed consolidated interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position at March 31, 2022 and the results of its operations for the three months ended March 31, 2022 and 2021 and its cash flows for the three months ended March 31, 2022 and 2021. The financial data and other information disclosed in these notes related to the three months ended March 31, 2022 and 2021 are also unaudited. The results for the three months ended March 31, 2022 are not necessarily indicative of results to be expected for the year ending December 31, 2022 or for any other subsequent interim period.

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.

Since December 31, 2021, there have been no new accounting pronouncements adopted by the Company or issued by FASB that are applicable to the Company, except as noted below.

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.

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - 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	8,103		8,103
Issuance of common stock, upon vesting of restricted stock, Shares		519,839
Unrealized (loss) gain on available-for-sale securities	42			42
Foreign currency translation adjustment	83			83
Net loss	(30,923)				(30,923)
Balance at Mar. 31, 2021	330,369	$ 7	486,375	13	(156,026)
Balance, Shares at Mar. 31, 2021		62,451,094
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	10,467		10,467
Issuance of common stock, upon vesting of restricted stock, Shares		698,241
Unrealized (loss) gain on available-for-sale securities	(195)			(195)
Foreign currency translation adjustment	0
Net loss	(43,863)				(43,863)
Balance at Mar. 31, 2022	$ 191,675	$ 7	$ 532,946	$ (350)	$ (340,928)
Balance, Shares at Mar. 31, 2022		64,264,127

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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+ Details

Stock-Based Compensation - Summary of Restricted Common Stock Activity (Details) - Restricted Common Stock	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Number of Shares
Number of Shares, Unvested at January 1, 2022 \| shares	2,866,909
Number of Shares, Granted \| shares	809,877
Number of Shares, Forfeited \| shares	(53,291)
Number of Shares, Vested \| shares	(698,241)
Number of Shares, Unvested at March 31, 2022 \| shares	2,925,254
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	9.20
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	29.96
Weighted Average Grant Date Fair Value, Vested \| $ / shares	12.83
Weighted Average Grant Date Fair Value, Unvested at March 31, 2022 \| $ / shares	$ 14.08

Leases - Additional Information (Details) - USD ($)	1 Months Ended					3 Months Ended
Leases - Additional Information (Details) - USD ($)	Feb. 28, 2022	Sep. 30, 2021	Feb. 28, 2021	Sep. 30, 2019	Jul. 31, 2019	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Mar. 31, 2019
Leases [Line Items]
ROU asset						$ 21,735,000		$ 29,743,000
Lease liability						23,132,000
Operating lease costs						1,600,000	$ 1,300,000
Cash paid for operating lease						1,200,000	1,100,000
Variable lease costs						$ 1,200,000	$ 900,000
Operating lease, weighted average remaining lease term						8 years 25 days
Operating lease, weighted average discount rate, percent						5.02%
DMS Agreement
Leases [Line Items]
Lease expiration month and year					2021-07
Term of agreement					2 years
Operating lease, existence of option to extend					true
Lease, option to extend						The term may be extended by agreement of the parties for additional two-year periods upon written notice to the supplier at least 30 days prior to expiration of the then-current term.
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				$ 6,300,000					$ 6,900,000
Lease liability				$ 6,300,000					$ 6,900,000
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			$ 3,100,000
Lease liability			2,500,000
Utilization fee			$ 3,200,000
Lessee operating lease, lease term including renewal option			2 years
Prepaid utilization fee			$ 600,000
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 March 31, 2022, the Company has no reasonable certainty that this option to extend will be exercised.
Tenant improvement allowance to be reimbursed		$ 3,100,000
Tenant improvement allowance, reimbursement period		2 years
Tenant improvement allowance						$ 0
Lease commencement month and year		2021-09
Additional one time lease period		5 years
New Lease Agreement with BP Bay Colony LLC
Leases [Line Items]
ROU asset		$ 6,000,000.0
Lease liability		6,000,000.0
Sublease with AMAG Pharmaceuticals
Leases [Line Items]
ROU asset		17,300,000
Lease liability		$ 17,300,000
Original SOW Amendment under DMS Agreement \| Lease Modification under ASC 842
Leases [Line Items]
ROU asset	$ (1,400,000)
Lease liability	$ (1,400,000)
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	$ (2,600,000)
Lease liability	(2,600,000)
Change Order to Modify Terms of SOW under 2020 DMS Agreement \| Lease Modification under ASC 842
Leases [Line Items]
ROU asset	(1,500,000)
Lease liability	$ (1,300,000)

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value On Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Cash equivalents:
Cash equivalents	$ 41,174	$ 150,129
Short-term investments:
Short-term investments	101,169	46,459
Commercial Paper
Cash equivalents:
Cash equivalents		7,998
Short-term investments:
Short-term investments	5,571	11,569
Corporate Bonds
Cash equivalents:
Cash equivalents		753
Short-term investments:
Short-term investments	10,760	9,818
Money Market Fund
Cash equivalents:
Cash equivalents	17,176	141,378
U.S. Government Treasury Securities
Cash equivalents:
Cash equivalents	23,998
U.S. Government Treasury Securities
Short-term investments:
Short-term investments	84,838	25,072
Level 1
Cash equivalents:
Cash equivalents	41,174	141,378
Short-term investments:
Short-term investments	84,838	25,072
Level 1 \| Money Market Fund
Cash equivalents:
Cash equivalents	17,176	141,378
Level 1 \| U.S. Government Treasury Securities
Cash equivalents:
Cash equivalents	23,998
Level 1 \| U.S. Government Treasury Securities
Short-term investments:
Short-term investments	84,838	25,072
Level 2
Cash equivalents:
Cash equivalents		8,751
Short-term investments:
Short-term investments	16,331	21,387
Level 2 \| Commercial Paper
Cash equivalents:
Cash equivalents		7,998
Short-term investments:
Short-term investments	5,571	11,569
Level 2 \| Corporate Bonds
Cash equivalents:
Cash equivalents		753
Short-term investments:
Short-term investments	$ 10,760	$ 9,818