0000950170-22-002998 | 10-K | XBRL Viewer

Print Document View Excel Document

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets
Cash	$ 46,922	$ 20,487
Short-term marketable securities	89,558	0
Prepaid expenses and other current assets	11,772	1,511
Total current assets	148,252	21,998
Long-term marketable securities	24,919	0
Other long term assets	70	2,633
Total assets	173,241	24,631
Current liabilities:
Accounts payable	1,404	1,086
Accounts payable, related party	0	207
Accrued expenses	4,588	1,219
Accrued expenses with related parties	39	0
Redeemable convertible preferred stock tranche liability	0	551
Total current liabilities	6,031	3,063
Other long-term liabilities	7	0
Total liabilities	6,038	3,063
Commitments and contingencies (Note 7)
Redeemable convertible preferred stock, $0.0001 par value per share, 10,000,000 and 12,909,389 shares authorized, 0 and 7,140,157 shares issued and outstanding with aggregate liquidation preference of $0 and $49,891 at December 31, 2021 and 2020, respectively	0	46,551
Stockholders' equity (deficit)
Common stock, $0.0001 par value per share, 13,100,000 and 40,000,000 shares authorized and 26,235,317 and 3,418,751 shares issued and outstanding at December 31, 2021 and 2020, respectively	3	1
Additional paid-in capital	242,939	3,152
Accumulated other comprehensive loss	(123)	0
Accumulated deficit	(75,616)	(28,136)
Total stockholders’ deficit	167,203	(24,983)
Total liabilities, redeemable convertible preferred stock and stockholders' equity	$ 173,241	$ 24,631

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Temporary Equity, par value	$ 0.0001	$ 0.0001
Temporary Equity, Shares Authorized	10,000,000	12,909,389
Temporary Equity, Shares Issued	0	7,140,157
Temporary Equity, Shares Outstanding	0	7,140,157
Temporary Equity, Liquidation preference	$ 0	$ 49,891
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	250,000,000	40,000,000
Common stock, shares issued	26,235,317	3,418,751
Common stock, shares outstanding	26,235,317	3,418,751

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating expenses:
Research and development	$ 22,046	$ 8,769
Research and development, related party	1,276	573
In-process research and development		9,158
General and administrative	12,350	2,425
Total operating expenses	35,672	20,925
Loss from operations	(35,672)	(20,925)
Other income (expense):
Change in fair value of redeemable convertible preferred stock tranche liability	11,718
Foreign currency gain (loss)	(170)	257
Other Income, net	80
Total other income (expense)	(11,808)	257
Net loss	(47,480)	(20,668)
Accretion of redeemable convertible preferred stock to redemption value and cumulative preferred stock dividends	(4,548)	(2,285)
Net loss attributable to common stockholders	$ (52,028)	$ (22,953)
Net loss per share attributable to common stockholders, basic and diluted	$ (4.24)	$ (10.49)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	12,260,551	2,187,813
Comprehensive loss:
Net loss	$ (47,480)	$ (20,668)
Other comprehensive loss:
Unrealized loss on investments, net of tax of $0	(123)
Comprehensive loss	$ (47,603)	$ (20,668)

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Income tax	$ 0	$ 0

- Definition

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

+ References + Details

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock [Member]	Series B Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2019	$ (5,562)			$ 1	$ 1,905		$ (7,468)
Beginning balance (in shares) at Dec. 31, 2019		3,999,133
Beginning balance at Dec. 31, 2019		$ 26,174
Beginning balance, (in shares) at Dec. 31, 2019				1,852,797
Issuance of Series A redeemable convertible preferred stock and common stock for the acquisition of in-process research and development from a related party	2,043	$ 14,500			2,043
Issuance of Series A redeemable convertible preferred stock and common stock for the acquisition of in-process research and development from a related party, shares		2,500,000		1,527,528
Issuance of Series A-1 Preferred Stock (net of issuance costs and tranche liability)		$ 4,374
Issuance of Series A-1 Preferred Stock (net of issuance costs and tranche liability), shares		641,024
Accretion of redeemable convertible preferred stock	(1,503)	$ 1,503			(1,503)
Vesting of restricted stock awards, shares				38,426
Stock-based compensation	707				707
Net loss	(20,668)						(20,668)
Ending balance at Dec. 31, 2020	$ (24,983)			$ 1	3,152		(28,136)
Ending balance, (in shares) at Dec. 31, 2020	7,140,157	7,140,157
Ending balance at Dec. 31, 2020	$ 46,551	$ 46,551
Ending balance (in shares) at Dec. 31, 2020				3,418,751
Reclassification Of Redeemable Convertible Preferred Stock Tranche Liability Upon Settlement	(12,269)	$ 12,269
Conversion of redeemable convertible preferred stock to common stock upon initial public offering, Shares		(15,345,279)		15,345,279
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	152,759	$ (152,759)		$ 1	152,758
Proceeds from issuance of common stock in initial public offering, Shares				7,360,000
Proceeds from issuance of common stock in initial public offering	83,144			$ 1	83,143
Issuance of Series A-1 Preferred Stock (net of issuance costs and tranche liability)		$ 33,978	$ 59,961
Issuance of Series A-1 Preferred Stock (net of issuance costs and tranche liability), shares		4,358,972	3,846,150
Exercise of stock options and vesting of restricted stock awards, shares				111,287
Exercise of stock options and vesting of restricted stock awards	149				149
Stock-based compensation	3,737				3,737
Other Comprehensive Income (Loss), Net of Tax	(123)					$ (123)
Net loss	(47,480)						(47,480)
Ending balance at Dec. 31, 2021	$ 167,203			$ 3	$ 242,939	$ (123)	$ (75,616)
Ending balance, (in shares) at Dec. 31, 2021	0	0
Ending balance at Dec. 31, 2021	$ 0	$ 0
Ending balance (in shares) at Dec. 31, 2021				26,235,317

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholder' Deficit (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Series A1 Preferred Stock [Member]
Stock issuance cost	$ 22	$ 75
Stock tranche liability		$ 551
Series B Preferred Stock [Member]
Stock issuance cost	39
Common Stock [Member]
Stock issuance cost	$ 8,856

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (47,480)	$ (20,668)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	3,737	707
Change in fair value of redeemable convertible preferred stock tranche liability	(11,718)
Investment amortization	(370)
Foreign currency gain from remeasurement	245	359
In-process research and development expenses		9,158
Changes in operating assets and liabilities:
Prepaid expenses and other assets	10,260	1,352
Long term assets	(2,563)	2,524
Accounts payable	318	(167)
Accrued liabilities	3,368	964
Accounts payable and accrued liabilities, related party	(168)	143
Long-term liabilities	7
Net cash used in operating activities	(36,072)	(14,098)
Cash flows from investing activities:
Assets acquired in asset acquisition including cash		8,279
Cash used for purchase of in-process research and development from a related party		(201)
Purchase of marketable securities	(114,970)
Net cash provided by (used in) investing activities	(114,970)	8,078
Cash flows from financing activities:
Proceeds from initial public offering, net issuance costs	83,144
Proceeds from issuance of redeemable convertible preferred stock and related tranche rights, net of issuance costs	93,939	4,925
Proceeds from exercise of stock options	149
Net cash provided by financing activities	177,232	4,925
Effect of exchange rate changes on cash	245	359
Net change in cash and cash equivalents	26,435	(736)
Cash and cash equivalents at beginning of period	20,487	21,223
Cash and cash equivalents at end of period	46,922	20,487
Supplemental disclosure of cash flow information:
Conversion of redeemable convertible preferred stock to common stock	152,759
Redeemable convertible preferred stock accretion		$ 1,503

Nature of Operations and Basis of Presentation

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Operations and Basis of Presentation

Note 1. Nature of Operations and Basis of Presentation

Organization

Eliem Therapeutics, Inc. (the Company) is a clinical-stage biotechnology company focused on developing novel therapies for neuronal excitability disorders to address unmet needs in chronic pain, neuropsychiatry, epilepsy and other disorders of the peripheral and central nervous systems. Headquartered in Redmond, Washington, the Company was incorporated on October 18, 2018 as a Delaware corporation.

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements of the Company and its wholly owned subsidiaries have been prepared in conformity with accounting principles generally accepted in the United States (U.S. GAAP). All intercompany transactions and balances have been eliminated in consolidation.

Reverse Stock Split

In July 2021, the Company's board of directors approved an amendment to the Company's certificate of incorporation to effect a reverse split of shares of the Company's common stock on a 1-for-2 basis, which was effected on July 29, 2021 (the Reverse Stock Split). The number of authorized shares and the par values of the common stock were not adjusted as a result of the Reverse Stock Split. In connection with the Reverse Stock Split, the number of authorized shares, outstanding shares, and the conversion ratio for the Company's redeemable convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. All references to common stock and options to purchase common stock share data, per share data, and related information contained in the consolidated financial statements have been retroactively adjusted to reflect the effect of the Reverse Stock Split for all periods presented.

Initial Public Offering

On August 12, 2021, the Company completed its initial public offering (IPO) of 7,360,000 shares of common stock, including the underwriters' full exercise of their over-allotment option at the IPO price of $12.50 per share. Gross proceeds from the IPO were $92.0 million, and the net proceeds were $83.1 million, after deducting underwriting discounts of $6.4 million and $2.5 million of offering costs payable by the Company. At the closing of the IPO, all of the Company's then outstanding redeemable convertible preferred stock was automatically converted into an aggregate of 15,345,279 shares of common stock. The related carrying value of the redeemable convertible preferred stock of $152.8 million was reclassified to common stock and additional paid-in capital.

Liquidity

Since inception, the Company has experienced recurring losses from operations and generated negative cash flows from operations. The Company has an accumulated deficit of $75.6 million and expects to incur additional losses from operations in the future. The Company estimates the available cash, cash equivalents, and marketable securities of $161.4 million as of December 31, 2021 will be sufficient to meet its projected operating requirements for at least the next twelve months from the filing date of these consolidated financial statements.

The Company will need to obtain substantial additional funding to develop and commercialize the Company's clinical programs as currently contemplated. The Company expects to finance future cash needs through equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other marketing and distribution arrangements. In addition, the Company expects to continue to rely on capital markets, and to a lesser extent, U.K. research and development tax credits and incentives for funding. There are no assurances that the Company will be able to raise sufficient amounts of funding in the future on acceptable terms, or at all.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

A summary of the significant accounting policies followed by the Company in the preparation of the accompanying consolidated financial statements follows:

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts and disclosures. Accordingly, actual results could differ from those estimates. Estimates include those related to the valuation of assets acquired, accrual of research and development expenses, the valuation of stock-based awards, the valuation of common stock and redeemable convertible preferred stock, and the valuation of redeemable convertible preferred stock tranche liabilities. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, and marketable securities. The Company’s cash is held by two financial institutions in the United States (U.S.) and two financial institutions in the United Kingdom (U.K.). The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company’s deposits held in the U.S. and U.K. may exceed the Federal Depository Insurance Corporation and Financial Services Compensation Scheme, respectively, insured limits. The Company has investments in money market funds, U.S. government debt securities, commercial paper, and corporate bonds with high-quality accredited financial institutions.

Comprehensive Loss

Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company presents comprehensive loss and its components as part of the statements of operations and comprehensive loss.

Risks and Uncertainties

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, reliance on single-source vendors and collaborators, availability of raw materials, patentability of the Company’s products and processes and clinical efficacy and safety of the Company’s products under development, compliance with government regulations and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical studies, clinical trials, and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance and reporting.

There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company operates in an environment of rapid technological change and substantial competition from other pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and other third parties.

Moreover, the current COVID-19 pandemic, which is impacting worldwide economic activity, poses risk that the Company or its employees, contractors, suppliers, and other partners may be prevented from conducting business activities for an indefinite period of time which may increase costs and could delay the start-up and conduct of the Company’s clinical trials, and negatively impact manufacturing and testing activities performed by third parties. Any significant delays and higher costs may impact the use and sufficiency of the Company’s existing cash reserves, and the Company may be required to raise additional capital earlier than it had previously planned. The Company may be unable to raise additional capital if and when needed, which may result in delays or suspension of its development plans. The extent to which the pandemic will impact the Company’s business will depend on future developments that are highly uncertain and cannot be predicted at this time.

Segments

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker (the CODM). The Company’s CODM is its chief executive officer who reviews financial information together with certain operating metrics principally to make decisions about how to allocate resources and to measure the Company’s performance. Management has determined that the Company operates as a single operating and reportable segment. The Company’s CODM evaluates financial information on a consolidated basis. As the Company operates as one operating segment, all required segment financial information is found in the consolidated financial statements.

Fair Value Measurement

Assets and liabilities recorded at fair value on a recurring basis in the balance sheet are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The Company measures fair value based on a three-tier hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows:

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the assets or liabilities. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

In determining fair value, the Company utilizes quoted market prices, or valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value.

There were no transfers into or out of Level 3 for any of the periods presented.

The following table identifies the Company’s assets and liabilities that were measured at fair value (in thousands):


	December 31, 2021
	Level 1		Level 2		Level 3		Balance
Assets:
Cash equivalents:
Money market funds	$	30,557	$	—	$	—	$	30,557
Marketable securities:
U.S. government debt securities		3,979		—		—		3,979
Commercial paper		—		54,363		—		54,363
Corporate bonds		—		56,135		—		56,135
Total marketable securities		3,979		110,498		—		114,477
Total assets	$	34,536	$	110,498	$	—	$	145,034


	December 31, 2020
	Level 1		Level 2		Level 3		Balance
Liabilities:
Redeemable convertible preferred stock
tranche liability	$	—	$	—	$	551	$	551
Total liabilities	$	—	$	—	$	551	$	551

As discussed further in Note 6, the redeemable convertible preferred stock tranche liability was settled on March 9, 2021, and the fair value of the liability was remeasured immediately prior to settlement.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. As of December 31, 2021, the Company's cash equivalents consisted of money market funds. There were no cash equivalents as of December 31, 2020.

Asset Acquisition

In accordance with the guidance in Topic 805, Business Combinations, in the Financial Accounting Standards Board’s (FASB) Accounting Standards Codification (ASC), the Company evaluates acquisitions of assets and related liabilities and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen test is met, the transaction is accounted for as an asset acquisition. If the screen test is not met, further determination is required as to whether or not the Company has acquired inputs and processes that have the ability to create outputs which would meet the requirements of a business.

The Company accounts for an asset acquisition by recognizing net assets based on the cost to the acquiring entity on a relative fair value basis, which includes transaction costs in addition to consideration given. Goodwill is not recognized in an asset acquisition; any excess consideration transferred over the fair value of the net assets acquired is allocated to the non-monetary identifiable assets and liabilities assumed based on relative fair values. In-process research and development acquired in an asset acquisition is expensed provided there is no alternative future use.

Investments in Marketable Securities

Marketable securities are classified as available-for-sale, primarily consisting of U.S. government debt securities, commercial paper, and corporate bonds, and are reported at fair value. Unrealized holding gains and losses are reflected as a separate component of stockholders' equity (deficit) in accumulated other comprehensive loss until realized. Realized gains and losses on the sale of these securities are recognized in other income, net. The cost of marketable securities sold is based on the specific identification method.

The Company periodically reviews its available-for-sale securities to assess for credit impairment. Some of the factors considered in assessing impairment include the extent to which the fair value is less than the amortized cost basis, adverse conditions related to the security, an industry or geographic area, changes to security rating or sector credit ratings, and other relevant market data.

Research and Development Expenses

Research and development expenses consist primarily of research and development services and, to a lesser extent, salaries, benefits, and other personnel-related costs, including stock-based compensation, professional service fees, and other related costs such as facility rent, partially offset by fully refundable U.K. research and development tax credits. The Company recognizes the benefit of refundable research and development tax credits as a reduction of research and development expenses when there is reasonable assurance that the amount claimed will be recovered.

Research and development expenses includes estimates of the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs. Management estimates accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known at that time. Examples of estimated accrued research and development expenses include those related to fees paid to:

•

vendors in connection with preclinical development activities;

•

contract research organizations (CROs) in connection with preclinical studies and clinical trials; and

•

contract development and manufacturing organizations (CDMOs) in connection with the production of preclinical and clinical trial materials.

All research and development costs are expensed in the period incurred, based on the estimates of the services received and efforts expended considering a number of factors, including, progress towards completion of the research, development and manufacturing activities, invoicing to date under the contracts, communication from the CROs, CDMOs and other companies of any actual costs incurred during the period that have not yet been invoiced and the costs included in the contracts and purchase orders. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which advance payments are made or payments made to vendors will exceed the level of services provided and result in a prepayment of the expense.

General and Administrative Expenses

General and administrative expenses consist primarily of personnel-related expenses, such as salaries, bonuses, benefits, and stock-based compensation, for our personnel in executive, finance and accounting, human resources, business development and other administrative functions. Other significant general and administrative expenses include legal fees relating to intellectual property and corporate matters, professional fees for accounting, tax and consulting services, insurance costs, and travel expenses. General and administrative costs are expensed as incurred.

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist primarily of amounts due for refundable research and development tax credits from the U.K. government and operating expenses paid in advance.

Leases

The Company leases office space in the U.S. and the U.K. The Company analyzes leases at the inception of each agreement for classification as either an operating or capital lease. The terms in the Company's lease agreements include rent holidays and rent escalation clauses. The Company recognizes rent expense on a straight-line basis equal to the amount of total minimum lease payments over the noncancelable term of the operating leases and, accordingly, records the
difference between cash rent payments and the recognition of rent expense as an increase or decrease in deferred rent liability.

Accretion and Classification of Redeemable Convertible Preferred Stock

The redeemable convertible preferred stock is classified outside of stockholders’ equity (deficit) on the consolidated balance sheets because the holders of such shares have liquidation rights in the event of a deemed liquidation that, in certain situations, are not solely within the control of the Company and would require the redemption of the then-outstanding redeemable convertible preferred stock.

The holders of the Company’s redeemable convertible preferred stock had the option to redeem their shares beginning in October 2026. As a result, these shares were considered probable of becoming redeemable since the redemption option depends solely on the passage of time. The Company accreted changes in the redemption value over the period from the date of issuance to the earliest redemption date of October 2026. In October 2020, the Company amended the terms of its Certificate of Incorporation to remove the redemption option of their Series A and Series A-1 redeemable convertible preferred stock, which was accounted for as a modification, and the Company ceased accretion.

Upon completion of the IPO on August 12, 2021, all of the Company's then outstanding redeemable convertible preferred stock were converted on a 1-for-1 basis to shares of common stock. As of December 31, 2021, the Company had no redeemable convertible preferred stock outstanding.

Redeemable Convertible Preferred Stock Tranche Liability

The Company’s Series A-1 redeemable convertible preferred stock included tranche rights that were determined to be freestanding financial instruments that should be accounted for as a liability at fair value (Note 6). This redeemable convertible preferred stock tranche liability was revalued at each reporting period until settlement with changes in the fair value recorded as a change in redeemable convertible preferred stock tranche liability in the consolidated statements of operations and comprehensive loss. Upon the closing of the redeemable convertible preferred stock, the redeemable convertible preferred stock purchase rights liability was extinguished, and the mark-to-market fair value of the liability was included in the carrying value of the redeemable convertible preferred stock issued.

As discussed further in Note 6, the Series A-1 redeemable convertible preferred tranche liability was settled on March 9, 2021 with the achievement of milestones set forth in the Series A-1 stock purchase agreement.

Stock-Based Compensation

The Company measures its stock-based awards granted to employees, non-employee directors, consultants and independent advisors based on the estimated grant-date fair value of the awards. For awards with only service conditions, including stock options and restricted stock awards, compensation expense is recognized over the requisite service period using the straight-line method. For awards that include performance conditions, compensation expense is not recognized until the performance condition is probable to occur. The Company uses the Black-Scholes option pricing model to estimate the fair value of its stock option awards. The Black-Scholes option pricing model requires the Company to make assumptions and judgements about the variables used in the calculations, including the fair value of common stock, expected term, expected volatility of the Company’s common stock, risk-free interest rate and expected dividend yield. As the stock-based compensation is based on awards ultimately expected to vest, it is reduced by forfeitures, which the Company accounts for as they occur.

Fair Value of Common Stock

Following the closing of the Company’s IPO, the fair market value of the Company's common stock is based on its closing price as reported on the date of grant on the Nasdaq Global Market, on which the Company’s common stock is traded.

Prior to the Company’s IPO, because there was no public market for the Company’s common stock, the estimated fair value of the Company’s common stock was determined by the board of directors as of the date of each option grant with input from management, considering the most recently available third-party valuation 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 the most recent valuation through the date of the grant. Management believes that the board of directors has the relevant experience and expertise to determine fair value of the common stock. Third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Management has considered numerous factors in determining the best estimate of fair value of our common stock, including the following:

•

valuations performed by independent third-party specialists;

•

the Company’s operating results, financial position, and capital resources;

•

the Company’s stage of development and material risks related to its business;

•

the progress of the Company’s research and development programs;

•

business conditions and projects;

•

the lack of marketability of the Company’s common stock and its redeemable convertible preferred stock as a private company;

•

the prices at which the Company sold shares of redeemable convertible preferred stock to outside investors in arms-length transactions;

•

the rights, preferences, and privileges of the Company’s redeemable convertible preferred stock relative to those of the Company’s common stock;

•

the analysis of IPOs and the market performance of similar companies in the biotechnology industry;

•

the likelihood of achieving a liquidity event for securityholders, such as an initial public offering or a sale of the Company, given prevailing market conditions;

•

the hiring of key personnel and the experience of management;

•

trends and developments in the industry; and

•

external market conditions affecting the life sciences and biotechnology industry sectors.

For valuations performed in the first and second quarter of 2021, in accordance with the Practice Aid, the Company determined that the Hybrid Method, was the most appropriate method for determining the fair value of its common stock based on its stage of development and other relevant factors.

The Hybrid Method is a combination of an Option Pricing Method (OPM) scenario and one or more scenarios using a Probability Weighted Expected Return Method (PWERM). The Hybrid Method estimates the probability-weighted value across multiple scenarios, and uses the OPM to estimate the allocation of value within one or more of those scenarios. Weighting allocations are assigned to the OPM and PWERM methods factoring possible future liquidity events. The Company applied the Hybrid Method when it considered both an IPO and trade sale scenarios.

The OPM uses option theory to value the various classes of a company’s securities in light of their respective claims to the enterprise value. Total stockholders’ deficit value is allocated to the various share classes based upon their respective claims on a series of call options with strike prices at various value levels depending upon the rights and preferences of each class. A Black-Scholes closed form option pricing model is employed in this analysis, with an option term assumption that is consistent with the expected time to a liquidity event and a volatility assumption based on the estimated stock price volatility of a peer group of comparable public companies over a similar term.

The PWERM values each class of equity based on an analysis of the range of potential future enterprise values of the company and the manner in which those values would accrue to the owners of the different classes of equity. This method involves estimating the overall value of the subject company under various liquidity event scenarios and allocating the value to the various share classes based on their respective claim on the proceeds as of the date of each event. These different scenarios typically include an initial public offering, an acquisition, or a liquidation of the business, each resulting in a different value. For each scenario, the future value of each share class is calculated and discounted to a present value. The results of each scenario are then probability weighted in order to arrive at an estimate of fair value for each share class as of a current date.

For valuations performed in 2020, in accordance with the Practice Aid, the Company determined that the OPM was the most appropriate method for determining the fair value of its common stock based on its stage of development and other relevant factors.

The assumptions underlying these valuations represented management’s best estimates, which involved inherent uncertainties and the application of management’s judgment. As a result, if the Company had used significantly different assumptions or estimates, the fair value of its common stock and stock-based compensation expense could have been materially different.

Income Taxes

Income taxes are accounted for using the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts or existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. 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 recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Foreign Currency

The Company’s reporting currency is the U.S. dollar. The functional currency of the Company and its subsidiaries is the U.S. dollar. Monetary assets and liabilities resulting from transactions denominated in currencies other than the functional currency are remeasured in the functional currency at exchange rates prevailing at the balance sheet date, and income items and expenses are translated into U.S. dollars at the average exchange rate in effect during the period. Exchange gains and losses resulting from remeasurement and foreign currency transactions are included in the determination of net loss.

Net Loss Per Share

Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, adjusted for outstanding shares that are subject to repurchase.

Diluted net loss per share attributable to common stockholders is computed by giving effect to all potentially dilutive securities outstanding for the period using the treasury stock method or the if-converted method based on the nature of such securities. For periods in which the Company reports net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, because potentially dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

Prior to completion of the IPO on August 12, 2021 (at which time the Company's then outstanding redeemable convertible preferred stock were converted on a 1-for-1 basis to shares of common stock, thereby eliminating the cumulative preferred stock dividend), basic net loss per share attributable to common stockholders was computed using the two-class method required for multiple classes of common stock and participating securities based upon their respective rights to receive dividends as if all income for the period has been distributed. The two-class method requires loss available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to share in undistributed earnings as if all loss for the period had been distributed. The Company’s participating securities included the Company’s redeemable convertible preferred stock, as the holders are entitled to receive dividends on a pari passu basis in the event that a dividend was paid on common stock. The holders of redeemable convertible preferred stock do not have a contractual obligation to share in losses of the Company, and therefore during periods of loss there was no allocation required under the two-class method.

Emerging Growth Company Status

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to avail itself of this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recently Adopted Accounting Pronouncements

In August 2018, the FASB issued Accounting Standards Update (ASU) 2018-15, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 requires customers in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification (ASC) 350-402 to determine which implementation costs to capitalize as assets, and is effective for non-public companies for annual periods beginning after 15 December 2020, and interim periods in annual periods beginning after 15 December 2021. The Company adopted ASU 2018-05 on January 1, 2021, which did not have a material impact on the Company’s consolidated financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), related to leases to increase transparency and comparability among organizations by requiring the recognition of right-of-use (ROU) assets obtained in exchange for lease liabilities on the balance sheet. Most prominent among the changes in the standard is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under the standard, disclosures are required to meet the objective of enabling users of consolidated financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The effective date of this update for nonpublic companies is for fiscal years beginning after December 15, 2021 and interim periods therein. The Company estimates that adoption will not have a material impact on its consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The standard changes how entities will measure credit losses for most financial assets, including accounts and notes receivables. The standard will replace today’s “incurred loss” approach with an “expected loss” model, under which companies will recognize allowances based on expected rather than incurred losses. Entities will apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The effective date of this update for non-public companies is for fiscal years beginning after December 15, 2022 and interim periods therein. The Company estimates that adoption will not have a material impact on its consolidated financial statements

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The standard simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and also improves consistent application by clarifying and amending existing guidance. The effective date of this update for non-public companies is for fiscal years beginning after December 15, 2021 and interim periods within fiscal years beginning after December 15, 2022. The Company is assessing the impact of this guidance and is continuing to evaluate the impact on its consolidated financial statements.

In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging —Contracts in Entity’s Own Equity (Subtopic 815-40)—Accounting For Convertible Instruments and Contracts in an Entity’s Own Equity. The standard simplifies accounting for convertible instruments by removing major separation models required under current GAAP. Consequently, more convertible debt instruments will be reported as a single liability instrument with no separate accounting for embedded conversion features. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for it. The standard also simplifies the diluted net income per share calculation in certain areas. The effective date of this update for non-public companies is for fiscal years beginning after December 15, 2023, including interim periods therein. Early adoption is permitted for fiscal years beginning after December 15, 2020 and interim periods therein. The Company is currently evaluating the impact that this new guidance will have on its consolidated financial statements.

Investments

12 Months Ended

Dec. 31, 2021

Investments [Abstract]

Investments

3. Investments

Investments consists of available-for-sale securities as follows (in thousands):


	December 31, 2021
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities:
Commercial paper	$	54,363	$	—	$	(1	)	$	54,362
Corporate bonds		35,231		—		(35	)		35,196
Total short-term marketable securities		89,594		—		(36	)		89,558
Long-term marketable securities:
U.S. government debt securities		3,996		—		(17	)		3,979
Corporate bonds		21,010		—		(70	)		20,940
Total long-term marketable securities	$	25,006	$	—	$	(87	)	$	24,919

All the commercial paper, U.S. government debt securities, and corporate bonds designated as short-term marketable securities have a contractual maturity date that is equal to or less than one year from the respective balance sheet date. Those that are designated as long-term marketable securities have a contractual maturity date that is more than one year from the respective balance sheet date.

Accrued interest receivable is excluded from the amortized cost and estimated fair value of the Company's marketable securities. Accrued interest receivable of $0.5 million is presented separately within the prepaid expenses and other current assets line items in the Company's consolidated balance sheet as of December 31, 2021.

As of December 31, 2021, there were $60.1 million of corporate bonds and $4.0 million of commercial paper in a continual unrealized loss position for less than 12 months. There were no investments in a continual unrealized loss position for greater than twelve months.

Furthermore, the Company did not intend, nor was the Company more likely than not to be required, to sell its available-for-sale investments before the recovery of the amortized cost basis, which may be maturity. Based on the Company's assessment, it concluded that none of the available-for-sale investments held as of December 31, 2021 were considered to be other-than-temporarily impaired, as such, no impairment loss was recorded for the year ended December 31, 2021. There was no realized gain or loss on available-for-sale securities in the periods presented.

There were no investments as of December 31, 2020.

Certain Balance Sheet Accounts

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Certain Balance Sheet Accounts

4. Certain Balance Sheet Accounts

Prepaid Expenses and Other Current Assets

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


	December 31, 2021		December 31, 2020
Recoverable research and development tax credits	$	6,523	$	—
Prepaid research and development expenses		2,906		1,500
Prepaid expenses		1,491		—
Other assets		852		11
Total prepaid expenses and other current assets	$	11,772	$	1,511

Accrued Expenses

Accrued expenses consist of the following (in thousands):


	December 31 2021		December 31, 2020
Accrued payroll	$	2,220	$	592
Accrued research and development expenses		2,159		627
Other accrued expenses		248		—
Total accrued expenses	$	4,627	$	1,219

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock

5. Redeemable Convertible Preferred Stock

Upon completion of the IPO on August 12, 2021, all of the Company’s then outstanding redeemable convertible preferred stock was converted into an aggregate of 15,345,279 shares of common stock. As of December 31, 2021, the Company had no redeemable convertible preferred stock outstanding.

As of December 31, 2020, the Company’s redeemable convertible preferred stock consisted of the following balance (in thousands, except share and per share amounts):


	As of December 31, 2020
	Issue		Shares		Shares Issued and		Carrying		Aggregate Liquidation
	Price		Authorized		Outstanding		Value		Preference
Series A	$	6.00		2,717,084		2,717,082	$	17,074	$	18,569
Series A (Athenen Acquisition)	$	5.80		2,500,000		2,500,000	$	14,500	$	15,253
Series A-1	$	7.80		7,692,305		1,923,075	$	14,977	$	16,069
Ending balance				12,909,389		7,140,157	$	46,551	$	49,891

In March 2021, Series A-1 preferred stockholders exercised their tranche rights in connection with milestone achievements related to Phase 1 clinical trial results of ETX-155. As a result, the Company issued an additional 4,358,972 shares of Series A-1 redeemable convertible preferred shares for gross proceeds of $34.0 million. Upon exercise of the tranche rights, the Company reclassified the $12.3 million in preferred stock tranche liability to Series A-1 redeemable convertible preferred stock on the consolidated balance sheet.

In May 2021, the Company issued 3,846,150 shares of Series B redeemable convertible preferred stock for gross proceeds of $60.0 million.

Prior to conversion, the holders of the Series A, Series A-1, and Series B redeemable convertible preferred stock had various rights, preferences, privileges, and restrictions, with respect to voting, dividends, liquidation, and conversion.

Liquidation

In the event of any liquidation event, either voluntarily or involuntary, the holders of the Series B redeemable convertible preferred stock were entitled to receive, out of the assets of the Company before any payment shall be made or any assets distributed to the holders of Series A and A-1 redeemable convertible preferred stock, the Series B redeemable convertible preferred stock liquidation preference of $15.60, adjusted for any stock splits, combinations, and reorganizations, plus all unpaid cumulative dividends on each such share. If upon the liquidation event, the assets distributed among the holders of the Series B redeemable convertible preferred stock were insufficient to permit the payment to such holders of the full liquidation preference for their shares, then the holders of shares of the Series B redeemable convertible preferred stock shared ratably in any distribution of the assets available for distribution in proportion to their respective amounts, which otherwise would have been payable in respect of the shares held by them upon such distribution if all amounts payable on or with respect to such shares were paid the full preferential amount.

After the payment to the holders of the Series B redeemable convertible preferred stock of the full preferential amount, the holders of the Series A and Series A-1 redeemable convertible preferred stock were entitled to receive, out of the assets of the Company, the applicable liquidation preference specified for each series of redeemable convertible preferred stock before any payment was made or any assets distributed to the holders of common stock. Liquidation preference was $6.00 for Series A and $7.80 for Series A-1, each adjusted for any stock splits, combinations, and reorganizations, plus all unpaid cumulative dividends on each such share. If upon the liquidation event, the assets distributed among the holders of the Series A and A-1 redeemable convertible preferred stock were insufficient to permit the payment to such holders of the full liquidation preference for their shares, then the holders of shares of the redeemable convertible preferred stock shared ratably in any distribution of the assets available for distribution in proportion to their respective amounts, which otherwise would have been payable in respect of the shares held by them upon such distribution if all amounts payable on or with respect to such shares were paid the full preferential amount.

After the payment to the holders of the redeemable convertible preferred stock of the full preferential amount specified above, any remaining assets of the Company would have been distributed pro rata among all holders of the preferred and common stock.

A liquidation event required approval by the holders of at least a majority of the outstanding shares of redeemable convertible preferred stock and at least 70% of the then outstanding shares of Series B redeemable convertible preferred stock.

Optional Conversion

Each share of redeemable convertible preferred stock was convertible into common stock at the stockholder’s option. The converted shares would have been determined by dividing the original issue price for each series by the applicable conversion price for such series in effect at the date of conversion. The conversion price for each share of redeemable convertible preferred stock was initially equal to the original issuance price applicable to such share, with the exception of the Series A redeemable convertible preferred stock issued related to the Athenen Acquisition, which were convertible at any time after the date of issuance into common stock at the original issue price of the original Series A of $6.00. The conversion ratio was subject to appropriate adjustments for anti-dilution provisions, including stock splits, stock dividends, subdivisions, combinations, recapitalization events or similar events.

Specific to the Series B redeemable convertible preferred stock, the conversion ratio was subject to specific anti-dilution provisions adjustments if there was common stock issued for consideration below the Series B issue price.

Automatic Conversion

Each share of redeemable convertible preferred stock was convertible into common stock at initial conversion rates described under the Optional Conversion heading above, subject to adjustments based on certain antidilution provisions, including stock splits, stock dividends, subdivision, combinations, recapitalization or similar events, as provided by the Company’s certificate of incorporation. Further, all shares of redeemable convertible preferred stock automatically would have converted into common stock upon the vote or written consent of the holders of a majority of the shares of redeemable convertible preferred stock or upon the closing of a firm-commitment underwritten public offering of the Company’s common stock at a stock price of at least $17.16 per share and with gross aggregate proceeds to the Company of at least $80.0 million.

Upon completion of the IPO, the Company's redeemable convertible preferred stock was converted into 15,345,279 shares of common stock.

Dividends

The holders of shares of Series A, Series A-1, and Series B redeemable convertible preferred stock were entitled to receive cumulative dividends of 8% per annum of the original issuance price on each share of redeemable convertible preferred stock. The dividends were payable in cash, out of the assets at the time legally available thereof, when, as and if declared by the Board of Directors, on an equal basis according to the number of shares of redeemable convertible preferred stock held by such holders, prior and in preference to the common stock. As of December 31, 2020, the Company had total dividends in arrears for the Series A redeemable convertible preferred stock of $2.5 million, or $0.48 per share, and for Series A-1 redeemable convertible preferred stock of $1.1 million, or $0.56 per share. As of December 31, 2021, the Company had no dividends in arrears as all shares of redeemable convertible preferred stock converted to common stock upon the completion of the IPO.

Redemption

Under certain circumstances, subsequent to the occurrence of a deemed liquidation event, defined as (1) a majority of the holders of the then outstanding redeemable convertible preferred stock and (2) at least 70% of the then outstanding shares of the Series B redeemable convertible preferred stock could have required the Company to redeem their shares at a price per share equal to the liquidation amount, to the extent that sufficient funds were available. Additionally, holders of the Company’s Series A and Series A-1 redeemable convertible preferred stock initially had the option to redeem their shares beginning in October 2026. As a result, these shares were considered probable of becoming redeemable since redemption is solely dependent on the passage of time. As such, the Company adjusted the carrying value of the redeemable convertible preferred stock by accreting changes in the redemption value over the period from the date of issuance to the earliest redemption date of October 2026. In October 2020, the Company amended the terms of their Certificate of Incorporation to remove the redemption option of their Series A and Series A-1 redeemable convertible preferred stock, as a result the Company ceased recording adjustments to the carrying value of its outstanding redeemable convertible preferred stock for accretion to redemption value. There was no change in value as a result of this modification. There was no accretion to redemption value recorded for the year ended December 31, 2021.

Voting

The holders of the Company’s Series B redeemable convertible preferred stock, voting together as a class, were entitled to elect one (1) member of the Board of Directors (the Series B director). The holders of the Company’s Series A and Series A-1 redeemable convertible preferred stock, voting together as a class, were entitled to elect two (2) members of the Board of Directors (the Series A directors). The holders of the shares of common stock and of any other class or series of voting stock (including the preferred stock), voting together as a class, were entitled to elect the balance of the Company’s directors.

Stockholder Rights

The holders of the Company’s redeemable convertible preferred stock had protective provisions that required preferred stockholders representing a majority of the outstanding redeemable convertible preferred stock, voting as a single class (on an as-converted basis), to consent to specific actions including the following: changes in the corporation’s certificate of incorporation or bylaws that would affect, alter or change the preference or rights of the redeemable convertible preferred stock, changes in the authorized number of shares, declaration or payment of dividends, repurchase of shares, changes in the size of the Board of directors, creation of a new class or series of stock, or taking any action that would cause a liquidation event.

Further, the holders of the Company's Series B redeemable convertible preferred stock had additional protective provisions that required Series B preferred stockholders representing 70% of the outstanding shares of the Series B redeemable convertible preferred stock to consent to specific actions including the following: changes in the corporation’s certificate of incorporation or bylaws that would affect, alter or change the preference or rights of the Series B redeemable convertible preferred stock, changes in the authorized number of shares of Series B redeemable convertible preferred stock, declaration or payment of dividends or distributions shares of capital stock other than the Series A, Series A-1, and Series B redeemable convertible preferred stock, sell shares of Common Stock to the public at price below $17.16 in a firm-commitment underwritten public offering, or taking any action that would cause a liquidation event that would results in proceeds of less than $17.16 per share of the Series B redeemable convertible preferred stock.

Additionally, the holders of the Company’s Series A and Series A-1 redeemable convertible preferred stock had additional protective provisions that required preferred stockholders representing a majority of the outstanding redeemable convertible preferred stock, voting as a single class (on an as-converted basis), to consent to specific actions including the following: changes in the corporation’s certificate of incorporation or bylaws that would affect, alter or change the preference or rights of the Series A and Series A-1 redeemable convertible preferred stock and changes or reclassifications of any existing security of the Company that is pari passu with the Series A and/or Series A-1 redeemable convertible preferred stock.

Redeemable Convertible Preferred Stock Tranche Liability

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock Tranche Liability

6. Redeemable Convertible Preferred Stock Tranche Liability

The purchasers of Series A-1 redeemable convertible preferred stock also received tranche rights (Series A-1 Tranche Rights), which provided them the right to purchase additional shares of Series A-1 redeemable convertible preferred stock in a future tranche. This tranche was for the purchase of Series A-1 redeemable convertible preferred stock and was valued based upon the Company achieving certain future milestones and utilized a valuation model that reflected both potential outcomes of success or failure to meet the milestone.

Upon issuance in October 2020, the Series A-1 redeemable convertible preferred tranche liability was valued at $0.86 per share. There was no change in value from the date of issuance and December 31, 2020.

The Company estimated the fair value of the Series A-1 Tranche Rights using a probability-weighted present value model that considered the probability of triggering the Series A-1 Tranche Rights through achievement of the clinical development milestones specified in the Series A-1 purchase agreement. These estimates were based, in part, on subjective assumptions. Changes to these assumptions could have had a significant impact on the reported fair value of the Series A-1 Tranche Rights.

The following reflects the significant quantitative inputs used in the valuation of the redeemable convertible preferred stock tranche liability:


	Series A-1
	Tranche
	Call Option
Estimated fair value of redeemable convertible preferred stock	$6.94 - $11.10
Discount rate		0.10	%
Dividend yield		0	%
Expected term (years)	0.25 - 0.45
Expected volatility	N/A
Probability of milestone achievement	80% - 100%
Strike price	$	7.80
Fair value of each tranche feature	$0.86 - $3.32

The Series A-1 redeemable convertible preferred tranche liability was settled on March 9, 2021 with the achievement of milestones set forth in the Series A-1 stock purchase agreement. The fair value of the liability was remeasured prior to settlement, resulting in the Company recognizing a loss in the consolidated statement of operations and comprehensive loss of $11.7 million during the year ended December 31, 2021. Immediately thereafter, the balance of the redeemable convertible preferred stock tranche liability of $12.3 million was reclassified to Series A-1 redeemable convertible preferred stock.

A rollforward of the redeemable convertible preferred stock tranche liability is as follows (in thousands):


Balance at December 31, 2020	$	551
Change in fair value		11,718
Settlement upon issuance of Series A-1 redeemable convertible preferred stock		(12,269	)
Balance at December 31, 2021	$	—

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 7. Commitments and Contingencies

Operating Leases

Total rent expense for the years ended December 31, 2021 and 2020 was $248,000 and $51,000, respectively.

In November 2021, the Company entered into an agreement to lease approximately 5,000 square feet of office space in Bellevue, Washington. The term of this lease is for a period of 39 months, which commenced on November 1, 2021. The lease contains rent escalation clauses and an option to extend the term of the lease for an additional 3-year period at a market rate determined according to the lease.

Future minimum lease commitments for non-cancelable operating leases at December 31, 2021, the terms of which expire on various dates through January 31, 2025, are as follows (in thousands)


Year ending December 31,	Amount
2022	$	459
2023		333
2024		172
2025		15
Total minimum lease commitments	$	979

Legal Proceedings

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. As of the date of these consolidated financial statements, we are not party to any material legal matters or claims.

Indemnification

In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless, and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company intends to enter into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. The Company currently has directors’ and officers’ insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. The Company believes the estimated fair value of these indemnification agreements in excess of applicable insurance coverage is immaterial.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

8. Stock-Based Compensation

2019 Plan

In 2019, the Company adopted the 2019 Equity Incentive Plan (the 2019 Plan). The 2019 Plan provides for the Company to grant qualified stock options, non-qualified stock options, and restricted stock awards to employees, non-employee directors and consultants of the Company under terms and provisions established by the board of directors. Under the terms of the 2019 Plan, options are granted at an exercise price no less than fair value of the Company’s common stock on the grant date, except in certain cases related to employees outside of the U.S. However, for any employee who is a 10% or greater stockholder, options are granted at an exercise price no less than 110% of the fair value of the Company’s common stock on the grant date. Option awards granted typically have 10-year terms measured from the option grant date. However, if any employee is a 10% or greater stockholder, the awards have 5-year terms measured from the option grant date. While no shares are available for future issuance under the 2019 Plan, it continues to govern outstanding equity awards granted thereunder.

2021 Plan and ESPP

The compensation committee of the Company's board of directors adopted and the Company's stockholders approved the 2021 Equity Incentive Plan (2021 Plan) and the 2021 Employee Stock Purchase Plan (the ESPP), which became effective immediately prior to the effectiveness of the Company's IPO. The 2021 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company's employees, officers, directors and consultants are eligible to receive awards under the 2021 Plan. Under the terms of the 2021 Plan, options are granted at an exercise price no less than fair value of the Company’s common stock on the grant date, except in certain cases related to significant corporate transactions. Option awards granted typically have 10-year terms measured from the option grant date. As of December 31, 2021, the total number of shares authorized for issuance under the 2021 Plan was 2,558,790. In addition, the number of shares of common stock reserved for issuance under our 2021 Plan will automatically increase on January 1 of each year, beginning on January 1, 2022, and continuing through and including January 1, 2031, by 5% of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by our board prior to the applicable January 1st.

The ESPP allows employees, including executive officers, to contribute up to 15% of their earnings, subject to certain limitations, for the purchase of the Company's common stock at a price per share equal to the lower of (a) 85% of the fair market value of a share of common stock on the first day of the offering period, or (b) 85% of the fair market value of a share of common stock on the last day of the offering period. As of December 31, 2021, there were 255,879 shares of common stock reserved for future issuance under our ESPP plan. The number of shares of common stock reserved for issuance under our ESPP will automatically increase on January 1 of each calendar year, beginning on January 1, 2022 and continuing through and including January 1, 2031, by the lesser of (1) 1% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year or (2) a number of shares determined by our board. Shares subject to purchase rights granted under our ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under the ESPP.

As of December 31, 2021, no shares have been granted or purchased under the ESPP.

Stock Options

Awards with vesting conditions under both plans typically include vesting 25% on the first anniversary of the grant date with the remainder vesting monthly over the following three years.


						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contract		Intrinsic
	Options			Exercise		Terms		Values
	Outstanding			Price		(in years)		(in thousands)
Balance as of December 31, 2020		435,342		$	0.52		9.19	$	415
Options granted		2,591,590			4.07
Options cancelled and forfeited		(25,551	)		1.84
Options exercised		(79,246	)		1.88				457
Balance as of December 31, 2021		2,922,135		$	3.62		9.14		21,144
Vested and expected to vest, December 31, 2021		2,922,135		$	3.62		9.14		21,144
Options exercisable as of December 31, 2021		550,292		$	1.01		8.76		5,219

The aggregate intrinsic value disclosed in the above table is based on the difference between the exercise price of the stock option and the estimated fair value of the Company’s common stock as of the respective period-end dates. The weighted-average grant-date fair value of stock options granted during the year ended December 31, 2021 was $7.39 per share.

The Black-Scholes option pricing model for employee and nonemployee stock options incorporates the following assumptions:

Fair Value of Common Stock — Prior to the completion of the Company's IPO, the fair value of the Company's common stock was determined by using straight-line interpolation between the value of common stock derived from valuations performed by independent third party specialists, further described in Note 2 to the consolidated financial statements Summary of Significant Accounting Policies – Fair Value of Common Stock. After the completion of the Company's IPO, the fair value of each share of common stock is based on the closing price of the Company's common stock on the date of grant as reported on the Nasdaq Global Market.

Volatility — The expected stock price volatilities are estimated based on the historical and implied volatilities of comparable publicly traded companies as the Company does not have sufficient history of trading its common stock.

Risk-free Interest Rate — The risk-free interest rates are based on US Treasury yields in effect at the grant date for notes with comparable terms as the awards.

Expected Term — The expected term represents the period that the Company’s stock options are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term).

Dividend Yield — The expected dividend yield assumption is based on the Company’s current expectations about its anticipated dividend policy.

The fair value of the Company’s stock option awards was estimated at the date of grant using a Black-Scholes option pricing model with the following assumptions for the years ended December 31, 2021 and 2020:


	Year Ended December 31,
	2021	2020
Expected term (in years)	5.78 - 6.08	5.70 - 6.12
Expected volatility	77.19% - 79.57%	76.58% - 78.53%
Risk-free interest rate	0.91% - 1.84%	0.36% - 1.47%
Expected dividend yield	0.00%	0.00%

Restricted Stock

The Company has restricted stock awards with service and performance conditions. Awards with a service condition vest 25% on the first anniversary of the grant date and monthly thereafter. Awards with a performance condition will vest upon the Company’s initiation of a registrational clinical trial to study the efficacy of ETX-810. The probability of achieving performance conditions is assessed each reporting period. As of December 31, 2021, this performance condition was assessed and deemed not probable, and the Company has recognized no stock-based compensation expense relating to these performance awards. The Company also granted restricted stock awards to employees and non-employees with service conditions that are subject to repurchase by the Company at the original purchase price in the event that the award recipient’s employment or relationship is terminated prior to the shares vesting.

The activity for restricted stock awards is as follows:


				Weighted-Average Grant-Date Fair
	Number of Shares			Value
Unvested at December 31, 2020(1)		66,681		$	1.00
Granted		297,724		$	8.55
Vested		(32,041	)	$	1.57
Forfeited		—			—
Unvested at December 31, 2021(2)		332,364		$	7.30

(1)

Includes 66,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2020, subject to only performance conditions.

(2)

Includes 21,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2021, subject to only performance conditions.

The fair value of restricted stock awards vested during 2021 was approximately $0.1 million.

The following table sets forth stock-based compensation for stock options, restricted stock awards, and performance awards included in the Company’s consolidated statements of operations and comprehensive loss (in thousands):


	Year Ended December 31,
	2021		2020
Research and development expense	$	987	$	334
General and administrative expense		2,750		373
Total stock-based compensation expense	$	3,737	$	707

As of December 31, 2021, there was $14.3 million of total unrecognized compensation cost related to unvested stock options and unvested restricted stock awards granted, which is expected to be recognized over a weighted-average period of 3.04 years.

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

Note 9. Net Loss Per Share Attributable to Common Stockholders

The following table shows the computation of basic and diluted net loss per share (in thousands, except share and per share data):


	Year Ended December 31,
	2021			2020
Net loss	$	(47,480	)	$	(20,668	)
Accretion of redeemable convertible preferred stock to redemption value and cumulative preferred stock dividends		(4,548	)		(2,285	)
Net loss attributable to common stockholders	$	(52,028	)	$	(22,953	)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		12,260,551			2,187,813
Net loss per share attributable to common stockholders, basic and diluted	$	(4.24	)	$	(10.49	)

The following outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share attributable to common stockholders for the periods presented because their effect would have been anti-dilutive:


	Year Ended December 31,
	2021		2020
Redeemable convertible preferred stock		—		7,140,157
Redeemable convertible preferred stock tranche liability		—		3,717,947
Common stock options		2,922,135		435,342
Unvested restricted stock awards		332,364		66,681
Total potentially dilutive shares		3,254,499		11,360,127

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

Note 10. Income Taxes

The components of net loss before tax provision from income taxes are as follows (in thousands):


	Year Ended December 31,
	2021			2020
United States	$	(13,310	)	$	(5,076	)
United Kingdom		(34,170	)		(15,592	)
Total	$	(47,480	)	$	(20,668	)

The following table presents a reconciliation of the Company’s expected tax computed at the U.S. statutory federal income tax rate to the total provision for income taxes (in thousands):


	Year Ended December 31,
	2021			2020
U.S. federal taxes at statutory rate	$	(9,959	)	$	(4,340	)
State taxes, net of federal benefit		4			1
Foreign rate differential		397			215
Non-deductible expenses		(11	)		—
Research credit addback		4,154			1,530
Refundable tax credit		(1,385	)		(510	)
In-process research and development		—			1,923
Mark-to-market adjustment		2,461			—
Stock-based compensation		480			71
Tax credits		(39	)		(72	)
U.K. tax rate change impact on deferred income taxes		(1,845	)		—
Other, net		219			—
Change in valuation allowance		5,524			1,182
Total	$	—		$	—

The significant components of the Company's deferred tax assets and liabilities are presented below (in thousands):


	Year Ended December 31,
	2021			2020
Deferred tax assets:
Stock-based compensation	$	385		$	77
Intangible asset		3,834			1,384
Accrued bonus		250			58
Accrued payroll taxes		7			4
Accrued vacation		19			—
Net operating losses		5,866			2,652
Research credits		410			450
Total gross deferred tax assets		10,771			4,625
Deferred tax liabilities:
Unrealized gain or loss		(89	)		(1	)
Other		(11	)		—
Total gross deferred tax liabilities		(100	)		(1	)
Valuation Allowance		(10,671	)		(4,624	)
Net deferred tax liabilities	$	—		$	—

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Due to the uncertainty of the business in which the Company operates, projections of future profitability are difficult and past profitability is not necessarily indicative of future profitability. The Company does not believe it is more likely than not that the deferred tax assets will be realized, and accordingly, the Company recorded a valuation allowance of $10.7 million and $4.6 million for the years ended December 31, 2021 and 2020, respectively. As of December 31, 2021, the Company had net operating loss carryforward of approximately $6.0 million for federal income tax purposes, $16.5 million for foreign income tax purposes and $7.3 million for state income tax purposes. These may be used to offset future taxable income. The federal net operation loss carryforward can be carried forward indefinitely while the state net operating loss carryforward will begin to expire in varying amounts in 2039. The Company also has research and development credits of approximately $0.4 million and $0.1 million for federal and state income taxes purposes, respectively. The federal credits may be used to offset future taxable income and will begin to expire in varying amounts in 2039. The state credits may be used to offset future taxable income and will begin to expire in varying amounts in 2040.

The Company is subject to taxation in the U.S. (federal and various states) and the U.K.. Currently, no historical years are under examination. The Company’s tax years starting in December 31, 2018 are open and subject to examination by the U.S. (federal and various states) and the U.K. taxing authorities due to the carryforward of utilized net operating losses and research and development credits.

Uncertain tax positions are recorded when it is more likely than not that a given tax position would not be sustained upon examination by taxing authorities. The Company’s policy for recording interest and penalties related to income taxes, including uncertain tax positions, is to record such items as a component of the provision for income taxes. As of December 31, 2021 and 2020, the Company does not have any uncertain tax positions.

The Company has not completed a Section 382 study to assess whether an ownership change has occurred or whether there have been multiple ownership changes since the Company’s formation. Pursuant to Internal Revenue Code Sections 382 and 383, annual use of the Company’s net operating loss and research and development tax credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. Due to the existence of the valuation allowance, limitations created by future ownership changes, if any, will not impact the Company’s effective tax rate.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI http://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: 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(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Asset Acquisitions with Related Parties

12 Months Ended

Dec. 31, 2021

Business Combinations [Abstract]

Asset Acquisitions with Related Parties

Note 11. Asset Acquisition with Related Parties

In October 2020, the Company acquired 100% of the share capital of Athenen Therapeutics, Inc. (the Athenen Acquisition) for a one-for-one exchange of outstanding preferred stock and common stock. As a result, the Company issued a total of 2.5 million Series A preferred shares and 1,550,000 shares of common stock, valued at $5.80 per share and $1.32 per share, respectively, for total purchase consideration of $16.5 million. Additionally, the Company incurred $0.2 million in legal fees related to the acquisition which was included in the value of the IPR&D asset acquired. The IPR&D acquired in this acquisition will enable the Company to develop ETX-155. The Athenen Acquisition is accounted for as an asset acquisition, as substantially all of the fair value of the gross assets acquired is concentrated in a single asset. Since the IPR&D did not have an alternative future use at the time of its acquisition, the Company recognized a charge of $9.2 million during the year ended December 31, 2020 which is included in in-process research and development expense on the consolidated statements of operations and comprehensive loss. RA Capital Healthcare Fund L.P. was a greater than 10% owner of the Company and Athenen prior to the acquisition.


Assets acquired and liabilities assumed in Athenen Acquisition (in thousands)
In-process research and development	$	9,158
Cash		8,279
Other assets and liabilities, net		(694	)
Total net assets acquired	$	16,743

Related Party Transactions

12 Months Ended

Dec. 31, 2021

Related Party Transactions

Note 12. Related Party Transactions

Services Provided by Related Parties

The Company has a services agreement with Carnot, LLC. Carnot, LLC was subsequently dissolved and the services agreement transitioned to its successor Carnot Pharma, LLC. The Company reimburses Carnot Pharma, LLC for research and development expenses incurred on its behalf. RA Capital Management, L.P. is the manager of the members of Carnot, LLC and Andrew Levin, a member of our board of directors and former CEO, is the President of Carnot Pharma, LLC. Adam Rosenberg, a member of our board of directors, is a Venture Partner at Carnot Pharma, LLC dba RA Ventures. Amounts invoiced and reimbursed for the years ended December 31, 2021 and 2020 were approximately $1.3 million and $0.6 million, respectively. See Note 11 for details on assets acquired from related parties.

Defined Contribution Plan

12 Months Ended

Dec. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Defined Contribution Plan

Note 13. Defined Contribution Plan

The Company began sponsoring a 401(k) defined contribution plan in 2020. Participation in the plan is available to substantially all US-based employees. Company contributions to the plan are discretionary. The Company made matching contributions of up to 4% of each participating employee’s eligible compensation. Total expense recognized from the 401(k) matching contributions for the years ended December 31, 2021 and 2020 was approximately $0.1 million and $20,000, respectively.

The Company also has a workplace pension contribution scheme for U.K.-based employees. For the years ended December 31, 2021 and 2020, the Company made discretionary contributions of approximately $0.1 million and $42,000 in excess of the minimum statutory requirements, respectively.

Subsequent Events

12 Months Ended

Dec. 31, 2021

Subsequent Events [Abstract]

Subsequent Events

Note 14. Subsequent Events

For purposes of the consolidated financial statements as of December 31, 2021 and the year then ended, the Company evaluated subsequent events for recognition and measurement purposes through March 7, 2022, the date the consolidated financial statements were issued.

Grants of Stock Options under 2021 Plan

In the first quarter of 2022, the Company granted additional options for the purchase of an aggregate of 1,295,412 shares of common stock, at an exercise price of $8.21 per share, to employees including executive management. The aggregate grant date-fair value of these awards was $7.2 million, which is expected to be recognized as stock-based compensation expense over a weighted-average period of 4.0 years.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Organization

Basis of Presentation and Principles of Consolidation

Reverse Stock Split

Initial Public Offering

Liquidity

Use of Estimates

Concentration of Credit Risk

Comprehensive Loss

Risks And Uncertainties

Risks and Uncertainties

Segments

Fair Value Measurement

Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

There were no transfers into or out of Level 3 for any of the periods presented.

The following table identifies the Company’s assets and liabilities that were measured at fair value (in thousands):


	December 31, 2021
	Level 1		Level 2		Level 3		Balance
Assets:
Cash equivalents:
Money market funds	$	30,557	$	—	$	—	$	30,557
Marketable securities:
U.S. government debt securities		3,979		—		—		3,979
Commercial paper		—		54,363		—		54,363
Corporate bonds		—		56,135		—		56,135
Total marketable securities		3,979		110,498		—		114,477
Total assets	$	34,536	$	110,498	$	—	$	145,034


	December 31, 2020
	Level 1		Level 2		Level 3		Balance
Liabilities:
Redeemable convertible preferred stock
tranche liability	$	—	$	—	$	551	$	551
Total liabilities	$	—	$	—	$	551	$	551

Cash and Cash Equivalents

Asset Acquisitions

Asset Acquisition

Investment In Marketable Securities

Investments in Marketable Securities

Research and Development Expenses

•

vendors in connection with preclinical development activities;

•

contract research organizations (CROs) in connection with preclinical studies and clinical trials; and

•

contract development and manufacturing organizations (CDMOs) in connection with the production of preclinical and clinical trial materials.

General And Administrative Expenses

General and Administrative Expenses

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist primarily of amounts due for refundable research and development tax credits from the U.K. government and operating expenses paid in advance.

Leases

Accretion and Classification of Redeemable Convertible Preferred Stock

Redeemable Convertible Preferred Stock Tranche Liability

Stock-Based Compensation

Fair Value of Common Stock

•

valuations performed by independent third-party specialists;

•

the Company’s operating results, financial position, and capital resources;

•

the Company’s stage of development and material risks related to its business;

•

the progress of the Company’s research and development programs;

•

business conditions and projects;

•

the lack of marketability of the Company’s common stock and its redeemable convertible preferred stock as a private company;

•

the prices at which the Company sold shares of redeemable convertible preferred stock to outside investors in arms-length transactions;

•

the rights, preferences, and privileges of the Company’s redeemable convertible preferred stock relative to those of the Company’s common stock;

•

the analysis of IPOs and the market performance of similar companies in the biotechnology industry;

•

the likelihood of achieving a liquidity event for securityholders, such as an initial public offering or a sale of the Company, given prevailing market conditions;

•

the hiring of key personnel and the experience of management;

•

trends and developments in the industry; and

•

external market conditions affecting the life sciences and biotechnology industry sectors.

Income Taxes

Foreign Currency

Net Loss Per Share

Emerging Growth Company Status

Recently Adopted Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Schedule of Fair Value Measurements

The following table identifies the Company’s assets and liabilities that were measured at fair value (in thousands):


	December 31, 2021
	Level 1		Level 2		Level 3		Balance
Assets:
Cash equivalents:
Money market funds	$	30,557	$	—	$	—	$	30,557
Marketable securities:
U.S. government debt securities		3,979		—		—		3,979
Commercial paper		—		54,363		—		54,363
Corporate bonds		—		56,135		—		56,135
Total marketable securities		3,979		110,498		—		114,477
Total assets	$	34,536	$	110,498	$	—	$	145,034


	December 31, 2020
	Level 1		Level 2		Level 3		Balance
Liabilities:
Redeemable convertible preferred stock
tranche liability	$	—	$	—	$	551	$	551
Total liabilities	$	—	$	—	$	551	$	551

Investments (Tables)

12 Months Ended

Dec. 31, 2021

Investments [Abstract]

Investments consists of available-for-sale securities

Investments consists of available-for-sale securities as follows (in thousands):


	December 31, 2021
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities:
Commercial paper	$	54,363	$	—	$	(1	)	$	54,362
Corporate bonds		35,231		—		(35	)		35,196
Total short-term marketable securities		89,594		—		(36	)		89,558
Long-term marketable securities:
U.S. government debt securities		3,996		—		(17	)		3,979
Corporate bonds		21,010		—		(70	)		20,940
Total long-term marketable securities	$	25,006	$	—	$	(87	)	$	24,919

Certain Balance Sheet Accounts (Tables)

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Summary of Prepaid Expenses and Other Current Assets

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


	December 31, 2021		December 31, 2020
Recoverable research and development tax credits	$	6,523	$	—
Prepaid research and development expenses		2,906		1,500
Prepaid expenses		1,491		—
Other assets		852		11
Total prepaid expenses and other current assets	$	11,772	$	1,511

Summary of Accrued Expenses

Accrued expenses consist of the following (in thousands):


	December 31 2021		December 31, 2020
Accrued payroll	$	2,220	$	592
Accrued research and development expenses		2,159		627
Other accrued expenses		248		—
Total accrued expenses	$	4,627	$	1,219

Redeemable Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Schedule of Redeemable Convertible Preferred Stock

As of December 31, 2020, the Company’s redeemable convertible preferred stock consisted of the following balance (in thousands, except share and per share amounts):


	As of December 31, 2020
	Issue		Shares		Shares Issued and		Carrying		Aggregate Liquidation
	Price		Authorized		Outstanding		Value		Preference
Series A	$	6.00		2,717,084		2,717,082	$	17,074	$	18,569
Series A (Athenen Acquisition)	$	5.80		2,500,000		2,500,000	$	14,500	$	15,253
Series A-1	$	7.80		7,692,305		1,923,075	$	14,977	$	16,069
Ending balance				12,909,389		7,140,157	$	46,551	$	49,891

Redeemable Convertible Preferred Stock Tranche Liability (Tables)

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Schedule of Valuation of the Redeemable Convertible Preferred Stock Tranche Liability

The following reflects the significant quantitative inputs used in the valuation of the redeemable convertible preferred stock tranche liability:


	Series A-1
	Tranche
	Call Option
Estimated fair value of redeemable convertible preferred stock	$6.94 - $11.10
Discount rate		0.10	%
Dividend yield		0	%
Expected term (years)	0.25 - 0.45
Expected volatility	N/A
Probability of milestone achievement	80% - 100%
Strike price	$	7.80
Fair value of each tranche feature	$0.86 - $3.32

Schedule of the Roll Forward Redeemable Convertible Preferred Stock Tranche Liability

A rollforward of the redeemable convertible preferred stock tranche liability is as follows (in thousands):


Balance at December 31, 2020	$	551
Change in fair value		11,718
Settlement upon issuance of Series A-1 redeemable convertible preferred stock		(12,269	)
Balance at December 31, 2021	$	—

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Future Minimum Lease Payments Under Non-Cancelable Operating Leases

Future minimum lease commitments for non-cancelable operating leases at December 31, 2021, the terms of which expire on various dates through January 31, 2025, are as follows (in thousands)


Year ending December 31,	Amount
2022	$	459
2023		333
2024		172
2025		15
Total minimum lease commitments	$	979

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activities


						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contract		Intrinsic
	Options			Exercise		Terms		Values
	Outstanding			Price		(in years)		(in thousands)
Balance as of December 31, 2020		435,342		$	0.52		9.19	$	415
Options granted		2,591,590			4.07
Options cancelled and forfeited		(25,551	)		1.84
Options exercised		(79,246	)		1.88				457
Balance as of December 31, 2021		2,922,135		$	3.62		9.14		21,144
Vested and expected to vest, December 31, 2021		2,922,135		$	3.62		9.14		21,144
Options exercisable as of December 31, 2021		550,292		$	1.01		8.76		5,219

ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock


	Year Ended December 31,
	2021	2020
Expected term (in years)	5.78 - 6.08	5.70 - 6.12
Expected volatility	77.19% - 79.57%	76.58% - 78.53%
Risk-free interest rate	0.91% - 1.84%	0.36% - 1.47%
Expected dividend yield	0.00%	0.00%

Summary of Restricted Stock Awards

The activity for restricted stock awards is as follows:


				Weighted-Average Grant-Date Fair
	Number of Shares			Value
Unvested at December 31, 2020(1)		66,681		$	1.00
Granted		297,724		$	8.55
Vested		(32,041	)	$	1.57
Forfeited		—			—
Unvested at December 31, 2021(2)		332,364		$	7.30

(1)

Includes 66,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2020, subject to only performance conditions.

(2)

Includes 21,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2021, subject to only performance conditions.

Summary of Share-based Compensation Expense


	Year Ended December 31,
	2021		2020
Research and development expense	$	987	$	334
General and administrative expense		2,750		373
Total stock-based compensation expense	$	3,737	$	707

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Share

The following table shows the computation of basic and diluted net loss per share (in thousands, except share and per share data):


	Year Ended December 31,
	2021			2020
Net loss	$	(47,480	)	$	(20,668	)
Accretion of redeemable convertible preferred stock to redemption value and cumulative preferred stock dividends		(4,548	)		(2,285	)
Net loss attributable to common stockholders	$	(52,028	)	$	(22,953	)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted		12,260,551			2,187,813
Net loss per share attributable to common stockholders, basic and diluted	$	(4.24	)	$	(10.49	)

Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share Attributable To Common Stockholders


	Year Ended December 31,
	2021		2020
Redeemable convertible preferred stock		—		7,140,157
Redeemable convertible preferred stock tranche liability		—		3,717,947
Common stock options		2,922,135		435,342
Unvested restricted stock awards		332,364		66,681
Total potentially dilutive shares		3,254,499		11,360,127

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Components of Net Loss Before Tax Provision from Income Taxes

The components of net loss before tax provision from income taxes are as follows (in thousands):


	Year Ended December 31,
	2021			2020
United States	$	(13,310	)	$	(5,076	)
United Kingdom		(34,170	)		(15,592	)
Total	$	(47,480	)	$	(20,668	)

Schedule of Reconciliation of Statutory Federal Income Tax Rate to Provision for Income Taxes

The following table presents a reconciliation of the Company’s expected tax computed at the U.S. statutory federal income tax rate to the total provision for income taxes (in thousands):


	Year Ended December 31,
	2021			2020
U.S. federal taxes at statutory rate	$	(9,959	)	$	(4,340	)
State taxes, net of federal benefit		4			1
Foreign rate differential		397			215
Non-deductible expenses		(11	)		—
Research credit addback		4,154			1,530
Refundable tax credit		(1,385	)		(510	)
In-process research and development		—			1,923
Mark-to-market adjustment		2,461			—
Stock-based compensation		480			71
Tax credits		(39	)		(72	)
U.K. tax rate change impact on deferred income taxes		(1,845	)		—
Other, net		219			—
Change in valuation allowance		5,524			1,182
Total	$	—		$	—

Schedule of Deferred Tax Assets and Liabilities

The significant components of the Company's deferred tax assets and liabilities are presented below (in thousands):


	Year Ended December 31,
	2021			2020
Deferred tax assets:
Stock-based compensation	$	385		$	77
Intangible asset		3,834			1,384
Accrued bonus		250			58
Accrued payroll taxes		7			4
Accrued vacation		19			—
Net operating losses		5,866			2,652
Research credits		410			450
Total gross deferred tax assets		10,771			4,625
Deferred tax liabilities:
Unrealized gain or loss		(89	)		(1	)
Other		(11	)		—
Total gross deferred tax liabilities		(100	)		(1	)
Valuation Allowance		(10,671	)		(4,624	)
Net deferred tax liabilities	$	—		$	—

Asset Acquisitions with Related Parties (Tables)

12 Months Ended

Dec. 31, 2021

Business Combinations [Abstract]

Schedule of Assets Acquired And Liabilities Assumed In Athenen Acquisition


Assets acquired and liabilities assumed in Athenen Acquisition (in thousands)
In-process research and development	$	9,158
Cash		8,279
Other assets and liabilities, net		(694	)
Total net assets acquired	$	16,743

Nature of Operations and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Aug. 12, 2021	Dec. 31, 2021	Dec. 31, 2020
Subsidiary Sale Of Stock [Line Items]
Entity incorporation date		Oct. 18, 2018
Reserve stock split, conversion ratio		1-for-2
Convertible preferred stock, shares issued upon conversion		152,800,000
Accumulated deficit		$ 75,616	$ 28,136
Cash, Cash Equivalents, and Short-term Investments		$ 161,400
IPO [Member]
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of common stock in initial public offering, Shares	7,360,000
Shares issued price per share	$ 12.50
Gross proceeds	$ 92,000
Proceeds from issuance initial public offering net	83,100
Underwriting Discount	6,400
Deferred offering costs	$ 2,500
Convertible preferred stock, shares issued upon conversion	15,345,279

Summary of Significant Accounting Policies - Schedule of Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Assets Fair Value Disclosure	$ 145,034
Liabilities:
Liabilities fair value		$ 551
Redeemable Convertible Preferred Stock Tranche Liability [Member]
Liabilities:
Liabilities fair value		551
Level 1 [Member]
Assets:
Assets Fair Value Disclosure	34,536
Liabilities:
Liabilities fair value
Level 1 [Member] \| Redeemable Convertible Preferred Stock Tranche Liability [Member]
Liabilities:
Liabilities fair value
Level 2 [Member]
Assets:
Assets Fair Value Disclosure	110,498
Liabilities:
Liabilities fair value
Level 2 [Member] \| Redeemable Convertible Preferred Stock Tranche Liability [Member]
Liabilities:
Liabilities fair value
Level 3 [Member]
Assets:
Assets Fair Value Disclosure	0
Liabilities:
Liabilities fair value		551
Level 3 [Member] \| Redeemable Convertible Preferred Stock Tranche Liability [Member]
Liabilities:
Liabilities fair value		$ 551
Money Market Funds [Member]
Assets:
Assets Fair Value Disclosure	30,557
Money Market Funds [Member] \| Level 1 [Member]
Assets:
Assets Fair Value Disclosure	30,557
Money Market Funds [Member] \| Level 2 [Member]
Assets:
Assets Fair Value Disclosure
Money Market Funds [Member] \| Level 3 [Member]
Assets:
Assets Fair Value Disclosure
US Government Debt Securities [Member]
Assets:
Assets Fair Value Disclosure	3,979
US Government Debt Securities [Member] \| Level 1 [Member]
Assets:
Assets Fair Value Disclosure	3,979
US Government Debt Securities [Member] \| Level 2 [Member]
Assets:
Assets Fair Value Disclosure
US Government Debt Securities [Member] \| Level 3 [Member]
Assets:
Assets Fair Value Disclosure
Commercial Paper [Member]
Assets:
Assets Fair Value Disclosure	54,363
Commercial Paper [Member] \| Level 1 [Member]
Assets:
Assets Fair Value Disclosure
Commercial Paper [Member] \| Level 2 [Member]
Assets:
Assets Fair Value Disclosure	54,363
Commercial Paper [Member] \| Level 3 [Member]
Assets:
Assets Fair Value Disclosure
Corporate Bond Securities [Member]
Assets:
Assets Fair Value Disclosure	56,135
Corporate Bond Securities [Member] \| Level 1 [Member]
Assets:
Assets Fair Value Disclosure
Corporate Bond Securities [Member] \| Level 2 [Member]
Assets:
Assets Fair Value Disclosure	56,135
Corporate Bond Securities [Member] \| Level 3 [Member]
Assets:
Assets Fair Value Disclosure
Total Marketable Securities [Member]
Assets:
Assets Fair Value Disclosure	114,477
Total Marketable Securities [Member] \| Level 1 [Member]
Assets:
Assets Fair Value Disclosure	3,979
Total Marketable Securities [Member] \| Level 2 [Member]
Assets:
Assets Fair Value Disclosure	110,498
Total Marketable Securities [Member] \| Level 3 [Member]
Assets:
Assets Fair Value Disclosure

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) Segments shares	Aug. 12, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares
Subsidiary Sale Of Stock [Line Items]
Cash Equivalents, at Carrying Value			$ 0
Number of Operating Segments \| Segments	1
Reserve stock split, conversion ratio	1-for-2
Common Stock, Conversion Basis	1-for-1
Temporary Equity, Shares Outstanding \| shares	0		7,140,157
Interest and penalties	$ 0
Redemption date	Oct. 31, 2026
IPO [Member]
Subsidiary Sale Of Stock [Line Items]
Deferred offering costs		$ 2,500
Redeemable Convertible Preferred Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Temporary Equity, Shares Outstanding \| shares	0	15,345,279	7,140,157	3,999,133
Redeemable Convertible Preferred Stock [Member] \| IPO [Member]
Subsidiary Sale Of Stock [Line Items]
Unit conversion ratio	1-for-1

Investments - Investments consists of available-for-sale securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Short Term Marketable Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 89,594
Unrealized Loss	36
Estimated Fair Value	89,558
Short Term Marketable Securities [Member] \| Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	54,363
Unrealized Loss	1
Estimated Fair Value	54,362
Short Term Marketable Securities [Member] \| Corporate Bond [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	35,231
Unrealized Loss	35
Estimated Fair Value	35,196
Long Term Marketable Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	25,006
Unrealized Loss	87
Estimated Fair Value	24,919
Long Term Marketable Securities [Member] \| US Government Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	3,996
Unrealized Loss	17
Estimated Fair Value	3,979
Long Term Marketable Securities [Member] \| Corporate Bond [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	21,010
Unrealized Loss	70
Estimated Fair Value	$ 20,940

Investments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Summary Of Investment Holdings [Line Items]
Continuous unrealized loss position, 12 months or longer	$ 0
Impairment loss on available for sale investment	0
Realized gain or loss on available-for-sale securities	0
Investments		$ 0
Commercial Paper [Member]
Summary Of Investment Holdings [Line Items]
Continuous unrealized loss position, less than 12 months	4,000
Corporate Bond [Member]
Summary Of Investment Holdings [Line Items]
Continuous unrealized loss position, less than 12 months	60,100
Prepaid Expenses and Other Current Assets
Summary Of Investment Holdings [Line Items]
Accrued interest receivable	$ 500

Certain Balance Sheet Accounts - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Recoverable research and development tax credits	$ 6,523	$ 0
Prepaid research and development expenses	2,906	1,500
Prepaid expenses	1,491	0
Other assets	852	11
Total prepaid expenses and other current assets	$ 11,772	$ 1,511

Certain Balance Sheet Accounts - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued payroll	$ 2,220	$ 592
Accrued research and development expenses	2,159	627
Other accrued expenses	248	0
Total accrued expenses	$ 4,627	$ 1,219

Redeemable Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Temporary Equity, Shares Authorized	10,000,000	12,909,389
Temporary Equity, Shares Issued	0	7,140,157
Temporary Equity, Shares Outstanding	0	7,140,157
Temporary Equity, Carrying Value	$ 0	$ 46,551
Temporary Equity, Liquidation preference	$ 0	$ 49,891
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary Equity, Issue Price		$ 6.00
Temporary Equity, Shares Authorized		2,717,084
Temporary Equity, Shares Issued		2,717,082
Temporary Equity, Shares Outstanding		2,717,082
Temporary Equity, Carrying Value		$ 17,074
Temporary Equity, Liquidation preference		$ 18,569
Series A Athenen Acquisition Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Temporary Equity, Issue Price		$ 5.80
Temporary Equity, Shares Authorized		2,500,000
Temporary Equity, Shares Issued		2,500,000
Temporary Equity, Shares Outstanding		2,500,000
Temporary Equity, Carrying Value		$ 14,500
Temporary Equity, Liquidation preference		$ 15,253
Series A1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary Equity, Issue Price		$ 7.80
Temporary Equity, Shares Authorized		7,692,305
Temporary Equity, Shares Issued		1,923,075
Temporary Equity, Shares Outstanding		1,923,075
Temporary Equity, Carrying Value		$ 14,977
Temporary Equity, Liquidation preference		$ 16,069

Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	May 31, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Aug. 12, 2021	Dec. 31, 2019
Temporary Equity [Line Items]
Proceeds from issuance of redeemable convertible preferred stock and related tranche rights, net of issuance costs			$ 93,939	$ 4,925
Redeemable convertible preferred stock tranche liability			$ 0	$ 551
Temporary Equity, Shares Outstanding			0	7,140,157
Common stock, shares issued			26,235,317	3,418,751
Percentage of cumulative dividends receive			8.00%
Redemption date			Oct. 31, 2026
Accretion of redeemable convertible preferred stock to redemption value			$ 0
Underwritten Public Offering [Member]
Temporary Equity [Line Items]
Temporary equity, automatic conversion, sale of common stock, price per share			$ 17.16
Series A1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Stock Issued During Period, Shares, New Issues		4,358,972
Proceeds from issuance of redeemable convertible preferred stock and related tranche rights, net of issuance costs		$ 34,000
Redeemable convertible preferred stock tranche liability			$ 12,300
Temporary Equity, Shares Outstanding				1,923,075
Temporary Equity, Liquidation Preference Per Share			$ 7.80
Dividends preferred stock				$ 1,100
Preferred dividend, per share				$ 0.56
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Stock Issued During Period, Shares, New Issues	3,846,150
Proceeds from issuance of redeemable convertible preferred stock and related tranche rights, net of issuance costs	$ 60,000
Temporary Equity, Liquidation Preference Per Share			15.60
Temporary equity, automatic conversion, sale of common stock, price per share			$ 17.16
Series B Redeemable Convertible Preferred Stock [Member] \| Minimum [Member]
Temporary Equity [Line Items]
Percentage of outstanding shares			70.00%
Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary Equity, Shares Outstanding			0	7,140,157	15,345,279	3,999,133
Temporary equity, automatic conversion, sale of common stock, price per share			$ 17.16
Temporary equity, automatic conversion, sale of common stock, gross proceeds			$ 80,000
Common stock, shares issued			15,345,279
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary Equity, Shares Outstanding				2,717,082
Temporary Equity, Liquidation Preference Per Share			$ 6.00
Sale of Stock, Price Per Share			$ 6.00
Dividends preferred stock				$ 2,500
Preferred dividend, per share				$ 0.48

Redeemable Convertible Preferred Stock Tranche Liability - Additional Information - (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Oct. 31, 2020
Temporary Equity [Line Items]
Temporary Equity, par value	$ 0.0001	$ 0.0001
Change in fair value of redeemable convertible preferred stock tranche liability	$ (11,718)
Series A1 Redeemable Convertible Preferred Tranche Liability
Temporary Equity [Line Items]
Redeemable convertible preferred equity value per share			$ 0.86
Change in fair value of redeemable convertible preferred stock tranche liability	11,700
Series A1 Preferred Stock [Member]
Temporary Equity [Line Items]
Change in fair value of redeemable convertible preferred stock tranche liability	$ 12,300

Redeemable Convertible Preferred Stock Tranche Liability - Schedule of Valuation of The Redeemable Convertible Preferred Stock Tranche Liability (Details) - Series A1 Tranche Call Option [Member]	12 Months Ended
	Dec. 31, 2021 $ / shares
Temporary Equity [Line Items]
Discount rate	0.10%
Dividend yield	0.00%
Strike price	$ 7.80
Minimum [Member]
Temporary Equity [Line Items]
Estimated fair value of redeemable convertible preferred stock	$ 6.94
Expected term (years)	3 months
Probability of milestone achievement	80.00%
Fair value of each tranche feature	$ 0.86
Maximum [Member]
Temporary Equity [Line Items]
Estimated fair value of redeemable convertible preferred stock	$ 11.10
Expected term (years)	5 months 12 days
Probability of milestone achievement	100.00%
Fair value of each tranche feature	$ 3.32

Redeemable Convertible Preferred Stock Tranche Liability - Schedule of The Roll Forward Redeemable Convertible Preferred Stock Tranche Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Beginning Balance	$ 551
Change in fair value of redeemable convertible preferred stock tranche liability	(11,718)
Reclassification Of Redeemable Convertible Preferred Stock Tranche Liability Upon Settlement	(12,269)
Ending Balance	$ 0	$ 551

Commitments and Contingencies - Additional Information (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2021 ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Rent expense \| $		$ 248,000	$ 51,000
Operating lease, total space of the office \| ft²	5,000
Operating lease, term of contract	39 months
Addional operating lease, term of contract	3 years
Lease expiration date		Jan. 31, 2025

Commitments and Contingencies - Future Minimum Lease Payments Under Non-Cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Leases [Abstract]
2022	$ 459
2023	333
2024	172
2025	15
Total minimum lease commitments	$ 979

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employees Including Executive Officers Earning Contribution	15.00%
Percentage of fair market value, common stock	85.00%
Number of shares, Granted			66,750
Unrecognized compensation cost	$ 14.3
Unrecognized compensation, weighted average amortization period	3 years 14 days
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, award vesting rights, percentage	25.00%
Options grants in period, weighted average grant date fair value	$ 7.39
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, award vesting rights, percentage	25.00%
Number of shares, Granted	297,724		21,750
Fair value of restricted stock vested	$ 0.1
2019 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, description	Under the terms of the 2019 Plan, options are granted at an exercise price no less than fair value of the Company’s common stock on the grant date, except in certain cases related to employees outside of the U.S. However, for any employee who is a 10% or greater stockholder, options are granted at an exercise price no less than 110% of the fair value of the Company’s common stock on the grant date. Option awards granted typically have 10-year terms measured from the option grant date. However, if any employee is a 10% or greater stockholder, the awards have 5-year terms measured from the option grant date. While no shares are available for future issuance under the 2019 Plan, it continues to govern outstanding equity awards granted thereunder.
Share based payment award, purchase price of common stock, percent	110.00%
Share-based payment award, expiration period	5 years	10 years
2021 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, description	The compensation committee of the Company's board of directors adopted and the Company's stockholders approved the 2021 Equity Incentive Plan (2021 Plan) and the 2021 Employee Stock Purchase Plan (the ESPP), which became effective immediately prior to the effectiveness of the Company's IPO. The 2021 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company's employees, officers, directors and consultants are eligible to receive awards under the 2021 Plan. Under the terms of the 2021 Plan, options are granted at an exercise price no less than fair value of the Company’s common stock on the grant date, except in certain cases related to significant corporate transactions. Option awards granted typically have 10-year terms measured from the option grant date. As of December 31, 2021, the total number of shares authorized for issuance under the 2021 Plan was 2,558,790. In addition, the number of shares of common stock reserved for issuance under our 2021 Plan will automatically increase on January 1 of each year, beginning on January 1, 2022, and continuing through and including January 1, 2031, by 5% of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by our board prior to the applicable January 1st.
Share-based payment award, expiration period	10 years
Share-based payment award, number of shares authorized	2,558,790
Number of shares of common stock outstanding percentage	5.00%
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, description	The ESPP allows employees, including executive officers, to contribute up to 15% of their earnings, subject to certain limitations, for the purchase of the Company's common stock at a price per share equal to the lower of (a) 85% of the fair market value of a share of common stock on the first day of the offering period, or (b) 85% of the fair market value of a share of common stock on the last day of the offering period. As of December 31, 2021, there were 255,879 shares of common stock reserved for future issuance under our ESPP plan. The number of shares of common stock reserved for issuance under our ESPP will automatically increase on January 1 of each calendar year, beginning on January 1, 2022 and continuing through and including January 1, 2031, by the lesser of (1) 1% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year or (2) a number of shares determined by our board. Shares subject to purchase rights granted under our ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under the ESPP.As of December 31, 2021, no shares have been granted or purchased under the ESPP.
Number of shares of common stock outstanding percentage	1.00%
Common stock reserved for future issuance	255,879
Number of shares, Granted	0

Stock-Based Compensation - Summary of Stock Option Activities (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of options outstanding, beginning of period	435,342
Number of options granted	2,591,590
Number of options, forfeited	(25,551)
Number of options exercised	(79,246)
Number of options outstanding, ending of period	2,922,135	435,342
Number of options, vested and expected to vest	2,922,135
Number of options exercisable, end of period	550,292
Weighted average exercise price outstanding, beginning of period	$ 0.52
Weighted average exercise price, options granted	4.07
Weighted average exercise price, options cancelled and forfeited	1.84
Weighted average exercise price, options exercised	1.88
Weighted average exercise price outstanding, end of period	3.62	$ 0.52
Weighted average exercise price, options vested and expected to vest	3.62
Weighted average exercise price, options exercisable	$ 1.01
Weighted average remaining contracted terms (in years) outstanding, beginning of period		9 years 2 months 8 days
Weighted average remaining contracted terms (in years) outstanding, end of period	9 years 1 month 20 days
Weighted average remaining contracted terms (in years), vested and expected to vest	9 years 1 month 20 days
Weighted average remaining contracted terms (in years), exercisable at end of period	8 years 9 months 3 days
Aggregate intrinsic value options exercised	$ 415
Aggregate intrinsic value options exercised	457
Aggregate intrinsic value outstanding, end of period	21,144	$ 415
Aggregate intrinsic value options vested and expected to vest	21,144
Aggregate intrinsic value options exercisable	$ 5,219

Stock-Based Compensation - Summary of Assumptions Used in Black-Scholes Model (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	0.91%	0.36%
Risk-free interest rate, Maximum	1.84%	1.47%
Dividend yield	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 9 months 10 days	5 years 8 months 12 days
Expected volatility, Minimum	77.19%	76.58%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 1 month 13 days
Expected volatility, Maximum	79.57%	78.53%

Stock-Based Compensation - Summary of Restricted Stock Awards (Details) - $ / shares

12 Months Ended

Dec. 31, 2021

Dec. 31, 2018

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares, Granted

66,750

Restricted Stock [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Number of shares, Unvested

^[1]

66,681

Number of shares, Granted

297,724

21,750

Number of shares, Vested

(32,041)

Number of shares, Forfeited

Number of shares, Unvested

^[2]

332,364

Unvested, weighted average grant date fair value per share, beginning balance

^[1]

$ 1.00

Granted, weighted average grant date fair value

8.55

Vested, weighted average grant date fair value per share

1.57

Forfeited, weighted average grant date fair value per share

Unvested, weighted average grant date fair value per share, ending balance

^[2]

$ 7.30

[1]	Includes 66,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2020, subject to only performance conditions.
[2]	Includes 21,750 restricted stock awards granted in 2018 and still outstanding for the period ended December 31, 2021, subject to only performance conditions.

Stock-Based Compensation - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 3,737	$ 707
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	987	334
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,750	$ 373

Net Loss Per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Net loss	$ (47,480)	$ (20,668)
Accretion of redeemable convertible preferred stock to redemption value and cumulative preferred stock dividends	(4,548)	(2,285)
Net loss attributable to common stockholders	$ (52,028)	$ (22,953)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	12,260,551	2,187,813
Net loss per share attributable to common stockholders, basic and diluted	$ (4.24)	$ (10.49)

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22595-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 65
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=124431353&loc=SL124452729-227067

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22663-107794

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 17: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22583-107794

Reference 20: 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(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=125511455&loc=SL5780133-109256

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22658-107794

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124509347&loc=SL7669619-108580

Reference 25: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8924-108599

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124509347&loc=SL7669625-108580

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-URI http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22595-107794

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=125511455&loc=d3e1448-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=125511455&loc=d3e1377-109256

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=125511455&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8924-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124431687&loc=d3e22583-107794

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

+ Details

Net Loss Per Share Attributable to Common Stockholders - Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share Attributable To Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Redeemable convertible preferred stock	3,254,499	11,360,127
Redeemable Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Redeemable convertible preferred stock	0	7,140,157
Redeemable Convertible Preferred Stock Tranche Liability [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Redeemable convertible preferred stock	0	3,717,947
Common stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Redeemable convertible preferred stock	2,922,135	435,342
Unvested restricted stock awards [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Redeemable convertible preferred stock	332,364	66,681

Income Taxes - Additional information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Deferred tax assets, Valuation allowance	$ 10,671	$ 4,624
Research and development credits	410	450
Uncertain tax positions	$ 0	$ 0
Cumulative change in ownership percentage	50.00%
Earliest Tax Year
Operating Loss Carryforwards [Line Items]
Taxable years	Dec. 31, 2018
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	$ 6,000
Research and development credits	$ 400
Tax credit carryforward expiration year	2039
State [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	$ 7,300
Net operating loss carryforward expiration year	2039
Research and development credits	$ 100
Tax credit carryforward expiration year	2040
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	$ 16,500

Income Taxes - Components of Net Loss Before Tax Provision from Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Net loss	$ (47,480)	$ (20,668)
United States
Operating Loss Carryforwards [Line Items]
Net loss	(13,310)	(5,076)
United Kingdom
Operating Loss Carryforwards [Line Items]
Net loss	$ (34,170)	$ (15,592)

- Definition

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

+ References

+ Details

Income Taxes - Schedule of Reconciliation of Statutory Federal Income Tax Rate to Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
U.S. federal taxes at statutory rate	$ (9,959)	$ (4,340)
State taxes, net of federal benefit	4	1
Foreign rate differential	397	215
Non-deductible expenses	(11)
Research credit addback	4,154	1,530
Refundable tax credit	(1,385)	(510)
In-process research and development		1,923
Mark-to-market adjustment	2,461	0
Stock-based compensation	480	71
Tax credits	(39)	(72)
U.K. tax rate change impact on deferred income taxes	(1,845)	0
Other, net	219	0
Change in valuation allowance	5,524	1,182
Total	$ 0	$ 0

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Stock-based compensation	$ 385	$ 77
Intangible asset	3,834	1,384
Accrued bonus	250	58
Accrued payroll taxes	7	4
Accrued vacation	19
Net operating losses	5,866	2,652
Research credits	410	450
Total gross deferred tax assets	10,771	4,625
Deferred tax liabilities:
Unrealized gain or loss	(89)	(1)
Other	(11)
Total gross deferred tax liabilities	(100)	(1)
Valuation Allowance	(10,671)	(4,624)
Net deferred tax liabilities	$ 0	$ 0

Asset Acquisitions with Related Parties - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Oct. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Asset Acquisition [Line Items]
Reserve stock split, conversion ratio		1-for-2
Common stock, shares issued		26,235,317	3,418,751
Common stock, par value		$ 0.0001	$ 0.0001
Athenen Therapeutics [Member]
Asset Acquisition [Line Items]
Preferred Stock, Shares Issued	2,500,000
Preferred Stock, Par or Stated Value Per Share	$ 5.80
Preferred and common stock, Conversion Basis	one-for-one
Common stock, shares issued	1,550,000
Common stock, par value	$ 1.32
Percentage of share capital acquired	100.00%
Purchase Consideration	$ 16.5
Legal Fees	$ 0.2
Acquired in process research and development expense			$ 9.2
RA Capital Healthcare Fund L.P [Member]
Asset Acquisition [Line Items]
Equity ownership interest before acquisition		10.00%

Asset Acquisitions with Related Parties - Schedule of Assets Acquired And Liabilities Assumed In Athenen Acquisition (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Business Combinations [Abstract]
In-process research and development	$ 9,158
Cash	8,279
Other assets and liabilities, net	(694)
Total net assets acquired	$ 16,743

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transaction, Amounts of Transaction	$ 1.3	$ 0.6

Defined Contribution Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Total expense recognized from matching contributions	$ 100,000	$ 20,000
Defined contribution plan, employer discretionary contribution amount	$ 100,000	$ 42,000
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percentage of employee's eligilble compensation	4.00%

Subsequent events - Additional Information (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 [Line Items]
Number of additional options granted		2,591,590
Aggregate grant-date fair value		$ 21,144	$ 415
Unrecognized compensation, weighted average amortization period		3 years 14 days
Subsequent Event [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional options granted	1,295,412
Sale of Stock, Price Per Share	$ 8.21
Aggregate grant-date fair value	$ 7,200
Unrecognized compensation, weighted average amortization period	4 years