0001711279-23-000008 | 10-K | XBRL Viewer

Unrealized loss on available-for-sale securities and other

(139,975)

(69,570)

(32,167)

^[1]

(565)

(169)

(4)

Comprehensive loss

$ (140,540)

$ (69,739)

$ (32,171)

Net loss per common share: basic (in usd per share)

$ (5.49)

$ (3.13)

$ (1.71)

Net loss per common share: diluted (in usd per share)

$ (5.49)

$ (3.13)

$ (1.71)

Weighted-average common shares outstanding: basic

25,491,721

22,196,846

18,787,161

Weighted-average common shares outstanding: diluted

25,491,721

22,196,846

18,787,161

[1]	Includes foreign currency translation loss of $78 thousand, gain of $7 thousand, and loss of $1 thousand for the years ended December 31, 2022, 2021, and 2020, respectively.

Consolidated Statements of Stockholders' Equity - USD ($)
$ in Thousands

Total

Common Stock

Additional Paid-in Capital

Accumulated Other Comprehensive Income (loss)

Accumulated Deficit

Beginning balance (in shares) at Dec. 31, 2019

17,354,310

Beginning balance at Dec. 31, 2019

$ 202,914

$ 0

$ 241,951

$ 10

$ (39,047)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Issuance of common stock, net (in shares)

2,359,910

Issuance of common stock, net

118,035

Stock-based compensation expense

3,306

Unrealized loss on investments and other

^[1]

(4)

Ending balance (in shares) at Dec. 31, 2020

(32,167)

19,714,220

Ending balance at Dec. 31, 2020

292,084

$ 0

363,292

(71,214)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Foreign currency translation gain/(loss)

(1)

Issuance of common stock, net (in shares)

5,493,765

Issuance of common stock, net

355,628

Stock-based compensation expense

15,603

Unrealized loss on investments and other

^[1]

(169)

Ending balance (in shares) at Dec. 31, 2021

(69,570)

25,207,985

Ending balance at Dec. 31, 2021

593,576

$ 0

734,523

(163)

(140,784)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Foreign currency translation gain/(loss)

Issuance of common stock, net (in shares)

573,637

Issuance of common stock, net

36,063

Shares surrendered for taxes and forfeitures (in shares)

(17,879)

Shares surrendered for taxes and forfeitures

(649)

Stock-based compensation expense

33,781

Unrealized loss on investments and other

^[1]

(565)

Ending balance (in shares) at Dec. 31, 2022

(139,975)

25,763,743

Ending balance at Dec. 31, 2022

522,231

$ 0

$ 803,718

$ (728)

$ (280,759)

Increase (Decrease) in Stockholders' Equity [Roll Forward]

Foreign currency translation gain/(loss)

$ (78)

[1]	Includes foreign currency translation loss of $78 thousand, gain of $7 thousand, and loss of $1 thousand for the years ended December 31, 2022, 2021, and 2020, respectively.

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities
Net loss	$ (139,975)	$ (69,570)	$ (32,167)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	4,055	2,769	1,851
Stock-based compensation expense	33,230	15,319	3,272
Loss on disposal of fixed assets	72	0	33
Non-cash interest expense	0	1,492	0
Other, net	(762)	(454)	11
Changes in operating assets and liabilities
Prepaid expenses and other current assets	(311)	(691)	(1,922)
Other non-current assets	(150)	65	(934)
Lease liability	(647)	(285)	685
Accounts payable	(1,254)	712	783
Accrued expenses and other current liabilities	5,173	2,705	2,305
Net cash used in operating activities	(100,569)	(47,938)	(26,083)
Investing Activities
Purchases of property and equipment	(52,979)	(68,336)	(14,843)
Purchases of investments	(318,781)	(190,462)	(3,205)
Proceeds from maturities of investments	257,677	32,028	6,867
Net cash used in investing activities	(114,083)	(226,770)	(11,181)
Financing Activities
Proceeds from issuance of common stock, net	35,996	355,645	118,019
Taxes paid related to settlement of restricted stock awards	(649)	0	0
Repayment of ASTRA build to suit liability	0	(7,960)	0
Net cash provided by financing activities	35,347	347,685	118,019
Effect of exchange rate changes on cash and cash equivalents	(41)	0	0
Net change in cash and cash equivalents	(179,346)	72,977	80,755
Cash and cash equivalents at beginning of year	341,246	268,269	187,514
Cash and cash equivalents at end of year	161,900	341,246	268,269
Supplemental Disclosures of Non-Cash Investing and Financing Activities
Unpaid purchases of property and equipment	14,927	15,363	9,697
Initial recognition of right-of-use assets	$ 1,556	$ 4,396	$ 911

Organization	12 Months Ended
Organization	Dec. 31, 2022
Accounting Policies [Abstract]
Organization	Organization Krystal Biotech, Inc. (the “Company,” or “we” or other similar pronouns) commenced operations in April 2016. In March 2017, the Company converted from a California limited liability company to a Delaware C-corporation, and changed its name from Krystal Biotech LLC to Krystal Biotech, Inc. In June 2018, the Company incorporated a wholly-owned subsidiary in Australia for the purpose of undertaking preclinical and clinical studies in Australia. In April 2019, the Company incorporated Jeune Aesthetics, Inc (“Jeune Aesthetics”), in Delaware, a wholly-owned subsidiary, for the purpose of undertaking preclinical and clinical studies for aesthetic skin conditions. In January 2022, August 2022, and December 2022, the Company incorporated wholly-owned subsidiaries in Switzerland, Netherlands, and France, respectively, for the purpose of establishing initial operations in Europe for the development and commercialization of Krystal's product pipeline. We are a biotechnology company focused on developing and commercializing genetic medicines for patients with rare diseases. Using our patented platform that is based on engineered HSV-1, we create vectors that efficiently deliver therapeutic transgenes to cells of interest in multiple organ systems. The cell’s own machinery then transcribes and translates the encoded effector to treat or prevent disease. We formulate our vectors for non-invasive or minimally invasive routes of administration at a healthcare professional’s office or potentially in the patient’s home by a healthcare professional. Our goal is to develop easy-to-use medicines to dramatically improve the lives of patients living with rare diseases and chronic conditions. Our innovative technology platform is supported by in-house, commercial scale Current Good Manufacturing Practice ("CGMP") manufacturing capabilities. Liquidity As of December 31, 2022, the Company had an accumulated deficit of $280.8 million. As the Company continues to incur losses, a transition to profitability is dependent upon the successful development, approval and commercialization of its product candidates and the achievement of a level of revenues adequate to support the Company’s cost structure. The Company may never achieve profitability, and unless and until it does the Company will continue to need to raise additional capital or obtain financing from other sources. Management intends to fund future operations through its on hand cash and cash equivalents, the sale of equity, and debt financings and may also seek additional capital through arrangements with strategic partners or other sources. There can be no assurance that additional funding will be available on terms acceptable to the Company, if at all. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to the failure of product candidates in clinical and preclinical studies, the development of competing product candidates or other technological innovations by competitors, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to commercialize product candidates. The Company expects to incur significant costs to expand it's commercialization capabilities in advance of the potential global regulatory approvals of it's lead product, B-VEC. The Company believes that its cash, cash equivalents and short-term investments of approximately $379.2 million as of December 31, 2022 will be sufficient to allow the Company to fund its planned operations for at least the next 12 months from the date of this Annual Report on Form 10-K.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). All intercompany balances and transactions have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform to the current period presentation. The reclassified amounts have no impact on the Company’s previously reported financial position or results of operations.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be

representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, including: stock-based compensation expense, accrued expenses, the fair value of financial instruments, the incremental borrowing rate for lease liabilities, and the valuation allowance included in the deferred income tax calculation.

Segment and Geographical Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company and the Company’s chief operating decision maker view the Company’s operations and manage its business in one operating segment, which is the business of developing and commercializing pharmaceutical products.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments that potentially subject the Company to credit risk consist of cash, cash equivalents and investments. The Company’s policy is to invest its cash, cash equivalents and investments in money market funds, corporate bonds, commercial paper, government agency securities and various other bank deposit accounts. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company is exposed to credit risk in the event of default by the financial institutions to the extent amounts recorded on the consolidated balance sheets are in excess of insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no financial instruments with off-balance sheet risk of loss.

Cash, Cash Equivalents and Investments

Cash and cash equivalents consist of money market funds and bank deposits. Cash equivalents are defined as short-term, highly liquid investments with original maturities of 90 days or less at the date of purchase.

Investments with maturities of less than one year are classified as short-term investments on the consolidated balance sheets and consist of commercial paper, corporate bonds, and government agency securities. Investments with maturities of greater than one year are classified as long-term investments on the consolidated balance sheets and consist of corporate bonds and government agency securities. Accrued interest on investments is also classified as short-term investments.

As our entire investment portfolio is considered available for use in current operations, we classify all investments as available-for-sale securities. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive loss, which is a separate component of stockholders’ equity in the consolidated balance sheets. Any premium arising at purchase is amortized to the earliest call date and any discount arising at purchase is accreted to maturity. Amortization and accretion of premiums and discounts are recorded in interest and other income, net, or general and administrative expenses in the consolidated statements of operations.

Fair Value of Financial Instruments

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. There is a three-level hierarchy that prioritizes the inputs used in determining fair value by their reliability and preferred use, as follows:

•Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities.

•Level 2—Valuations based on quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets and liabilities in inactive markets, or other inputs that are observable, or can be corroborated by observable market data.

•Level 3—Valuations based on inputs that are both significant to the fair value measurement and unobservable.

To the extent that a 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 within 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.

There have been no significant changes to the valuation methods utilized by the Company during the periods presented. There have been no transfers between Level 1, Level 2, and Level 3 in any periods presented.

The carrying amounts of financial instruments consisting of cash and cash equivalents, investments, prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities included in the Company’s consolidated financial statements, are reasonable estimates of fair value, primarily due to their short maturities.

Our available-for-sale, short-term and long-term investments, which consist of commercial paper, corporate bonds, and U.S. government agency securities are considered to be Level 2 financial instruments. The fair value of Level 2 financial assets is determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis.

Property and Equipment, net

Property and equipment, net, is stated at cost, less accumulated depreciation. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred, while costs of major additions and betterments are capitalized. Upon disposal, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Depreciation is recorded using the straight-line method over the estimated useful lives of the respective assets, which are as follows:


Computer equipment and software			3 - 7 years
Laboratory and manufacturing equipment			3 - 20 years
Furniture and fixtures			3 - 7 years
Leasehold improvements			lesser of remaining useful life or remaining life of lease

The Company reviews the estimated useful lives of its property and equipment on a continuing basis. In evaluating the useful lives, the Company considers how long assets will remain functionally effective, whether the technology continues to be relevant and considers other competitive and economic factors. If the assessment indicates that the assets will be used for a shorter or longer period than previously anticipated, the useful life of the assets is adjusted, resulting in a change in estimate. Changes in estimates are accounted for on a prospective basis by depreciating the current carrying values of the assets over their revised remaining useful lives.

A review performed by the Company in the current year indicated that certain pieces of lab equipment would be functional for a longer term than previously estimated and as a result, the Company increased the useful lives of these assets from 7 to 15 years. This change was effective and accounted for prospectively beginning in Q3 2022. The effect of this change in useful life estimate did not result in a material change to depreciation expense for the year ended December 31, 2022.

Construction-in-progress (“CIP”) is not depreciated until the asset is placed in service.

Impairment of Long-Lived Assets

The Company evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. We review the recoverability of the net book value of long-lived assets whenever events and circumstances indicate ("triggering events") that the net book value of an asset may not be recoverable from the estimated undiscounted future cash flows expected to result from its use and eventual disposition. In cases where a triggering event occurs and undiscounted expected future cash flows are less than the net book value, we recognize an impairment loss equal to an amount by which the net book value exceeds the fair value of the asset. Long-lived assets to be disposed of are reported at the lower of carrying amount or fair value less cost to sell. The Company not experienced any triggering events or recognized any impairment losses for the years ended December 31, 2022, 2021, and 2020.

Leases

The Company accounts for its lease agreements in accordance with FASB ASC Topic 842, Leases. Right-of-use lease assets represent the right to use an underlying asset during the lease term and the lease liabilities represent the commitment to make lease payments arising from the lease. Right-of-use lease assets and obligations are recognized based on the present value of remaining lease payments over the lease term. As the Company’s existing lease agreements do not provide an implicit rate and as the Company does not have any external borrowings, the Company has used an estimated incremental borrowing rate based on the information available at lease commencement in determining the present value of lease payments. Operating lease expense is recognized on a straight-line basis over the lease term. Variable lease expense is recognized in the period in which the obligation for the payment is incurred. In addition, the Company also has made an accounting policy election to exclude leases with an initial term of twelve months or less from its consolidated balance sheets and to account for lease and non-lease components of its operating leases as a single component.

For lease arrangements where it has been determined that the Company has control over an asset that is under construction and is thus considered the accounting owner of the asset during the construction period, the Company records a construction in progress asset and corresponding financial obligation on the consolidated balance sheet. Once the construction is complete, an assessment is performed to determine whether the lease meets certain “sale-leaseback” criteria. If the sale-leaseback criteria are determined to be met, the Company will remove the asset and related financial obligation from the consolidated balance sheet and treat the lease as either an operating or finance lease based on an assessment of the guidance. If, upon completion of construction, the project does not meet the “sale-leaseback” criteria, the lease will be treated as a financing obligation and the Company will depreciate the asset over its estimated useful life for financial reporting purposes once the asset has been placed into service.

Research and Development Expenses

Research and development costs are charged to expense as incurred in performing research and development activities. These costs include employee compensation costs, facilities and overhead, preclinical and clinical activities, clinical manufacturing costs, contract management services, regulatory and other related costs.

The Company estimates contract research and manufacturing expenses based on the services performed pursuant to contracts with research organization and manufacturing organizations that manufacture materials used in the Company’s ongoing preclinical and clinical studies. Non-refundable advanced payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed.

In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. These estimates are based on communications with third-party service providers and the Company’s estimates of accrued expenses using information available at each balance sheet date. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly.

Stock-Based Compensation Expense

The Company applies the fair value recognition provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 718, Compensation—Stock Compensation (“ASC 718”), to account for stock-based compensation. Compensation costs related to stock options granted are based on the estimated fair value of the awards on the date of grant.

ASC 718 requires all stock-based payments, including grants of stock options and restricted stock, to be recognized in the consolidated statements of operations based on their grant-date fair values. Compensation expense is recognized on a straight-line basis based on the grant-date fair value over the associated service period of the award, which is generally the vesting term.

The Company estimates the fair value of its stock options using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including: (i) the expected stock price volatility; (ii) the expected term of the award; (iii) the risk-free interest rate; and (iv) expected dividends. Once the Company's own sufficient historical volatility data was obtained in 2021, the Company eliminated the use of a representative peer group and began using only its own historical volatility data in its estimate of expected volatility.

The Company estimates the expected term of its stock options using the “simplified” method, whereby the expected term equals the arithmetic mean of the vesting term and the original contractual term of the option. The risk-free interest rates are based on US Treasury securities with a maturity date commensurate with the expected term of the associated award. The Company has never paid and does not expect to pay dividends in the foreseeable future. The Company accounts for forfeitures as they occur. Stock-based compensation expense recognized in the financial statements is based on awards for which service conditions are expected to be satisfied.

Income Taxes

For the years ended December 31, 2022, 2021, and 2020, income taxes were recorded in accordance with FASB ASC Topic 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. Under this method, we record deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect when the differences are expected to reverse. Valuation allowances are provided when necessary to reduce net deferred tax assets to the amount that is more likely than not to be realized. Based on the available evidence, we are unable, at this time, to support the determination that it is more likely than not that our deferred tax assets will be utilized in the future. Accordingly, we recorded a full valuation allowance as of December 31, 2022 and 2021. We intend to maintain a valuation allowance until sufficient evidence exists to support its reversal.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of December 31, 2022 and 2021, the Company did not have any significant uncertain tax positions.

The Company may recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2022 and 2021, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statements of operations and comprehensive loss.

Comprehensive Loss

Comprehensive loss is defined as the change in equity during a period from transactions from non-owner sources. Unrealized gains or losses on available-for-sale securities is a component of other comprehensive gains or losses and is presented net of taxes. We record reclassifications from other comprehensive gains or losses to interest and other income, net on the consolidated statements of operations related to realized gains on sales of available-for-sale securities.

The Company reviews its securities quarterly to determine whether an other-than-temporary impairment has occurred. The Company determined that there were no other-than-temporary impairments during the years ended December 31, 2022, 2021, and 2020.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB that the Company adopts as of the specified effective date. There were no recently adopted accounting pronouncements that had a material impact on the Company's financial statements, and no recently issued accounting pronouncements that are expected to have a material impact on the Company's financial statements.

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

Basic net loss per share attributable to common stockholders is calculated by dividing net loss attributable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss by the weighted-average number of shares of common stock and common share equivalents outstanding for the period. Common share equivalents consist of common stock issuable upon exercise of stock options and vesting of restricted stock awards. There were 3,582,181, 2,043,179, and 853,614 common share equivalents outstanding in the form of stock options and 66,600, 98,800, and zero unvested restricted stock awards as of December 31, 2022, 2021 and 2020, respectively, that have been excluded from the calculation of diluted net loss per common share as their effect would be anti-dilutive for all periods presented.


(In thousands, except share and per share data)	Years Ended December 31,
	2022		2021		2020
Net loss per common share	$	(139,975)	$	(69,570)	$	(32,167)
Weighted-average basic and diluted common shares	25,491,721		22,196,846		18,787,161
Basic and diluted net loss per common share	$	(5.49)	$	(3.13)	$	(1.71)

Fair Value Instruments

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Instruments

Fair Value InstrumentsThe following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities (1)		Long-term Marketable Securities (2)
Level 1:
Cash and cash equivalents	$	161,900	$	—	$	—	$	161,900	$	161,900	$	—	$	—
Subtotal	161,900		—		—		161,900		161,900		—		—
Level 2:
Commercial paper	63,624		5		(23)		63,606		—		63,606		—
Corporate bonds	82,241		13		(419)		81,835		—		77,214		4,621
U.S government agency securities	76,683		161		(393)		76,451		—		76,451		—
Subtotal	222,548		179		(835)		221,892		—		217,271		4,621
Total	$	384,448	$	179	$	(835)	$	383,792	$	161,900	$	217,271	$	4,621


	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities (1)		Long-term Marketable Securities (2)
Level 1:
Cash and cash equivalents	$	341,246	$	—	$	—	$	341,246	$	341,246	$	—	$	—
Subtotal	341,246		—		—		341,246		341,246		—		—
Level 2:
Commercial paper	40,469		1		(4)		40,466		—		40,466		—
Corporate bonds	83,300		10		(114)		83,196		—		35,768		47,428
U.S government agency securities	37,621		—		(62)		37,559		—		20,616		16,943
Subtotal	161,390		11		(180)		161,221		—		96,850		64,371
Total	$	502,636	$	11	$	(180)	$	502,467	$	341,246	$	96,850	$	64,371

(1)The Company’s short-term marketable securities mature in one year or less.

(2)The Company’s long-term marketable securities mature between one year and two years.

See Note 2 to these consolidated financial statements for additional discussion regarding the Company’s fair value measurements.

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

Balance Sheet Components

12 Months Ended

Dec. 31, 2022

Balance Sheet Components [Abstract]

Balance Sheet Components

Property and Equipment, Net

Property and equipment, net consist of the following as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022		December 31, 2021
Construction-in-progress	$	131,331	$	104,340
Leasehold improvements	24,217		5,723
Furniture and fixtures	957		891
Computer equipment and software	100		85
Laboratory and manufacturing equipment	11,872		5,530
Total property and equipment	168,477		116,569
Accumulated depreciation and amortization	(6,793)		(4,214)
Property and equipment, net	$	161,684	$	112,355

Depreciation expense was $2.6 million, $1.8 million and $1.5 million for the years ended December 31, 2022, 2021, and 2020, respectively.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022		December 31, 2021
Accrued preclinical and clinical expenses	$	1,365	$	1,602
Accrued professional fees	3,397		2,011
Accrued payroll and benefits	6,781		2,882
Accrued construction in progress	11,452		9,606
Accrued financing fees	—		26
Accrued taxes	43		83
Other current liabilities	267		87
Total	$	23,305	$	16,297

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Significant Contracts and Agreements Agreements with Contract Manufacturing Organizations and Contract Research Organizations The Company enters into various agreements in the normal course of business with Contract Research Organizations (“CROs”), Contract Manufacturing Organizations (“CMOs”) and other third parties for preclinical research studies, clinical trials and testing and manufacturing services. The agreements with CMOs relate to the manufacturing of sterile gel that is mixed with in-house produced vectors as part of the final drug product applied in certain of our clinical trials. These agreements may also include research and development activities, storage, packaging, labeling, and/or testing of our preclinical and clinical-stage products. The Company is obligated to make milestone payments under certain of these agreements. The estimated remaining commitment as of December 31, 2022 under these agreements is approximately $2.1 million. The Company may also be responsible for the payment of a monthly service fee for project management services for the duration of any agreements. The Company has incurred research and development expenses under these agreements of $6.0 million, $5.0 million and $4.6 million for the years ended December 31, 2022, 2021, and 2020, respectively. Commercial Preparedness Activities The Company has contracted with various third parties to facilitate, coordinate and perform agreed upon commercial preparedness and market research activities relating to our lead product candidate, B-VEC. These contracts typically call for the payment of fees for services upon the achievement of certain milestones or as services are rendered. The estimated remaining commitment as of December 31, 2022 is $8.4 million. The Company has incurred expenses under these activities of $14.2 million, $6.1 million and $1.9 million for the years ended December 31, 2022, 2021, and 2020, respectively. ASTRA Contractual Obligations The Company has contracted with various third parties to complete the interior build-out of our second CGMP facility, ASTRA. Additionally, the Company has entered into various non-cancellable purchase agreements for long-lead materials to help avoid potential schedule disruptions or material shortages. These contracts typically call for the payment of fees for services or materials upon the achievement of certain milestones. The estimated remaining commitment as of December 31, 2022 is $16.3 million. The Company has included costs incurred to-date associated with ASTRA within construction-in-progress as of December 31, 2022. In June 2021, the Company entered into a Standard Form of Contract for Construction and the corresponding General Conditions of the Contract for Construction (collectively, the “Agreement”) with The Whiting-Turner Contracting Company (“Whiting-Turner”), pursuant to which Whiting-Turner is constructing and managing the construction of ASTRA. Subject to certain conditions in the Agreement, the Company will pay Whiting-Turner a contract price consisting of the cost of work plus a fee equal to 1.75% of the cost of work. Effective September 2021, the Company entered into a guaranteed maximum price amendment (the "Amendment") to the Agreement to set forth the guaranteed maximum price, as well as the date by which Whiting-Turner is to achieve Substantial Completion (as defined in the Agreement). Under the Amendment, the guaranteed maximum price to be paid by the Company, which has been amended from time to time for change orders additional work is awarded to Whiting-Turner, is currently $85.5 million. Whiting-Turner’s work under the Agreement represents a portion of the work necessary to complete construction of the ASTRA facility and, therefore the date of Substantial Completion of Whiting-Turner’s work under the Agreement may not equate to the date of completion of ASTRA. The guaranteed maximum price under the Agreement with Whiting-Turner constitutes only a portion of the total estimated cost of building and equipping ASTRA as there are various other third parties engaged in the project for which contracts are not individually material. Legal Proceedings In May 2020, a complaint was filed against the Company in the United States District Court for the Western District of Pennsylvania by PeriphaGen, Inc. (“PeriphaGen”), which also named our Chief Executive Officer and President, R&D, Krish Krishnan and Suma Krishnan, respectively. The complaint alleged breach of contract and misappropriation of trade secrets, which secrets the plaintiff asserts were used to develop our product candidates, including the vector backbones, and our STAR-D platform. We answered the complaint in June 2020 by denying the allegations and brought a counterclaim asking the court to declare that we did not misappropriate PeriphaGen’s trade secrets or confidential information, and to further declare that we are the rightful and sole owner of our product candidates and STAR-D platform. In addition, the Company filed a third-party complaint against two principals of PeriphaGen, James Wechuck and David Krisky, alleging breach of contract and seeking contribution and indemnification from them in the event PeriphaGen is awarded damages. On March 9, 2022, the court officially ordered the parties to attend mediation on March 11, 2022. During the course of the mediation process, the parties were able to exchange information, allowing the parties to value their positions. On March 12, 2022, the Company entered into a binding term sheet to settle the dispute. In April 2022, the Company entered into a final settlement agreement and paid PeriphaGen an upfront payment of $25.0 million on April 28, 2022 for: (i) the release of all claims in the trade secret litigation with PeriphaGen; (ii) the acquisition of certain PeriphaGen assets, and (iii) the grant of a license by PeriphaGen for dermatological applications. Upon approval of the Company's first product by the U.S. Food and Drug Administration, the Company will pay PeriphaGen an additional $12.5 million, followed by three additional $12.5 million contingent milestone payments upon reaching $100.0 million in total cumulative sales, $200.0 million in total cumulative sales and $300.0 million in total cumulative sales. As defined in the settlement agreement, cumulative sales shall include all revenue from sales of the Company products by the Company and its affiliates and licensees, as reported by the Company in its annual Form 10-K filings. If all milestones are achieved, the total consideration for settling the dispute, acquiring certain assets, and granting of a license from PeriphaGen will be $75.0 million. The Company recorded the $25.0 million within litigation settlement expense on the consolidated statements of operations for the year ended December 31, 2022. The additional contingent milestone payments were not deemed probable due to uncertainty in the achievement of these milestones as of December 31, 2022, and therefore no additional accrual has been recorded. The Company has received $1.1 million and $1.6 million of insurance proceeds during fiscal years ending December 31, 2022 and 2021, respectively. Additionally, the Company had outstanding receivables of zero and $560 thousand as of December 31, 2022 and 2021, respectively, recorded within prepaid expenses and other current assets on the consolidated balance sheets, as management determined that the amounts were probable of collection. The reimbursements have been recorded as an offset to our legal fees included in general and administrative expenses on the consolidated statements of operations and within operating activities on the consolidated statements of cash flows.

Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Lessee, Operating Leases

Leases

Lease Agreements

In May 2016, the Company signed an operating lease for laboratory and office space in Pittsburgh, Pennsylvania that commenced in June 2016 and was scheduled to expire in October 2017 (the “2016 Lease”). The 2016 Lease has been amended several times to increase the area leased, which currently consists of approximately 54,000 square feet and includes the commercial scale CGMP-compliant manufacturing facility, (“ANCORIS”). As a result of the lease amendments, the 2016 Lease expiration date was extended to October 2031. In September 2022, the Company amended the 2016 Lease (“Short-Term Amendment”) to add a short-term lease for additional office space that commenced in October 2022 and expires on September 2023. The Short-Term Amendment increased the area leased by approximately 7,000 square feet through September 2023. Due to the short-term nature of this amendment and the Company's lease accounting policy, the Company did not record a right-of-use asset or corresponding lease liability.

In December 2019, the Company entered into a lease agreement for a second commercial gene therapy facility, (“ASTRA”), in the Pittsburgh, Pennsylvania area (“ASTRA lease”) with Northfield I, LLC (the “Landlord”, “Northfield”, or “Lessor”) with an initial lease term that expired on October 2035. The ASTRA lease contained an option (“Purchase Option”) to purchase the building, related improvements and take corresponding assignment of the Landlord's rights under its existing Ground Lease (the “Ground Lease”).

In October 2020, the Company was provided with notice that the initial delivery conditions of the building had been met, including completion of the building shell, interior slab, and exterior doors, and the Company gave the Landlord notice of its intent to purchase ASTRA for approximately $9.4 million, subject to the parties entering into a commercially reasonable purchase and sale agreement. As a result of the Company's ability to exercise its option to purchase ASTRA, the Company obtained control over the construction in progress of ASTRA. The Company recorded a $10 million CIP asset and a corresponding build-to-suit lease liability related to the costs incurred by the Landlord, offset by the previous cash contributions of $2.4 million.

In January 2021, the Company entered into a Purchase and Sale Agreement (“PSA”) for ASTRA with Northfield related to the purchase option exercised by the Company in October 2020, for a purchase price of $9.4 million. The Company held approximately $1.5 million on deposit with Northfield under the existing lease agreement and applied this deposit as a credit against the purchase price at closing. In February 2021, Northfield delivered the space as substantially complete and made the space available for access by the Company, thus triggering lease commencement. As a result, the Company concluded that this transaction did not qualify for sale-leaseback accounting because it did not meet the definition of a sale. As control did not transfer to the Lessor at lease commencement, the transaction continued to be accounted for as construction in progress and a financing obligation. In March 2021, the purchase closed and the Company determined that reclassification of the construction in progress to buildings and leasehold improvements was not appropriate as the interior of the building was not yet ready for its intended use. From construction completion to the closing of the purchase, the Company recognized interest expense to accrete the financial obligation to a balance that equaled the cash consideration that was paid upon the close of purchase. The building continues to be held under construction-in-progress as of December 31, 2022. The interior of the building is currently under construction and is expected to be completed and validated in 2023. For more information about the expected construction costs associated with ASTRA, see “ASTRA Contractual Obligations” below.

As part of the transaction, the Company also became the accounting owner of the Ground Lease, due to obtaining control over ASTRA, and recorded the applicable operating right-of-use asset and corresponding lease liability in October 2020. When the PSA was finalized, the Company took assignment of the Lessor's Ground Lease, in accordance with the Purchase Option, of which lease payments are based on annual payments of $82 thousand, and are subject to a cumulative 10% escalation clause every 5 years through 2071.

In December 2021, the Company entered into a 3 year lease agreement for the Boston, Massachusetts office that commenced in January 2022 and expires in January 2025.

In May 2022, the Company entered into a 16 month lease agreement for the Zug, Switzerland office that commenced in September 2022 and expires December 2023.

As of December 31, 2022, future minimum commitments under the Company’s operating leases were as follows (in thousands):


	Operating Leases
2023	$	1,648
2024	1,539
2025	1,277
2026	1,277
2027	1,300
Thereafter	10,762
Future minimum operating lease payments	$	17,803
Less: Interest	8,870
Present value of lease liability	$	8,933

Supplemental balance sheet information related to leases is as follows:


	December 31, 2022			December 31, 2021
Operating leases:
Right-of-use assets	$	8,042		$	7,228
Current portion of lease liability	1,561			1,041
Lease liability	7,372			6,983
Total lease liability	$	8,933		$	8,024
Weighted average remaining lease term, in years	12.5			14.4
Weighted average discount rate	9.4		%	9.5		%

The components of the Company's lease expense are as follows:



	Years Ended December 31,
	2022		2021		2020
Lease cost:
Operating lease expense	$	1,532	$	1,275	$	767
Variable lease expense	226		160		57
Total lease expense	$	1,758	$	1,435	$	824

Capitalization	12 Months Ended
Capitalization	Dec. 31, 2022
Equity [Abstract]
Capitalization	Capitalization Sale of Common Stock In December 2021, the Company completed an underwritten public offering of 2,866,667 shares of its common stock, including 200,000 shares purchased by the underwriters pursuant to their option to purchase additional shares, at $75.00 per share. Net proceeds to the Company from the offering were $201.9 million after deducting underwriting discounts and commissions of approximately $12.9 million, and other offering expenses payable by the Company of $227 thousand. In February 2021, the Company completed an underwritten public offering of 2,211,538 shares of its common stock, including 288,461 shares purchased by the underwriters pursuant to their option to purchase additional shares, at $65.00 per share. Net proceeds to the Company from the offering were $134.9 million after deducting underwriting discounts and commissions of approximately $8.6 million, and other offering expenses payable by the Company of $198 thousand. In May 2020, the Company completed a public offering of 2,275,000 shares of its common stock to the public at $55.00 per share. Net proceeds to the Company from the offering were $117.2 million after deducting underwriting discounts and commissions of approximately $7.5 million, and other offering expenses payable by the Company of approximately $463 thousand. ATM Program The Company sells shares of common stock from time to time pursuant to its previously executed sales agreement (the "Sales Agreement") with Cowen and Company, LLC (“Cowen”) with respect to an at-the-market equity offering program (“ATM”) finalized on December 31, 2020, under which Cowen acts as the Company's agent and/or principal and may issue and sell from time to time, during the term of the Sales Agreement, shares of common stock having an aggregate offering price up to $150.0 million (“Placement Shares”). The issuance and sale of the Placement Shares by the Company under the Sales Agreement are made pursuant to the Company's effective “shelf” registration statement on Form S-3. During 2021, the Company issued and sold 262,500 shares of common stock at a weighted average price of $66.50 per share for net proceeds of $16.9 million after deducting selling commissions of approximately $524 thousand. During the year ended December 31, 2022, the Company issued and sold 434,782 shares of common stock at a weighted average price of $69.00 per share for net proceeds of $29.1 million after deducting selling commissions of approximately $900 thousand, resulting in a remaining $102.5 million available for issuance under the ATM Program.

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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Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Stock-Based Compensation

Stock Options

In 2017, the Company adopted the 2017 IPO Stock Plan (the “Plan”), which governs the issuance of stock options to employees, certain non-employee consultants, and directors. Initially, the Company reserved 900 thousand shares for issuance under the Plan with an initial sublimit for incentive stock options of 900 thousand shares. On an annual basis, the amount of shares available for issuance under the Plan increases by an amount equal to four percent of the total outstanding shares as of the last day of the preceding calendar year. The sublimit of incentive stock options is not subject to the increase.

Options granted to employees and non-employees vest ratably over a four-year period and stock options granted to directors of the company vest ratably over one-year to three-year periods. Stock options have a life of ten years.

The Company granted 2,130,500 and 1,422,450 stock options to employees, non-employees, and directors during the years ended December 31, 2022 and 2021, respectively.

The following table summarizes the Company’s stock option activity:


	Stock Options Outstanding	Weighted- average Exercise Price		Weighted- average Remaining Contractual Life (Years)	Aggregate Intrinsic Value (In thousands) (1)
Balance at January 1, 2021	853,614	$	40.31	9.0	$	16,804
Granted	1,422,450	66.88
Exercised	(54,260)	38.12
Cancelled or forfeited	(175,750)	61.35
Expired	(2,875)	75.82
Balance at December 31, 2021	2,043,179	$	57.00	9.0	$	31,331
Granted	2,130,500	64.14
Exercised	(138,855)	50.47
Cancelled or forfeited	(438,892)	59.22
Expired	(13,751)	78.80
Balance at December 31, 2022	3,582,181	$	61.50	8.7	$	64,880
Exercisable at December 31, 2022	666,886	$	49.20	7.5	$	20,055

(1)Aggregate intrinsic value represents the difference between the closing stock price of our common stock on December 31, 2022 and the exercise price of outstanding in-the-money options.

The total intrinsic value (the amount by which the fair market value exceeded the exercise price) of stock options exercised during the years ended December 31, 2022 and 2021 was $2.9 million and $1.3 million, respectively.

The weighted-average grant-date fair value per share of options granted to employees, non-employees, and directors during the years ended December 31, 2022 and 2021 was $44.50 and $43.05, respectively.

There was $104.4 million of unrecognized stock-based compensation expense related to employees’, non-employees’, and directors’ awards that is expected to be recognized over a weighted-average period of 2.9 years as of December 31, 2022.

The Company has recorded aggregate stock-based compensation expense related to the issuance of stock option awards in the consolidated statements of operations for the years ended December 31, 2022, 2021, and 2020 as follows (in thousands):


	Years Ended December 31,
	2022		2021		2020
Research and development	$	7,897	$	3,434	$	994
General and administrative	23,551		10,235		2,278
Total stock-based compensation	$	31,448	$	13,669	$	3,272

We capitalize the portion of stock-based compensation that relates to work performed on the construction of manufacturing facilities. There was $551 thousand, $284 thousand, and $34 thousand of stock-based compensation that was capitalized in the years ended December 31, 2022, 2021, 2020, respectively.

The fair value of options granted was estimated at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions for the years ended December 31, 2022, 2021, and 2020:


	Years Ended December 31,
	2022			2021			2020
Expected stock price volatility	78		%	72		%	75		%
Expected term of the award (years)	6.2			6.2			6.2
Risk-free interest rate	2.42		%	1.10		%	0.64		%
Weighted average exercise price	$	64.14		$	66.88		$	47.29
Forfeiture Rate	—		%	—		%	14.74		%
Dividend Yield	—		%	—		%	—		%

Restricted Stock Awards

Restricted stock awards (“RSAs”) granted to employees vest ratably over a four-year period. The Company granted zero and 98,800 RSAs to employees of the Company during the year ended December 31, 2022 and 2021 respectively.

The following table summarizes the Company’s RSA activity:


	Number of Shares	Weighted Average Grant Date Fair Value
Non-vested RSAs as of December 31, 2021	98,800	$	78.89
Granted	—	—
Vested	(14,321)	78.89
Surrendered or forfeited	(17,879)	78.89
Non-vested RSAs as of December 31, 2022	66,600	$	78.89

There was $3.8 million of unrecognized stock-based compensation expense related to employees’ awards that is expected to be recognized over a weighted-average period of 2.2 years as of December 31, 2022.

The Company recorded the following stock-based compensation expense related to RSAs within general and administrative expenses in the accompanying consolidated statements of operations (in thousands):


	Years Ended December 31,
	2022		2021		2020
General and administrative	$	1,782	$	1,650	$	—
Total stock-based compensation	$	1,782	$	1,650	$	—

Shares remaining available for grant under the Company's stock incentive plan were 469,616, with a remaining sublimit for incentive stock options of 5,581, at December 31, 2022.

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

The Company did not record a current or deferred income tax expense or benefit for the years ended December 31, 2022 and 2021 due to the valuation allowance position. A reconciliation of income tax (benefit) expense computed at the statutory federal and state income tax rate for the year to income tax (benefit) expense as reflected in our financial statements for years ended December 31, 2022, 2021 and 2020 are as follows (in thousands):



	Years Ended December 31,
	2022		2021		2020
Federal income tax (benefit) at statutory rate	$	(29,395)	$	(14,578)	$	(6,752)
Change in valuation allowance	39,781		20,689		11,112
State income tax expense net of federal benefit	(10,438)		(5,436)		(2,632)
Credits	(1,736)		(1,295)		(887)
Other non-deductible expenses	2,182		675		(216)
Other	(394)		(55)		(625)
Total tax expense (benefit)	$	—	$	—	$	—

The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2022 and 2021 are as follows (in thousands):


	December 31,		December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	52,569	$	33,170
Stock compensation	7,445		3,906

Lease liability	2,572		2,344
Depreciation	—		679
Accrued expenses	2,206		817
Capitalized costs	14,124		884
Credits	6,708		3,607
Unrealized loss on marketable securities	192		49
Total deferred tax assets	85,816		45,456
Valuation allowance	(82,513)		(42,732)
Deferred tax assets	$	3,303	$	2,724
Deferred tax liabilities:
Depreciation	(137)		—
Right-of-use assets	(2,312)		(2,111)
Prepaid expenses	(854)		(613)

Total deferred tax liabilities	$	(3,303)	$	(2,724)
Net deferred tax assets	$	—	$	—

The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based on the Company’s history of operating losses, the Company has concluded that it is not more likely than not that the benefit of its deferred tax assets will be realized. Accordingly, the Company has provided a full valuation allowance for deferred tax assets as of December 31, 2022 and 2021.

As of December 31, 2022 and 2021, the Company had federal research and development credit carryforwards of approximately $2.0 million and $2.4 million, respectively. The federal tax credit carryforwards will begin to expire in 2039 if not utilized. As of December 31, 2022 and 2021, the Company also had orphan drug tax credit carryforwards of approximately $4.4 million and $910 thousand, respectively. The orphan drug tax credit carryforwards will begin to expire in 2038 if not utilized.

As of December 31, 2022 and 2021, the Company had state research and development credit carryforwards of approximately $457 thousand and $321 thousand, respectively. The state tax credit carryforwards will begin to expire in 2032 if not utilized.

As of December 31, 2022, the Company had cumulative U.S. federal NOL carryforwards of approximately $177.7 million. Of this amount, $5.0 million is available to offset future income tax liabilities and will expire in 2037, the remaining $172.7 million is available indefinitely to offset future income tax liabilities with no expiration period.

As of December 31, 2022, the Company had cumulative U.S. state NOL carryforwards of approximately $186.0 million. The state NOLs are available to offset future state income tax liabilities and will begin to expire in 2037.

Under the provisions of the Internal Revenue Code, the NOL carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Internal Revenue Code Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities.

No deferred tax assets have been recognized on our consolidated balance sheets related to these NOLs, as they are fully offset by a valuation allowance. If we have previously had, or have in the future, one or more Section 382 “ownership changes,” including in connection with our initial public offering or another offering, or if we do not generate sufficient taxable income, we may not be able to utilize a material portion of our NOLs, even if we achieve profitability.

The Company files income tax returns in the United States at the federal and state level and in foreign jurisdictions in which the Company conducts business activities. The federal and state income tax returns are subject to tax examinations for the tax year ended December 31, 2019, 2020 and 2021. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period. Additionally, the Company is subject to tax examinations by taxing authorities in foreign jurisdictions where it has business operations. At this time, the Company is not undergoing examination by the Internal Revenue Service or any foreign taxing authorities.

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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Segment and Geographical Information

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company evaluates events or transactions that occur after the balance sheet date, but prior to the issuance of the financial statements, to identify matters that require disclosure. The Company concluded that no subsequent events have occurred that would require recognition or disclosure in the consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Concentrations of Credit Risk and Off-Balance Sheet Risk

Cash, Cash Equivalents and Investments

Fair Value of Financial Instruments

•Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities.

•Level 3—Valuations based on inputs that are both significant to the fair value measurement and unobservable.

Property and Equipment, net


Computer equipment and software			3 - 7 years
Laboratory and manufacturing equipment			3 - 20 years
Furniture and fixtures			3 - 7 years
Leasehold improvements			lesser of remaining useful life or remaining life of lease

Construction-in-progress (“CIP”) is not depreciated until the asset is placed in service.

Impairment of Long-Lived Assets

Leases

Research and Development Expenses

Stock-Based Compensation Expense

Income Taxes

Comprehensive Loss

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Estimated Useful Lives of Assets

Depreciation is recorded using the straight-line method over the estimated useful lives of the respective assets, which are as follows:


Computer equipment and software			3 - 7 years
Laboratory and manufacturing equipment			3 - 20 years
Furniture and fixtures			3 - 7 years
Leasehold improvements			lesser of remaining useful life or remaining life of lease

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Net Loss Per Share Attributable to Common Stockholders


(In thousands, except share and per share data)	Years Ended December 31,
	2022		2021		2020
Net loss per common share	$	(139,975)	$	(69,570)	$	(32,167)
Weighted-average basic and diluted common shares	25,491,721		22,196,846		18,787,161
Basic and diluted net loss per common share	$	(5.49)	$	(3.13)	$	(1.71)

Fair Value Instruments (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Summary of Cash, Cash Equivalents and Available-for-Sale Securities

The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities (1)		Long-term Marketable Securities (2)
Level 1:
Cash and cash equivalents	$	161,900	$	—	$	—	$	161,900	$	161,900	$	—	$	—
Subtotal	161,900		—		—		161,900		161,900		—		—
Level 2:
Commercial paper	63,624		5		(23)		63,606		—		63,606		—
Corporate bonds	82,241		13		(419)		81,835		—		77,214		4,621
U.S government agency securities	76,683		161		(393)		76,451		—		76,451		—
Subtotal	222,548		179		(835)		221,892		—		217,271		4,621
Total	$	384,448	$	179	$	(835)	$	383,792	$	161,900	$	217,271	$	4,621


	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities (1)		Long-term Marketable Securities (2)
Level 1:
Cash and cash equivalents	$	341,246	$	—	$	—	$	341,246	$	341,246	$	—	$	—
Subtotal	341,246		—		—		341,246		341,246		—		—
Level 2:
Commercial paper	40,469		1		(4)		40,466		—		40,466		—
Corporate bonds	83,300		10		(114)		83,196		—		35,768		47,428
U.S government agency securities	37,621		—		(62)		37,559		—		20,616		16,943
Subtotal	161,390		11		(180)		161,221		—		96,850		64,371
Total	$	502,636	$	11	$	(180)	$	502,467	$	341,246	$	96,850	$	64,371

(1)The Company’s short-term marketable securities mature in one year or less.

(2)The Company’s long-term marketable securities mature between one year and two years.

Schedule of Property and Equipment, Net

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2022

Balance Sheet Components [Abstract]

Property and equipment, net consist of the following as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022		December 31, 2021
Construction-in-progress	$	131,331	$	104,340
Leasehold improvements	24,217		5,723
Furniture and fixtures	957		891
Computer equipment and software	100		85
Laboratory and manufacturing equipment	11,872		5,530
Total property and equipment	168,477		116,569
Accumulated depreciation and amortization	(6,793)		(4,214)
Property and equipment, net	$	161,684	$	112,355

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of December 31, 2022 and 2021, respectively (in thousands):


	December 31, 2022		December 31, 2021
Accrued preclinical and clinical expenses	$	1,365	$	1,602
Accrued professional fees	3,397		2,011
Accrued payroll and benefits	6,781		2,882
Accrued construction in progress	11,452		9,606
Accrued financing fees	—		26
Accrued taxes	43		83
Other current liabilities	267		87
Total	$	23,305	$	16,297

Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Schedule of Future Minimum Operating Lease Payments

As of December 31, 2022, future minimum commitments under the Company’s operating leases were as follows (in thousands):


	Operating Leases
2023	$	1,648
2024	1,539
2025	1,277
2026	1,277
2027	1,300
Thereafter	10,762
Future minimum operating lease payments	$	17,803
Less: Interest	8,870
Present value of lease liability	$	8,933

Schedule of Supplemental Condensed Consolidated Balance Sheet Information Related to Leases

Supplemental balance sheet information related to leases is as follows:


	December 31, 2022			December 31, 2021
Operating leases:
Right-of-use assets	$	8,042		$	7,228
Current portion of lease liability	1,561			1,041
Lease liability	7,372			6,983
Total lease liability	$	8,933		$	8,024
Weighted average remaining lease term, in years	12.5			14.4
Weighted average discount rate	9.4		%	9.5		%

Lease Expense

The components of the Company's lease expense are as follows:



	Years Ended December 31,
	2022		2021		2020
Lease cost:
Operating lease expense	$	1,532	$	1,275	$	767
Variable lease expense	226		160		57
Total lease expense	$	1,758	$	1,435	$	824

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Company's Stock Option Activity

The following table summarizes the Company’s stock option activity:


	Stock Options Outstanding	Weighted- average Exercise Price		Weighted- average Remaining Contractual Life (Years)	Aggregate Intrinsic Value (In thousands) (1)
Balance at January 1, 2021	853,614	$	40.31	9.0	$	16,804
Granted	1,422,450	66.88
Exercised	(54,260)	38.12
Cancelled or forfeited	(175,750)	61.35
Expired	(2,875)	75.82
Balance at December 31, 2021	2,043,179	$	57.00	9.0	$	31,331
Granted	2,130,500	64.14
Exercised	(138,855)	50.47
Cancelled or forfeited	(438,892)	59.22
Expired	(13,751)	78.80
Balance at December 31, 2022	3,582,181	$	61.50	8.7	$	64,880
Exercisable at December 31, 2022	666,886	$	49.20	7.5	$	20,055

(1)Aggregate intrinsic value represents the difference between the closing stock price of our common stock on December 31, 2022 and the exercise price of outstanding in-the-money options.

Summary of Stock Based Compensation Expense Related to Issuance of Stock Option Awards


	Years Ended December 31,
	2022		2021		2020
Research and development	$	7,897	$	3,434	$	994
General and administrative	23,551		10,235		2,278
Total stock-based compensation	$	31,448	$	13,669	$	3,272


	Years Ended December 31,
	2022		2021		2020
General and administrative	$	1,782	$	1,650	$	—
Total stock-based compensation	$	1,782	$	1,650	$	—

Fair Value of Stock Options, Valuation Assumptions


	Years Ended December 31,
	2022			2021			2020
Expected stock price volatility	78		%	72		%	75		%
Expected term of the award (years)	6.2			6.2			6.2
Risk-free interest rate	2.42		%	1.10		%	0.64		%
Weighted average exercise price	$	64.14		$	66.88		$	47.29
Forfeiture Rate	—		%	—		%	14.74		%
Dividend Yield	—		%	—		%	—		%

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity

The following table summarizes the Company’s RSA activity:


	Number of Shares	Weighted Average Grant Date Fair Value
Non-vested RSAs as of December 31, 2021	98,800	$	78.89
Granted	—	—
Vested	(14,321)	78.89
Surrendered or forfeited	(17,879)	78.89
Non-vested RSAs as of December 31, 2022	66,600	$	78.89

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Summary of Reconciliation of Income Tax Expense (Benefit) Computed at Statutory Federal and State Income Tax Rate

A reconciliation of income tax (benefit) expense computed at the statutory federal and state income tax rate for the year to income tax (benefit) expense as reflected in our financial statements for years ended December 31, 2022, 2021 and 2020 are as follows (in thousands):



	Years Ended December 31,
	2022		2021		2020
Federal income tax (benefit) at statutory rate	$	(29,395)	$	(14,578)	$	(6,752)
Change in valuation allowance	39,781		20,689		11,112
State income tax expense net of federal benefit	(10,438)		(5,436)		(2,632)
Credits	(1,736)		(1,295)		(887)
Other non-deductible expenses	2,182		675		(216)
Other	(394)		(55)		(625)
Total tax expense (benefit)	$	—	$	—	$	—

Significant Components of Deferred Tax Assets

The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2022 and 2021 are as follows (in thousands):


	December 31,		December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	52,569	$	33,170
Stock compensation	7,445		3,906

Lease liability	2,572		2,344
Depreciation	—		679
Accrued expenses	2,206		817
Capitalized costs	14,124		884
Credits	6,708		3,607
Unrealized loss on marketable securities	192		49
Total deferred tax assets	85,816		45,456
Valuation allowance	(82,513)		(42,732)
Deferred tax assets	$	3,303	$	2,724
Deferred tax liabilities:
Depreciation	(137)		—
Right-of-use assets	(2,312)		(2,111)
Prepaid expenses	(854)		(613)

Total deferred tax liabilities	$	(3,303)	$	(2,724)
Net deferred tax assets	$	—	$	—

Organization - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Accumulated deficit	$ (280,759)	$ (140,784)
Cash, cash equivalents and short-term investments	$ 379,200

Summary of Significant Accounting Policies - Additional Information (Detail)	6 Months Ended		12 Months Ended
	Dec. 31, 2022 USD ($)	Jun. 30, 2022	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounting Policies [Abstract]
Number of operating segment \| segment			1
Property, Plant and Equipment [Line Items]
Recognized impairment losses for long lived assets			$ 0	$ 0	$ 0
Accrued interest or penalties related to uncertain tax positions	$ 0		0	0
Interest and penalties amounts recognized			$ 0	$ 0
Equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	15 years	7 years

Summary of Significant Accounting Policies - Summary of Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2022
Computer equipment and software \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Computer equipment and software \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	7 years
Laboratory and manufacturing equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Laboratory and manufacturing equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	20 years
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	7 years

Net Loss Per Share Attributable to Common Stockholders - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common share equivalents outstanding, excluded from the calculation of diluted net loss per common stockholders	3,582,181	2,043,179	853,614
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common share equivalents outstanding, excluded from the calculation of diluted net loss per common stockholders	66,600	98,800	0

Net Loss Per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Share and Per Unit (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Net loss per common share	$ (139,975)	$ (69,570)	$ (32,167)
Weighted-average common shares outstanding: basic	25,491,721	22,196,846	18,787,161
Weighted-average common shares outstanding: diluted	25,491,721	22,196,846	18,787,161
Diluted net loss per common share (in usd per share)	$ (5.49)	$ (3.13)	$ (1.71)
Basic net loss per common share (in usd per share)	$ (5.49)	$ (3.13)	$ (1.71)

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

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

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Fair Value Instruments - Summary of Cash, Cash Equivalents and Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 161,900	$ 341,246
Gross Unrealized Gains	179	11
Gross Unrealized Losses	(835)	(180)
Amortized cost, total	384,448	502,636
Aggregate fair value, total	383,792	502,467
Level 1:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	161,900	341,246
Level 2:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	222,548	161,390
Gross Unrealized Gains	179	11
Gross Unrealized Losses	(835)	(180)
Aggregate Fair Value	221,892	161,221
Cash and cash equivalents \| Level 1:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	161,900	341,246
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	63,624	40,469
Gross Unrealized Gains	5	1
Gross Unrealized Losses	(23)	(4)
Aggregate Fair Value	63,606	40,466
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	82,241	83,300
Gross Unrealized Gains	13	10
Gross Unrealized Losses	(419)	(114)
Aggregate Fair Value	81,835	83,196
US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	76,683	37,621
Gross Unrealized Gains	161	0
Gross Unrealized Losses	(393)	(62)
Aggregate Fair Value	76,451	37,559
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate fair value, total	161,900	341,246
Cash and Cash Equivalents \| Level 1:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, aggregate fair value	161,900	341,246
Cash and Cash Equivalents \| Cash and cash equivalents \| Level 1:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, aggregate fair value	161,900	341,246
Short-term Marketable Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate fair value, total	217,271	96,850
Short-term Marketable Securities \| Level 2:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 217,271	96,850
Debt securities, available-for-sale, term	1 year
Short-term Marketable Securities \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 63,606	40,466
Short-term Marketable Securities \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	77,214	35,768
Short-term Marketable Securities \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	76,451	20,616
Long-term Marketable Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate fair value, total	4,621	64,371
Long-term Marketable Securities \| Level 2:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 4,621	64,371
Long-term Marketable Securities \| Level 2: \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, term	1 year
Long-term Marketable Securities \| Level 2: \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, term	2 years
Long-term Marketable Securities \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 0	0
Long-term Marketable Securities \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	4,621	47,428
Long-term Marketable Securities \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate Fair Value	$ 0	$ 16,943

Balance Sheet Components - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 168,477	$ 116,569
Accumulated depreciation and amortization	(6,793)	(4,214)
Property and equipment, net	161,684	112,355
Construction-in-progress
Property, Plant and Equipment [Line Items]
Total property and equipment	131,331	104,340
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	24,217	5,723
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	957	891
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	100	85
Laboratory and manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 11,872	$ 5,530

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
Depreciation expense	$ 2.6	$ 1.8	$ 1.5

Balance Sheet Components - Schedule of Accrued Expenses And Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Components [Abstract]
Accrued preclinical and clinical expenses	$ 1,365	$ 1,602
Accrued professional fees	3,397	2,011
Accrued payroll and benefits	6,781	2,882
Accrued construction in progress	11,452	9,606
Accrued financing fees	0	26
Accrued taxes	43	83
Other current liabilities	267	87
Total	$ 23,305	$ 16,297

Commitments and Contingencies - Additional Information (Detail)				12 Months Ended
	Apr. 28, 2022 USD ($)	Mar. 12, 2022 USD ($)	Oct. 31, 2020 USD ($)	Dec. 31, 2022 USD ($) milestone	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 13, 2021 USD ($)
Operating Leased Assets [Line Items]
Research and development				$ 42,461,000	$ 27,884,000	$ 17,936,000
Purchase price of potential building purchase			$ 9,400,000	16,300,000
Loss contingency, guaranteed maximum price to be paid							$ 85,500,000
Litigation settlement				25,000,000	0	0
Proceeds from insurance settlement, operating activities				1,100,000	1,600,000
Gain related to litigation settlement				0	560,000
PeriphaGen
Operating Leased Assets [Line Items]
Litigation settlement	$ 25,000,000			25,000,000
Litigation settlement, amount awarded to other party				$ 12,500,000
Number of milestones \| milestone				3
Litigation settlement, total consideration		$ 75,000,000
PeriphaGen \| Milestone Three
Operating Leased Assets [Line Items]
Litigation settlement, amount awarded to other party				$ 12,500,000
Litigation settlement, milestone payments, sales threshold		300,000,000
PeriphaGen \| Milestone Two
Operating Leased Assets [Line Items]
Litigation settlement, amount awarded to other party				12,500,000
Litigation settlement, milestone payments, sales threshold		200,000,000
PeriphaGen \| Milestone One
Operating Leased Assets [Line Items]
Litigation settlement, amount awarded to other party				12,500,000
Litigation settlement, milestone payments, sales threshold		$ 100,000,000
Clinical Supply Agreements
Operating Leased Assets [Line Items]
Estimated remaining commitment				2,100,000
Research and development				6,000,000	5,000,000	4,600,000
Other Contractual Obligations
Operating Leased Assets [Line Items]
Estimated remaining commitment				8,400,000
Project management service fee				$ 14,200,000	$ 6,100,000	$ 1,900,000
A S T R A Facility
Operating Leased Assets [Line Items]
Cost of work, percentage				0.0175

Leases - Additional information (Details) ft² in Thousands, $ in Thousands		12 Months Ended
	Oct. 31, 2020 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 ft²	Mar. 16, 2022	Dec. 15, 2021
Lessee, Lease, Description [Line Items]
Purchase price of potential building purchase	$ 9,400	$ 16,300
Construction in progress, gross	10,000
Cash contribution	2,400
Escrow deposit	$ 1,500
Annual lease payments		$ 82
Cumulative escalation clause, percent		0.10
Cumulative escalation clause, term		5 years
2016 Lease Agreement
Lessee, Lease, Description [Line Items]
Additional area of real estate property leased \| ft²			54
Short-Term Amendment
Lessee, Lease, Description [Line Items]
Additional area of real estate property leased \| ft²			7
Boston, Massachusetts Lease
Lessee, Lease, Description [Line Items]
Lease term					3 years
Switzerland Lease
Lessee, Lease, Description [Line Items]
Lease term				16 months

Leases - Minimum commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2023	$ 1,648
2024	1,539
2025	1,277
2026	1,277
2027	1,300
Thereafter	10,762
Future minimum operating lease payments	17,803
Less: Interest	8,870
Present value of lease liability	$ 8,933	$ 8,024

Leases - Schedule of Supplemental Condensed Consolidated Balance Sheet Information Related to Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Right-of-use assets	$ 8,042	$ 7,228
Current portion of lease liability	1,561	1,041
Lease liability	7,372	6,983
Present value of lease liability	$ 8,933	$ 8,024
Weighted average remaining lease term, in years	12 years 6 months	14 years 4 months 24 days
Weighted average discount rate	9.40%	9.50%

Leases - Lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease expense (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease expense	$ 1,532	$ 1,275	$ 767
Variable lease expense	226	160	57
Total lease expense	$ 1,758	$ 1,435	$ 824

Capitalization - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Dec. 03, 2021	Feb. 01, 2021	May 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Capitalization, Equity [Line Items]
Adjustments to additional paid in capital, stock issued, issuance costs	$ 227	$ 198
Public Offering
Schedule of Capitalization, Equity [Line Items]
Issuance of common stock (in shares)	2,866,667	2,211,538	2,275,000
Shares issued, price per share (in usd per share)	$ 75.00	$ 65.00	$ 55.00
Proceeds from initial offering of shares	$ 201,900	$ 134,900	$ 117,200	$ 29,100
Underwriting discounts and commissions	$ 12,900	$ 8,600	7,500
Adjustments to additional paid in capital, stock issued, issuance costs			$ 463
Number of shares issued in transaction				434,782	262,500
Sale of stock, price per share (in usd per share)				$ 69.00	$ 66.50
Over-Allotment Option
Schedule of Capitalization, Equity [Line Items]
Issuance of common stock (in shares)	200,000	288,461
Placement Shares
Schedule of Capitalization, Equity [Line Items]
Aggregate offering price						$ 150,000
ATM Program
Schedule of Capitalization, Equity [Line Items]
Proceeds from initial offering of shares					$ 16,900
Underwriting discounts and commissions				$ 900	$ 524
Remaining available issuance amount				$ 102,500

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expiration period	10 years
Granted (in shares)	2,130,500	1,422,450
Share-based payment arrangement, amount capitalized \| $	$ 551	$ 284	$ 34
Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options available for grant (in shares)	469,616
2017 IPO Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance				900,000
Annual increase in number of shares authorized				0.04
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	2,130,500	1,422,450
Intrinsic value of options exercised \| $	$ 2,900	$ 1,300
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	4 years
Weighted-average grant-date fair value per share of options granted (in usd per share) \| $ / shares	$ 44.50	$ 43.05
Employee Stock Option \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense \| $	$ 104,400
Estimated weighted average period	2 years 10 months 24 days
Non-Employee Stock Option \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	1 year
Non-Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting period	4 years
Unrecognized stock-based compensation expense \| $	$ 3,800
Estimated weighted average period	2 years 2 months 12 days
Restricted stock award granted (in shares)	0	98,800
Incentive Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options available for grant (in shares)	5,581

Stock-Based Compensation - Schedule of Company's Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock Options Outstanding
Beginning balance (in shares)	2,043,179	853,614
Granted (in shares)	2,130,500	1,422,450
Exercised (in shares)	(138,855)	(54,260)
Cancelled or forfeited (in shares)	(438,892)	(175,750)
Expired (in shares)	(13,751)	(2,875)
Ending balance (in shares)	3,582,181	2,043,179	853,614
Exercisable at end of period (in shares)	666,886
Weighted- average Exercise Price
Beginning balance (in usd per share)	$ 57.00	$ 40.31
Granted (in usd per share)	64.14	66.88
Exercised (in usd per share)	50.47	38.12
Cancelled or forfeited (in usd per share)	59.22	61.35
Expired (in usd per share)	78.80	75.82
Ending balance (in usd per share)	61.50	$ 57.00	$ 40.31
Exercisable at end of period (in usd per share)	$ 49.20
Weighted- average Remaining Contractual Life (Years)
Weighted-average remaining contractual life (years)	8 years 8 months 12 days	9 years	9 years
Weighted-average remaining contractual Life (years), exercisable	7 years 6 months
Aggregate Intrinsic Value
Aggregate intrinsic value, outstanding	$ 64,880	$ 31,331	$ 16,804
Aggregate intrinsic value, exercisable	$ 20,055

Stock-Based Compensation - Summary of Stock Based Compensation Expense Related to Issuance of Stock Option Awards (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 31,448	$ 13,669	$ 3,272
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	1,782	1,650	0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	7,897	3,434	994
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	23,551	10,235	2,278
General and administrative \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 1,782	$ 1,650	$ 0

Stock-Based Compensation - Fair Value of Stock Options, Valuation Assumptions (Detail) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected stock price volatility	78.00%	72.00%	75.00%
Expected term of the award (years)	6 years 2 months 12 days	6 years 2 months 12 days	6 years 2 months 12 days
Risk-free interest rate	2.42%	1.10%	0.64%
Weighted average exercise price (in usd per share)	$ 64.14	$ 66.88	$ 47.29
Forfeiture Rate	0.00%	0.00%	14.74%
Dividend Yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Schedule of Company's Restricted Stock Activity (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Number of Shares
Beginning balance (in shares)	98,800
Granted (in shares)	0	98,800
Vested (in shares)	(14,321)
Surrendered or forfeited (in shares)	(17,879)
Ending balance (in shares)	66,600	98,800
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share)	$ 78.89
Granted (in dollars per share)	0
Vested (in dollars per share)	78.89
Surrendered or forfeited (in dollars per share)	78.89
Ending balance (in dollars per share)	$ 78.89	$ 78.89

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Current income tax expense (benefit)	$ 0	$ 0
Deferred income tax expense (benefit)	0	0
Cumulative NOL carry forwards	$ 52,569,000	33,170,000
Cumulative changes in ownership interest rate period	3 years
Minimum
Income Taxes [Line Items]
Cumulative changes in ownership interest of shareholders	50.00%
U.S. Federal
Income Taxes [Line Items]
Tax credit carryforward, amount		2,400,000
Cumulative NOL carry forwards	$ 177,700,000
Cumulative NOL carry forwards with expiration	5,000,000
Cumulative NOL carry forwards with no expiration	172,700,000
U.S. Federal \| Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforward, amount	2,000,000
U.S. Federal \| Orphan Drug Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforward, amount	4,400,000	910,000
State and Local Jurisdiction
Income Taxes [Line Items]
Cumulative NOL carry forwards	186,000,000
State and Local Jurisdiction \| Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforward, amount	$ 457,000	$ 321,000

Income Taxes - Summary of Reconciliation of Income Tax Expense (Benefit) Computed at Statutory Federal and State Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal income tax (benefit) at statutory rate	$ (29,395)	$ (14,578)	$ (6,752)
Change in valuation allowance	39,781	20,689	11,112
State income tax expense net of federal benefit	(10,438)	(5,436)	(2,632)
Credits	(1,736)	(1,295)	(887)
Other non-deductible expenses	2,182	675	(216)
Other	(394)	(55)	(625)
Total tax expense (benefit)	$ 0	$ 0	$ 0