0000950170-22-004426 | 10-K | XBRL Viewer

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Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 38,129	$ 128,535
Investments in marketable securities	213,171
Prepaid expenses and other current assets	4,058	1,429
Total current assets	255,358	129,964
Property and equipment, net	43,020	17,185
Operating lease right-of-use assets	11,685
Restricted cash, non-current	547	547
Other non-current assets	3,579	465
Total assets	314,189	148,161
Current liabilities:
Accounts payable	10,721	1,017
Accrued expenses and other current liabilities	9,059	3,161
Deferred rent and other lease liabilities, current		863
Operating lease liabilities, current	1,994
Total current liabilities	21,774	5,041
Deferred rent and other lease liabilities, non-current		3,662
Operating lease liabilities, non-current	13,707
Other non-current liabilities	182	19
Total liabilities	35,663	8,722
Commitments and contingencies (Note 6)
Convertible preferred stock, $0.0001 par value; zero and 26,102,301 shares authorized as of December 31, 2021 and 2020; zero and 24,493,528 shares issued and outstanding as of December 31, 2021 and 2020		220,754
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value; 200,000,000 and zero shares authorized as of December 31, 2021 and 2020; zero shares issued and outstanding as of December 31, 2021 and 2020.
Common stock, $0.0001 par value; 1,000,000,000 and 30,330,000 shares authorized as of December 31, 2021 and 2020; 41,291,374 and 1,210,306 shares issued and outstanding as of December 31, 2021 and 2020.	4
Additional paid-in capital	434,196	1,584
Notes receivable from stockholders		(87)
Accumulated other comprehensive loss	(141)
Accumulated deficit	(155,533)	(82,812)
Total stockholders’ equity (deficit)	278,526	(81,315)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 314,189	$ 148,161

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Temporary equity, par value	$ 0.0001	$ 0.0001
Shares Authorized	0	26,102,301
Convertible preferred stock shares issued	0	24,493,528
Temporary equity, outstanding	0	24,493,528
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, authorized	200,000,000	0
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized	1,000,000,000	30,330,000
Common stock, issued	41,291,374	1,210,306
Common stock, outstanding	41,291,374	1,210,306

Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating expenses:
Research and development	$ 54,393,000	$ 31,099,000
General and administrative	18,413,000	7,813,000
Total operating expenses	72,806,000	38,912,000
Loss from operations	(72,806,000)	(38,912,000)
Other (expense) income, net:
Interest income	108,000	87,000
Change in fair value of convertible preferred stock tranche liability		75,000
Other (expense) income net	(23,000)	355,000
Total other income (expense), net	85,000	517,000
Net loss before income tax expense	(72,721,000)	(38,395,000)
Income tax expense	0	0
Net loss	(72,721,000)	(38,395,000)
Other comprehensive loss:
Unrealized loss on marketable securities	(141,000)
Comprehensive loss	$ (72,862,000)	$ (38,395,000)
Net loss per share, basic and diluted	$ (4.10)	$ (39.50)
Weighted-average shares used in computing net loss per share, basic and diluted	17,734,166	972,091

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Notes Receivable from Stockholders	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2019	$ (43,739)					$ 764	$ (86)		$ (44,417)
Temporary equity balance, shares at Dec. 31, 2019		11,403,077
Temporary equity, balance at Dec. 31, 2019		$ 73,042
Balance, shares at Dec. 31, 2019					1,193,488
Issuance of convertible preferred stock, net of issuance costs			$ 61,995	$ 85,717
Issuance of convertible preferred stock, net of issuance costs, shares			6,172,830	6,917,621
Issuance of common stock upon exercise of stock options	34					34
Issuance of common stock upon exercise of stock options, shares					17,846
Repurchase of common stock related to early exercise of options, shares					(1,028)
Vesting of early exercised stock options	45					45
Notes receivable from stockholders	(1)						(1)
Stock-based compensation	741					741
Net loss	(38,395)								(38,395)
Balance at Dec. 31, 2020	$ (81,315)					1,584	(87)		(82,812)
Temporary equity balance, shares at Dec. 31, 2020	24,493,528	24,493,528	9,259,245	6,917,621
Temporary equity, balance at Dec. 31, 2020	$ 220,754	$ 220,754	$ 91,644	$ 85,717
Balance, shares at Dec. 31, 2020					1,210,306
Issuance of convertible preferred stock, net of issuance costs				$ 19,981
Issuance of convertible preferred stock, net of issuance costs, shares				1,608,750
Conversion of convertible preferred stock to common stock upon completion of initial public offering	240,735				$ 3	240,732
Temporary equity, Conversion of convertible preferred stock to common stock upon completion of initial public offering, shares		(26,102,278)
Temporary equity, Conversion of convertible preferred stock to common stock upon completion of initial public offering		$ (240,735)
Conversion of convertible preferred stock to common stock upon completion of initial public offering, shares					26,102,278
Issuance of common stock upon initial public offering, net of issuance costs	188,541				$ 1	188,540
Issuance of common stock					13,800,000
Issuance of common stock upon exercise of stock options	358					358
Issuance of common stock upon exercise of stock options, shares					195,749
Repurchase of common stock related to early exercise of options, shares					(16,959)
Vesting of early exercised stock options	32					32
Notes receivable from stockholders	87						$ 87
Stock-based compensation	2,950					2,950
Other comprehensive loss	(141)							$ (141)
Net loss	(72,721)								(72,721)
Balance at Dec. 31, 2021	$ 278,526				$ 4	$ 434,196		$ (141)	$ (155,533)
Temporary equity balance, shares at Dec. 31, 2021	0
Balance, shares at Dec. 31, 2021					41,291,374

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Initial Public Offering
Stock issuance costs	$ 18,459
Series B Convertible Preferred Stock
Stock issuance costs		$ 49
Partial settlement of stock, tranche liability		711
Series C Convertible Preferred Stock
Stock issuance costs	$ 20	$ 283

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (72,721)	$ (38,395)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,961	2,483
Amortization of premium on marketable securities	131
Stock-based compensation	2,950	741
Loss on disposal of property and equipment	61	33
Non-cash operating lease expense	1,064
Change in fair value of convertible preferred stock tranche liability		(75)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,730)	(312)
Other non-current assets	(3,114)
Accounts payable	8,600	142
Accrued expenses and other current liabilities	3,295	925
Deferred rent and other lease liabilities		(775)
Operating lease liabilities	(1,472)
Other non-current liabilities	163	(34)
Net cash used in operating activities	(60,812)	(35,447)
Cash flows from investing activities:
Purchases of property and equipment	(25,121)	(9,763)
Purchases of marketable securities	(213,443)
Proceeds from maturities of marketable securities		2,753
Net cash used in investing activities	(238,564)	(7,010)
Cash flows from financing activities:
Proceeds from initial public offering, net of issuance costs	188,541
Proceeds from exercise of stock options	374	34
Repurchases of common stock	(13)	(1)
Proceeds from repayments on notes receivable from stockholders	87
Net cash provided by financing activities	208,970	147,268
Net change in cash, cash equivalents and restricted cash	(90,406)	104,811
Cash and cash equivalents and restricted cash at beginning of period	129,082	24,271
Cash and cash equivalents and restricted cash at end of period	38,676	129,082
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	38,129	128,535
Restricted cash, non-current	547	547
Cash, cash equivalents and restricted cash	38,676	129,082
Supplemental disclosure of cash operating activities:
Cash paid for leases included in operating cash outflows	6,110
Supplemental disclosure of non-cash operating activities:
Lease liability obtained in exchange for right-of-use asset	8,558
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock to common stock upon completion of initial public offering	240,735
Property and equipment included in accounts payable and accrued expenses and other current liabilities	4,100	364
Settlement of convertible preferred stock tranche liability in connection with the issuance of Series B convertible preferred stock		711
Offering costs related to Series C convertible preferred stock included in accounts payable and accrued expenses and other current liabilities		234
Series B Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs		61,284
Series C Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs	$ 19,981	$ 85,951

Organization and Description of the Business

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Description of the Business

Note 1. Organization and Description of the Business

Description of the Business

Tenaya Therapeutics, Inc. (the “Company”) was incorporated in the state of Delaware in August 2016 and is headquartered in South San Francisco, California. The Company is a preclinical stage biotechnology company focused on discovering, developing and delivering curative therapies that address the underlying drivers of heart disease. The Company is advancing product candidates from three distinct but interrelated product platforms: gene therapy, cellular regeneration and precision medicine.

Reverse Stock Split

In July 2021, the Company’s board of directors approved an amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock, convertible preferred stock, and authorized shares on a 1-for-6 basis (the “Reverse Stock Split”) effective on July 23, 2021. The par value of the common stock and convertible preferred stock was not adjusted as a result of the Reverse Stock Split. All share data, per share data and related information for all periods presented in the accompanying financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split.

Initial Public Offering

On August 3, 2021, the Company completed its initial public offering (IPO), at which time the Company issued an aggregate of 13,800,000 shares of its common stock (inclusive of 1,800,000 shares pursuant to the underwriters’ overallotment option) at a price of $15.00 per share. The Company received net proceeds of $188.5 million, after deducting underwriting discounts and commissions of $14.5 million and other offering expenses of $4.0 million. Immediately prior to the completion of the IPO, all of the Company’s outstanding shares of convertible preferred stock automatically converted into 26,102,278 shares of common stock.

Liquidity

The Company has incurred net losses since inception and expects such losses to continue in the future as it conducts research and development activities. As of December 31, 2021, the Company had an accumulated deficit of $155.5 million. The Company incurred a net loss of $72.7 million and $38.4 million during the years ended December 31, 2021 and 2020, respectively. The Company had $251.3 million of cash, cash equivalents and investments in marketable securities as of December 31, 2021.

Management recognizes the need to raise additional capital to fully implement its business plan. The Company may seek to raise capital through equity financings, debt financings, license agreements, collaborative agreements or other sources of financing. Management believes that its existing cash, cash equivalents and investments in marketable securities as of December 31, 2021 will be sufficient to fund the Company’s operations for at least the next twelve months following the date these financial statements are filed with the Securities and Exchange Commission (SEC).

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

Basis of Presentation

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

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and

liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to, the fair value of common stock, the valuation of equity-based awards, the useful lives of property and equipment, the fair value of the convertible preferred stock tranche liability, accrued expenses related to research and development activities and the valuation allowance for deferred tax assets. The Company bases its estimates on historical experience, the current economic environment, and on various other assumptions that are believed to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.

Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date. Fair value measurement establishes a three-level fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The three-level hierarchy of inputs is as follows:

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

Level 2—Inputs (other than quoted prices included within Level 1) that are directly observable for the asset or liability or indirectly observable for similar assets or liabilities; and

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

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

The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short-term nature.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to concentration of risk consist principally of cash, cash equivalents and marketable securities. The Company maintains bank deposits in federally insured financial institutions, and these deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and the issuers of its investments in marketable securities to the extent recorded in the balance sheets. The Company has not experienced any losses on its deposits of cash and cash equivalents.

Risks and Uncertainties

The Company is subject to certain risks similar to that of other early-stage biopharmaceutical companies, including, but not limited to, the ability to obtain future financing, possible failure of future clinical trials, the need to obtain regulatory approvals for its product candidates, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, competitive developments, protection of the proprietary technology, the ability to make milestone, royalty or other payments due under licensing agreements, and the Company’s ability to attract and retain employees necessary to support its growth.

The ongoing COVID-19 pandemic has disrupted and may continue to disrupt the Company’s business and delay its programs and timelines. The Company does not yet know the full extent of potential delays to its preclinical trials, which could prevent or delay the Company from initiating clinical trials and obtaining approval for its product candidates. The extent to which the COVID-19 pandemic may impact the Company’s future operating results and financial condition is uncertain.

Segment Information and Geographical Information

The Company has one operating segment and one reportable segment, which is the business of developing treatments that address heart failure. The Company’s chief operating decision maker, its Chief Executive Officer, reviews financial information on an aggregate basis for the purpose of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents primarily consist of money market funds that are stated at fair value.

Restricted Cash

The Company had restricted cash of $0.5 million for both years ended December 31, 2021 and 2020. The restricted cash represents security deposits for the Company’s operating leases in South San Francisco, California. The security deposits are in the form of a letter of credit secured by restricted cash.

Marketable Securities

The Company invests in marketable securities, primarily securities issued by the U.S. government and its agencies, commercial paper and corporate bonds. All marketable securities have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in other income (expense), net. There are no material realized gains or losses on marketable securities for all periods presented. The cost of securities sold is based on the specific-identification method. Interest earned on marketable securities is included in interest income.

Property and Equipment, Net

Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the assets’ expected lives or the remaining lease term. Costs for capital assets not yet placed into service are capitalized as construction in progress and are not depreciated until the asset is placed in service.

Upon retirement or sale, the cost of disposed assets and their related accumulated depreciation are removed from the balance sheets. Any resulting gains or losses on dispositions of property and equipment are included as a component of other income (expense), net, within the Company’s statements of operations and comprehensive loss. Repair and maintenance costs, which are not considered improvements and do not extend the useful life of property and equipment, are expensed as incurred.

Impairment for Long-Lived Assets

Long-lived assets, including construction in progress, are reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by comparing the carrying amount of an asset to the estimated undiscounted future net cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. Impairment of long-lived assets were not material for any of the periods presented.

Convertible Preferred Stock Tranche Liability

The obligation to issue additional shares of the Company’s Series B convertible preferred stock at a fixed price on future dates was determined to be a freestanding financial instrument that was accounted for as a liability. On issuance, the Company recorded the convertible preferred stock tranche liability on the balance sheet at its estimated fair value. The liability is subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss on remeasurement as a component of other income (expense), net in the statements of operations and comprehensive loss until settlement or extinguishment. The convertible preferred stock tranche liability was settled upon the second and third closings of the Company’s Series B convertible preferred stock in March and August 2020, respectively.

Leases

The Company adopted Accounting Standards Codification (ASC) Topic 842, Leases (ASC 842) on January 1, 2021, as discussed below in the section titled “Recently Adopted Accounting Standards”. Under ASC 842, the Company determines if an arrangement is a lease at inception.

Operating lease right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term at the commencement date of the lease. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less any lease incentive received. The Company uses the rate implicit in the lease in determining the present value of lease payments and, if that rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at the date of lease commencement. The incremental borrowing rate reflects the rate of interest that a lessee would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

The Company’s non-lease components are primarily related to property taxes, insurance, and common area maintenance, which vary based on future outcomes, and are recognized as rent expense when incurred.

Asset Retirement Obligation

The Company records asset retirement obligations (AROs) for the estimated cost of removing constructed leasehold improvement assets and restoring the leased premises back to their original condition, at the time when the contractual obligations are incurred. AROs represent the present value of the expected costs for the related restoration activities. The ARO assets and liabilities are recorded in property, plant and equipment and other long-term liabilities, respectively, in the Company’s balance sheets. The Company records accretion expense, which represents the increase in the asset retirement obligations, over the remaining or operational life of the associated leasehold improvements. Accretion expense is recorded as operating expense in the statements of operations using an accretion rate based on the credit adjusted risk-free interest rate. Changes resulting from revisions to the timing or amount of the original estimate of cash flows are recognized as an increase or a decrease in the asset retirement cost, or income when the asset retirement cost is depleted.

Research and Development Expenses

Research and development (R&D) costs are expensed as incurred. Research and development expenses include, among others, consulting fees, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocated facilities and overhead costs, amounts owed under licensing agreements, amounts paid to contract research organizations (CRO) that conduct research and development activities on the Company’s behalf and costs related to compliance with regulatory requirements.

Goods or services incurred for research and development activities that have not yet been invoiced are recorded as liabilities within accrued expenses and other current liabilities on the Company’s balance sheets. Amounts recorded for unbilled services often represent estimates, which are typically based on contracted amounts for the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the associated services. The Company makes judgments and

estimates in determining the accrued and other current liabilities balance. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts accrued expenses or prepaid expenses accordingly, which impact research and development expenses. The Company has not experienced any material differences between accrued costs and actual costs incurred. Changes in these estimates that result in material changes to the Company’s accrued costs could materially affect the Company’s results of operations.

The Company has and may continue to acquire the rights to licensed technology that represents in-process research and development to use and develop in the commercialization of new product candidates. The upfront payments made to acquire licenses, product or rights, or payments made related to future milestone payments are recognized as research and development expenses provided that there is no alternative future use of the rights in other research and development projects, up to the point of regulatory approval. Milestone payments are expensed when the specific milestone has been achieved.

Non-refundable advance payments for goods or services to be rendered as part of future research and development activities are capitalized on the Company’s balance sheets until the goods or services are received.

Classification between prepaid expenses and other current assets and other non-current assets is based on an evaluation of when the goods will be delivered and/or services will be performed, with such amounts subsequently amortized to expense once incurred.

Stock-Based Compensation

The Company measures and records expense related to all equity awards granted to employees and non-employees in the statements of operations and comprehensive loss based on their grant date fair values, including stock options and restricted stock awards. For stock-based awards that vest subject to the satisfaction of a service requirement, the expense is recognized using the straight-line method over the requisite service period, which is generally the vesting period. Forfeitures are recognized as they occur.

The fair value of restricted stock awards is determined on the date of grant based on the estimated fair value of the Company’s common stock on that date.

For purposes of determining the estimated fair value of options granted to employees and nonemployees, the Company uses the Black-Scholes option pricing model.

The assumptions used to determine the fair value of options granted were as follows. Each of these inputs is subjective and generally requires significant judgement.

Fair Value of Common Stock—Prior to the Company's IPO, there was no public market for its common stock. As such, the estimated fair value of its common stock and underlying stock options was determined at each grant date by the Company's board of directors, with input from management, based on the information known to the Company on the grant date and upon a review of any recent events and their potential impact on the estimated per share fair value of its common stock. As part of these fair value determinations, the Company's board of directors obtained and considered valuation reports prepared by a third-party valuation firm in accordance with the guidance outlined in the American Institute of Certified Public Accountants' Accounting & Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. For grants subsequent to the Company's IPO, the grant date fair value of common stock was determined by using the closing price per share of common stock as reported on the Nasdaq Global Select Market.

Expected Term— The Company determines the expected term, which represents the period that stock-based awards are expected to be outstanding, in accordance with the simplified method due to its limited operating history, which is presumed to be the mid-point between the contractual term and the vesting period.

Expected Volatility— As there is limited trading history for the Company’s common stock, the Company determines its computation of expected volatility on the historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term assumption.

Risk-Free Interest Rate— The Company bases the risk-free interest rate on U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term assumption.

Expected Dividend— The expected dividend yield is assumed to be zero as the Company has never paid and has no plans to pay any dividends on its common stock.

Income Taxes

The Company accounts for income taxes using the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse.

A valuation allowance is recorded for deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. In evaluating the ability to recover its deferred income tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. In the event the Company determines that it would be able to realize its deferred income tax assets in the future in excess of their net recorded amount, it would make an adjustment to the valuation allowance that would reduce the provision for income taxes. Conversely, in the event that all or part of the net deferred tax assets are determined not to be realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period when such determination is made. As of December 31, 2021 and 2020, the Company has recorded a full valuation allowance on its net deferred tax assets.

Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties, if any, related to unrecognized tax benefits are included within the provision for income tax.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of the Company’s common stock outstanding for the period, without consideration for potential dilutive shares of common stock. As the Company is in a loss position for the periods presented, diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive. Shares related to early exercised stock options and restricted stock that are subject to repurchase are excluded from the basic and diluted net loss per share calculation until the Company’s repurchase right lapses.

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 use 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 (a) is no longer an emerging growth company or (b) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these 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 Standards

On January 1, 2021, the Company adopted ASC 842 using the modified retrospective transition method and elected the practical expedients to not reassess whether any expired or existing contracts are or contain leases, carry forward its historical lease classification and not reassess initial direct costs for existing leases. The Company elected to not separate non-lease components from the associated lease components and to not recognize ROU assets and lease liabilities for leases with a term of twelve months or less. Upon adoption of ASC 842, the Company recorded an operating right-of-use asset of $4.6 million, operating lease liabilities of $9.1 million and derecognized deferred rent and other lease liabilities of $4.5 million. Results for the year ended December 31, 2021, are presented under ASC 842. Prior period amounts before January 1, 2021, have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC 840: Leases (Topic 840).

Recently Issued Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which replaces the existing incurred loss impairment model with an expected credit loss model. This standard will require companies to recognize an allowance for credit losses on available-for-sale debt securities rather than the current approach of recording a reduction to the carrying value of the asset. As an emerging growth company, ASU 2016-13 is effective for the Company beginning January 1, 2023. The Company is evaluating the impact of this standard on its financial statements.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. This standard eliminates certain exceptions to the approach for intra period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. As an emerging growth company, ASU 2019-12 is effective for the Company beginning January 1, 2022. The Company does not expect the adoption of this standard to have any impact on its financial statements.

In November 2021, the FASB issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance (ASU 2021-10), which requires business entities to make annual disclosures about transactions with a government they account for by analogizing to a grant or contribution accounting model. The required annual disclosures include the nature of the transaction, the entity’s related accounting policy, the financial statement line items affected and the amounts reflected in the current period financial statements, and any significant terms and conditions. ASU 2021-10 is effective for the Company beginning January 1, 2022. The Company does not expect the adoption of this standard to have a material impact on its financial statements.

Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 3. Fair Value Measurements

Financial assets and liabilities are recognized at fair value on a recurring basis. The following tables summarize the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy:


		December 31, 2021
	Valuation Hierarchy	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
		(In thousands)
Assets:
Cash equivalents:
Money market funds	Level 1	$	37,129	$	—	$	—		$	37,129
Marketable securities:
U.S. treasuries	Level 1		78,097		—		(85	)		78,012
Commercial paper	Level 2		121,634		—		(50	)		121,584
Corporate bonds	Level 2		8,979		—		(3	)		8,976
Government agencies bonds	Level 2		4,602		—		(3	)		4,599
Total financial assets		$	250,441	$	—	$	(141	)	$	250,300


		December 31, 2020
	Valuation Hierarchy	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
		(In thousands)
Assets:
Cash equivalents:
Money market funds	Level 1	$	127,535	$	—	$	—	$	127,535
Total financial assets		$	127,535	$	—	$	—	$	127,535

Money market funds and U.S. treasuries are classified as Level 1 because they are valued using quoted market prices in active markets for identical assets. Financial instruments classified within Level 2 of the fair value hierarchy are valued based on observable inputs or can be derived from non-binding quotes from the Company’s

investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments, or historical pricing trends of a security relative to its peers. To validate the fair value determination provided by its investment managers, the Company reviews the pricing movement in the context of overall market trends and trading information from its investment managers. In addition, the Company considers the inputs and methods used in determining the fair value in order to determine the classification of securities in the fair value hierarchy.

The Company believes it is more likely than not that its marketable securities in an unrealized loss position will be held until maturity or the recovery of the cost basis of the investment. To date, the Company has not recorded any impairment charges on marketable securities related to other-than-temporary declines in market value. All available-for-sale marketable securities held as of December 31, 2021 are short-term investments with contractual maturities of less than one year.

Convertible Preferred Stock Tranche Liability

The Company’s convertible preferred stock tranche liability was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. Fair value was calculated using an option pricing model that required significant unobservable inputs supported by little or no market activity. The convertible preferred stock tranche liability was considered a non-contingent forward and the standard forward pricing model was used with the following key assumptions: (a) calculation of an expected term and (b) a risk-free interest rate. The convertible preferred stock tranche liability was initially recorded in connection with the first closing of the Company’s Series B convertible stock financing in August 2019. On the second and third closings of the Company’s Series B convertible preferred stock financings in March and August 2020, the convertible preferred stock tranche liability was settled and reclassified to Series B convertible preferred stock. Accordingly, there is no convertible preferred stock tranche liability as of December 31, 2021 and 2020.

The following table summarizes the significant unobservable assumptions used to value the convertible preferred stock tranche liability as of the settlement date of August 24, 2020:


	August 24, 2020
Term to valuation date (in years)		0.00
Discount rate		5.0	%

The following table summarizes the changes in the estimated fair value of the Company’s convertible preferred stock tranche liability measured on a recurring basis using significant Level 3 inputs:


	Year Ended December 31, 2020
	(In thousands)
Beginning balance	$	786
Change in fair value upon remeasurement		(75	)
Settlement of convertible preferred stock tranche liability on second and third closings of the Series B convertible preferred stock		(711	)
Ending balance	$	—

- Definition

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

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

Note 4. Balance Sheet Components

Property and Equipment, Net

Property and equipment, net, consists of the following:


	December 31,
	2021			2020
	(In thousands)
Construction in progress	$	32,561		$	7,678
Laboratory equipment		11,891			8,182
Leasehold improvements		7,241			7,237
Furniture and fixtures		534			534
Computer equipment and software		218			257
Total property and equipment	$	52,445		$	23,888
Less: accumulated depreciation and amortization		(9,425	)		(6,703	)
Total property and equipment, net	$	43,020		$	17,185

Depreciation and amortization expense for the years ended December 31, 2021 and 2020, was $3.0 million and $2.5 million, respectively. Construction in progress primarily consists of costs directly incurred for the construction of the Company’s manufacturing and office space located in Union City, California, and capitalized machinery and equipment (see Note 6).

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


	December 31,
	2021		2020
	(In thousands)
Accrued compensation and related expenses	$	3,667	$	2,090
Accrued property and equipment		2,863		231
Accrued research and development expenses		2,023		391
Accrued professional services		344		328
Other current liabilities		162		121
Total accrued expenses and other current liabilities	$	9,059	$	3,161

License Agreements

12 Months Ended

Dec. 31, 2021

License Agreements [Abstract]

License Agreements

Note 5. License Agreements

Gladstone License Agreement

In October 2016, the Company entered into a license agreement with the J. David Gladstone Institute (Gladstone), pursuant to which Gladstone granted the Company a worldwide, royalty-bearing exclusive patent license and a non-exclusive technology license to develop and commercialize certain products for certain diseases (Gladstone License Agreement). Pursuant to the Gladstone License Agreement, the Company is obligated, among other things, to pay Gladstone (i) annual license maintenance fees ranging from $25,000 up to $0.1 million per year, which will be creditable against royalties paid in the following twelve month period, (ii) milestone payments up to $4.1 million for royalty-bearing products directed to a particular target, which are contingent upon achieving specific clinical and commercialization milestone events, and (iii) tiered low-single digit royalties on future net sales of each royalty-bearing product. Under the agreement, the Company is subject to diligence requirements to develop and commercialize at least one royalty-bearing product. The Company may pay $50,000 to $100,000 to extend the deadline for its diligence milestone obligations for up to four additional one-year terms. As of December 31, 2021, the Company has not recognized any milestone and royalty payments under the Gladstone License Agreement.

During the years ended December 31, 2021 and 2020, amounts recorded related to annual license fees payable pursuant to the Gladstone License Agreement were immaterial.

University of Texas Southwestern License Agreement

In January 2020, the Company entered into a license agreement with the University of Texas Southwestern (UTSW License), pursuant to which UTSW granted the Company a royalty-bearing exclusive and sublicensable patent license and a non-exclusive, non-sublicensable license for mutually agreed upon development activities. Under the UTSW License, the Company is obligated to pay UTSW (i) a non-refundable upfront license fee of $0.1 million, which was paid by the Company in 2020, (ii) milestone payments up to a total of $14.8 million in aggregate, which are contingent upon achieving specific development and commercialization milestone events, and (iii) royalties on future net sales of each royalty-bearing product ranging in the low-single digits. As of December 31, 2021, the Company has not recognized any milestone and royalty payments under the UTSW License.

Other License Agreements

In addition to the agreements described above, the Company has also entered into other license agreements with various institutions and business entities, none of which are material individually or in the aggregate.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 6. Commitments and Contingencies

Facility Leases

In December 2016, the Company entered into a lease agreement for office and laboratory space in South San Francisco, California. The lease expires in May 2025 and the Company may renew the lease term for two additional five-year periods. Pursuant to the lease agreement, the Company received a tenant improvement allowance of $5.8 million in aggregate for leasehold improvements to the facility.

In December 2020, the Company entered into a short-term sublease agreement for additional office and laboratory space in South San Francisco, California with a lease term that expired on November 30, 2021.

In February 2021, the Company entered into a lease agreement for manufacturing and office space located in Union City, California. The lease commenced in May 2021 and has a ten-year term with one five-year renewal option. Upon the execution of the lease agreement, the Company provided the landlord with a refundable security deposit of $3.3 million, which is included in other non-current assets on the balance sheets.

In November 2021, the Company entered into a short-term sublease agreement for additional office and laboratory space in South San Francisco, California with a lease term that expires on June 30, 2022.

On January 1, 2021, the Company adopted ASC 842 and the following disclosures as of and for the year ended December 31, 2021 are presented under ASC 842. As of December 31, 2021, the remaining weighted-average lease term was 6.6 years and the weighted-average incremental borrowing rate used to determine the operating lease liabilities was 9.5%.

During the year ended December 31, 2021, the Company incurred $5.7 million of lease costs, of which $1.7 million is related to the Company’s short-term leases and $1.6 million is related to variable lease payments. During the year ended December 31, 2020, the Company incurred $2.4 million in rent expense.

As of December 31, 2021, the undiscounted future minimum lease payments due under the Company’s non-cancelable operating leases are as follows:


	Amount
	(In thousands)
2022	$	3,678
2023		3,792
2024		3,910
2025		2,445
2026		1,386
Thereafter		6,905
Total undiscounted future minimum lease payments	$	22,116
Present value adjustment for minimum lease commitments		(6,133	)
Tenant improvement receivable		(282	)
Total operating lease liabilities	$	15,701

As of December 31, 2020, undiscounted future minimum lease payments due under the Company's non-cancelable operating lease are as follows:


	Amount
	(In thousands)
2021	$	3,752
2022		2,206
2023		2,283
2024		2,363
2025		999
Total future minimum lease payments	$	11,603

The Company has previously entered into agreements to sublease portions of the Company’s facilities in South San Francisco to two different subtenants, both of which were expired as of December 31, 2020. Pursuant to the sublease agreements, the Company received sublease income of $0.4 million during the year ended December 31, 2020, which is included in other income (expense), net on the statements of operations and comprehensive loss.

Asset Retirement Obligation

Under the lease agreement for the manufacturing and office facility in Union City, the Company is contractually obligated to remove constructed leasehold improvements related to capitalized machinery and equipment (see Note 4) and to restore the leased space to its original condition upon termination of the lease agreement. The Company applies the proportionate method to account for the buildup of the asset retirement obligation while leasehold improvements are in progress. As of December 31, 2021, the balance of the asset retirement obligation liability was not material. The Company elected to defer the commencement of accretion of the asset retirement obligation until the underlying construction is completed, on the basis that the financial statement impact from the deferral is immaterial.

Purchase Commitments

The Company enters into contractual agreements with various suppliers in the normal course of its business, including vendors that provide machinery and equipment. All contracts are terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, the Company would only be obligated for the products or services that the Company had received through the time of termination.

Indemnification

In the normal 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. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amounts of future payments the Company could be required to make under these provisions is not determinable. In addition, the Company has entered into indemnification agreements with its directors and certain officers that may require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. As of December 31, 2021 and 2020, the Company does not have any material indemnification claims that were probable or reasonably possible and, consequently, has not recorded any related liabilities.

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Convertible Preferred Stock

Note 7. Convertible Preferred Stock

On August 3, 2021, immediately prior to the completion of the Company’s IPO, all outstanding shares of convertible preferred stock were converted into 26,102,278 shares of the Company’s common stock.

Prior to the Company’s IPO, convertible preferred stock as of December 31, 2020, consists of the following:


	December 31, 2020
	Shares Authorized		Shares Issued and Outstanding		Net Carrying Value		Liquidation Preference
	(In thousands, except share data)
Convertible Preferred Stock
Series A		8,316,666		8,316,662	$	43,393	$	49,900
Series B		9,259,254		9,259,245		91,644		92,000
Series C		8,526,381		6,917,621		85,717		86,000
Total		26,102,301		24,493,528	$	220,754	$	227,900

The Company classified its convertible preferred stock outside of total stockholders’ deficit because, in the event of certain change of control events that are not solely within the control of the Company (including liquidation, sale or transfer of the Company), the shares would become redeemable at the option of the holders. As a result, the Company classified its convertible preferred stock as mezzanine equity on the balance sheet as the preferred stock was contingently redeemable.

Series C Convertible Preferred Stock Financing

In December 2020, the Company entered into a Series C preferred stock purchase agreement for the issuance of up to 8,526,381 shares of the Company’s Series C convertible preferred stock at a purchase price of $12.432 per share in two closings. The Company completed the initial closing in December 2020, whereby 6,917,621 shares of Series C convertible preferred stock were issued for gross proceeds of $86.0 million.

In January 2021, the Company sold an additional 1,608,750 shares of Series C convertible preferred stock at a purchase price of $12.432 per share for gross proceeds of $20.0 million.

Common Stock

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Common Stock

Note 8. Common Stock

The holders of common stock are entitled to one vote per share on all matters to be voted on by the stockholders of the Company and are entitled to dividends, if and when declared by the board of directors, subject to the prior rights of the preferred stockholders. Common stock issued and outstanding on the balance sheets and statements of convertible preferred stock and stockholders’ equity (deficit) includes shares related to early exercised options and restricted stock that are subject to repurchase. Common stock issued and outstanding is reduced for any repurchases of early exercised stock options and restricted stock. As of December 31, 2021 and 2020, outstanding common stock included 28,905 and 138,127 shares, respectively, related to early exercised stock options and restricted stock that are unvested and subject to repurchase.

Total shares of common stock reserved for issuance, on an as-if converted basis, is as follows:


	December 31,
	2021		2020
Conversion of outstanding shares of convertible preferred stock		—		24,493,528
Stock options issued and outstanding		2,772,154		1,160,808
Stock options available for future grant		3,594,158		412,170
Total		6,366,312		26,066,506

- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

Note 9. Stock-Based Compensation

2021 Equity Incentive Plan

In July 2021, the Company adopted the 2021 Equity Incentive Plan (the “2021 Plan”), which became effective in connection with the IPO. Under the 2021 Plan, 4,000,000 shares of the Company's common stock were initially reserved for issuance of equity awards to employees, directors, and consultants, under terms and provisions established by the Board of Directors. The number of shares of common stock available for issuance under the 2021 Plan will automatically increase on the first day of January for a period of ten years, commencing on January 1, 2022, in an amount equal to the lesser of: 4,000,000 shares; 4% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the Company’s Board of

Directors may determine. In addition, the Company’s 2016 Equity Incentive Plan (the “2016 Plan”) was terminated in connection with the IPO. Shares subject to awards granted under the 2016 Plan that are repurchased by or forfeited to the Company will be reserved for issuance under the 2021 Plan.

Total shares reserved and available for grant under the 2021 Plan as of December 31, 2021, are 3,594,158.

Stock Option Activity

The following table summarizes stock option activity:


	Number of Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life		Aggregate Intrinsic Value
						(Years)		(In thousands)
Outstanding as of December 31, 2020		1,160,808		$	1.74		8.40
Options granted		1,850,036			11.05
Options exercised		(195,749	)		1.91
Options cancelled		(42,941	)		3.68
Outstanding as of December 31, 2021		2,772,154		$	7.90		8.74	$	31,420
Exercisable as of December 31, 2021		705,577		$	2.65		7.61	$	11,500

The aggregate intrinsic value is the value of the Company's closing stock price on the last trading day of the year in excess of the weighted-average exercise price multiplied by the number of options outstanding or exercisable. The total intrinsic value of options exercised during the years ended December 31, 2021 and 2020, was $1.7 million and $37,000.

The weighted-average grant-date fair value of options granted during the years ended December 31, 2021 and 2020 was $9.50 and $4.98 per share.

2021 Employee Stock Purchase Plan

In July 2021, the Company adopted the 2021 Employee Stock Purchase Plan (the “ESPP”), which became effective in connection with the IPO. The Company initially reserved 800,000 shares for future issuance under the ESPP. The ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. The number of shares of common stock available for issuance under the ESPP will automatically increase on the first day of each fiscal year beginning with 2022 in an amount equal to the lesser of: 800,000 shares; 1% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the board of directors may determine. The first offering period has not commenced as of December 31, 2021 and there is no stock-based compensation related to the ESPP for the year ended December 31, 2021.

Stock-Based Compensation

The following table summarizes stock-based compensation recognized in the Company’s statements of operations and comprehensive loss:


	Year Ended December 31,
	2021		2020
	(In thousands)
Research and development	$	1,179	$	378
General and administrative		1,771		363
Total stock-based compensation	$	2,950	$	741

As of December 31, 2021, there was approximately $16.7 million of unrecognized stock-based compensation, which the Company expects to recognize over a weighted-average period of 3.1 years.

Stock Option Valuation

The fair value of the Company’s stock option awards is estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:


	Year Ended December 31,
	2021	2020
Expected term (in years)	5.0 - 6.1	5.9 - 6.1
Expected volatility	95% - 103%	178% - 183%
Risk-free interest rate	0.6% - 1.4%	0.4% - 1.5%
Expected dividend yield	—%	—%

The assumptions used to determine the fair value of options granted were as follows. Each of these inputs is subjective, involve inherent uncertainties, and generally requires significant judgment. The assumptions used to determine the fair value of the awards represent management’s best estimates.

Expected Dividend— The expected dividend yield is assumed to be zero as the Company has never paid and has no plans to pay any dividends on its common stock.

Restricted Stock

During the year ended December 31, 2021, the restricted stock activities were due to shares of restricted common stock issued pursuant to the permitted early exercise of stock options and vesting of immaterial shares of RSAs granted in 2016. As of December 31, 2021, 28,905 shares of restricted stocks pursuant to the early exercise of stock options were outstanding and all RSAs had been fully vested.

Employee Recourse Notes

In 2017 and 2018, the Company entered into full recourse notes with certain employees, including one of its officers, upon the exercise of stock options that are treated as substantive exercises for accounting purposes. The Company has the right to repurchase unvested shares up to 90 days after employment is terminated. As of December 31, 2021, the principal and accrued interest amount of the notes have been fully repaid. The notes are presented in the statements of convertible preferred stock and stockholders’ equity (deficit).

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

Note 10. Income Taxes

No provision for or benefit from income taxes was recorded during the years ended December 31, 2021 and 2020. The Company has established a full valuation allowance against its net deferred tax assets due to the uncertainty regarding the realization of such assets. All losses to date have been incurred in the United States. Deferred income taxes reflect the net tax effects of (a) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, and (b) operating losses and tax credit carryforwards.

Effective Tax Rate Reconciliation

The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate and the effective tax rate reconciliation is as follows:


	December 31,
	2021			2020
U.S. federal taxes at statutory rate		21.0	%		21.0	%
State taxes (net of federal benefit)		0.6			8.1
Credits		3.1			3.6
Stock-based compensation		(0.3	)		(0.3	)
Section 382 limitation on tax attribute carryforwards		—			(9.0	)
Change in valuation allowance		(23.3	)		(23.1	)
Other		(1.1	)		(0.3	)
Total	—%			—%

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2021			2020
	(In thousands)
Balance at beginning of year	$	571		$	744
Additions based on tax positions related to current year		901			293
Additions based on tax positions related to prior years		—			—
Reductions for tax positions related to prior years		(2	)		(466	)
Balance at end of year	$	1,470		$	571

The Company does not expect that its uncertain tax positions will materially change in the next twelve months. The reversal of the uncertain tax benefits would not impact the Company’s effective tax rate as the Company continues to maintain a full valuation allowance against its deferred tax assets.

The Company files tax returns in U.S. federal and state jurisdictions with varying statutes of limitations. Due to net operating loss and credit carryforwards, all of the tax years since inception through the 2021 tax year remain subject to examination by the U.S. federal and state authorities. The Company is currently not subject to any income tax audits by federal or state taxing authorities.

Deferred Income Taxes

The tax effects of significant items comprising the Company’s deferred income taxes are as follows:


	December 31,
	2021			2020
	(In thousands)
Deferred tax assets:
Net operating losses	$	34,746		$	20,917
Tax credits		4,443			1,346
Lease liability		3,362			—
Accrued expenses and other		727			1,825
Stock-based compensation		309			79
Property and equipment		152			120
Total deferred tax assets		43,739			24,287
Valuation allowance		(41,281	)		(24,287	)
Deferred tax assets, net of valuation allowance		2,458			—
Deferred tax liabilities:
Right-of-use asset		(2,458	)		—
Net deferred tax assets	$	—		$	—

The tax benefit of net operating losses, temporary differences and credit carryforwards are recorded as an asset to the extent that the Company assesses that realization is more likely than not. Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. As a result of the Company’s recent history of operating losses, the Company believes that recognition of deferred tax assets arising from the above-mentioned future tax benefits is currently not likely to be realized and, accordingly,

has provided a full valuation allowance. The valuation allowance increased by $17.0 million and $8.9 million during the years ended December 31, 2021 and 2020. The increase in valuation allowances during the year ended December 31, 2021, was primarily due to the increase in deferred tax assets from 2021 federal net operating losses. The valuation allowances would have been larger for the year ended December 31, 2020, if not for the reduction in net operating loss and tax credit carryforwards limited under Section 382. The impact of the Section 382 limitation resulted in the reduction of deferred tax assets for federal research credits and state net operating loss carryforwards, with an offsetting reduction of the valuation allowance.

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2021, the Company’s net operating loss and tax carryforwards are summarized as follows:


	Amount		Expiration in years
Net operating losses, federal (post-December 31, 2017)	$	140,666	Do Not Expire
Net operating losses, federal (pre-January 1, 2018)	$	3,093	Begins to Expire 2036
Net operating losses, state	$	62,817	Begins to Expire 2036
Tax credits, federal	$	3,433	Begins to Expire 2036
Tax credits, state	$	3,258	Do Not Expire

Under Section 382 of the Internal Revenue Code of 1986, as amended, the ability to utilize net operating loss carryforwards or other tax attributes, such as research tax credits, in any taxable year may be limited if the Company has experienced an “ownership change”. This annual limitation may result in the expiration of net operating losses and credits before utilization. As of December 31, 2021, a study was updated and we concluded that there were no ownership changes during 2021. As previously disclosed, the Company experienced an ownership change in 2020. As a result, in 2020, the Company removed $3.1 million of deferred tax assets related to net operating loss carryforwards and research tax credit carryforwards due to Section 382 limitations. The Company’s ability to use its remaining net operating loss carryforwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership.

The Company recognizes interest and penalties related to taxes and uncertain tax positions as a component of income tax expense. During the years ended December 31, 2021 and 2020, no interest and penalties were accrued by the Company.

- 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

Net Loss Per Share

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss Per Share

Note 11. Net Loss Per Share

The following potentially dilutive securities were not included in the calculation of diluted net loss per share for the periods presented because the effect would have been anti-dilutive:


	December 31,
	2021		2020
Convertible preferred stock		—		24,493,528
Outstanding stock options		2,772,154		1,160,808
Restricted stock subject to future vesting		28,905		138,127
Total		2,801,059		25,792,463

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying financial statements include, but are not limited to, the fair value of common stock, the valuation of equity-based awards, the useful lives of property and equipment, the fair value of the convertible preferred stock tranche liability, accrued expenses related to research and development activities and the valuation allowance for deferred tax assets. The Company bases its estimates on historical experience, the current economic environment, and on various other assumptions that are believed to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date. Fair value measurement establishes a three-level fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The three-level hierarchy of inputs is as follows: Level 1—Observable inputs such as unadjusted quoted prices in active markets for identical assets or liabilities as of the measurement date; Level 2—Inputs (other than quoted prices included within Level 1) that are directly observable for the asset or liability or indirectly observable for similar assets or liabilities; and Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate their fair value due to their short-term nature.
Concentration of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentration of risk consist principally of cash, cash equivalents and marketable securities. The Company maintains bank deposits in federally insured financial institutions, and these deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents and the issuers of its investments in marketable securities to the extent recorded in the balance sheets. The Company has not experienced any losses on its deposits of cash and cash equivalents.
Segment Information and Geographical Information	Segment Information and Geographical Information The Company has one operating segment and one reportable segment, which is the business of developing treatments that address heart failure. The Company’s chief operating decision maker, its Chief Executive Officer, reviews financial information on an aggregate basis for the purpose of allocating resources and evaluating financial performance. All of the Company’s assets are located in the United States.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less on the date of purchase to be cash equivalents. Cash equivalents primarily consist of money market funds that are stated at fair value.
Restricted Cash	Restricted Cash The Company had restricted cash of $0.5 million for both years ended December 31, 2021 and 2020. The restricted cash represents security deposits for the Company’s operating leases in South San Francisco, California. The security deposits are in the form of a letter of credit secured by restricted cash.
Marketable Securities	Marketable Securities The Company invests in marketable securities, primarily securities issued by the U.S. government and its agencies, commercial paper and corporate bonds. All marketable securities have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in other income (expense), net. There are no material realized gains or losses on marketable securities for all periods presented. The cost of securities sold is based on the specific-identification method. Interest earned on marketable securities is included in interest income.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the assets’ expected lives or the remaining lease term. Costs for capital assets not yet placed into service are capitalized as construction in progress and are not depreciated until the asset is placed in service. Upon retirement or sale, the cost of disposed assets and their related accumulated depreciation are removed from the balance sheets. Any resulting gains or losses on dispositions of property and equipment are included as a component of other income (expense), net, within the Company’s statements of operations and comprehensive loss. Repair and maintenance costs, which are not considered improvements and do not extend the useful life of property and equipment, are expensed as incurred.
Impairment for Long-Lived Assets	Impairment for Long-Lived Assets Long-lived assets, including construction in progress, are reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by comparing the carrying amount of an asset to the estimated undiscounted future net cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. Impairment of long-lived assets were not material for any of the periods presented.
Convertible Preferred Stock Tranche Liability	Convertible Preferred Stock Tranche Liability The obligation to issue additional shares of the Company’s Series B convertible preferred stock at a fixed price on future dates was determined to be a freestanding financial instrument that was accounted for as a liability. On issuance, the Company recorded the convertible preferred stock tranche liability on the balance sheet at its estimated fair value. The liability is subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss on remeasurement as a component of other income (expense), net in the statements of operations and comprehensive loss until settlement or extinguishment. The convertible preferred stock tranche liability was settled upon the second and third closings of the Company’s Series B convertible preferred stock in March and August 2020, respectively.
Leases	Leases The Company adopted Accounting Standards Codification (ASC) Topic 842, Leases (ASC 842) on January 1, 2021, as discussed below in the section titled “Recently Adopted Accounting Standards”. Under ASC 842, the Company determines if an arrangement is a lease at inception. Operating lease right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized based on the present value of lease payments over the lease term at the commencement date of the lease. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less any lease incentive received. The Company uses the rate implicit in the lease in determining the present value of lease payments and, if that rate is not readily determinable, the Company uses its incremental borrowing rate based on the information available at the date of lease commencement. The incremental borrowing rate reflects the rate of interest that a lessee would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The Company’s non-lease components are primarily related to property taxes, insurance, and common area maintenance, which vary based on future outcomes, and are recognized as rent expense when incurred.
Asset Retirement Obligation	Asset Retirement Obligation The Company records asset retirement obligations (AROs) for the estimated cost of removing constructed leasehold improvement assets and restoring the leased premises back to their original condition, at the time when the contractual obligations are incurred. AROs represent the present value of the expected costs for the related restoration activities. The ARO assets and liabilities are recorded in property, plant and equipment and other long-term liabilities, respectively, in the Company’s balance sheets. The Company records accretion expense, which represents the increase in the asset retirement obligations, over the remaining or operational life of the associated leasehold improvements. Accretion expense is recorded as operating expense in the statements of operations using an accretion rate based on the credit adjusted risk-free interest rate. Changes resulting from revisions to the timing or amount of the original estimate of cash flows are recognized as an increase or a decrease in the asset retirement cost, or income when the asset retirement cost is depleted.
Research and Development Expense	Research and Development Expenses Research and development (R&D) costs are expensed as incurred. Research and development expenses include, among others, consulting fees, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocated facilities and overhead costs, amounts owed under licensing agreements, amounts paid to contract research organizations (CRO) that conduct research and development activities on the Company’s behalf and costs related to compliance with regulatory requirements. Goods or services incurred for research and development activities that have not yet been invoiced are recorded as liabilities within accrued expenses and other current liabilities on the Company’s balance sheets. Amounts recorded for unbilled services often represent estimates, which are typically based on contracted amounts for the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the associated services. The Company makes judgments and estimates in determining the accrued and other current liabilities balance. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company adjusts accrued expenses or prepaid expenses accordingly, which impact research and development expenses. The Company has not experienced any material differences between accrued costs and actual costs incurred. Changes in these estimates that result in material changes to the Company’s accrued costs could materially affect the Company’s results of operations. The Company has and may continue to acquire the rights to licensed technology that represents in-process research and development to use and develop in the commercialization of new product candidates. The upfront payments made to acquire licenses, product or rights, or payments made related to future milestone payments are recognized as research and development expenses provided that there is no alternative future use of the rights in other research and development projects, up to the point of regulatory approval. Milestone payments are expensed when the specific milestone has been achieved. Non-refundable advance payments for goods or services to be rendered as part of future research and development activities are capitalized on the Company’s balance sheets until the goods or services are received. Classification between prepaid expenses and other current assets and other non-current assets is based on an evaluation of when the goods will be delivered and/or services will be performed, with such amounts subsequently amortized to expense once incurred.
Stock-Based Compensation	Stock-Based Compensation The Company measures and records expense related to all equity awards granted to employees and non-employees in the statements of operations and comprehensive loss based on their grant date fair values, including stock options and restricted stock awards. For stock-based awards that vest subject to the satisfaction of a service requirement, the expense is recognized using the straight-line method over the requisite service period, which is generally the vesting period. Forfeitures are recognized as they occur. The fair value of restricted stock awards is determined on the date of grant based on the estimated fair value of the Company’s common stock on that date. For purposes of determining the estimated fair value of options granted to employees and nonemployees, the Company uses the Black-Scholes option pricing model. The assumptions used to determine the fair value of options granted were as follows. Each of these inputs is subjective and generally requires significant judgement. Fair Value of Common Stock—Prior to the Company's IPO, there was no public market for its common stock. As such, the estimated fair value of its common stock and underlying stock options was determined at each grant date by the Company's board of directors, with input from management, based on the information known to the Company on the grant date and upon a review of any recent events and their potential impact on the estimated per share fair value of its common stock. As part of these fair value determinations, the Company's board of directors obtained and considered valuation reports prepared by a third-party valuation firm in accordance with the guidance outlined in the American Institute of Certified Public Accountants' Accounting & Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. For grants subsequent to the Company's IPO, the grant date fair value of common stock was determined by using the closing price per share of common stock as reported on the Nasdaq Global Select Market. Expected Term— The Company determines the expected term, which represents the period that stock-based awards are expected to be outstanding, in accordance with the simplified method due to its limited operating history, which is presumed to be the mid-point between the contractual term and the vesting period. Expected Volatility— As there is limited trading history for the Company’s common stock, the Company determines its computation of expected volatility on the historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. Risk-Free Interest Rate— The Company bases the risk-free interest rate on U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term assumption. Expected Dividend— The expected dividend yield is assumed to be zero as the Company has never paid and has no plans to pay any dividends on its common stock.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded for deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. In evaluating the ability to recover its deferred income tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. In the event the Company determines that it would be able to realize its deferred income tax assets in the future in excess of their net recorded amount, it would make an adjustment to the valuation allowance that would reduce the provision for income taxes. Conversely, in the event that all or part of the net deferred tax assets are determined not to be realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period when such determination is made. As of December 31, 2021 and 2020, the Company has recorded a full valuation allowance on its net deferred tax assets. Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties, if any, related to unrecognized tax benefits are included within the provision for income tax.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of the Company’s common stock outstanding for the period, without consideration for potential dilutive shares of common stock. As the Company is in a loss position for the periods presented, diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive. Shares related to early exercised stock options and restricted stock that are subject to repurchase are excluded from the basic and diluted net loss per share calculation until the Company’s repurchase right lapses.
Emerging Growth Company Status	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 use 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 (a) is no longer an emerging growth company or (b) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these 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 Standards and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Standards On January 1, 2021, the Company adopted ASC 842 using the modified retrospective transition method and elected the practical expedients to not reassess whether any expired or existing contracts are or contain leases, carry forward its historical lease classification and not reassess initial direct costs for existing leases. The Company elected to not separate non-lease components from the associated lease components and to not recognize ROU assets and lease liabilities for leases with a term of twelve months or less. Upon adoption of ASC 842, the Company recorded an operating right-of-use asset of $4.6 million, operating lease liabilities of $9.1 million and derecognized deferred rent and other lease liabilities of $4.5 million. Results for the year ended December 31, 2021, are presented under ASC 842. Prior period amounts before January 1, 2021, have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC 840: Leases (Topic 840). Recently Issued Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which replaces the existing incurred loss impairment model with an expected credit loss model. This standard will require companies to recognize an allowance for credit losses on available-for-sale debt securities rather than the current approach of recording a reduction to the carrying value of the asset. As an emerging growth company, ASU 2016-13 is effective for the Company beginning January 1, 2023. The Company is evaluating the impact of this standard on its financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. This standard eliminates certain exceptions to the approach for intra period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. As an emerging growth company, ASU 2019-12 is effective for the Company beginning January 1, 2022. The Company does not expect the adoption of this standard to have any impact on its financial statements. In November 2021, the FASB issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance (ASU 2021-10), which requires business entities to make annual disclosures about transactions with a government they account for by analogizing to a grant or contribution accounting model. The required annual disclosures include the nature of the transaction, the entity’s related accounting policy, the financial statement line items affected and the amounts reflected in the current period financial statements, and any significant terms and conditions. ASU 2021-10 is effective for the Company beginning January 1, 2022. The Company does not expect the adoption of this standard to have a material impact on its financial statements.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

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


		December 31, 2021
	Valuation Hierarchy	Amortized Cost		Unrealized Gain		Unrealized Loss			Fair Value
		(In thousands)
Assets:
Cash equivalents:
Money market funds	Level 1	$	37,129	$	—	$	—		$	37,129
Marketable securities:
U.S. treasuries	Level 1		78,097		—		(85	)		78,012
Commercial paper	Level 2		121,634		—		(50	)		121,584
Corporate bonds	Level 2		8,979		—		(3	)		8,976
Government agencies bonds	Level 2		4,602		—		(3	)		4,599
Total financial assets		$	250,441	$	—	$	(141	)	$	250,300


		December 31, 2020
	Valuation Hierarchy	Amortized Cost		Unrealized Gain		Unrealized Loss		Fair Value
		(In thousands)
Assets:
Cash equivalents:
Money market funds	Level 1	$	127,535	$	—	$	—	$	127,535
Total financial assets		$	127,535	$	—	$	—	$	127,535

Summary of Significant Unobservable Assumptions used to Convertible Preferred Stock Tranche Liability

The following table summarizes the significant unobservable assumptions used to value the convertible preferred stock tranche liability as of the settlement date of August 24, 2020:


	August 24, 2020
Term to valuation date (in years)		0.00
Discount rate		5.0	%

Summary of Changes in Estimated Fair Value Liabilities Measures at Fair Value on a Recurring Basis

The following table summarizes the changes in the estimated fair value of the Company’s convertible preferred stock tranche liability measured on a recurring basis using significant Level 3 inputs:


	Year Ended December 31, 2020
	(In thousands)
Beginning balance	$	786
Change in fair value upon remeasurement		(75	)
Settlement of convertible preferred stock tranche liability on second and third closings of the Series B convertible preferred stock		(711	)
Ending balance	$	—

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2021

Balance Sheet Related Disclosures [Abstract]

Summary of Property and Equipment, Net

Property and equipment, net, consists of the following:


	December 31,
	2021			2020
	(In thousands)
Construction in progress	$	32,561		$	7,678
Laboratory equipment		11,891			8,182
Leasehold improvements		7,241			7,237
Furniture and fixtures		534			534
Computer equipment and software		218			257
Total property and equipment	$	52,445		$	23,888
Less: accumulated depreciation and amortization		(9,425	)		(6,703	)
Total property and equipment, net	$	43,020		$	17,185

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


	December 31,
	2021		2020
	(In thousands)
Accrued compensation and related expenses	$	3,667	$	2,090
Accrued property and equipment		2,863		231
Accrued research and development expenses		2,023		391
Accrued professional services		344		328
Other current liabilities		162		121
Total accrued expenses and other current liabilities	$	9,059	$	3,161

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Summary of Undiscounted Future Minimum Lease Payments Due Under Non-cancelable Operating Lease

As of December 31, 2021, the undiscounted future minimum lease payments due under the Company’s non-cancelable operating leases are as follows:


	Amount
	(In thousands)
2022	$	3,678
2023		3,792
2024		3,910
2025		2,445
2026		1,386
Thereafter		6,905
Total undiscounted future minimum lease payments	$	22,116
Present value adjustment for minimum lease commitments		(6,133	)
Tenant improvement receivable		(282	)
Total operating lease liabilities	$	15,701

As of December 31, 2020, undiscounted future minimum lease payments due under the Company's non-cancelable operating lease are as follows:


	Amount
	(In thousands)
2021	$	3,752
2022		2,206
2023		2,283
2024		2,363
2025		999
Total future minimum lease payments	$	11,603

Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2021

Temporary Equity Disclosure [Abstract]

Schedule of Convertible Preferred Stock

Prior to the Company’s IPO, convertible preferred stock as of December 31, 2020, consists of the following:


	December 31, 2020
	Shares Authorized		Shares Issued and Outstanding		Net Carrying Value		Liquidation Preference
	(In thousands, except share data)
Convertible Preferred Stock
Series A		8,316,666		8,316,662	$	43,393	$	49,900
Series B		9,259,254		9,259,245		91,644		92,000
Series C		8,526,381		6,917,621		85,717		86,000
Total		26,102,301		24,493,528	$	220,754	$	227,900

Common Stock (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Schedule of Common Stock Reserved for Issuance

Total shares of common stock reserved for issuance, on an as-if converted basis, is as follows:


	December 31,
	2021		2020
Conversion of outstanding shares of convertible preferred stock		—		24,493,528
Stock options issued and outstanding		2,772,154		1,160,808
Stock options available for future grant		3,594,158		412,170
Total		6,366,312		26,066,506

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity:


	Number of Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life		Aggregate Intrinsic Value
						(Years)		(In thousands)
Outstanding as of December 31, 2020		1,160,808		$	1.74		8.40
Options granted		1,850,036			11.05
Options exercised		(195,749	)		1.91
Options cancelled		(42,941	)		3.68
Outstanding as of December 31, 2021		2,772,154		$	7.90		8.74	$	31,420
Exercisable as of December 31, 2021		705,577		$	2.65		7.61	$	11,500

Summary of Stock-based Compensation

The following table summarizes stock-based compensation recognized in the Company’s statements of operations and comprehensive loss:


	Year Ended December 31,
	2021		2020
	(In thousands)
Research and development	$	1,179	$	378
General and administrative		1,771		363
Total stock-based compensation	$	2,950	$	741

Summary of Fair Value of Stock Option Awards

The fair value of the Company’s stock option awards is estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:


	Year Ended December 31,
	2021	2020
Expected term (in years)	5.0 - 6.1	5.9 - 6.1
Expected volatility	95% - 103%	178% - 183%
Risk-free interest rate	0.6% - 1.4%	0.4% - 1.5%
Expected dividend yield	—%	—%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Effective Tax Rate Reconciliation

The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate and the effective tax rate reconciliation is as follows:


	December 31,
	2021			2020
U.S. federal taxes at statutory rate		21.0	%		21.0	%
State taxes (net of federal benefit)		0.6			8.1
Credits		3.1			3.6
Stock-based compensation		(0.3	)		(0.3	)
Section 382 limitation on tax attribute carryforwards		—			(9.0	)
Change in valuation allowance		(23.3	)		(23.1	)
Other		(1.1	)		(0.3	)
Total	—%			—%

Schedule of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
	2021			2020
	(In thousands)
Balance at beginning of year	$	571		$	744
Additions based on tax positions related to current year		901			293
Additions based on tax positions related to prior years		—			—
Reductions for tax positions related to prior years		(2	)		(466	)
Balance at end of year	$	1,470		$	571

Schedule of Deferred Income Taxes

The tax effects of significant items comprising the Company’s deferred income taxes are as follows:


	December 31,
	2021			2020
	(In thousands)
Deferred tax assets:
Net operating losses	$	34,746		$	20,917
Tax credits		4,443			1,346
Lease liability		3,362			—
Accrued expenses and other		727			1,825
Stock-based compensation		309			79
Property and equipment		152			120
Total deferred tax assets		43,739			24,287
Valuation allowance		(41,281	)		(24,287	)
Deferred tax assets, net of valuation allowance		2,458			—
Deferred tax liabilities:
Right-of-use asset		(2,458	)		—
Net deferred tax assets	$	—		$	—

Summary of Net Operating Loss and Tax Carryforwards

As of December 31, 2021, the Company’s net operating loss and tax carryforwards are summarized as follows:


	Amount		Expiration in years
Net operating losses, federal (post-December 31, 2017)	$	140,666	Do Not Expire
Net operating losses, federal (pre-January 1, 2018)	$	3,093	Begins to Expire 2036
Net operating losses, state	$	62,817	Begins to Expire 2036
Tax credits, federal	$	3,433	Begins to Expire 2036
Tax credits, state	$	3,258	Do Not Expire

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share

The following potentially dilutive securities were not included in the calculation of diluted net loss per share for the periods presented because the effect would have been anti-dilutive:


	December 31,
	2021		2020
Convertible preferred stock		—		24,493,528
Outstanding stock options		2,772,154		1,160,808
Restricted stock subject to future vesting		28,905		138,127
Total		2,801,059		25,792,463

Organization and Description of the Business - Additional Information (Details)			12 Months Ended
	Aug. 03, 2021 USD ($) $ / shares shares	Jul. 23, 2021	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)
Organization And Description Of Business [Line Items]
Reverse stock split description		1-for-6
Reverse stock split		0.1667
Net proceeds of after deducting underwriting discounts and commissions			$ 188,541,000
Accumulated deficit			(155,533,000)	$ (82,812,000)
Net loss			(72,721,000)	$ (38,395,000)
Cash, cash equivalents and investments in marketable securities			$ 251,300,000
Common Stock
Organization And Description Of Business [Line Items]
Issuance of common stock \| shares			13,800,000
Net proceeds of after deducting underwriting discounts and commissions	$ 188,500
Conversion of outstanding shares of convertible preferred stock \| shares	26,102,278
Common Stock \| Initial Public Offering
Organization And Description Of Business [Line Items]
Issuance of common stock \| shares	13,800,000
Share price \| $ / shares	$ 15.00
Underwriting discounts and commissions	$ 14,500
Other offering expenses	$ 4,000.0
Common Stock \| Overallotment Option
Organization And Description Of Business [Line Items]
Issuance of common stock \| shares	1,800,000

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) Segment	Jan. 01, 2021 USD ($)	Dec. 31, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Number of reportable segment \| Segment	1
Restricted cash, non-current	$ 547		$ 547
Operating lease right-of-use assets	11,685
Operating lease liabilities	$ 15,701
ASC 842
Significant Accounting Policies [Line Items]
Operating lease right-of-use assets		$ 4,600
Operating lease liabilities		9,100
Derecognized deferred rent and other lease liabilities		$ 4,500
Accounting standards update, adopted [true false]	true
Accounting standards update, adoption date	Jan. 01, 2021
Minimum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Maximum
Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years

Fair Value Measurements - Summary of Fair Value of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 250,441	$ 127,535
Unrealized Loss	(141)
Fair Value	250,300	127,535
Money Market Funds \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	37,129	127,535
Fair Value	37,129	$ 127,535
Commercial Paper \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	121,634
Unrealized Loss	(50)
Fair Value	121,584
U.S. Treasuries \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	78,097
Unrealized Loss	(85)
Fair Value	78,012
Corporate Bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	8,979
Unrealized Loss	(3)
Fair Value	8,976
Government Agencies Bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	4,602
Unrealized Loss	(3)
Fair Value	$ 4,599

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment charges on marketable securities related to other-than-temporary	$ 0
Convertible preferred stock tranche liability	$ 0	$ 0
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale marketable securities contractual maturities term	1 year

Fair Value Measurements - Summary of Significant Unobservable Assumptions used to Convertible Preferred Stock Tranche Liability (Details) - Convertible Preferred Stock Tranche Liability	Aug. 24, 2020 USD ($)
Term to Valuation Date
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Term to valuation date (in years)	0 years
Discount rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement input	5.0

Fair Value Measurements - Summary of Changes in Estimated Fair Value Liabilities Measures at Fair Value on a Recurring Basis (Details) - Level 3 - Convertible Preferred Stock Tranche Liability $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning balance	$ 786
Change in fair value upon remeasurement	(75)
Settlement of convertible preferred stock tranche liability on second and third closings of the Series B convertible preferred stock	(711)
Ending balance	$ 0

Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total property and equipment	$ 52,445	$ 23,888
Less: accumulated depreciation and amortization	(9,425)	(6,703)
Total property and equipment, net	43,020	17,185
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	32,561	7,678
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	11,891	8,182
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	7,241	7,237
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	534	534
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment	$ 218	$ 257

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 3.0	$ 2.5

Balance Sheet Components - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related expenses	$ 3,667	$ 2,090
Accrued property and equipment	2,863	231
Accrued research and development expenses	2,023	391
Accrued professional services	344	328
Other current liabilities	162	121
Total accrued expenses and other current liabilities	$ 9,059	$ 3,161

License Agreements (Details)	1 Months Ended		12 Months Ended
License Agreements (Details)	Jan. 31, 2020 USD ($)	Oct. 31, 2016 USD ($) Option	Dec. 31, 2021 USD ($)
University of Texas Southwestern License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone and royalty payments recognized			$ 0
Non-refundable upfront license fee	$ 100,000
University of Texas Southwestern License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments contingent upon achieving specific development and commercialization milestone events	$ 14,800,000
Gladstone \| Gladstone License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of additional option to extend milestone payment \| Option		4
Milestone obligation additional extended payment terms		1 year
Milestone and royalty payments recognized			$ 0
Gladstone \| Gladstone License Agreement \| Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual license maintenance fees		$ 25,000
Milestone obligation amount		50,000
Gladstone \| Gladstone License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual license maintenance fees		100,000
Milestone payments for royalty-bearing products contingent upon achieving specific clinical and commercialization milestone events		4,100,000
Milestone obligation amount		$ 100,000

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended				12 Months Ended
	Nov. 30, 2021	Feb. 28, 2021 USD ($) RenewalOption	Dec. 31, 2020	Dec. 31, 2016 USD ($) RenewalOption	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Rent expense					$ 5.7	$ 2.4
Short-term lease					1.7
Variable lease payments					$ 1.6
Sublease agreements expiration date					Dec. 31, 2020
Other Income (Expense), Net
Commitments And Contingencies [Line Items]
Sublease Income						$ 0.4
ASC 842
Commitments And Contingencies [Line Items]
Remaining weighted-average lease term					6 years 7 months 6 days
Weighted-average incremental borrowing rate used to determine operating lease liability					9.50%
Office and Laboratory Space \| South San Francisco, California
Commitments And Contingencies [Line Items]
Lease expiration month and year				2025-05
Number of lease renewal term \| RenewalOption				2
Lease renewal term				5 years
Tenant improvement allowance				$ 5.8
Additional Office and Laboratory Space \| South San Francisco, California
Commitments And Contingencies [Line Items]
Lease Expiration Date	Jun. 30, 2022		Nov. 30, 2021
Manufacturing and Office Space \| Union City, California
Commitments And Contingencies [Line Items]
Number of lease renewal term \| RenewalOption		1
Lease renewal term		5 years
Lease commenced month and year		2021-05
Term of lease		10 years
Manufacturing and Office Space \| Union City, California \| Other Noncurrent Assets
Commitments And Contingencies [Line Items]
Security deposit		$ 3.3

Commitments and Contingencies - Summary of Undiscounted Future Minimum Lease Payments Due Under Non-cancelable Operating Lease (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
2022	$ 3,678
2023	3,792
2024	3,910
2025	2,445
2026	1,386
Thereafter	6,905
Total undiscounted future minimum lease payments	22,116
Present value adjustment for minimum lease commitments	(6,133)
Tenant improvement receivable	(282)
Total operating lease liabilities	$ 15,701
2021		$ 3,752
2022		2,206
2023		2,283
2024		2,363
2025		999
Total future minimum lease payments		$ 11,603

Convertible Preferred Stock - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Aug. 03, 2021 shares	Jan. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) Closing $ / shares shares
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			0	26,102,301
Convertible preferred stock shares issued			0	24,493,528
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized				8,526,381
Convertible preferred stock purchase price per share \| $ / shares		$ 12.432
Convertible preferred stock shares issued		1,608,750		6,917,621
Proceeds from issuance of convertible preferred stock, net of issuance costs \| $		$ 20,000	$ 19,981	$ 85,951
Series C Preferred Stock Purchase Agreement \| Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized				8,526,381
Convertible preferred stock purchase price per share \| $ / shares				$ 12.432
Number of closings \| Closing				2
Convertible preferred stock shares issued				6,917,621
Proceeds from issuance of convertible preferred stock, net of issuance costs \| $				$ 86,000
Common Stock
Temporary Equity [Line Items]
Conversion of outstanding shares of convertible preferred stock	26,102,278

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Jan. 31, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Shares Authorized	0		26,102,301
Shares Issued	0		24,493,528
Shares Outstanding	0		24,493,528
Net Carrying Value			$ 220,754
Liquidation Preference			$ 227,900
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized			8,316,666
Shares Issued			8,316,662
Shares Outstanding			8,316,662
Net Carrying Value			$ 43,393
Liquidation Preference			$ 49,900
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized			9,259,254
Shares Issued			9,259,245
Shares Outstanding			9,259,245
Net Carrying Value			$ 91,644
Liquidation Preference			$ 92,000
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Shares Authorized			8,526,381
Shares Issued		1,608,750	6,917,621
Shares Outstanding			6,917,621
Net Carrying Value			$ 85,717
Liquidation Preference			$ 86,000

- Definition

Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

+ References + Details

Common Stock - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common stock voting rights	The holders of common stock are entitled to one vote per share on all matters to be voted on by the stockholders of the Company and are entitled to dividends, if and when declared by the board of directors, subject to the prior rights of the preferred stockholders.
Common stock, outstanding	41,291,374	1,210,306
Early Exercised Stock Options and Restricted Stock That are Unvested and Subject to Repurchase
Class Of Stock [Line Items]
Common stock, outstanding	28,905	138,127

Common Stock - Schedule of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common stock reserved for issuance	6,366,312	26,066,506
Stock Options Issued and Outstanding
Class Of Stock [Line Items]
Common stock reserved for issuance	2,772,154	1,160,808
Stock Options Available for Future Grant
Class Of Stock [Line Items]
Common stock reserved for issuance	3,594,158	412,170
Conversion of Outstanding Shares of Convertible Preferred Stock
Class Of Stock [Line Items]
Common stock reserved for issuance		24,493,528

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value of options exercised		$ 1,700,000	$ 37,000
Weighted-average grant-date fair value of options granted		$ 9.50	$ 4.98
Common stock reserved for issuance		6,366,312	26,066,506
Stock-based compensation		$ 2,950,000	$ 741,000
Unrecognized stock-based compensation		$ 16,700,000
Weighted-average period		3 years 1 month 6 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Repurchase unvested shares after unemployment, terminated		90 days
Restricted stocks exercise of stock options, outstanding		28,905
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock that may be issued in accordance with the plan	800,000
Percentage of shares of common stock outstanding on last day of immediately preceding year	1.00%
Common stock reserved for issuance	800,000
Participants to purchase common stock through payroll deduction maximum percentage of eligible compensation	15.00%
Stock-based compensation		$ 0
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for issuance period	10 years
Number of shares of common stock that may be issued in accordance with the plan	4,000,000
Percentage of shares of common stock outstanding on last day of immediately preceding year	4.00%
Shares reserved and available for grant		3,594,158
Intrinsic value of options exercised		$ 11,500,000
Weighted-average grant-date fair value of options granted		$ 11.05
Common stock reserved for issuance	4,000,000

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate Intrinsic Value, Exercisable as of December 31, 2021	$ 1,700,000	$ 37,000
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding, Outstanding Beginning Balance	1,160,808
Number of Options Outstanding, Options granted	1,850,036
Number of Options Outstanding, Options exercised	(195,749)
Number of Options Outstanding, Options cancelled	(42,941)
Number of Options Outstanding, Outstanding Ending Balance	2,772,154	1,160,808
Number of Options Outstanding, Exercisable as of December 31, 2021	705,577
Weighted-Average Exercise Price Per Share, Outstanding Beginning Balance	$ 1.74
Weighted-Average Exercise Price Per Share, Options granted	11.05
Weighted-Average Exercise Price Per Share, Options exercised	1.91
Weighted-Average Exercise Price Per Share, Options cancelled	3.68
Weighted-Average Exercise Price Per Share, Outstanding Ending Balance	7.90	$ 1.74
Weighted-Average Exercise Price Per Share, Exercisable as of December 31, 2021	$ 2.65
Weighted-Average Remaining Contractual Life, Outstanding	8 years 8 months 26 days	8 years 4 months 24 days
Weighted-Average Remaining Contractual Life, Exercisable as of December 31, 2021	7 years 7 months 9 days
Aggregate Intrinsic Value, Outstanding	$ 31,420,000
Aggregate Intrinsic Value, Exercisable as of December 31, 2021	$ 11,500,000

Stock-Based Compensation - Summary of Stock-based Compensation (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	$ 2,950	$ 741
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	1,179	378
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 1,771	$ 363

Stock-Based Compensation - Summary of Fair Value of Stock Option Awards (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	95.00%	178.00%
Expected volatility, maximum	103.00%	183.00%
Risk-free interest rate, minimum	0.60%	0.40%
Risk free interest rate, maximum	1.40%	1.50%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years	5 years 10 months 24 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income taxes expense	$ 0	$ 0
Increase in valuation allowance, deferred tax assets	17,000,000.0	8,900,000
Deferred tax assets removed related to net operating loss carryforwards and research tax credit		3,100,000
Interest and penalties related to taxes and uncertain tax positions	$ 0	$ 0

- Definition

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

+ References + Details

Income Taxes - Schedule of Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
U.S. federal taxes at statutory rate	21.00%	21.00%
State taxes (net of federal benefit)	0.60%	8.10%
Credits	3.10%	3.60%
Stock-based compensation	(0.30%)	(0.30%)
Section 382 limitation on tax attribute carryforwards		(9.00%)
Change in valuation allowance	(23.30%)	(23.10%)
Other	(1.10%)	(0.30%)

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 571	$ 744
Additions based on tax positions related to current year	901	293
Reductions for tax positions related to prior years	(2)	(466)
Balance at end of year	$ 1,470	$ 571

Income Taxes - Schedule of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating losses	$ 34,746	$ 20,917
Tax credits	4,443	1,346
Lease liability	3,362
Accrued expenses and other	727	1,825
Stock-based compensation	309	79
Property and equipment	152	120
Total deferred tax assets	43,739	24,287
Valuation allowance	(41,281)	$ (24,287)
Deferred tax assets, net of valuation allowance	2,458
Deferred tax liabilities:
Right-of-use asset	$ (2,458)

Income Taxes - Summary of Net Operating Loss and Tax Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Operating Loss Carryforwards [Line Items]
Net operating losses, state expiration begin year	2036
Tax credits, federal expiration begin year	2036
Tax credits, state expiration description	Do Not Expire
Federal
Operating Loss Carryforwards [Line Items]
Tax credits	$ 3,433
State
Operating Loss Carryforwards [Line Items]
Net operating losses	62,817
Tax credits	$ 3,258
Post-December 31, 2017
Operating Loss Carryforwards [Line Items]
Net operating losses, federal expiration description	Do Not Expire
Post-December 31, 2017 \| Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 140,666
Pre-January 1, 2018
Operating Loss Carryforwards [Line Items]
Net operating losses, federal expiration begin year	2036
Pre-January 1, 2018 \| Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 3,093

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share	2,801,059	25,792,463
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share		24,493,528
Outstanding Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share	2,772,154	1,160,808
Restricted stock subject to future vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities were not included in the calculation of diluted net loss per share	28,905	138,127