0000950170-22-009714 | 10-Q | XBRL Viewer

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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2022	May 02, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	TALS
Entity Registrant Name	TALARIS THERAPEUTICS, INC.
Entity Central Index Key	0001827506
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		41,463,782
Entity Current Reporting Status	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity File Number	001-40384
Entity Tax Identification Number	83-2377352
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	93 Worcester St.
Entity Address, City or Town	Wellesley
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02481
City Area Code	502
Local Phone Number	398-9250

Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 22,791	$ 18,614
Marketable securities	202,738	225,357
Prepaid and other current assets	2,889	2,543
Total current assets	228,418	246,514
Property and equipment, net	5,486	4,804
Right-of-use assets	3,231
Other assets	111	104
Total assets	237,246	251,422
Current liabilities:
Accounts payable	3,485	2,556
Accrued expenses	3,840	5,431
Lease liability, current	740
Total current liabilities	8,065	7,987
Share repurchase liability	492	593
Other liabilities		33
Lease liability, net of current	2,659
Total liabilities	11,216	8,613
Commitments and contingencies (Note 8)
Stockholders' equity
Common stock, $0.0001 par value, 140,000,000 shares authorized and 39,873,868 issued and outstanding and 10,000,000 non-voting shares authorized and 1,150,000 issued and outstanding as of March 31, 2022 and 140,000,000 shares authorized and 39,763,049 issued and outstanding and 10,000,000 non-voting shares authorized and 1,150,000 issued and outstanding as of December 31, 2021	4	4
Additional paid-in-capital	336,058	333,730
Accumulated deficit	(109,106)	(90,847)
Accumulated other comprehensive loss	(926)	(78)
Total stockholders' equity	226,030	242,809
Total liabilities and stockholders' equity	$ 237,246	$ 251,422

Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Common stock, par value	$ 0.0001
Common stock, shares authorized	140,000,000	140,000,000
Common stock, shares issued	39,873,868	39,763,049
Common stock, shares outstanding	39,873,868	39,763,049
Non-voting Shares
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	1,150,000	1,150,000
Common stock, shares outstanding	1,150,000	1,150,000

Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses
Research and development	$ 14,196	$ 6,468
General and administrative	4,218	2,537
Total operating expenses	18,414	9,005
Loss from operations	(18,414)	(9,005)
Interest and other income (expense), net	155	(294)
Net loss	(18,259)	(9,299)
Unrealized loss on marketable securities	(848)	22
Total other comprehensive loss	(848)	(9,277)
Total comprehensive loss	(19,107)	(9,277)
Net loss	$ (18,259)	$ (9,299)
Net loss per common share, basic and diluted	$ (0.45)	$ (1.30)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted	40,980,213	7,160,631

Statements of Convertible Preferred Stock and Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series A-1 Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2020	$ (38,147)				$ 1	$ 4,879	$ (43,014)	$ (13)
Beginning balance, shares at Dec. 31, 2020		40,000,000	28,000,000	62,499,993
Beginning balance at Dec. 31, 2020		$ 37,383	$ 34,272	$ 114,496
Beginning balance, shares at Dec. 31, 2020					7,087,130
Issuance of common stock upon exercise of stock options	123					123
Issuance of common stock upon exercise of stock options, shares					117,181
Stock-based compensation expense	835					835
Net loss	(9,299)						(9,299)
Unrealized (loss) gain on marketable securities	22							22
Ending balance at Mar. 31, 2021	(46,466)				$ 1	5,837	(52,313)	9
Ending balance, shares at Mar. 31, 2021		40,000,000	28,000,000	62,499,993
Ending balance at Mar. 31, 2021		$ 37,383	$ 34,272	$ 114,496
Ending balance, shares at Mar. 31, 2021					7,204,311
Beginning balance at Dec. 31, 2020	$ (38,147)				$ 1	4,879	(43,014)	(13)
Beginning balance, shares at Dec. 31, 2020		40,000,000	28,000,000	62,499,993
Beginning balance at Dec. 31, 2020		$ 37,383	$ 34,272	$ 114,496
Beginning balance, shares at Dec. 31, 2020					7,087,130
Issuance of common stock upon exercise of stock options, shares	149,707
Net loss	$ (47,800)
Ending balance at Dec. 31, 2021	$ 242,809				$ 4	333,730	(90,847)	(78)
Ending balance, shares at Dec. 31, 2021	39,763,049				40,913,049
Issuance of common stock upon exercise of stock options	$ 131					131
Issuance of common stock upon exercise of stock options, shares	10,680				110,819
Stock-based compensation expense	$ 2,197					2,197
Net loss	(18,259)						(18,259)
Unrealized (loss) gain on marketable securities	(848)							(848)
Ending balance at Mar. 31, 2022	$ 226,030				$ 4	$ 336,058	$ (109,106)	$ (926)
Ending balance, shares at Mar. 31, 2022	39,873,868				41,023,868

- Definition

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

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

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+ References + Details

Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (18,259)	$ (9,299)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	297	135
Accretion and amortization of marketable securities, net	3	193
Amortization of right-of-use assets	191
Stock-based compensation expense	2,197	835
Fair value adjustment of contingent stock liability		360	$ 375
Changes in operating assets and liabilities:
Prepaid and other current assets	(346)	(400)
Other assets	(7)
Accounts payable	755	1
Accrued expenses	(1,054)	(872)
Operating lease liability	(129)
Other liabilities	72
Net cash used in operating activities	(16,280)	(9,047)	(40,000)
Cash flows from investing activities:
Purchases of property and equipment	(1,341)	(187)
Purchases of marketable securities	(39,982)	(34,297)
Maturities of marketable securities	61,750	35,814
Net cash provided by investing activities	20,427	1,330
Cash flows from financing activities:
Preferred stock issuance costs		(11)
Proceeds from exercise of stock options	30	28
Net cash provided by financing activities	30	17
Net increase (decrease) in cash and cash equivalents	4,177	(7,700)
Cash and cash equivalents at beginning of period	18,614	17,589	17,589
Cash and cash equivalents at end of period	22,791	9,889	$ 18,614
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment additions included in accounts payable and accrued expenses	$ 667	106
Deferred issuance costs included in accounts payable and accrued expenses		$ 1,039

Nature of Business and Liquidity

3 Months Ended

Mar. 31, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Business and Liquidity

1. Nature of Business and Liquidity

Talaris Therapeutics, Inc. (“Talaris” or the “Company”) is a late-clinical stage, cell therapy company developing an innovative method of allogeneic hematopoietic stem cell transplantation (“allo-HSCT”), called Facilitated Allo-HSCT Therapy, that the Company believes has the potential to transform the standard of care in solid organ transplantation, certain severe autoimmune diseases and certain severe non-malignant blood, immune and metabolic disorders. The Company believes that these indications, individually and collectively, represent a significant unmet need and commercial opportunity. The Company maintains corporate offices in Boston, Massachusetts, a laboratory in Houston, Texas and its cell processing facility in Louisville, Kentucky.

Initial Public Offering

The Company completed an initial public offering (“IPO”) on May 11, 2021 in which the Company issued and sold 8,825,000 shares of its common stock at a public offering price of $17.00 per share. The Company’s aggregate gross proceeds from the sale of shares in the IPO was $150.0 million before underwriting discounts and commissions and other expenses of approximately $12.9 million. Upon completion of the offering, the Company’s outstanding convertible preferred stock was automatically converted into shares of common stock and non-voting common stock. Following the IPO, there were no shares of preferred stock outstanding. Prior to the IPO, on April 30, 2021, the Company’s board of directors and shareholders approved a one-for-5.35 reverse share split of issued and outstanding common shares and incentive shares and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock.

Liquidity

The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. Management has evaluated whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. Since its inception, the Company has incurred net losses and negative cash flows from operations. During the three months ended March 31, 2022 and the year ended December 31, 2021, the Company incurred a net loss of $18.3 million and $47.8 million, respectively, and used $16.3 million and $40.0 million in cash for operations, respectively. In addition, as of March 31, 2022, the Company had an accumulated deficit of $109.1 million. The Company expects to continue to generate operating losses and negative cash flows for the foreseeable future. The Company currently expects the cash and cash equivalents of $22.8 million and marketable securities of $202.7 million as of March 31, 2022, will be sufficient to fund its operating expenses and capital requirements for more than 12 months from the date the financial statements are available to be issued.

Additional funding will be needed to finance future clinical, pre-clinical, manufacturing and commercial activities. There is no assurance the Company will be successful in obtaining such additional financing on terms acceptable to it, if at all, and it may not be able to enter into other arrangements. If the Company is unable to obtain funding, it could be forced to delay, reduce or eliminate our research and development programs, portfolio expansion or commercialization efforts, which could adversely affect its business prospects and ability to continue operations.

The Company is subject to risks common to companies in the biopharmaceutical industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for its intellectual property will be maintained, that any products developed will obtain required regulatory approval, or that any approved products will be commercially viable. Even if the development efforts are successful, it is uncertain when, if ever, the Company will generate significant product sales and ultimately net income.

Coronavirus Pandemic

In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. The worldwide COVID-19 pandemic has affected and may affect in the future the Company’s ability to initiate and complete preclinical studies, delay the initiation and completion of its current and planned clinical trials, disrupt regulatory activities or have other adverse effects on its business, results of operations, financial condition and prospects. In addition, the pandemic has caused substantial disruption in the financial markets and may adversely impact economies worldwide, both of which could adversely affect the Company’s business, operations and ability to raise funds to support its operations.

The Company cannot be certain what the overall impact of the COVID-19 pandemic will be on its business, and it has the potential to adversely affect its business, financial condition, results of operations and prospects.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Summary Of Significant Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions, and estimates that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the determination of the fair value of stock option grants and estimates related to the amount of prepaid and accrued research and development expenses as of the balance sheet date. For periods presented prior to the Company’s IPO, significant estimates were used in the determination of the fair value of the Company’s common stock. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when the facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. As of March 31, 2022 and December 31, 2021, cash and cash equivalents consisted primarily of checking and savings deposits, money market fund holdings, and commercial paper.

Marketable Securities

The Company classifies its marketable securities as available-for-sale securities, which are carried at their fair value based on the quoted market prices of the securities. Unrealized gains and losses are reported as accumulated other comprehensive loss, a separate component of stockholders’ deficit. Realized gains and losses on available-for-sale securities are included in net loss in the period earned or incurred.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful life of each asset. Equipment and furniture and fixtures are depreciated over five or seven year lives. Leasehold improvements are amortized over the shorter of the lease term or the five-year estimated useful life of the asset. Computer equipment and computer software are depreciated over three years. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are expensed as incurred.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. No impairments have been identified as of March 31, 2022 and December 31, 2021.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents. The Company’s investment policy includes guidelines regarding the quality of the financial institutions and financial instruments and defines allowable investments that it believes minimizes the exposure to concentration of credit risk. The Company may invest in money market funds (minimum of $1 billion in assets), U.S. Treasury securities, corporate debt, bank debt, U.S.

government-related agency securities, other sovereign debt, municipal debt and commercial paper. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts and believes that it is not exposed to significant credit risk as its deposits are held at financial institutions that management believes to be of high credit quality.

Fair Value of Financial Instruments

Fair value is defined as the price that the Company would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 investments) and the lowest priority to unobservable inputs (Level 3 investments).

The three levels of the fair value hierarchy are as follows:

•

Level 1 inputs: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level 2 inputs: Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level 3 inputs: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment.

The Company’s money market funds and marketable securities are carried at fair value determined according to the fair value hierarchy described above (Level 1 and Level 2, respectively).

The Company’s contingent stock liability as of March 31, 2021 (see Note 3) is carried at fair value determined according to the fair value hierarchy described above (Level 3).

Research and Development Expenses

Research and development expenses include (i) employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research organization agreements, investigational sites, and consultants; (iii) the cost of acquiring, developing, and manufacturing clinical study materials; (iv) costs associated with preclinical and clinical activities and regulatory operations; (v) costs incurred in development of intellectual property; and (vi) an allocated portion of facilities and other infrastructure costs associated with our research and development activities. Costs incurred in connection with research and development activities are expensed as incurred.

The Company enters into consulting, research, and other agreements with commercial entities, researchers, universities, and others for the provision of goods and services. Such arrangements are generally cancelable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the respective vendors, including the Company’s clinical sites. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved, and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees, nonemployees, and directors based on the fair value on the date of the grant and recognizes stock-based compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock option awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company’s policy is to account for forfeitures when they occur.

The Company classifies stock-based compensation expense in its statement of operations in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified.

The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company recently completed its IPO and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employees is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the US Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero because the Company has never paid cash dividends on common stock and does not expect to pay any cash dividends in the foreseeable future.

Prior to the Company’s IPO, the Company considered the estimated fair value of the common stock as of the measurement date in determining the exercise price for options granted. The estimated fair value of the common stock was determined at each grant date based upon a variety of factors, including the illiquid nature of the common stock, arm’s-length sales of the Company’s capital stock (including convertible preferred stock), the effect of the rights and preferences of the preferred shareholders, and the prospects of a liquidity event. Among other factors are the Company’s financial position and historical financial performance, forecasted future operations of the Company, an evaluation or benchmark of the Company’s competition, and the current business climate in the marketplace. Significant changes to the key assumptions underlying the factors used could result in different fair values of common stock at each valuation date. The fair value for options granted since the Company’s IPO are based on the closing stock price on grant date.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions. These reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. The Company had no significant uncertain tax positions as of March 31, 2022 and December 31, 2021.

Basic and Diluted Net Loss Per Share

The Company calculates basic and diluted net loss per share using the two-class method. The two-class method requires income available to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company’s Series A convertible preferred stock, Series A-1 convertible preferred stock and Series B convertible preferred stock are participating securities. These participating securities do not contractually require the holders of such shares to participate in the Company’s losses. As such, net losses for the years presented were not allocated to the Company’s participating securities. Accordingly, basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the dilutive effects of potentially dilutive securities outstanding during the period. Potentially dilutive

securities include vested and unexercised stock options, restricted stock issued upon early exercise of stock options, convertible preferred shares and contingent stock liabilities. The dilutive effect of stock options and contingent stock liabilities are computed using the treasury stock method and the dilutive effect of convertible preferred shares is calculated using the if-converted method. The Company has generated a net loss for all periods presented, therefore diluted net loss per share is the same as basic net loss per share since the inclusion of potentially dilutive securities would be anti-dilutive.

Segments

Operating segments are defined as components of an entity for which separate financial information is made available and is regularly evaluated by the chief operating decision maker (“CODM”) in making decisions regarding resource allocation and assessing performance. The Company’s CODM is the chief executive officer and operations are managed as a single segment for the purposes of assessing performance and making operating decisions.

Comprehensive Loss

Comprehensive loss represents net loss for the period plus the results of certain other changes in stockholders’ equity (deficit). The Company’s comprehensive loss included unrealized gains related to marketable securities for the three months ended March 31, 2022 and 2021.

Recently Issued Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments—Credit Losses, (“ASC 326”), which introduces a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. The new model will apply to (1) loans, accounts receivable, trade receivables, and other financial assets measured at amortized cost; (2) loan commitments and certain other off-balance-sheet credit exposures; (3) debt securities and other financial assets measured at fair value through other comprehensive income; and (4) beneficial interests in securitized financial assets. The adoption of ASC 326 in January 2021 had no material impact on the Company’s financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), and subsequently has issued additional guidance (collectively, “ASC 842”), which requires companies to generally recognize operating and financing lease liabilities and corresponding right-of-use assets on the balance sheet. The Company adopted ASC 842 on January 1, 2022 using the modified retrospective approach, with no restatement of prior periods. Upon adoption, the Company elected the package of transitional practical expedients which allowed the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. In addition, the Company made an accounting policy election to not apply the recognition requirements in the leasing standards to short-term leases, which is a lease that at commencement date has a lease term of 12 months or less and does not contain a purchase option that it is reasonably certain to exercise.

The Company determines if an arrangement is a lease at contract inception. The Company’s contracts are determined to contain a lease when all of the following criteria based on the specific circumstances of the arrangement are met: (1) there is an identified asset for which there are no substantive substitution rights; (2) the Company has the right to obtain substantially all of the economic benefits from the identified asset; and (3) the Company has the right to direct the use of the identified asset.

At the commencement date, operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of future lease payments over the expected lease term. The Company’s lease agreements do not provide an implicit rate. As a result, the Company utilizes an estimated incremental borrowing rate to discount lease payments, which is based on the rate of interest the Company would have to pay to borrow a similar amount on a collateralized basis over a similar term. Certain adjustments to the right-of-use asset may be required for items such as lease incentives received. Operating lease cost is recognized over the expected term on a straight-line basis.

The expected lease term for those leases commencing prior to January 1, 2022 did not change with the adoption of the new leasing standards. The expected lease term for leases commencing after the adoption of the new leasing standards includes noncancelable lease periods and, when applicable, periods covered by an option to extend the lease if the Company is reasonably certain to exercise that option, as well as periods covered by an option to terminate the lease if the Company is reasonably certain not to exercise that option.

As a result of the adoption of the new leasing standards, on January 1, 2022, the Company recorded right-of-use assets of $3.4 million and operating lease liabilities of $3.5 million. The adoption did not have a material impact on the statement of operations or the statement of cash flows. For additional information on the adoption of the new leasing standard, refer to Note 8.

The following table presents the cumulative effect of adoption of ASC 842 on January 1, 2022 (in thousands):


	January 1, 2022 (in thousands)
	Prior to adoption of new leasing standards		Adjustment for adoption of new leasing standards			As adjusted
Right-of-use assets (1)	$	—	$	3,422		$	3,422
Deferred rent (2)	$	105	$	(105	)	$	—
Operating lease liability (3)	$	—	$	645		$	645
Operating lease liability, net of current portion (3)	$	—	$	2,882		$	2,882

(1) Represents capitalization of operating right-of-use assets
(2) Represents reclassification of deferred rent and incentives as a reduction of operating right-of-use assets
(3) Represents recognition of operating right-of-use assets

Fair Value of Financial Assets and Liabilities

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the inputs the Company utilized to determine such fair value (in thousands):


	March 31, 2022
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	17,248	$	17,248	$	—	$	—
Marketable securities		202,738		34,887		167,851		—
Total financial assets measured at fair value	$	219,986	$	52,135	$	167,851	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	10,319	$	10,319	$	—	$	—
Marketable securities		225,357		27,186		198,171		—
Total financial assets measured at fair value	$	235,676	$	37,505	$	198,171	$	—

The Company had a contingent stock liability that represented the fair value of contingent equity consideration equal to 65,186 shares of common stock contingently issuable to the University of Louisville Research Foundation Inc. (“ULRF”) in connection with its amended and restated exclusive license agreement with the Company. In conjunction with the Company’s IPO, the Company issued 48,889 shares of common stock and paid the cash equivalent fair value of 16,297 shares, or $0.3 million, to ULRF in May 2021 (see Note 8). A rollforward of the contingent common stock liability, which was measured at fair value as of March 31, 2021 and December 31, 2021, is represented as follows (in thousands):


Fair value as of December 31, 2020	$	373
Change in fair value		360
Fair value as of March 31, 2021		733
Change in fair value		375
Share issuance in partial settlement of contingent stock		(831	)
Cash payment in partial settlement of contingent stock		(277	)
Fair value as of December 31, 2021	$	—

Valuation techniques used to measure fair value maximize the use of relevant observable inputs and minimize the use of unobservable inputs. Prior to the Company’s IPO, the Company’s contingent stock liability was classified within Level 3 of the fair value hierarchy because its fair value measurement is based, in part, on significant inputs not observed in the market, which incorporates assumptions and estimates to value the Company’s common stock. As there was no public market for the Company’s common stock prior to May 2021, the estimated fair value was determined by the Company’s board of directors with input from management, considering the most recently available third-party valuations of common stock, and the board of directors’ assessment of additional

objective and subjective factors that it believed were relevant and which may have changed from the date of each valuation. Historically, these third-party valuations of the Company’s common stock were performed contemporaneously when events occurred which management believed would have an impact on the valuation of the Company. The Company’s common stock valuation was prepared using the option-pricing method, (“OPM”), which uses a market approach to estimate enterprise value. The fair value of the Company’s common stock used to value the contingent stock liability as of March 31, 2021 was $5.72.

- Definition

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

+ References + Details

Marketable Securities

3 Months Ended

Mar. 31, 2022

Marketable Securities [Abstract]

Marketable Securities

4. Marketable Securities

The fair value of the Company’s marketable securities as of March 31, 2022 and December 31, 2021 is based on level 1 and level 2 inputs. The Company’s investments consist mainly of U.S. government and agency securities, government-sponsored bond obligations and certain other corporate debt securities. Fair value is determined by taking into consideration valuations obtained from third-party pricing services. The third-party pricing services utilize industry standard valuation models, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; and other observable inputs. There were no transfers between levels within the hierarchy during the three months ended March 31, 2022 and the year ended December 31, 2021. The Company has assessed U.S. government treasuries as level 1 and all other marketable securities as level 2 within the fair value hierarchy of ASC 820. The Company classifies its entire investment portfolio as available-for-sale as defined in ASC 320, Debt Securities. Securities are carried at fair value with the unrealized gains (losses) reported in other comprehensive loss.

As of March 31, 2022 and December 31, 2021, none of the Company’s investments were determined to be other than temporarily impaired.

The following table summarizes the Company’s investments (in thousands):


	March 31, 2022
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	153,924	$	—	$	(512	)	$	153,412
Government and agency securities		42,241		—		(362	)		41,879
Corporate debt securities		7,496		—		(49	)		7,447
Total	$	203,661	$	—	$	(923	)	$	202,738


	December 31, 2021
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	179,151	$	38	$	(47	)	$	179,142
Government and agency securities		31,244		—		(58	)		31,186
Corporate debt securities		15,040		—		(11	)		15,029
Total	$	225,435	$	38	$	(116	)	$	225,357

Prepaid and Other Current Assets

3 Months Ended

Mar. 31, 2022

Prepaid Expense And Other Assets Current [Abstract]

Prepaid and Other Current Assets

5. Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following (in thousands):


	March 31,		December 31,
	2022		2021
Prepaid insurance	$	315	$	1,121
Prepaid research and development expenses		1,777		782
Other current assets		797		640
Total prepaid and other current assets	$	2,889	$	2,543

Property and Equipment, Net

3 Months Ended

Mar. 31, 2022

Property Plant And Equipment [Abstract]

Property and Equipment, Net

6. Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	March 31,			December 31,
	2022			2021
Equipment	$	5,313		$	4,449
Leasehold improvements		1,108			821
Computer equipment		960			953
Furniture and fixtures		426			426
Construction in progress		773			952
Total property and equipment		8,580			7,601
Less accumulated depreciation		(3,094	)		(2,797	)
Property and equipment, net	$	5,486		$	4,804

Depreciation expense was $0.3 million and $0.1 million for the three months ended March 31, 2022 and 2021, respectively.

Accrued Expenses

3 Months Ended

Mar. 31, 2022

Accrued Liabilities Current [Abstract]

Accrued Expenses

7. Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	March 31,		December 31,
	2022		2021
Compensation and benefit costs	$	1,929	$	3,320
Research and development expenses		1,146		854
Professional fees, consulting and other		765		1,257
Total accrued expenses	$	3,840	$	5,431

Commitments and Contingencies

3 Months Ended

Mar. 31, 2022

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and Contingencies

Leases

The Company currently has four active lease agreements for office and laboratory space and related equipment. The primary lease is located on the University of Louisville campus in Louisville, Kentucky (the “Louisville Lease”). This lease has a termination date in November 2023, with an option to extend for three additional years at the Company’s discretion. In May 2020, the Company added additional office and laboratory space to the Louisville Lease. In September 2021, the Company entered into a sublease agreement for additional office space in Louisville, Kentucky. This sublease has a termination date in November 2023.

The Company maintains a lease for office space in Wellesley, Massachusetts, that had an original termination date in March 2021. The Company entered into a month-to-month lease agreement for the office space in Wellesley effective as of April 2021 and in June 2021, finalized an amended lease agreement. The amended lease commencement date will be the later of April 2022 or the date the landlord substantially completes agreed-upon renovations. The term of the lease will be 39 months from the commencement date. The Company will maintain its current office space in Wellesley until the commencement of the amended lease agreement. In February 2022, the Company further amended the lease agreement to reflect minor alterations to the improvements to be completed by the landlord. The amended lease had not commenced as of March 31, 2022.

In July 2021, the Company entered into a lease agreement for laboratory space in Houston, Texas (the “Houston Lease”). The Houston Lease commenced in January 2022. The term of the lease is 36 months from the commencement date.

The future minimum rent payments relating to all four of the Company’s ongoing facility operating leases under the terms and conditions existing as of March 31, 2022, as well as amendments the Company has entered into between the date of these financial statements and the date they were available to be issued, are summarized as follows (in thousands):


Years Ending December 31,
2022	$	668
2023		1,064
2024		936
2025		756
2026 and beyond		437
Total lease payments	$	3,861
Less: imputed interest		(462	)
Present value of lease liabilities	$	3,399

The Company incurred rent expense of $0.2 million and $0.1 million for the three months ended March 31, 2022 and 2021, respectively.

The following table summarizes the operating lease term and discount rate as of March 31, 2022:


	As of March 31, 2022
Weighted-average remaining lease term (years)		4.0
Weighted-average discount rate		6.5	%

Cash paid for amounts included in the measurement of the Company's operating lease liability was $0.2 million for the three months ended March 31, 2022.

License Agreement

In October 2018, the Company entered an amended and restated exclusive license agreement with ULRF related to certain licensed patent rights and know-how related to human facilitating cells for its Facilitated Allo-HSCT Therapy approach. Pursuant to the ULRF License Agreement, ULRF granted the Company an exclusive, worldwide license under such patents and a nonexclusive royalty-bearing, worldwide license for such know-how to research, develop, commercialize and manufacture FCR001 and products containing FCR001 in all fields, without limitation. ULRF also granted the Company the right to grant sublicenses in accordance with the ULRF License Agreement. Under the terms of the agreement, the Company is obligated to compensate ULRF three percent of net sales of all licensed products sold, one third of any non-royalty sublicensing income, and up to $1.625 million in regulatory and sales milestones on each licensed product upon the occurrence of specific events as outlined in the license agreement; and annual license maintenance fees.

In addition, upon execution of the ULRF License Agreement, the Company granted contingent equity consideration equal to 65,186 shares of common stock to ULRF. Pursuant to the ULRF License Agreement, on or prior to the Company’s first underwritten public offering or any transaction that is treated as a deemed liquidation event, the Company is required to either issue to ULRF the 65,186 shares in common stock or make a cash payment equal to the 65,186 shares of common stock multiplied by either the price per share of common stock in the underwritten public offering or by the price per share of common stock received in connection with such deemed liquidation event.

Coincident with the completion of the Company’s IPO, the Company issued 48,889 shares of common stock to ULRF and provided a cash payment of approximately $0.3 million in lieu of issuing the remaining 16,297 shares of common stock. As of March 31, 2022, the contingent stock liability was fully satisfied. As of March 31, 2021, the Company measured the fair value of the contingent equity consideration and recorded a contingent stock liability of $0.7 million in other liabilities (see Note 3).

The Company incurred $0.1 million in expense in February 2022 related to an annual maintenance fee pursuant to the ULRF License Agreement for the year ended December 31, 2022. The Company incurred $0.1 million in expense in February 2021 related to an annual maintenance fee pursuant to the license agreement for the year ended December 31, 2021.

Legal Proceedings

The Company is not currently a party to any material legal proceedings. At each reporting date, the Company evaluates whether a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to its legal proceedings.

Convertible Preferred Stock

3 Months Ended

Mar. 31, 2022

Convertible Preferred Stock [Abstract]

Convertible Preferred Stock

9. Convertible Preferred Stock

Upon the completion of the Company’s IPO in May 2021, all Convertible Preferred Stock was converted to shares of common stock or non-voting common stock. Series A Convertible Preferred Stock was converted into 7,476,632 shares of common stock, Series A-1 Convertible Preferred Stock was converted into 5,233,637 shares of common stock and Series B Convertible Preferred Stock was converted into 10,532,229 shares of common stock and 1,150,000 shares of non-voting common stock. Please refer to the Company's Annual Report on Form 10-K for the year ended December 31, 2021 for further disclosure regarding historical balances of Convertible Preferred Stock.

Common Stock

3 Months Ended

Mar. 31, 2022

Stockholders Equity Note [Abstract]

Common Stock

10. Common Stock

Common Stock

On April 30, 2021, the Company’s stockholders approved the third amended and restated certificate of incorporation of the Company, which included the authorization of 10,000,000 shares of undesignated preferred stock with a par value of $0.0001, authorization of 140,000,000 shares of voting common stock and 10,000,000 shares of non-voting common stock. As of March 31, 2022, no undesignated preferred stock was outstanding.

Common Stock Reserved

The number of shares of common stock that have been reserved for the potential conversion of Preferred Stock, outstanding stock options granted and stock options available for grant under the Company’s 2021 Stock Option and Incentive Plan (the “2021 Plan”) and the 2018 Equity Incentive Plan (the “2018 Plan”) and shares reserved for issuance under the Company’s 2021 Employee Stock Purchase Plan (the “2021 ESPP”) are as follows:


	March 31,		December 31,
	2022		2021
Restricted stock related to early exercise of common stock options		438,201		538,340
Restricted stock units outstanding		859,769		—
Outstanding common stock options		5,957,614		3,643,796
Shares reserved for issuance under equity incentive plans		2,451,066		2,702,995
Shares reserved for issuance under the 2021 Employee Stock Purchase Plan		1,251,601		837,088
Total		10,958,251		7,722,219

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-URI http://asc.fasb.org/topic&trid=2208762

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
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-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 16
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496180-112644

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

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

+ Details

Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

11. Stock-Based Compensation

2021 Employee Stock Purchase Plan

In April 2021, the Company’s board of directors and stockholders approved the 2021 ESPP. The 2021 ESPP became effective immediately prior to the effectiveness of the Company’s registration statement on Form S-1 for its IPO. The 2021 ESPP provides employees the opportunity to purchase shares at a 15% discount at the lower of the share price at the beginning or end of six-month offering periods. 852,971 shares have been reserved and approved for this purpose for the 2021 plan year. Beginning on January 1, 2022, the number of shares reserved and available for issuance under the plan will increase on each January 1 through January 1, 2031, by the lesser of (A) 3,000,000 shares of common stock, (B) 1% of the cumulative number of shares of common stock issued and outstanding on the immediately preceding December 31st or (C) such lesser number of shares of common stock as determined by the Board. On January 1, 2022, an additional 414,513 shares were added to the 2021 ESPP, representing 1% of total common shares outstanding at December 31, 2021.The expense incurred under this plan for the three months ended March 31, 2022 was immaterial to the financial statements. The amounts have been included in the total stock-based compensation line items in the accompanying financial statements and disclosures.

Equity Incentive Plans

In April 2021, the Company’s board of directors and stockholders approved the 2021 Plan and terminated the 2018 Plan with respect to any unissued awards. The 2021 Plan became effective immediately prior to the effectiveness of the Company’s registration statement on Form S-1 for its IPO. The 2021 Plan provides for the issuance of up to 3,015,907 new share-based awards, as well as the 3,381,382 options to purchase common stock then outstanding under the 2018 Plan, for a total of 6,397,289 shares. To the extent outstanding options granted under the 2018 Plan are cancelled, forfeited, or otherwise terminated without being exercised and would otherwise have been returned to the share reserve under the 2018 Plan, the number of shares underlying such awards will be available for future grant under the 2021 Plan. Beginning on January 1, 2022, the number of shares reserved and available for issuance under the 2021 Plan will increase on each January 1 through January 1, 2031 by the lesser of (A) 5% percent of the number of shares of stock issued and outstanding on the immediately preceding December 31st or (B) such lesser number of shares of common stock as determined

by the Board. On January 1, 2022 an additional 2,072,569 shares were added to the 2021 Plan, representing 5% of total common shares outstanding at December 31, 2021.

As of March 31, 2022, 2,451,066 shares remained available for future grant under the 2021 Plan. 5,882,848 options were outstanding under the 2021 Plan and 2018 Plan as of March 31, 2022.

The Company’s 2021 Plan provides for the Company to sell or issue common stock or restricted common stock or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, nonemployees and members of the board of directors of the Company. The 2021 Plan is administered by the board of directors or at the discretion of the board of directors by the compensation committee of the board. The exercise prices, vesting periods, and other restrictions are determined at the discretion of the compensation committee of the board of directors, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the contractual term of stock option may not be greater than 10 years. Stock options granted to date typically vest over four years.

Stock Option Valuation

The assumptions used to determine the fair values of stock options granted to employees and directors under the 2021 Plan and 2018 Plan are presented as follows:


	Three months ended March 31,
	2022	2021
Fair value of common stock	$7.58 - 16.56	$5.72 - 6.79
Dividend yield	—%	—%
Volatility	82.7% - 82.9%	80.6% - 83.0%
Risk-free interest rate	1.46 % - 1.70%	0.50% - 1.07%
Expected term (years)	6.25	6.25

Summary of Option Activity

The Company’s stock option activity regarding employees, directors, and nonemployees is summarized as follows (in thousands excepts share and per share amounts):


	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Options outstanding—January 1, 2021		2,745,185		$	4.20		9.40	$	4,183
Granted		1,076,022			9.19
Exercised		(149,707	)		2.12
Cancelled		(7,605	)		1.38
Forfeited		(20,099	)		5.79
Options outstanding—December 31, 2021		3,643,796		$	5.75		8.69	$	34,754
Granted		2,473,700			9.07
Exercised		(10,680	)		2.83
Cancelled		—			—
Forfeited		(149,202	)		7.71
Options outstanding—March 31, 2022		5,957,614		$	7.09		9.02	$	16,418
Options exercisable—March 31, 2022		1,297,253		$	4.34		8.12
Options vested and expected to vest—March 31, 2022		2,652,637		$	2.69		7.58

Additional information with regard to stock option activity involving employees and directors is as follows (in thousands except per share amounts):


	Three months ended March 31,
	2022		2021
Weighted-average grant-date fair value per option of total options granted	$	6.49	$	4.73
Aggregate intrinsic value of stock options exercised		76		166

As of March 31, 2022, total unrecognized compensation cost related to the unvested awards to employees, directors, and nonemployees is $25.0 million, which is expected to be recognized over a weighted-average period of 3.4 years.

Restricted Stock Units

The fair values of restricted stock units (“RSUs”) are based on the fair market value of the Company’s common stock on the date of grant. Each RSU represents a contingent right to receive one share of the Company’s common stock upon vesting. In general, RSUs vest (i) annually in four equal installments on the grant anniversary or (ii) incrementally over two years. The following table summarizes the Company’s RSU activity for the three months ended March 31, 2022:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value
Outstanding at January 1, 2022		—		$	—
Granted		864,802			9.08
Vested		—			—
Forfeited		(5,033	)		9.10
Outstanding at March 31, 2022		859,769		$	9.08

As of March 31, 2022, total unrecognized compensation cost related to the unvested awards to employees is $7.2 million, which is expected to be recognized over a weighted-average period of 2.3 years.

Stock-Based Compensation

The Company recorded stock-based compensation expense regarding its employees, directors, and nonemployees as follows (in thousands):


	Three months ended March 31,
	2022		2021
Research and development expense	$	1,276	$	326
General and administrative expense		921		509
Total	$	2,197	$	835

Net Loss Per Share Attributable to Common Stockholders

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

12. Net Loss Per Share Attributable to Common Stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company (in thousands except share and per share amounts).


	For the three months ended March 31,
	2022			2021
Net loss and net loss attributable to common stockholders	$	(18,259	)	$	(9,299	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.45	)	$	(1.30	)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted		40,980,213			7,160,631

The Company’s potential dilutive securities, which include convertible preferred stock, contingent stock liabilities, restricted stock related to early exercise of common stock options and common stock options, have been excluded from the computation of diluted net loss per share as the effect would be antidilutive. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	For the three months ended March 31,
	2022		2021
Convertible preferred shares (as converted to common stock and non-voting common stock)		—		24,392,498
Options to purchase common stock		5,957,614		3,456,153
Restricted stock units		859,769		—
Restricted stock related to early exercise of options to purchase common stock		438,201		839,540
Contingent common stock (as converted to common stock)		—		65,186
		7,255,584		28,753,377

Subsequent Events

3 Months Ended

Mar. 31, 2022

Subsequent Events [Abstract]

Subsequent Events

13. Subsequent Events

The Company has evaluated subsequent events through May 12, 2022, the date the financial statements were available to be issued. The Company has concluded no subsequent events have occurred that require disclosure, except for those referenced below.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

Summary Of Significant Accounting Policies [Abstract]

Basis of Presentation

The financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).

Use of Estimates

Cash and Cash Equivalents

Marketable Securities

Property and Equipment

Impairment of Long-Lived Assets

Concentration of Credit Risk

Fair Value of Financial Instruments

The three levels of the fair value hierarchy are as follows:

•

Level 1 inputs: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

•

Level 2 inputs: Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and

•

Level 3 inputs: Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

The Company’s money market funds and marketable securities are carried at fair value determined according to the fair value hierarchy described above (Level 1 and Level 2, respectively).

The Company’s contingent stock liability as of March 31, 2021 (see Note 3) is carried at fair value determined according to the fair value hierarchy described above (Level 3).

Research and Development Expenses

Stock-Based Compensation

Income Taxes

Basic and Diluted Net Loss Per Share

Segments

Comprehensive Loss

Recently Issued Accounting Pronouncements

The following table presents the cumulative effect of adoption of ASC 842 on January 1, 2022 (in thousands):


	January 1, 2022 (in thousands)
	Prior to adoption of new leasing standards		Adjustment for adoption of new leasing standards			As adjusted
Right-of-use assets (1)	$	—	$	3,422		$	3,422
Deferred rent (2)	$	105	$	(105	)	$	—
Operating lease liability (3)	$	—	$	645		$	645
Operating lease liability, net of current portion (3)	$	—	$	2,882		$	2,882

(1) Represents capitalization of operating right-of-use assets
(2) Represents reclassification of deferred rent and incentives as a reduction of operating right-of-use assets
(3) Represents recognition of operating right-of-use assets

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2022

Summary Of Significant Accounting Policies [Abstract]

Summary of Cumulative Effect of Adoption of ASC 842

The following table presents the cumulative effect of adoption of ASC 842 on January 1, 2022 (in thousands):


	January 1, 2022 (in thousands)
	Prior to adoption of new leasing standards		Adjustment for adoption of new leasing standards			As adjusted
Right-of-use assets (1)	$	—	$	3,422		$	3,422
Deferred rent (2)	$	105	$	(105	)	$	—
Operating lease liability (3)	$	—	$	645		$	645
Operating lease liability, net of current portion (3)	$	—	$	2,882		$	2,882

(1) Represents capitalization of operating right-of-use assets
(2) Represents reclassification of deferred rent and incentives as a reduction of operating right-of-use assets
(3) Represents recognition of operating right-of-use assets

Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Summary of Financial Instruments Measured at Fair Value on Recurring Basis


	March 31, 2022
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	17,248	$	17,248	$	—	$	—
Marketable securities		202,738		34,887		167,851		—
Total financial assets measured at fair value	$	219,986	$	52,135	$	167,851	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Financial assets:
Money market funds (cash equivalents)	$	10,319	$	10,319	$	—	$	—
Marketable securities		225,357		27,186		198,171		—
Total financial assets measured at fair value	$	235,676	$	37,505	$	198,171	$	—

Schedule of Contingent Common Stock Liability Measured at Fair Value

A rollforward of the contingent common stock liability, which was measured at fair value as of March 31, 2021 and December 31, 2021, is represented as follows (in thousands):


Fair value as of December 31, 2020	$	373
Change in fair value		360
Fair value as of March 31, 2021		733
Change in fair value		375
Share issuance in partial settlement of contingent stock		(831	)
Cash payment in partial settlement of contingent stock		(277	)
Fair value as of December 31, 2021	$	—

- Definition

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

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2022

Marketable Securities [Abstract]

Summary of Company's Investments

The following table summarizes the Company’s investments (in thousands):


	March 31, 2022
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	153,924	$	—	$	(512	)	$	153,412
Government and agency securities		42,241		—		(362	)		41,879
Corporate debt securities		7,496		—		(49	)		7,447
Total	$	203,661	$	—	$	(923	)	$	202,738


	December 31, 2021
	Amortized Cost		Unrealized Gain		Unrealized (Loss)			Estimated Fair Value
Commercial paper	$	179,151	$	38	$	(47	)	$	179,142
Government and agency securities		31,244		—		(58	)		31,186
Corporate debt securities		15,040		—		(11	)		15,029
Total	$	225,435	$	38	$	(116	)	$	225,357

Prepaid and Other Current Assets (Tables)

3 Months Ended

Mar. 31, 2022

Prepaid Expense And Other Assets Current [Abstract]

Summary of Prepaid and Other Current Assets

Prepaid and other current assets consisted of the following (in thousands):


	March 31,		December 31,
	2022		2021
Prepaid insurance	$	315	$	1,121
Prepaid research and development expenses		1,777		782
Other current assets		797		640
Total prepaid and other current assets	$	2,889	$	2,543

Property and Equipment, Net (Tables)

3 Months Ended

Mar. 31, 2022

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	March 31,			December 31,
	2022			2021
Equipment	$	5,313		$	4,449
Leasehold improvements		1,108			821
Computer equipment		960			953
Furniture and fixtures		426			426
Construction in progress		773			952
Total property and equipment		8,580			7,601
Less accumulated depreciation		(3,094	)		(2,797	)
Property and equipment, net	$	5,486		$	4,804

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2022

Accrued Liabilities Current [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	March 31,		December 31,
	2022		2021
Compensation and benefit costs	$	1,929	$	3,320
Research and development expenses		1,146		854
Professional fees, consulting and other		765		1,257
Total accrued expenses	$	3,840	$	5,431

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2022

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rent Payments


Years Ending December 31,
2022	$	668
2023		1,064
2024		936
2025		756
2026 and beyond		437
Total lease payments	$	3,861
Less: imputed interest		(462	)
Present value of lease liabilities	$	3,399

Summary of Operating Lease Term and Discount Rate

The following table summarizes the operating lease term and discount rate as of March 31, 2022:


	As of March 31, 2022
Weighted-average remaining lease term (years)		4.0
Weighted-average discount rate		6.5	%

Common Stock (Table)

3 Months Ended

Mar. 31, 2022

Stockholders Equity Note [Abstract]

Schedule of Common Stock Reserved


	March 31,		December 31,
	2022		2021
Restricted stock related to early exercise of common stock options		438,201		538,340
Restricted stock units outstanding		859,769		—
Outstanding common stock options		5,957,614		3,643,796
Shares reserved for issuance under equity incentive plans		2,451,066		2,702,995
Shares reserved for issuance under the 2021 Employee Stock Purchase Plan		1,251,601		837,088
Total		10,958,251		7,722,219

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used to Determine the Fair Values of Stock Options Granted

The assumptions used to determine the fair values of stock options granted to employees and directors under the 2021 Plan and 2018 Plan are presented as follows:


	Three months ended March 31,
	2022	2021
Fair value of common stock	$7.58 - 16.56	$5.72 - 6.79
Dividend yield	—%	—%
Volatility	82.7% - 82.9%	80.6% - 83.0%
Risk-free interest rate	1.46 % - 1.70%	0.50% - 1.07%
Expected term (years)	6.25	6.25

Summary of Option Activity

The Company’s stock option activity regarding employees, directors, and nonemployees is summarized as follows (in thousands excepts share and per share amounts):


	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate intrinsic value
Options outstanding—January 1, 2021		2,745,185		$	4.20		9.40	$	4,183
Granted		1,076,022			9.19
Exercised		(149,707	)		2.12
Cancelled		(7,605	)		1.38
Forfeited		(20,099	)		5.79
Options outstanding—December 31, 2021		3,643,796		$	5.75		8.69	$	34,754
Granted		2,473,700			9.07
Exercised		(10,680	)		2.83
Cancelled		—			—
Forfeited		(149,202	)		7.71
Options outstanding—March 31, 2022		5,957,614		$	7.09		9.02	$	16,418
Options exercisable—March 31, 2022		1,297,253		$	4.34		8.12
Options vested and expected to vest—March 31, 2022		2,652,637		$	2.69		7.58

Summary of Additional Information to Stock Option Activity Involving Employees and Directors

Additional information with regard to stock option activity involving employees and directors is as follows (in thousands except per share amounts):


	Three months ended March 31,
	2022		2021
Weighted-average grant-date fair value per option of total options granted	$	6.49	$	4.73
Aggregate intrinsic value of stock options exercised		76		166

Summary of RSU Activity

The following table summarizes the Company’s RSU activity for the three months ended March 31, 2022:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value
Outstanding at January 1, 2022		—		$	—
Granted		864,802			9.08
Vested		—			—
Forfeited		(5,033	)		9.10
Outstanding at March 31, 2022		859,769		$	9.08

Summary of Stock-based Compensation Expense

The Company recorded stock-based compensation expense regarding its employees, directors, and nonemployees as follows (in thousands):


	Three months ended March 31,
	2022		2021
Research and development expense	$	1,276	$	326
General and administrative expense		921		509
Total	$	2,197	$	835

Net Loss Per Share Attributable to Common Stockholders (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Summary of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company (in thousands except share and per share amounts).


	For the three months ended March 31,
	2022			2021
Net loss and net loss attributable to common stockholders	$	(18,259	)	$	(9,299	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.45	)	$	(1.30	)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted		40,980,213			7,160,631

Summary of Potential Dilutive Securities Excluded From Calculation of Net Loss Per Share Due to Anti-dilutive Effect

The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect:


	For the three months ended March 31,
	2022		2021
Convertible preferred shares (as converted to common stock and non-voting common stock)		—		24,392,498
Options to purchase common stock		5,957,614		3,456,153
Restricted stock units		859,769		—
Restricted stock related to early exercise of options to purchase common stock		438,201		839,540
Contingent common stock (as converted to common stock)		—		65,186
		7,255,584		28,753,377

Nature of Business and Liquidity - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	May 11, 2021 USD ($) $ / shares shares	Apr. 30, 2021	Mar. 31, 2022 USD ($) shares	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Underwriting discounts and commissions and other expenses				$ 11
Preferred stock outstanding \| shares	0		0
Reverse stock split ratio		0.1869
Net loss			$ 18,259	9,299	$ 47,800
Cash used for operation			16,280	$ 9,047	40,000
Accumulated deficit			109,106		90,847
Cash and cash equivalents			22,791		$ 18,614
Marketable securities			$ 202,700
Common Stock \| Initial Public Offering
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of shares issued and sold \| shares	8,825,000
Offering price \| $ / shares	$ 17.00
Gross proceeds from sale of shares	$ 150,000
Underwriting discounts and commissions and other expenses	$ 12,900

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Jan. 01, 2022
Summary Of Significant Accounting Policies [Line Items]
Impairments of long-lived assets	$ 0	$ 0
Expected dividend yield	0.00%
Right-of-use assets	$ 3,231,000		$ 3,400,000
Operating lease liability	$ 3,399,000		$ 3,500,000
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	5 years
Property, plant and equipment, useful life	amortized over the shorter of the lease term or the five-year estimated useful life of the asset
Computer Equipment and Computer Software
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	3 years
Minimum \| Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Investment in assets	$ 1,000,000,000
Minimum \| Equipment and Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	5 years
Maximum \| Equipment and Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	7 years

Summary of Significant Accounting Policies - Summary of Cumulative Effect of Adoption of ASC 842 (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Jan. 01, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets	$ 3,231	$ 3,400
Operating lease liability	3,399	3,500
Operating lease liability, net of current portion	$ 740
Adoption of ASC 842
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets		3,422
Operating lease liability		645
Operating lease liability, net of current portion		2,882
Adoption of ASC 842 \| Prior to adoption of new leasing standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent		105
Adoption of ASC 842 \| Adjustment for adoption of new leasing standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets		3,422
Deferred rent		(105)
Operating lease liability		645
Operating lease liability, net of current portion		$ 2,882

Fair Value of Financial Assets and Liabilities - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financial assets:
Total financial assets measured at fair value	$ 219,986	$ 235,676
Money Market Funds \| Cash Equivalents
Financial assets:
Total financial assets measured at fair value	17,248	10,319
Marketable Securities
Financial assets:
Total financial assets measured at fair value	202,738	225,357
Level 1
Financial assets:
Total financial assets measured at fair value	52,135	37,505
Level 1 \| Money Market Funds \| Cash Equivalents
Financial assets:
Total financial assets measured at fair value	17,248	10,319
Level 1 \| Marketable Securities
Financial assets:
Total financial assets measured at fair value	34,887	27,186
Level 2
Financial assets:
Total financial assets measured at fair value	167,851	198,171
Level 2 \| Marketable Securities
Financial assets:
Total financial assets measured at fair value	$ 167,851	$ 198,171

Fair Value of Financial Assets and Liabilities - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2021 USD ($) shares	Mar. 31, 2022 shares	Dec. 31, 2021 USD ($) shares	Mar. 31, 2021 UsdPerShares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Number of shares equal to fair value of contingent equity consideration		65,186
Common stock, shares issued		39,873,868	39,763,049
Cash payment for contingent equity settlement \| $			$ 277
Measurement Input, Share Price
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of common stock used to value contingent stock liability \| UsdPerShares				5.72
ULRF
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Common stock, shares issued	16,297
Cash payment for contingent equity settlement \| $	$ 300
ULRF \| IPO
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Common stock, shares issued	48,889
Cash payment for contingent equity settlement \| $	$ 300

Fair Value of Financial Assets and Liabilities - Schedule of Contingent Common Stock Liability Measured at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair value, Beginning balance	$ 373	$ 373
Change in fair value	360	375
Share issuance in partial settlement of contingent stock		(831)
Cash payment in partial settlement of contingent stock		(277)
Fair value, Ending balance	$ 733	$ 0

Marketable Securities - Summary of Company's Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 203,661	$ 225,435
Unrealized Gain		38
Unrealized (Loss)	(923)	(116)
Estimated Fair Value	202,738	225,357
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	153,924	179,151
Unrealized Gain		38
Unrealized (Loss)	(512)	(47)
Estimated Fair Value	153,412	179,142
Corporate debt securities
Marketable Securities [Line Items]
Amortized Cost	7,496	15,040
Unrealized (Loss)	(49)	(11)
Estimated Fair Value	7,447	15,029
Government and agency securities
Marketable Securities [Line Items]
Amortized Cost	42,241	31,244
Unrealized (Loss)	(362)	(58)
Estimated Fair Value	$ 41,879	$ 31,186

Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Prepaid Expense And Other Assets Current [Abstract]
Prepaid insurance	$ 315	$ 1,121
Prepaid research and development expenses	1,777	782
Other current assets	797	640
Total prepaid and other current assets	$ 2,889	$ 2,543

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8,580	$ 7,601
Less accumulated depreciation	(3,094)	(2,797)
Property and equipment, net	5,486	4,804
Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,313	4,449
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,108	821
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	960	953
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	426	426
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 773	$ 952

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Depreciation expense	$ 0.3	$ 0.1

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accrued Liabilities Current [Abstract]
Compensation and benefit costs	$ 1,929	$ 3,320
Research and development expenses	1,146	854
Professional fees, consulting and other	765	1,257
Total accrued expenses	$ 3,840	$ 5,431

Commitments and Contingencies - Additional Information (Details)	1 Months Ended					3 Months Ended		12 Months Ended
	Feb. 28, 2022 USD ($)	Sep. 30, 2021	May 31, 2021 USD ($) shares	Feb. 28, 2021 USD ($)	Oct. 31, 2018 USD ($) shares	Mar. 31, 2022 USD ($) Leaseagreement shares	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) shares	Jul. 31, 2021	Dec. 31, 2020 USD ($)
Loss Contingencies [Line Items]
Number of active lease agreements \| Leaseagreement						4
Lessee, operating lease, existence of option to extend						true
Lease option to extend						three additional years
Lease termination date						Nov. 30, 2023
Lease term period						39 months
Rent expense						$ 200,000	$ 100,000
Common stock issued \| shares						39,873,868		39,763,049
Contingent stock liability							733,000	$ 0		$ 373,000
Cash payment for contingent equity settlement								$ 277,000
Annual maintenance fee pursuant to license agreement				$ 100,000
Annual maintenance fee pursuant to ULRF license agreement	$ 100,000
Cash paid for measurement of operating lease liability						$ 200,000
Other Liabilities
Loss Contingencies [Line Items]
Contingent stock liability							$ 700,000
ULRF
Loss Contingencies [Line Items]
Common stock issued \| shares			16,297
Cash payment for contingent equity settlement			$ 300,000
ULRF \| IPO
Loss Contingencies [Line Items]
Common stock issued \| shares			48,889
Cash payment for contingent equity settlement			$ 300,000
ULRF License Agreement \| ULRF
Loss Contingencies [Line Items]
Percentage of compensation on net sales of all licensed products sold					3.00%
Compensation on non-royalty sublicensing income						one third
Common stock issued \| shares					65,186
ULRF License Agreement \| ULRF \| Contingent Equity Consideration
Loss Contingencies [Line Items]
Common stock issued \| shares					65,186
ULRF License Agreement \| ULRF \| Maximum
Loss Contingencies [Line Items]
Compensation on regulatory and sales milestones					$ 1,625,000
Kentucky
Loss Contingencies [Line Items]
Lease termination date		Nov. 30, 2023
Wellesley
Loss Contingencies [Line Items]
Lease commencement date						Apr. 30, 2021
Massachusetts
Loss Contingencies [Line Items]
Lease termination date						Mar. 31, 2021
Houston, Texas
Loss Contingencies [Line Items]
Lease term period									36 months

Commitments and Contingencies - Summary of Future Minimum Rent Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Jan. 01, 2022
Operating Lease Liabilities Payments Due Rolling Maturity [Abstract]
2022	$ 668
2023	1,064
2024	936
2025	756
2026 and beyond	437
Total lease payments	3,861
Less: imputed interest	(462)
Present value of lease liabilities	$ 3,399	$ 3,500

Commitments and Contingencies - Summary of Operating Lease Term and Discount Rate (Details)	Mar. 31, 2022
Lessee, Operating Lease, Description [Abstract]
Weighted-average remaining lease term (years)	4 years
Weighted-average discount rate	6.50%

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	May 31, 2021	Dec. 31, 2020
Convertible Preferred Stock [Line Items]
Issuance costs, incurred	$ 11
Series A Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	40,000,000		40,000,000
Series A Convertible Preferred Stock \| Common Stock
Convertible Preferred Stock [Line Items]
Conversion of preferred stock		7,476,632
Series A-1 Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	28,000,000		28,000,000
Series A-1 Convertible Preferred Stock \| Common Stock
Convertible Preferred Stock [Line Items]
Conversion of preferred stock		5,233,637
Series B Convertible Preferred Stock
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	62,499,993		62,499,993
Series B Convertible Preferred Stock \| Non-voting Common Stock
Convertible Preferred Stock [Line Items]
Conversion of preferred stock		1,150,000
Series B Convertible Preferred Stock \| Common Stock
Convertible Preferred Stock [Line Items]
Conversion of preferred stock		10,532,229

Common Stock (Additional Information) (Details) - $ / shares	Mar. 31, 2022	Dec. 31, 2021	May 11, 2021	Apr. 30, 2021
Class Of Stock [Line Items]
Authorization of undesignated preferred stock				10,000,000
Undesignated preferred stock, par value				$ 0.0001
Common stock, shares authorized	140,000,000	140,000,000
Undesignated preferred stock, outstanding	0		0
Voting Shares
Class Of Stock [Line Items]
Common stock, shares authorized				140,000,000
Non-voting Shares
Class Of Stock [Line Items]
Common stock, shares authorized	10,000,000	10,000,000		10,000,000

Common Stock - Schedule of Common Stock Reserved (Details) - shares	Mar. 31, 2022	Dec. 31, 2021	Apr. 30, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Outstanding common stock options	5,957,614	3,643,796		2,745,185
2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares reserved for issuance			852,971
Common Stock
Class Of Stock [Line Items]
Restricted stock related to early exercise of common stock options	438,201	538,340
Outstanding common stock options	5,957,614	3,643,796
Total	10,958,251	7,722,219
Common Stock \| Restricted Stock Units
Class Of Stock [Line Items]
Total	859,769
Common Stock \| Equity Incentive Plans
Class Of Stock [Line Items]
Shares reserved for issuance	2,451,066	2,702,995
Common Stock \| 2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares reserved for issuance	1,251,601	837,088

Stock-Based Compensation - Additional Information (Details) $ in Millions			3 Months Ended	12 Months Ended
	Jan. 01, 2022 shares	Apr. 30, 2021 shares	Mar. 31, 2022 USD ($) Installment shares	Dec. 31, 2021 shares	Dec. 31, 2020 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, shares			5,957,614	3,643,796	2,745,185
Contractual term of stock option			9 years 7 days	8 years 8 months 8 days	9 years 4 months 24 days
Unrecognized compensation cost \| $			$ 25.0
Unrecognized compensation cost, expected to be recognized period			3 years 4 months 24 days
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increment in number of shares authorized possible	2,072,569
Number of shares remained available for future grant		6,397,289	2,451,066
Percentage of shares issued and outstanding				5.00%
Percentage of fair market value of common stock			100.00%
Stock options vesting period			4 years
2021 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized under the plan		3,015,907
Contractual term of stock option			10 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares remained available for future grant		3,381,382
Options outstanding, shares			5,882,848
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Discount percentage to purchase shares		15.00%
Offering periods		6 months
Increment in number of shares authorized possible	414,513	3,000,000
Number of shares authorized under the plan		852,971
Percentage of cumulative number of shares of common stock issued and outstanding		1.00%
Percentage Of cumulative number of shares of common stock outstanding	1.00%
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost \| $			$ 7.2
Unrecognized compensation cost, expected to be recognized period			2 years 3 months 18 days
Number of installments, vested \| Installment			4
Incremental period of vesting			2 years

Stock-Based Compensation - Schedule of Assumptions Used to Determine the Fair Values of Stock Options Granted (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Stock Option \| 2021 and 2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility, minimum	82.70%	80.60%
Volatility, maximum	82.90%	83.00%
Risk-free interest rate, minimum	1.46%	0.50%
Risk-free interest rate, maximum	1.70%	1.07%
Expected term (years)	6 years 3 months	6 years 3 months
Common Stock \| Stock Option \| 2021 and 2018 Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 7.58	$ 5.72
Common Stock \| Stock Option \| 2021 and 2018 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 16.56	$ 6.79

Stock-Based Compensation - Summary of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award Additional General Disclosures [Abstract]
Options outstanding, beginning balance, shares	3,643,796	2,745,185
Granted, shares	2,473,700	1,076,022
Exercised, shares	(10,680)	(149,707)
Cancelled, shares		(7,605)
Forfeited, shares	(149,202)	(20,099)
Options outstanding, ending balance, shares	5,957,614	3,643,796	2,745,185
Options exercisable, shares	1,297,253
Options vested and expected to vest, shares	2,652,637
Options outstanding, weighted- average exercise price	$ 5.75	$ 4.20
Granted, weighted- average exercise price	9.07	9.19
Exercised, weighted- average exercise price	2.83	2.12
Cancelled, weighted-average exercise price		1.38
Forfeited, weighted- average exercise price	7.71	5.79
Options outstanding, weighted- average exercise price	7.09	$ 5.75	$ 4.20
Options exercisable, weighted- average exercise price	4.34
Options vested and expected to vest, weighted- average exercise price	$ 2.69
Options outstanding, weighted- average remaining contractual life	9 years 7 days	8 years 8 months 8 days	9 years 4 months 24 days
Options exercisable, weighted- average remaining contractual life	8 years 1 month 13 days
Options vested and expected to vest, weighted- average remaining contractual life	7 years 6 months 29 days
Options outstanding, aggregate intrinsic value	$ 16,418	$ 34,754	$ 4,183

Stock-Based Compensation - Summary of Additional Information to Stock Option Activity Involving Employees and Directors (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract]
Weighted-average grant-date fair value per option of total options granted	$ 6.49	$ 4.73
Aggregate intrinsic value of stock options exercised	$ 76	$ 166

Stock-Based Compensation - Summary of RSU Activity (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, Number of Restricted Stock Units \| shares	864,802
Forfeited, Number of Restricted Stock Units \| shares	(5,033)
Outstanding, Number of Restricted Stock Units, ending balance \| shares	859,769
Granted, Weighted-Average Grant Date Fair Value \| $ / shares	$ 9.08
Forfeited, Weighted-Average Grant Date Fair Value \| $ / shares	9.10
Outstanding, Weighted-Average Grant Date Fair Value, ending balance \| $ / shares	$ 9.08

Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,197	$ 835
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,276	326
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 921	$ 509

Net Loss Per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Earnings Per Share [Abstract]
Net loss and net loss attributable to common stockholders	$ (18,259)	$ (9,299)	$ (47,800)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.45)	$ (1.30)
Weighted average number of common shares outstanding used in computation of net loss per common share, basic and diluted	40,980,213	7,160,631

- Definition

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

+ References

+ Details

Net Loss Per Share Attributable to Common Stockholders - Summary of Potential Dilutive Securities Excluded From Calculation of Net Loss Per Share Due to Anti-dilutive Effect (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	7,255,584	28,753,377
Convertible Preferred Shares (as Converted to Common Stock and Non-voting Common Stock)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect		24,392,498
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	5,957,614	3,456,153
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	859,769
Restricted Stock Related to Early Exercise of Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect	438,201	839,540
Contingent Common Stock (as Converted to Common Stock)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from calculation of net loss per share due to anti-dilutive effect		65,186

Subsequent Events - Additional Information (Details)	Mar. 31, 2022
Subsequent Event [Line Items]
Lease term period	39 months