ALX Oncology (ALXO) 10-K 9 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 02, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Registrant Name	ALX ONCOLOGY HOLDINGS INC
Entity Central Index Key	0001810182
Entity File Number	001-39386
Entity Tax Identification Number	85-0642577
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	323 Allerton Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	466-7125
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding		40,863,049
Entity Public Float			$ 172.6
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	ALXO
Security Exchange Name	NASDAQ
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Document Annual Report	true
Document Transition Report	false
Auditor Name	KPMG LLP
Auditor Firm ID	185
Auditor Location	San Francisco, California
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Certain portions of the registrant’s definitive proxy statement relating to the Company's 2023 Annual Meeting of Stockholders, to be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2022 , are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 48,822	$ 363,667
Short-term investments	217,385
Prepaid expenses and other current assets	4,762	3,352
Total current assets	270,969	367,019
Property and equipment, net	3,889	897
Long-term investments	16,699
Other assets	14,932	12,267
Total assets	306,489	380,183
Current liabilities:
Accounts payable	8,073	3,764
Payable and accrued liabilities due to related party	1,650	1,630
Accrued expenses and other current liabilities	18,602	9,901
Total current liabilities	28,325	15,295
Term loan, non-current, net	9,389
Other non-current liabilities	5,311	1,839
Total liabilities	43,025	17,134
Commitments and contingencies (Note 13)
Stockholders’ equity
Common stock, $0.001 par value; 1,000,000,000 shares authorized as of December 31, 2022 and December 31, 2021; 40,861,386 and 40,587,067 shares issued and outstanding as of December 31, 202 and December 31, 2021, respectively	41	41
Additional paid-in capital	589,735	564,993
Accumulated other comprehensive loss	(845)
Accumulated deficit	(325,467)	(201,985)
Total stockholders’ equity	263,464	363,049
Total liabilities and stockholders’ equity	$ 306,489	$ 380,183

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	40,861,386	40,587,067
Common stock, shares outstanding	40,861,386	40,587,067

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Related-party revenue	$ 0	$ 0	$ 1,182
Type of revenue description	Related-party revenue	Related-party revenue	Related-party revenue
Operating expenses:
Research and development	$ 98,400	$ 60,170	$ 28,961
General and administrative	29,036	23,385	14,809
Cost of services for related-party revenue			1,075
Total operating expenses	127,436	83,555	44,845
Loss from operations	(127,436)	(83,555)	(43,663)
Interest income	4,278	91	124
Other expense, net	(260)	(20)	(1,339)
Loss on early debt extinguishment			(621)
Loss before income taxes	(123,418)	(83,484)	(45,499)
Income tax (provision) benefit	(64)	21	(241)
Net loss	(123,482)	(83,463)	(45,740)
Cumulative dividends allocated to preferred stockholders			(5,202)
Net loss attributable to common stockholders	$ (123,482)	$ (83,463)	$ (50,942)
Net loss per share attributable to common stockholders, basic	$ (3.03)	$ (2.07)	$ (2.76)
Net loss per share attributable to common stockholders, diluted	$ (3.03)	$ (2.07)	$ (2.76)
Weighted-average shares of common stock used to compute net loss per share attributable to common stockholders, basic	40,699,612	40,308,050	18,485,343
Weighted-average shares of common stock used to compute net loss per share attributable to common stockholders, diluted	40,699,612	40,308,050	18,485,343

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (123,482)	$ (83,463)	$ (45,740)
Cumulative preferred dividends allocated to preferred stockholders			(5,202)
Net loss attributable to common stockholders	(123,482)	(83,463)	(50,942)
Other comprehensive loss, net of tax:
Unrealized loss on available-for-sale investments	(845)
Total comprehensive loss	$ (124,327)	$ (83,463)	$ (50,942)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2019	$ (70,639)		$ 3	$ 2,140		$ (72,782)
Temporary equity, shares at Dec. 31, 2019		10,313,808
Temporary equity, balance at Dec. 31, 2019		$ 70,363
Balance, shares at Dec. 31, 2019			3,166,946
Issuance of convertible preferred stock, net of issuance costs		$ 104,680
Issuance of convertible preferred stock, net of issuance costs, shares		11,055,966
Reclassification of warrants from liability to equity	1,019			1,019
Conversion of convertible preferred stock in to common stock	175,043	$ (175,043)	$ 21	175,022
Conversion of convertible preferred stock into common stock, shares		(21,369,774)	21,369,774
Cumulative dividends			$ 3	(3)
Cumulative dividends, shares			2,564,759
Issuance of common stock in connection with equity offerings, net of underwriter discounts and issuance costs	364,400		$ 13	364,387
Issuance of common stock in connection with equity offerings, net of underwriter discounts and issuance costs, shares			12,512,000
Issuance of common stock upon net exercise of warrants			48,932
Issuance of common stock under equity incentive plans	299			299
Issuance of common stock under equity incentive plans, shares			182,111
Vesting of early exercised stock options	27			27
Stock-based compensation	5,436			5,436
Net loss	(45,740)					(45,740)
Balance at Dec. 31, 2020	429,845		$ 40	548,327		(118,522)
Balance, shares at Dec. 31, 2020			39,844,522
Issuance of common stock under equity incentive plans	2,551		$ 1	2,550
Issuance of common stock under equity incentive plans, shares			734,922
Issuance of common stock under employee stock purchase plan	202			202
Issuance of common stock under employee stock purchase plan, shares			7,623
Stock-based compensation	13,914			13,914
Net loss	(83,463)					(83,463)
Balance at Dec. 31, 2021	363,049		$ 41	564,993		(201,985)
Balance, shares at Dec. 31, 2021			40,587,067
Issuance of common stock under equity incentive plans	567			567
Issuance of common stock under equity incentive plans, shares			225,612
Issuance of common stock under employee stock purchase plan	336			336
Issuance of common stock under employee stock purchase plan, shares			48,707
Stock-based compensation	23,839			23,839
Unrealized loss on available-for-sale investments	(845)				$ (845)
Net loss	(123,482)					(123,482)
Balance at Dec. 31, 2022	$ 263,464		$ 41	$ 589,735	$ (845)	$ (325,467)
Balance, shares at Dec. 31, 2022			40,861,386

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net loss	$ (123,482)	$ (83,463)	$ (45,740)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	342	51	202
Non-cash lease costs	1,124	685
Acquired in-process research and development		4,739
Stock-based compensation	23,839	13,914	5,436
Net amortization of premiums and accretion of discounts on investments	(940)
Accretion of term loan discount and issuance costs	44		421
Changes in fair value of compound derivative liability and warrants			650
Gain on assignment of lease			(126)
Loss on early debt extinguishment			621
Changes in operating assets and liabilities
Receivables due from related-party			536
Prepaid expenses and other current assets	(1,476)	(1,662)	(1,514)
Other assets	750	(9,682)	(10)
Accounts payable	4,506	3,290	(3,744)
Payable and accrued liabilities due to related party	20	1,419
Accrued expenses and other current liabilities	7,027	3,306	4,983
Other non-current liabilities	(977)	(698)	(4)
Net cash used in operating activities	(89,223)	(68,101)	(38,289)
Investing activities
Purchase of investments	(376,789)
Maturities of investments	142,800
Purchase of property and equipment	(1,427)	(666)	(31)
Acquisition of in-process research and development		(4,257)
Proceeds from assets held for sale			641
Net cash provided by (used in) investing activities	(235,416)	(4,923)	610
Financing activities
Proceeds from common stock offerings, net			368,256
Payments of offering costs			(3,848)
Proceeds from exercise of stock options under equity incentive plan	567	2,551	299
Proceeds from issuance of common stock under employee stock purchase plan	336	202
Proceeds from issuance of convertible preferred stock, net			104,680
Principal payments on finance leases	(388)	(281)
Proceeds from issuance of term loan, net	10,000
Payments of debt issuance costs	(655)
Cash paid for early debt extinguishment			(6,506)
Net cash provided by financing activities	9,860	2,472	462,881
Net increase (decrease) in cash, cash equivalents and restricted cash	(314,779)	(70,552)	425,202
Cash, cash equivalents and restricted cash at beginning of year	363,667	434,219	9,017
Cash, cash equivalents and restricted cash at end of period	48,888	363,667	434,219
Supplemental disclosure
Cash paid for interest	103	11	427
Cash paid for taxes		274	47
Supplemental disclosure of non-cash investing and financing activities
Vesting of early exercised stock options			27
Purchase of property and equipment in accounts payable and accrued expenses	2,145	237	7
Acquisition of in-process research and development in accounts payable and accrued expenses		482
Conversion of convertible preferred stock into common stock upon closing of initial public offering			175,043
Accumulated dividend on convertible preferred stock			3
Right-of-use asset acquired under operating leases	4,613	1,780
Right-of-use asset acquired under finance leases		776
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents	48,822	363,667	434,219
Restricted cash (included in other assets)	66
Total cash and cash equivalents and restricted cash	$ 48,888	$ 363,667	$ 434,219

Organization

Organization	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
ORGANIZATION	(1) ORGANIZATION Organization ALX Oncology Holdings Inc., or the Company, was formed as a Delaware corporation on April 1, 2020, or Inception. The Company was formed for the purpose of completing the Company’s initial public offering of its common stock and related transactions in order to carry on the business of ALX Oncology Limited. The Company is a clinical-stage immuno-oncology company focused on helping patients fight cancer by developing therapies that block the CD47 checkpoint pathway and bridge the innate and adaptive immune system. ALX Oncology Holdings Inc. is incorporated in Delaware. ALX Oncology Limited, incorporated in Ireland, is a wholly-owned subsidiary of ALX Oncology Holdings Inc. ALX Oncology Inc., incorporated in Delaware, is a wholly-owned subsidiary of ALX Oncology Limited. Alexo International Holdings Limited, incorporated in Malta, is a wholly-owned subsidiary of ALX Oncology Inc. All the companies are collectively known as the Subsidiaries. As of December 31, 2022, the Company has devoted substantially all of its efforts to the formation and financing of the Company, as well as product development, and has not realized product revenues from its planned principal operations. The Company does not have manufacturing facilities and all manufacturing related activities are contracted out to third-party service providers. Management expects to incur additional losses in the future to conduct product candidate research and development and to conduct pre-commercialization activities and recognizes that the Company will likely raise additional capital to fully implement its business plan. The Company intends to raise such capital through the sale of additional equity, debt financings and/or strategic alliances with third parties. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms acceptable to the Company. If the Company is unsuccessful in its efforts to raise additional financing, the Company could be required to significantly reduce operating expenses and delay, reduce the scope of or eliminate some of its development programs or its future commercialization efforts, out-license intellectual property rights to its product candidates and sell unsecured assets, or a combination of the above, any of which may have a material adverse effect on the Company’s business, results of operations, financial condition and/or its ability to fund its scheduled obligations on a timely basis or at all. The Company believes that the existing capital resources will be sufficient to fund the projected operating requirements for at least the next twelve months.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	(2) SIGNIFICANT ACCOUNTING POLICIES Basis of Preparation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and the applicable rules and regulations of the U.S. Securities and Exchange Commission, or SEC. Reclassifications Certain reclassifications have also been made within the consolidated statements of operations for the years ended December 31, 2021 and 2020 to conform to the current year presentation. For the year ended December 31, 2021, the Company reclassified approximately $ 0.1 million out of other income (expense), net into a separate interest income financial statement line item as well as combined a nominal amount of interest expense into other income (expense), net, which is now renamed other expense, net. For the year ended December 31, 2020, the Company reclassified approximately $ 0.1 million out of other income (expense), net into a separate interest income financial statement line item as well as combined approximately $ 0.8 million amount of interest expense into other income (expense), net, which is now renamed other expense, net. Total loss before income taxes as of December 31, 2021 and 2020 did not change as a result of these reclassifications. Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation. Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806 reverse split of its common stock and convertible preferred stock. The par values of the common and convertible preferred stock were not adjusted as a result of the reverse stock split. All authorized, issued and outstanding common stock, convertible preferred stock, stock options, warrants, and related per share amounts contained in the consolidated financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The reverse stock split was effected on July 9, 2020. Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including, but not limited to, those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, fair value of investments, valuation of the Company’s common stock in periods prior to its initial public offering and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Cash and Cash Equivalents The Company holds its cash and cash equivalents in checking and money market accounts. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and U.S. government agency securities that are stated at cost, which approximate fair value. Investments Investments consist of money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt securities, commercial paper and asset-backed securities. The Company’s investments are classified as available-for-sale and carried at estimated fair values and reported in cash equivalents, short-term investments and long-term investments. Management determines the appropriate classification of the investments at the time they are purchased and evaluates the appropriateness of such classifications at each balance sheet date. Investments with contractual maturities greater than 12 months are considered long-term investments. The Company regularly reviews its investments for declines in estimated fair value below amortized cost. The factors considered in determining whether a credit loss exists include the creditworthiness of the security issuers, the number of investments in an unrealized loss position, the severity and duration of the unrealized losses, and whether it is more likely than not that the Company will be required to sell the investments before the recovery of their amortized cost basis. The cost of investments sold is based on the specific identification method. In circumstances when an unrealized loss is determined to be credit-related, or when the Company intends to sell or is more likely than not required to sell a security before it recovers its amortized cost basis, the difference between the fair value and the amortized cost of the security is recognized within other expense, net in the consolidated statements of operations, and an allowance for credit loss is recorded on the consolidated balance sheets. In circumstances when the decline in fair value is non-credit related, the difference is reported in accumulated other comprehensive loss, net of tax as a separate component of consolidated stockholders’ equity. Concentration of Credit Risk, Credit Losses and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash, cash equivalents, and investments. The primary objectives for the Company’s investment portfolio are the preservation of capital and the maintenance of liquidity. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash, cash equivalents and investments and issuers of investments. The Company manages its credit risk by holding its cash, cash equivalents and investments in large financial institutions within the U.S. In addition, the Company’s investment policy limits investments to certain types of instruments such as money market funds, debt securities issued by the U.S. government and its agencies, corporate debt securities, commercial paper as well as asset-backed securities, and places restrictions on the credit ratings, maturities and concentration by type and issuer. The Company has not experienced any losses on its deposits of cash, cash equivalents and investments. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the U.S. Food and Drug Administration, or FDA, and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized on a straight-line basis over the shorter of the term of the lease, or the useful life of the assets. Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in the consolidated statement of operations. Maintenance and repairs are charged to the consolidated statement of operations as incurred. Leases On January 1, 2021, the Company adopted Accounting Standards Update No. 2016-02, Leases, Topic 842, or Accounting Standards Codification (ASC) 842, using the alternative modified transition method, which applies the standard as of the adoption date. Results and disclosure requirements for reporting periods beginning after January 1, 2021 are presented under ASC 842. The Company determines if an arrangement contains a lease at inception. For arrangements where the Company is the lessee, leases are included in operating or finance lease right-of-use, or ROU, assets; current operating or finance lease liabilities; and non-current operating or finance lease liabilities. Lease ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. ROU assets also include any initial direct costs incurred and any lease payments made on or before the lease commencement date, less lease incentives received. The Company uses its incremental borrowing rate based on the information available at the commencement date in determining the lease liabilities as the Company’s leases generally do not provide an implicit rate. The incremental borrowing rate is reevaluated upon a lease modification. The Company considered information available at the adoption date of ASC 842 to determine the incremental borrowing rate for leases in existence as of this date. Lease terms may include options to extend or terminate the lease when the Company is reasonably certain that the option will be exercised. Lease expense for operating leases is recognized on a straight-line basis over the lease term. For finance leases, ROU assets are amortized on a straight-line basis over the shorter of the expected useful life or the lease term, and the carrying amount of the lease liability is adjusted to reflect interest, which is recorded in interest expense. The Company elected to apply each of the practical expedients described in ASC 842 which allow companies (i) not to reassess prior conclusions on whether any expired or existing contracts are or contain a lease, lease classification, and initial direct costs, (ii) combine lease and non-lease components for all underlying assets groups, and (iii) not recognize ROU assets or lease liabilities for short term leases. A short-term lease is a lease that, at the commencement date, has a lease term of 12 months or less and does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise. Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. The Company has no t recorded impairment of any long-lived assets. Fair Value of Financial Instruments The fair value of the Company’s financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC 820, Fair Value Measurements and Disclosures. ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels: Level 1—Observable inputs, such as quoted prices in active markets; Level 2—Inputs, other than the quoted prices in active markets, which are observable either directly or indirectly such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life; and Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company classifies money market funds and U.S. treasury securities as Level 1 within the fair value hierarchy as the fair value is based on quoted prices. The Company classifies its investments in U.S. government agency securities, corporate debt securities, commercial paper, and asset-backed securities as Level 2 within the fair value hierarchy as the fair value is estimated by third-party pricing sources using quoted prices for identical or similar instruments in markets that are not active and industry-standard model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to benchmark yields, reported trades and broker/dealer quotes. Where applicable the market approach utilizes prices and information from market transactions for similar or identical assets. Debt Issuance Costs Debt issuance costs consist of payments made to secure commitments under certain debt financing arrangements. These amounts are recognized as interest expense over the period of the financing arrangement using the effective interest method. If the financing arrangement is canceled or forfeited, or if the utility of the arrangement to the Company is otherwise compromised, these costs are recognized as interest expense immediately. The Company’s consolidated financial statements present debt issuance costs related to a recognized debt liability as a direct reduction from the carrying amount of that debt liability. Convertible Preferred Stock The Company records convertible preferred stock net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its organization documents unless the holders of convertible preferred stock have converted their convertible preferred stock into common stock. Convertible preferred stock is classified outside of stockholders’ equity (deficit) on the accompanying consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. Upon the consummation of the Company’s initial public offering in July 2020, all shares of convertible preferred stock outstanding and accrued cumulative dividends automatically converted into 23,934,533 shares of common stock. Series B Convertible Preferred Stock Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred stock. Freestanding warrants for the Company’s convertible preferred stock that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement at the end of every period until the earlier of the exercise of the warrants or the completion of a liquidation event, including the completion of an initial public offering. Upon exercise, the Series B convertible preferred stock warrant liability would be reclassified to additional paid-in capital, with any change in fair value recognized as a component of other expense, net. Following the Company’s initial public offering, the warrants were automatically converted to warrants to purchase shares of common stock. The Company revalued the Series B convertible preferred stock warrants as of the completion of the initial public offering and reclassified the outstanding preferred stock warrant liability balance to additional paid-in capital with no further re-measurement required as common stock warrants are considered permanent equity. Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. No such revenue was earned in either 2021 or 2022. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, Revenue from Contracts with Customers , the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of ASC 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying consolidated statements of operations. Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, stock-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed. Asset Acquisition including Acquired In-Process Research and Development Expenses When determining whether a transaction gives rise to an acquisition of a business or asset group, the Company applies a screening test to determine whether substantially all of the fair value of the gross assets acquired in the transaction is concentrated in a single identifiable asset or group of similar identifiable assets. If so, then the assets are not considered a business and the transaction is accounted for as an asset acquisition. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the asset or group of assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions or transactions to license intellectual property. In an asset acquisition, the cost allocated to acquired in-process research and development (IPR&D) with no alternative future use is recognized as an expense on the acquisition date. When a transaction is accounted for as an asset acquisition, an in-process research and development, or IPR&D asset is only capitalized if it has an alternative future use other than in a particular research and development project. Otherwise, amounts allocated to IPR&D that have no alternative use are expensed. Upfront and milestone payments made related to an asset acquisition are accrued for and expensed when the achievement of the milestone is considered probable. Clinical and Contract Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from its clinical and non-clinical studies and other third-party vendors. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. Through December 31, 2022 , there have been no material differences from the Company’s accrued estimated expenses to the actual clinical trial expenses. However, variations in the assumptions used to estimate accruals, including, but not limited to, the number of patients enrolled, the rate of patient enrollment, the actual services performed, and related costs may vary from the Company’s estimates, resulting in adjustments to clinical trial expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect its financial position and results of operations. Stock-based Compensation Expense The Company incurs stock-based compensation expense primarily from stock options, restricted stock units, and ESPP purchase rights. The Company estimates the fair value of stock options granted to employees, directors and non-employees and ESPP purchase rights using the Black-Scholes option-pricing model. The Black-Scholes model requires the input of subjective assumptions, including expected volatility, expected dividend yield, expected term, risk-free rate of return and the estimated fair value of the underlying common stock on the date of grant. Prior to the Company’s initial public offering, the fair value of the common stock underlying the stock-based awards was determined on each grant date by the board of directors, with input from management, considering the most recently available third-party valuation of common shares. The grant-date fair value of restricted stock units is the fair value of the underlying stock on the award’s grant date. The Company uses the straight-line method to allocate compensation expense to reporting periods over the requisite service period, which is generally the vesting period. The Company accounts for the effect of forfeitures as they occur. Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s long-lived assets are located in the United States. Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and recorded in other expense, net, and were immaterial for the years December 31, 2022, 2021 and 2020 . Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statements of operations in the period that includes the enactment date. Deferred income taxes comprise the impact of temporary differences between assets and liabilities recognized for financial reporting purposes and the amounts recognized for income tax reporting purposes, net operating loss carryforwards, and other tax credits measured by applying currently enacted tax laws. A valuation allowance is provided when necessary to reduce deferred tax assets to an amount that is more likely than not to be realized . If the Company determines that it would be able to realize its deferred tax assets in the future in excess of their net recorded amount, it would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on investments for all periods presented. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. Recent Accounting Pronouncements None.

Acquisition of Assets and Owner

Acquisition of Assets and Ownership	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
ACQUISITION OF ASSETS AND OWNERSHIP	(3) ACQUISITION OF ASSETS AND OWNERSHIP On October 4, 2021, the Company entered into a stock purchase agreement with ScalmiBio, Inc., or ScalmiBio, as the Company expands its pipeline with plans to develop new anti-cancer drug candidates based on ScalmiBio’s platform. Under the terms of the stock purchase agreement, the Company made an initial payment to the stockholders of ScalmiBio at closing on October 4, 2021 of approximately $ 4.5 million in cash, net of certain expenses and adjustments, and made an additional payment of $ 2.0 million at the one-year anniversary of the transaction on October 4, 2022 to the stockholders of ScalmiBio. This additional payment was recorded as research and development costs within the consolidated statements of operations and consolidated statements of comprehensive loss over the one-year period given the payment was contingent on the majority stockholder remaining employed with the Company through the one-year anniversary of the closing. In addition, the Company has agreed to pay up to $ 35.0 million, in aggregate, in certain milestones based on the clinical development of the acquired ScalmiBio technology and has also agreed to pay a low single digit royalty on net sales of any products developed from the ScalmiBio acquired technology for a defined term. The Company has the option to buy-out the royalty payment, prior to the first marketing approval of the developed product. The Company’s CEO and President, who is also a director, was also a director of ScalmiBio prior to the acquisition, and owned 31.7 % of ScalmiBio stock. As a result, he received or will receive a proportional share of the consideration to ScalmiBio stockholders as described above. He also received approximately $ 87,000 out of the closing proceeds for the repayment of a note and accrued interest for a loan to ScalmiBio. Given his interest in the ScalmiBio acquisition, the Company’s audit committee approved the acquisition under its related-party transaction policy and the Company’s CEO recused himself from the negotiation and approval of the transaction. To determine the accounting for this transaction, an assessment was made as to whether an integrated set of assets and activities should be accounted for as a business combination or an asset acquisition. The guidance requires an initial screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single asset or group of similar assets. If that screen is met, the set is not considered a business. The Company concluded that substantially all of the fair value is concentrated in a group of similar identifiable assets. Pursuant to asset acquisition accounting, acquired IPR&D with no alternative future use is expensed at acquisition. Accordingly, $ 4.7 million including $ 0.2 million of legal and other professional fees related to the acquisition, was recognized in “Research and development” expenses in the consolidated statements of operations and consolidated statements of comprehensive loss for the year ended December 31, 2021.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	(4) FAIR VALUE OF FINANCIAL INSTRUMENTS The following table presents the Company’s financial assets that are measured at fair value on a recur ring basis by level within the fair value hierarchy as of December 31, 2022 and 2021 (in thousands): December 31, 2022 Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents Money market funds Level 1 $ 36,690 $ — $ — $ 36,690 U.S. government agency securities Level 2 3,484 — — 3,484 Short-term investments U.S. Treasury securities Level 1 73,058 3 ( 438 ) 72,623 U.S. government agency securities Level 2 16,227 36 — 16,263 Corporate debt securities Level 2 56,318 — ( 367 ) 55,951 Commercial paper Level 2 62,087 — — 62,087 Asset-backed securities Level 2 10,512 — ( 51 ) 10,461 Long-term investments U.S. Treasury securities Level 1 5,242 2 — 5,244 U.S. government agency securities Level 2 9,760 — ( 15 ) 9,745 Asset-backed securities Level 2 1,725 — ( 15 ) 1,710 Total $ 275,103 $ 41 $ ( 886 ) $ 274,258 December 31, 2021 Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 357,181 $ — $ — $ 357,181 The Company did no t have any outstanding financial liabilities to be re-measured on a recurring basis as of December 31, 2022 and 2021. The fair value of cash equivalents and available-for-sale investments by classification included in the consolidated balance sheets was as follows as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Cash and cash equivalents $ 40,174 $ 357,181 Short-term investments 217,385 — Long-term investments 16,699 — Total $ 274,258 $ 357,181 Cash and cash equivalents in the above table excludes bank account cash of $ 8.6 million and $ 6.5 million as of December 31, 2022 and 2021, respectively. The fair value of cash equivalents and available-for-sale investments by contractual maturity was as follows as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Maturing in one year or less $ 257,559 $ 357,181 Maturing after one year through five years 16,699 — Total $ 274,258 $ 357,181 The primary objective of the Company’s investment portfolio is to maintain safety of principal, prudent levels of liquidity and acceptable levels of risk. The Company’s investment policy limits investments to certain types of instruments issued by institutions with investment-grade credit ratings, and it places restrictions on maturities and concentration by asset class and issuer. There were no transfers of assets or liabilities between the fair value measurement levels during the years ended December 31, 2022 and 2021 and there were no financial instruments classified as Level 3 as of December 31, 2 0 22 and 2021. As of December 31, 2022 and 2021, accrued interest receivable related to the Company’s investments of $ 1.0 million and zero , respectively, was included in prepaid expenses and other current assets as well as other assets on the consolidated balance sheet. As of December 31, 2022, the unrealized losses for available-for-sale investments were non-credit related and the Company does not intend to sell the investments that were in an unrealized loss position, nor will it be required to sell those investments before recovery of their amortized costs basis, which may be maturity. As of December 31, 2022 and 2021 , no allowance for credit losses for the Company’s investments was recorded. As of December 31, 2022 and 2021 , there were no securities in a continuous net unrealized loss position for more than 12 months. As of December 31, 2022 and 2021 , the Company has no t recognized any impairment losses on available-for-sale investments.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
BALANCE SHEET COMPONENTS	(5) BALANCE SHEET COMPONENTS Property and Equipment, Net The following table presents the components of property and equipment, net as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Leasehold improvements $ 2,360 $ 229 Laboratory equipment 1,422 324 Computer hardware and software 344 241 Furniture and fixtures 166 166 Property and equipment, gross 4,292 960 Less: accumulated depreciation ( 403 ) ( 63 ) Property and equipment, net $ 3,889 $ 897 Depreciation was $ 0.3 million , nominal, and $ 0.2 million for years ended December 31, 2022, 2021 and 2020, respectively. Other Assets The following table presents the components of other assets, net as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Long-term prepaid clinical expenses $ 7,264 $ 6,694 Operating lease right-of-use assets 5,626 1,829 Long-term prepaid contract manufacturing costs 1,456 2,854 Finance lease right-of-use assets 298 746 Deposits 144 144 Accrued interest receivable 78 — Restricted cash 66 — Total other assets $ 14,932 $ 12,267 Accrued Expenses and Other Current Liabilities The following table presents the components of accrued expenses and other current liabilities as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Accrued clinical and nonclinical study costs $ 5,485 $ 4,119 Accrued contract manufacturing 5,249 693 Accrued compensation and related expenses 3,708 3,294 Accrued property and equipment 2,110 27 Accrued professional fees 835 790 Operating lease liabilities, current 755 313 Finance lease liabilities, current 286 429 Other 174 236 Total accrued expenses and other current liabilities $ 18,602 $ 9,901

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
LEASES	(6) LEASES In conjunction with the adoption of ASC 842 on January 1, 2021, the Company evaluated its vendor contracts to identify embedded leases, if any, and noted that a pharmaceutical support services agreement entered into in May 2016 included leases under ASC 842 because the Company has the right to direct the use of certain equipment. The embedded leases commenced in September 2020 and expire in August 2023 with no stated option to extend the term. The Company classified the leases as finance leases. In May 2021, the Company entered into a lease agreement for approximately 10,000 square feet of office space located in South San Francisco, California. The lease commenced on June 6, 2021 and expires on August 31, 2026 . The lease does no t provide an option to extend after it expires. The total lease payments for the life of the lease are approximately $ 2.0 million. The Company classified the lease as an operating lease. In February 2022, the Company entered into a lease agreement totaling approximately 11,074 square feet of office and laboratory space located in Palo Alto, California. The lease consists of two premises and expires in February 2030 . The lease provides for an option to extend for two years after expiration . The lease for one of the premises commenced in February 2022 and the lease for the second premises commenced in April 2022 . The lease provides for an annual base rent of approximately $ 0.8 million, which increases on an annual basis by 3 %. The total lease payments for the life of the lease are approximately $ 6.9 million. The Company is also responsible for leasehold improvement costs related to the second premises, which are expected to be approximately $ 2.1 million, of which $ 1.5 million is to be paid with interest at a rate of 7 % per annum as additional payments over the life of the lease. The Company classified the lease as an operating lease. Under the terms of the lease agreement, the Company issued a letter of credit to the landlord in the amount of $ 0.1 million, which is collateralized by a restricted cash deposit of $ 0.1 million (see Note 5 “Other Assets”). As of December 31, 2022, the ROU assets recorded for operating leases and finance leases were $ 5.6 million and $ 0.3 million , respectively. As of December 31, 2021, the ROU assets recorded for operating leases and finance leases were $ 1.8 million and $ 0.7 million , respectively. The amounts were included in the other assets on the consolidated balance sheet. The following table presents the maturities and balance sheet information of the Company’s operating and finance lease liabilities as of December 31, 2022 (in thousands, except lease term and discount rate): December 31, 2022 Operating Leases Finance Leases 2023 $ 1,240 $ 288 2024 1,267 — 2025 1,305 — 2026 1,187 — 2027 912 — Thereafter 2,069 — Total lease payments 7,980 288 Less: imputed interest ( 1,957 ) ( 2 ) Total lease liabilities $ 6,023 $ 286 Lease liabilities: current (i) $ 765 $ 286 Lease liabilities: non-current (ii) 5,258 — Total lease liabilities $ 6,023 $ 286 Weighted average remaining lease term (in years) 6.3 0.7 Weighted average discount rate 8.4 % 1.7 % (i) Current lease liabilities are presented within accrued expenses and other current liabilities and payable and accrued liabilities due to related party on the consolidated balance sheets and includes a nominal amount due to Tallac Therapeutics, Inc. for an operating lease. Refer to Note 11 “Related-Party Transactions” for additional discussion. (ii) Non-current lease liabilities are presented within other non-current liabilities on the consolidated balance sheet. The following table presents the components of lease costs for the years ended December 31, 2022 and 2021 (in thousands): Year Ended December 31, 2022 2021 Operating lease cost $ 1,159 $ 360 Variable lease cost and other, net (i) 262 84 Short-term lease cost 88 — Finance lease cost: Amortization of right-of-use assets 447 369 Interest 9 13 Total lease costs $ 1,965 $ 826 (i) The variable lease cost and other, net is comprised primarily of common area maintenance charges for the operating lease, which are dependent on usage. These costs are classified as operating lease expense due to the election to not separate lease and non-lease components. These costs were not included within the measurement of the Company’s operating lease ROU assets and operating lease liabilities. The following table presents the supplemental cash flow disclosures for cash paid for the years ended December 31, 2022 and 2021 (in thousands): Year Ended December 31, 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 933 $ 243 Operating cash flows from finance leases $ 8 $ 11 Financing cash flows from finance leases $ 388 $ 281 Right-of-use asset acquired under leases Operating leases $ 4,613 $ 1,780 Finance leases $ — $ 776

Term Loan

Term Loan	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
TERM LOAN	(7) TERM LOAN Silicon Valley Bank and WestRiver Loan The Company’s wholly-owned subsidiaries Alexo Therapeutics International and Sirpant Therapeutics, as borrowers, entered into a Loan and Security Agreement, or the SVB-WestRiver Loan Agreement, dated as of December 20, 2019, with Silicon Valley Bank, or SVB, and WestRiver, collectively as lenders, and SVB, as administrative agent and collateral agent. On the closing date of the Loan Agreement in December 2019, $ 6.0 million was funded to the Company. In December 2020, the Company fully repaid the loan balance. In conjunction with the SVB-WestRiver Loan Agreement, the Company issued warrants to purchase Series B convertible preferred stock to SVB and WestRiver, and recorded a warrant liability of approximately $ 0.4 million at the date of issuance. The Company also determined that certain loan features were embedded derivatives requiring bifurcation and separate accounting, and recorded a term loan compound derivative liability of approximately $ 51,000 . The Company measured its Series B convertible preferred stock warrant liability and term loan compound derivative liability at fair value on a recurring basis, which were classified as Level 3 liabilities. During the year ended December 31, 2020, the increase in fair value in warrant liability was approximately $ 658,000 . During the year ended December 31, 2020, the decreases in fair value in compound derivative liability was approximately $ 8,000 . Those amounts were recognized as a component of other expense, net in the consolidated statement of operations. The Company reclassified the preferred stock warrant liability balance into additional paid-in capital in July 2020 with no further re-measurement required, as the common stock warrants are considered permanent equity effective with the completion of the initial public offering. The compound derivative liability was extinguished upon the extinguishment of the host instrument in December 2020. Oxford Finance and Silicon Valley Bank Loan In October 2022, the Company entered into a loan and security agreement, or the Loan Agreement, with Oxford Finance LLC, Oxford Finance Credit Fund II LP, and Silicon Valley Bank, or Lenders, for a secured term loan facility of up to $ 100.0 million. Pursuant to the Loan Agreement, the Company drew an initial loan of $ 10.0 million and has access to draw an additional $ 40.0 million through the end of 2023. The Loan Agreement provides for an additional $ 50.0 million over three tranches, with $ 12.5 million available in each of two tranches based upon the achievement of milestones related to the development of evorpacept and one preclinical product candidate, and $ 25.0 million at the Lenders’ sole discretion. The proceeds of the loans may be used by the Company for working capital and to fund its general business requirements. Borrowings under the Loan Agreement bear interest at a floating rate per annum equal to the greater of (i) 1-month term Secured Overnight Financing Rate, or SOFR, and (ii) 2.33 %, plus 6.25 %. The minimum per annum interest rate is 8.58 %. Interest on the term loans is payable monthly in arrears. The Company will begin to make principal payments in equal monthly installments beginning on December 1, 2025. However, if either of the milestone related tranche term loans are funded, then the Company will begin to make principal payments in equal monthly installments beginning on December 1, 2026. The term loans mature on October 1, 2027 . The term loans may be prepaid in full or in part, in increments of $ 10.0 million, with various prepayment premiums. Upon the earlier prepayment or maturity of any term loan, the Company is required to pay a final payment fee of 6.0 % of the original principal amount of such funded term loan. The final payment will be accreted to the final payment amount as interest expense using the effective interest method over the term of the loan through maturity date. The term loans once repaid or prepaid may not be reborrowed. The Company is also obligated to pay other customary fees for a loan facility of this size and type. The term loans under the Loan Agreement are secured by substantially all of the Company’s assets, except the Company’s intellectual property, which is the subject of a negative pledge, and will be guaranteed by the Company’s future subsidiaries, subject to certain limitations. Upon the outstanding balance of the term loans reaching $ 75.0 million or greater, the Company’s intellectual property will become collateral. The Company and its subsidiary, ALX Oncology Limited, have guaranteed the obligations under the Loan Agreement. The Loan Agreement contains customary affirmative and negative covenants, including covenants limiting the ability of the Company to, among other things, dispose of assets, effect certain mergers, incur debt, grant liens, pay dividends and distributions on its capital stock, make investments and acquisitions, and enter into transactions with affiliates, in each case subject to customary exceptions for a loan facility of this size and type. The Loan Agreement contains customary events of default, which include, but are not limited to payment defaults, material misrepresentations, breaches of covenants, cross defaults with certain other material indebtedness, bankruptcy and insolvency events, and judgment defaults. The occurrence of an event of default could result in the acceleration of our obligations under the Loan Agreement, the termination of the Lenders’ commitments, a 5.0 % increase in the applicable rate of interest and the exercise by the Lender of other rights and remedies provided for under the Loan Agreement. The Company received net proceeds from issuance of the term loan of $ 9.3 million after deducting debt issuance costs of approximately $ 0.7 million. Debt issuance costs were recorded as debt discount on the term loan, offsetting term loan, non-current on the consolidated balance sheet. The debt discount will be amortized over the term of the loan as interest expense using the effective interest method. During the year ended December 31, 2022, interest expense incurred in connection with the Loan Agreement was $ 0.2 million . We had no outstanding debt and did no t incur interest expense in 2021. The Company determined that certain loan features were embedded derivatives requiring bifurcation and separate accounting. Those embedded derivatives were bundled together as a single, compound embedded derivative and then bifurcated and accounted for separately from the host contract. As of December 31, 2022, the value of the embedded derivative is not material, but could become material in future periods if an event of default became more probable than is currently estimated. As of December 31, 2022, we were in compliance with all financial reporting covenants under the Loan Agreement. As of December 31, 2022, the future maturities under the Loan Agreement are as follows (in thousands): December 31, 2022 2023 $ — 2024 — 2025 435 2026 5,217 2027 4,948 Total future maturities 10,600 Less: current portion of term loan — Total term loan, net of current portion 10,600 Less: unamortized debt issuance costs ( 993 ) Less: unaccreted final payment costs ( 218 ) Term loan, non-current, net $ 9,389

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
STOCKHOLDERS' EQUITY	(8) STOCKHOLDERS’ EQUITY On July 21, 2020, the Company’s amended and restated certificate of incorporation became effective, authorizing 1,000,000,000 shares of common stock, $ 0.001 par value per share, and 100,000,000 shares of undesignated preferred stock, $ 0.001 par value per share. As of December 31, 2022 and 2021, the Company had 40,861,386 and 40,587,067 shares of common stock outstanding, respectively. Common Stock In July 2020, the Company consummated its initial public offering and issued 9,775,000 shares of common stock for net proceeds of approximately $ 169.5 million, after deducting underwriting discounts and commissions of $ 13.0 million and offering-related expenses of $ 3.2 million. Upon the closing of the initial public offering, all shares of convertible preferred stock outstanding and accrued cumulative dividends were automatically converted into 23,934,533 shares of common stock. In December 2020, the Company consummated its follow-on public offering and issued 2,737,000 shares of common stock for net proceeds of approximately $ 194.9 million, after deducting underwriting discounts and commissions of $ 12.5 million and offering-related expenses of $ 0.7 million. Common stock reserved for future issuance as of December 31, 2022 consists of the following: December 31, 2022 Stock options issued and outstanding 6,196,848 Stock options authorized for future issuance 2,932,309 Employee Stock Purchase Plan shares authorized for future issuance 1,147,986 Restricted stock issued and outstanding 820,326 Total 11,097,469 Dividends Prior to the Company’s initial public offering, cumulative dividends of 6.0 % per annum of the original issue price for each convertible preferred stock series were payable when and as declared by the Company’s Board of Directors, or Board of Directors, upon the occurrence of a liquidation event or upon a contingent mandatory conversion of the convertible preferred stock in connection with a qualified initial public offering as described below. The Series A original issue price was $ 6.58 , and the Series B and Series C original issue price was $ 9.4972 . The original issue price was subject to adjustment in the event of any share dividend, share split, combination, consolidation or other recapitalization. The dividends accrued from day to day from the issue date of such preferred stock whether or not declared and were cumulative. In addition, the preferred stockholders participated on an as-converted basis in any dividends payable to common stockholders. As of July 20, 2020, there were approximately $ 18.0 million of accrued cumulative dividends on the Series A, Series B and Series C convertible preferred stock, which became payable upon the consummation of the Company’s initial public offering and automatically converted into 2,564,759 shares of the Company’s common stock.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	(9) STOCK-BASED COMPENSATION Equity Incentive Plans 2015 Share Award Scheme During 2015, the Company adopted an equity compensation plan, the 2015 Share Award Scheme, or the 2015 Share Award Scheme, for eligible employees, officers, directors, advisors, and consultants. The 2015 Share Award Scheme provided for the grant of incentive and non-statutory stock options. The 2015 Share Award Scheme permitted the Company to grant up to 2,143,117 shares of common stock pursuant to awards granted thereunder, including incentive stock options, non-statutory stock options, conditional share awards and restricted share awards. 2020 Equity Incentive Plan On April 1, 2020, the Board of Directors approved a new equity incentive plan, or the 2020 Equity Incentive Plan, that replaced the 2015 Share Award Scheme. The 2020 Equity Incentive Plan permitted the issuance of up to 4,379,139 shares of the Company’s common stock pursuant to awards granted under it, and authorized the award of stock options, restricted stock awards, stock appreciation rights and restricted stock units to employees, directors, and consultants. Amended and Restated 2020 Equity Incentive Plan In July 2020, the Company adopted the Amended and Restated 2020 Equity Incentive Plan, or the 2020 Plan. The 2020 Plan replaced the Company’s 2020 Equity Incentive Plan and a total of 7,874,862 shares were reserved under the 2020 Plan. Unless the Board of Directors provides otherwise, beginning on January 1, 2021, the maximum number of shares which shall be made available for issuance under the 2020 Plan will automatically increase on the first day in January of each calendar year (i.e., the first day of our fiscal year) by an amount equal to the least of: • 4,000,000 shares; • four percent of the outstanding shares of our common stock on the last day of our immediately preceding fiscal year; or • such number of shares as our board of directors may determine no later than the last day of our immediately preceding fiscal year. The terms of the stock option agreements, including vesting requirements, are determined by the Board of Directors, subject to the provisions of the 2020 Plan. The term of the options generally expire, upon the earliest of (i) termination of continuous service for cause (ii) three months after the termination of continuous service for reasons other than cause, death or disability (iii) twelve months after the termination of continuous service due to disability (iv) eighteen months after the employee’s death if the employee died during the period of continuous service (v) expiration date in the grant notice or (vi) the day before the tenth anniversary of the date of grant. The per share exercise price of the incentive stock options must equal at least the fair market value of a share underlying such options on the date of grant. All awards that are canceled, forfeited or expired are returned to the 2020 Plan and are available for grant in conjunction with the issuance of new awards. Stock options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over an agreed service period, usually four years . Certain stock options granted under the 2020 Plan provide option holders the right to elect to exercise unvested options in exchange for common stock. Such unvested common stock is subject to a repurchase right held by the Company at the original issuance price in the event the optionee’s service to the Company is terminated either voluntarily or involuntarily. The right lapses as the underlying repurchase right expires. These repurchase terms are considered to be a forfeiture provision. The cash received from employees for exercise of unvested options is treated as a refundable deposit and is classified as a liability on the consolidated balance sheets. At December 31, 2022 , there was no such unvested early exercised options and related liability. Shares Available for Grant The following table provides a summary of shares available for grant under the 2020 Plan: Amended and Restated 2020 Equity Incentive Plan Shares available for grant at December 31, 2021 3,407,898 Authorized 1,623,483 Granted ( 2,385,984 ) Canceled/forfeited 286,912 Shares available for grant at December 31, 2022 2,932,309 Stock Option Modification In connection with the transfer of employees to Tallac Therapeutics, the Company’s former Chief Scientific Officer, and eight of the Company’s employees, or Transferred Employees, terminated their employment with the Company effective as of June 30, 2020 and became employees of Tallac Therapeutics effective as of July 1, 2020. The options to purchase shares of the Company’s common stock that were previously granted to the Transferred Employees will continue to vest and be exercisable subject to the Transferred Employees remaining service providers to the Company under the original terms of the award. The Company evaluated the change in status from an employee to a consultant in accordance with ASC 718. While the Company concluded that the change in status did not affect the vesting condition or the classification of the initial awards, the significant reduction in the level of services that the grantees were expected to provide under the original awards as compared to the level of services expected under the Tallac Services Agreement will no longer meet the substantive service condition requirements and therefore the compensation cost for the unvested awards was recognized immediately with no future service requirement. In September 2020, in connection with the resignation of the Company’s former Chief Business Officer and the entry into a consulting agreement, the Company evaluated the change in status from an employee to a consultant in accordance with ASC 718. While the Company concluded that the change in status did not affect the vesting condition or the classification of the initial awards, the significant reduction in the level of services that the grantee was expected to provide under the original awards as compared to the level of services expected under the consulting agreement will no longer meet the substantive service condition requirements and therefore the compensation expense for the unvested awards expected to vest during the consultancy was recognized immediately with no future service requirement. The Company recorded $ 1.7 million in stock-based compensation expenses related to the modifications for the year ended December 31, 2020. There were no significant stock option modifications for the years ended December 31, 2021 and 2022. Employee Stock Purchase Plan In July 2020, the Board of Directors and stockholders approved the ALX Oncology Holdings Inc. 2020 Employee Stock Purchase Plan, or the ESPP. The ESPP allows eligible employees to have up to 15 percent of their eligible compensation withheld and used to purchase common stock, subject to a maximum of $ 25,000 worth of stock purchased in a calendar year or no more than 3,000 shares in an offering period, whichever is less. An offering period consists of a six-month purchase period, with a look back feature to our stock price at the commencement of the offering period. Eligible employees can purchase the Company’s common stock at the end of the offering period at 85 % of the lower of the closing price of our common stock on The Nasdaq Global Select Market on the first and last day of the offering period. The initial number of shares of common stock available for issuance under the ESPP, was 400,000 . Unless the Board of Directors provides otherwise, beginning on January 1, 2021, the maximum number of shares which shall be made available for sale under the ESPP will automatically increase on the first day in January of each calendar year (i.e., the first day of our fiscal year) during the term of the ESPP by an amount equal to the least of: • 800,000 shares; • one percent of the outstanding shares of our common stock on the last day of our immediately preceding fiscal year; or • such number of shares as our board of directors may determine no later than the last day of our immediately preceding fiscal year. Accordingly, on January 1, 2022 and 2021, the number of shares available under the ESPP was increased by 405,871 and 398,445 shares respectively. As of December 31, 2022, 56,330 shares of common stock have been purchased under the ESPP, and the number of shares of common stock available for issuance under the ESPP was 1,147,986 . Stock Option Activity The following table provides a summary of stock option activity under the 2020 Plan and related information: Outstanding Options Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2021 5,128,639 $ 23.91 8.28 $ 49,745 Granted 1,481,234 10.89 Exercised ( 171,838 ) 3.30 Canceled/forfeited ( 241,187 ) 44.58 Outstanding at December 31, 2022 6,196,848 $ 20.56 7.78 $ 19,872 Exercisable at December 31, 2022 3,663,358 $ 14.73 7.03 $ 18,824 The aggregate intrinsic values represent the total pre-tax intrinsic value, of options outstanding and exercisable calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock as of December 31, 2022 and 2021. The total intrinsic value of options exercised during the years ended December 31, 2022, 2021 and 2020 were $ 1.7 million , $ 48.1 million and $ 4.4 million , respectively. Stock Option Valuation Assumptions The Company uses the Black-Scholes option pricing model to determine the estimated fair value of stock options at the date of the grant, and stock-based compensation is adjusted for actual forfeitures as they occur. The fair value of each option grant during the years ended December 31, 2022, 2021 and 2020 was estimated with the following assumptions:   Year Ended December 31,   2022 2021 2020 Expected term (in years)  5.3 - 6.1  5.3 - 6.1  5.8 - 6.1 Risk-free interest rate  1.6 % - 4.4 %  0.8 % - 1.4 %  0.3 % - 0.8 % Expected dividend rate  -  -  - Expected stock price volatility  81.9 % - 84.7 %  79.7 % - 86.9 %  78.7 % - 89.0 % Expected Term. The expected term of the options represents the average period the stock options are expected to remain outstanding. As the Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior, the expected term of options granted is derived from the average midpoint between the weighted average vesting and the contractual term, also known as the simplified method. Risk-Free Interest Rate. The risk-free interest rate is based on the yield of U.S. Treasury notes as of the grant date with terms commensurate with the expected term of the option. Dividend Yield. The expected dividends assumption is based on the Company’s expectation of not paying dividends in the foreseeable future. Volatility. Since the Company does not have sufficient trading history for its common stock, the expected volatility is based on a combination of the historical volatilities of the common shares of comparable publicly traded companies as well as the historical volatilities of the Company’s common shares. The Company selected companies with comparable characteristics, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the Company’s share-based awards. Fair Value . Historically, for all periods prior to our initial public offering, the fair value of the shares of common stock underlying our stock option was determined by the Company’s board of directors. Because there was no public market for the Company’s common stock, the board of directors determined fair value of the common stock at the time of grant of the options by considering a number of objective and subjective factors including important developments in the Company’s operations, valuations performed by an independent third party, sales of convertible preferred stock, actual operating results and financial performance, the conditions in the biotechnology industry and the economy in general, the stock price performance and volatility of comparable public companies, and the lack of liquidity of the Company’s common stock, among other factors the board of directors deemed relevant to such determination. Since the completion of our initial public offering, the fair value of each share of common stock underlying stock option grants is based on the closing price of our common stock on the Nasdaq Global Select Market as reported on the date of grant. Restricted Stock Unit Activity The following table provides a summary of restricted stock unit activity under the 2020 Plan and related information: Outstanding RSUs Number of RSUs Weighted- Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Unvested as of December 31, 2021 15,075 $ 58.56 1.83 $ 324 Granted 904,750 13.55 Vested ( 53,774 ) 14.71 Canceled/forfeited ( 45,725 ) 16.55 Unvested as of December 31, 2022 820,326 $ 14.13 1.68 $ 9,245 Stock-based Compensation Expenses Stock options granted are measured based on the grant-date fair value estimated using the Black-Scholes option pricing model. The grant-date fair value of restricted stock units is the fair value of the underlying stock on the award’s grant date. Compensation expense is recognized over the vesting period of the applicable awards on a straight-line basis. The weighted-average grant date fair value per share for stock options granted during the years ended December 31, 2022, 2021 and 2020 was $ 7.88 , $ 42.29 and $ 7.74 , respectively. The weighted-average grant date fair value per share for restricted stock units granted during the years ended December 31, 2022 and 2021 was $ 13.55 and $ 58.56 , respectively. There were no restricted stock units granted in 2020. Stock-based compensation expense includes stock options and restricted stock units and has been reported in the Company’s consolidated statements of operations as follows (in thousands): Year Ended December 31, 2022 2021 2020 Research and development $ 10,741 $ 5,211 $ 2,551 General and administrative 13,098 8,703 2,885 Total $ 23,839 $ 13,914 $ 5,436 As of December 31, 2022, there was unrecognized share-based compensation expense of $ 52.4 million , related to unvested stock options which the Company expects to recognize over a weighted-average period of 2.5 years. There was unrecognized share-based compensation expense of $ 9.8 million , related to unvested restricted stock units which the Company expects to recognize over a weighted-average period of 3.2 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
INCOME TAXES	(10) INCOME TAXES The U.S. domestic and international components of pre-tax loss for the years ending December 31, 2022, 2021 and 2020 are as follows (in thousands): Year Ended December 31, 2022 2021 2020 United States $ ( 111,360 ) $ ( 30,565 ) $ ( 9,457 ) International ( 12,058 ) ( 52,919 ) ( 36,042 ) Loss before income taxes $ ( 123,418 ) $ ( 83,484 ) $ ( 45,499 ) The federal and state provision (benefit) for income taxes consist of the following (in thousands): Year Ended December 31, 2022 2021 2020 Current provision for income taxes: Federal $ 64 $ ( 21 ) $ 239 State — — 2 International — — — Total current 64 ( 21 ) 241 Deferred tax provision: Federal — — — State — — — International — — — Total deferred — — — Provision (benefit) for income taxes $ 64 $ ( 21 ) $ 241 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. A reconciliation of the U.S. federal statutory income tax rate to the effective tax for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): Year Ended December 31, 2022 2021 2020 At federal statutory income tax rate $ ( 25,918 ) $ ( 17,532 ) $ ( 9,555 ) State income taxes ( 2,659 ) ( 105 ) ( 3,098 ) Stock-based compensation 2,368 ( 4,031 ) ( 5 ) Research & Development credits ( 1,779 ) ( 2,131 ) ( 512 ) Change in valuation allowance 9,067 11,476 5,710 Other 36 172 321 Foreign rate differential 18,949 11,032 7,380 Prior period true ups — 1,098 — Provision (benefit) for income taxes $ 64 $ ( 21 ) $ 241 Significant components of the Company’s deferred tax assets as of December 31, 2022 and 2021 are as follows (in thousands): December 31, 2022 2021 Deferred tax assets: Loss carryforwards $ 16,319 $ 15,407 Research & other credits 8,435 5,325 Other 14 16 Accrued expenses 1,860 529 Stock options 3,860 1,530 Lease Liabilities 1,323 542 Capitalized R&D 1,702 — Total deferred tax assets 33,513 23,349 Deferred tax liabilities: Fixed assets 215 73 Lease ROU assets 1,244 541 Prepaid expenses 252 — Total deferred tax liabilities 1,711 614 Valuation allowance ( 31,802 ) ( 22,735 ) Net deferred tax assets $ — $ — ASC 740 requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management 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. Because of the Company’s recent history of operating losses, management believes that recognition of the deferred tax assets arising from the above-mentioned future tax benefits is currently not likely to be realized and, accordingly, has provided a valuation allowance. The valuation allowance increased by approximately $ 9.1 million and $ 11.4 million for the years ended December 31, 2022 and 2021, respectively. The Tax Cuts and Jobs Act eliminated the option to deduct research and development expenditures currently and requires taxpayers to capitalize and amortize them pursuant to Internal Revenue Code Section 174 beginning in 2022. Net operating losses and tax credit carryforwards as of December 31, 2022 are as follows (in thousands): Amount Expiration Years Net operating losses, federal (Post December 31, 2017) $ 46,835 Do Not Expire Net operating losses, state $ 68,993 2038 - 2040 Tax credits, federal $ 5,978 2039 - 2042 Tax credits, state $ 4,177 N/A Net operating losses, foreign $ 4,554 N/A Utilization of the Company’s U.S. net operating loss and credit carryforwards may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Such annual limitation could result in the expiration of the U.S. net operating loss and credit carryforwards before utilization. To date, the Company has not performed an analysis to determine whether there would be a substantial annual limitation due to a change in ownership. Unrecognized Tax Benefits The Company recognizes the tax benefit from uncertain tax positions if it is more likely than not that the tax positions will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefit is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense. The Company will file income tax returns in the U.S. federal and California jurisdiction, which is not currently under exam, and all years since inception are opened to examination. The unrecognized tax benefits as of December 31, 2022, 2021 and 2020 were $ 1.7 million , $ 1.2 million and $ 0.8 million , respectively. Future changes in the unrecognized tax benefits will not impact the effective tax rate due to the Company’s full valuation allowance. The Company has the following activity relating to unrecognized tax benefits (in thousands): Year Ended December 31, 2022 2021 2020 Balance at beginning of year $ 1,217 $ 842 $ 692 Additions/reversals based on tax positions of prior years 13 ( 69 ) ( 64 ) Additions based on tax positions related to the current year 443 494 240 Lapses in statutes of limitations ( 12 ) ( 50 ) ( 26 ) Balance at end of year $ 1,661 $ 1,217 $ 842 Although it is reasonably possible that certain unrecognized tax benefits may increase or decrease within the next 12 months due to tax examination changes, settlement activities, expirations of statute of limitations or the impact on recognition and measurement considerations related to the results of published tax cases or other similar activities, the Company does not anticipate any significant changes to unrecognized tax benefits over the next 12 months. During the years ended December 31, 2022, 2021 and 2020 , no interest or penalties were required to be recognized relating to unrecognized tax benefits.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2022
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	(11) RELATED-PARTY TRANSACTIONS Related-party revenue In June 2018, the Company entered into a Research and Development Services Agreement, or Tollnine Agreement, with Tollnine Therapeutics, Inc., or Tollnine, a related-party of the Company, to provide research and development services to Tollnine. The Company’s Chief Executive Officer was the Chief Executive Officer of Tollnine until April 2020 but remains on the Board of Directors. In addition, two of the Company’s investors were also investors in Tollnine. As such, Tollnine was deemed to be a related-party. The Tollnine Agreement had an initial term of 3 years. The services were provided at a price based on the costs incurred by the Company plus a mark-up equal to 10 % of such costs. The Company recognized revenue when Tollnine, as the Company’s customer, obtained control of promised goods or services, in an amount that reflects the consideration which the Company received in exchange for those goods or services. The Company recognized related-party revenues of zero , zero and $ 1.2 million for the years ended December 31, 2022, 2021 and 2020, respectively, under the Tollnine Agreement. Effective as of July 1, 2020, the Company terminated the Tollnine Agreement and entered into the Tallac Services Agreement with Tallac Therapeutics. Tallac Service Agreement The Company entered into a research and development services agreement, or the Tallac Services Agreement, with Tallac Therapeutics, Inc., or Tallac, effective as of July 1, 2020. The Tallac Services Agreement provides that Tallac will provide certain preclinical research services to the Company for a service fee based on the costs incurred by Tallac plus a mark-up equal to 10.0 % of such costs. The Tallac Services Agreement has an initial term of four years and is renewed automatically for additional one year terms thereafter. The Company records the payments for the research and development services as research and development, or R&D, costs within the consolidated statement of operations. For the years ended December 31, 2022, 2021 and 2020, the Company recorded $ 0.6 million , $ 0.8 million and $ 0.6 million, respectively, as R&D costs in relation to the Tallac Services Agreement. Tallac Collaboration Agreement On March 4, 2021, the Company entered into a Collaboration Agreement with Tallac, or the Tallac Collaboration Agreement, to jointly develop, manufacture, and commercialize a novel class of cancer immunotherapy. The collaboration builds on the Company’s expertise in developing therapies that block the CD47 checkpoint pathway and expands its immuno-oncology pipeline. The companies will leverage their respective scientific and technical expertise to advance an anti-SIRPα antibody conjugated to a Toll-like receptor 9, or TLR9, agonist for targeted activation of both the innate and adaptive immune systems. The key economic components of the collaboration transaction include that both parties will share equally (a) in the cost and expenses of research and development and (b) any profit or loss. The Company accounts for R&D costs in accordance with ASC 730, Research and Development, which states R&D costs must be charged to expense as incurred. Accordingly, the Company records its internal and third-party costs associated with the collaboration as R&D expenses as incurred. When the Company is entitled to reimbursement of the R&D expenses that it incurs under the collaboration, the Company records those reimbursable amounts as a reduction to R&D expenses. The Company also records as R&D expenses, the portion of Tallac’s expenses that the Company is obligated to reimburse, in the period when Tallac incurs such expenses. During the years ended December 31, 2022 and 2021, the Company recorded $ 7.8 million and $ 2.8 million , respectively, as R&D costs in relation to the Tallac Collaboration Agreement. The Tallac Collaboration Agreement includes the right to set off clause, as such, the Company records the amount due to or reimbursable from Tallac on a net basis. As of December 31, 2022 and 2021, the Company had accrued expenses of $ 1.6 million and $ 1.4 million , respectively, related to the Tallac Collaboration Agreement which was presented within the payable and accrued liabilities due to related party on the consolidated balance sheet. Transfer of assets to Tallac In July 2020, the Company transferred certain lab equipment and other assets to Tallac Therapeutics in exchange for $ 0.6 million. Operating sub-lease agreement with Tallac The Company leases office space in Burlingame, California under a single operating sub-lease agreement with Tallac. Refer to Note 6 “Leases” for additional discussion. Acquisition of assets and ownership of ScalmiBio On October 4, 2021, the Company entered into a stock purchase agreement with ScalmiBio. The Company’s CEO and President, who is a director, was also a director of ScalmiBio prior to the acquisition, and owned 31.7 % of ScalmiBio stock. Refer to Note 3 “Acquisition of assets and ownership” for additional discussion. On October 4, 2022, the Company made a $ 2.0 million payment to stockholders of ScalmiBio at the one-year anniversary of the transaction to stockholders of ScalmiBio, including 31.7 %, or $ 0.6 million, to the Company's CEO and President. This payment was recorded as R&D costs within the consolidated statements of operations over the one-year period.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS	(12) NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Year Ended December 31, 2022 2021 2020 Numerator: Net loss $ ( 123,482 ) $ ( 83,463 ) $ ( 45,740 ) Less: cumulative preferred dividends allocated to — — ( 5,202 ) Net loss attributable to common stockholders $ ( 123,482 ) $ ( 83,463 ) $ ( 50,942 ) Denominator: Weighted-average shares of common stock 40,699,612 40,308,050 18,485,343 Net loss per share attributable to common stockholders, $ ( 3.03 ) $ ( 2.07 ) $ ( 2.76 ) Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods presented as the inclusion of all potential common stock outstanding would have been anti-dilutive. The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share for the years ended December 31, 2022, 2021 and 2020, because including them would have been anti-dilutive: Year Ended December 31, 2022 2021 2020 Common stock subject to repurchase — — 63 Stock options issued and outstanding 6,196,848 5,128,639 4,857,308 Restricted stock issued and outstanding 820,326 15,075 — Employee Stock Purchase Plan estimated shares issuable — — — Total 7,017,174 5,143,714 4,857,371

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	(13) COMMITMENTS AND CONTINGENCIES Guarantees and Indemnifications In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its officers and directors for specified events or occurrences, subject to some limits, while they are serving at the Company’s request in such capacities. There have been no claims to date and the Company has director and officer insurance that may enable the Company to recover a portion of any amounts paid for future potential claims. The Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company has no t recorded any liabilities for these agreements as of December 31, 2022. Contingencies From time to time, the Company may be a party to various claims in the normal course of business. Legal fees and other costs associated with such actions will be expensed as incurred. The Company will assess, in conjunction with its legal counsel, the need to record a liability for litigation and contingencies. Reserve estimates will be recorded when and if it is determined that a loss related matter is both probable and reasonably estimable. For the years ended December 31, 2022, 2021 and 2020 , the Company had no pending or threatened litigation. License Agreements In March 2015, the Company entered into a license agreement, or the Stanford Agreement, with the Board of Trustees of the Leland Stanford Junior University, or Stanford, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents relating to the Company’s current product candidates, to develop, manufacture and commercialize products for use in certain licensed fields, the scope of which would include the application of the licensed intellectual property in oncology. The Company paid Stanford a nonrefundable license royalty and reimbursed Stanford for past patent expenses, together totaling less than $ 0.1 million, and granted Stanford a specified number of shares of common stock of the Company. The Company is required to make milestone payments up to an aggregate of $ 5.0 million in respect of a specified number of licensed products that successfully satisfy certain clinical and regulatory milestones. The Company recorded the first milestone payment of $ 0.2 million during the year ended December 31, 2021. There was no milestone payment recorded for the year ended December 31, 2022. In June 2016, the Company entered into a license agreement with Selexis SA, or Selexis, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents, know-how and other intellectual property, to use Selexis generated cell lines to manufacture evorpacept, and to make, use and sell licensed product containing such compound in all fields of use. The Company paid Selexis a nominal one-time fee and will pay Selexis an annual maintenance fee. The Company also agreed to pay Selexis milestone payments up to an aggregate of 1.2 million Swiss Francs in respect of all licensed products developed and/or commercialized under the grant that successfully satisfies certain milestone events. The Company recorded a milestone payment of $ 0.1 million during the year ended December 31, 2021. There was no milestone payment recorded for the year ended December 31, 2022. In March 2017, the Company entered into an agreement with Crystal Bioscience Inc. (now a subsidiary of Ligand Pharmaceuticals Incorporated), or Crystal, under which the Company obtained an assignment of certain patents, covering certain SIRPα antibodies. Under this agreement, the Company also received a worldwide, royalty-bearing non-exclusive license, with the right to grant sublicenses through multiple tiers of sublicenses, under certain of Crystal’s background patents and know-how necessary to commercialize the rights under the assigned patents. The Company agreed to pay Crystal milestone payments up to $ 11.1 million in respect of all licensed products developed under the assigned patents, that successfully satisfy certain clinical and regulatory milestones, each milestone being paid only once for all products. The Company recorded the first milestone payment of $ 0.3 million during the year ended December 31, 2022. Other Contractual Obligations and Other Commitments We have other contractual obligations and other commitments from manufacturing and service contracts, which are presented as follows as of December 31, 2022 (in thousands): December 31, 2022 Total 2023 2024-2025 2026-2027 Thereafter Manufacturing and service contracts 10,953 9,590 1,323 40 — Total $ 10,953 $ 9,590 $ 1,323 $ 40 $ — In November 2015, we entered into a Master Service Agreement, or the MSA, with KBI Biopharma, Inc. relating to formulation development, process development and cGMP manufacturing of evorpacept for use in clinical trials on a project basis. The MSA had an initial term of three years with successive one-year renewal periods, which was extended an additional eight years until November 2026, is cancellable upon notice and is non-exclusive. Statements of work under the MSA commit us to certain future purchase obligations of approximately $ 11.0 million . These amounts are based on non-cancellable commitments and forecasts that include estimates of future market demand, quantity discounts and manufacturing efficiencies that may impact timing of purchases. The Company enters into contracts in the normal course of business with various third parties for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts generally provide for termination upon notice. Payments due upon cancellation consist only of payments for services provided or expenses incurred, including non-cancellable obligations of our service providers, up to the date of cancellation.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	(14) SUBSEQUENT EVENTS In preparing the consolidated financial statements as of December 31, 2022 , the Company evaluated subsequent events for recognition and measurement purposes through the filing date of this Annual Report on Form 10-K. The Company concluded that no events or transactions have occurred that require disclosure in the accompanying consolidated financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Basis of Presentation	Basis of Preparation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and the applicable rules and regulations of the U.S. Securities and Exchange Commission, or SEC.
Reclassifications	Reclassifications Certain reclassifications have also been made within the consolidated statements of operations for the years ended December 31, 2021 and 2020 to conform to the current year presentation. For the year ended December 31, 2021, the Company reclassified approximately $ 0.1 million out of other income (expense), net into a separate interest income financial statement line item as well as combined a nominal amount of interest expense into other income (expense), net, which is now renamed other expense, net. For the year ended December 31, 2020, the Company reclassified approximately $ 0.1 million out of other income (expense), net into a separate interest income financial statement line item as well as combined approximately $ 0.8 million amount of interest expense into other income (expense), net, which is now renamed other expense, net. Total loss before income taxes as of December 31, 2021 and 2020 did not change as a result of these reclassifications.
Principles of Consolidation	Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation.
Reverse Stock Split	Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806 reverse split of its common stock and convertible preferred stock. The par values of the common and convertible preferred stock were not adjusted as a result of the reverse stock split. All authorized, issued and outstanding common stock, convertible preferred stock, stock options, warrants, and related per share amounts contained in the consolidated financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented. The reverse stock split was effected on July 9, 2020.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including, but not limited to, those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, fair value of investments, valuation of the Company’s common stock in periods prior to its initial public offering and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company holds its cash and cash equivalents in checking and money market accounts. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and U.S. government agency securities that are stated at cost, which approximate fair value.
Investments	Investments Investments consist of money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt securities, commercial paper and asset-backed securities. The Company’s investments are classified as available-for-sale and carried at estimated fair values and reported in cash equivalents, short-term investments and long-term investments. Management determines the appropriate classification of the investments at the time they are purchased and evaluates the appropriateness of such classifications at each balance sheet date. Investments with contractual maturities greater than 12 months are considered long-term investments. The Company regularly reviews its investments for declines in estimated fair value below amortized cost. The factors considered in determining whether a credit loss exists include the creditworthiness of the security issuers, the number of investments in an unrealized loss position, the severity and duration of the unrealized losses, and whether it is more likely than not that the Company will be required to sell the investments before the recovery of their amortized cost basis. The cost of investments sold is based on the specific identification method. In circumstances when an unrealized loss is determined to be credit-related, or when the Company intends to sell or is more likely than not required to sell a security before it recovers its amortized cost basis, the difference between the fair value and the amortized cost of the security is recognized within other expense, net in the consolidated statements of operations, and an allowance for credit loss is recorded on the consolidated balance sheets. In circumstances when the decline in fair value is non-credit related, the difference is reported in accumulated other comprehensive loss, net of tax as a separate component of consolidated stockholders’ equity.
Concentration Of Credit Risk, Credit Losses And Other Risks And Uncertainties	Concentration of Credit Risk, Credit Losses and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash, cash equivalents, and investments. The primary objectives for the Company’s investment portfolio are the preservation of capital and the maintenance of liquidity. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash, cash equivalents and investments and issuers of investments. The Company manages its credit risk by holding its cash, cash equivalents and investments in large financial institutions within the U.S. In addition, the Company’s investment policy limits investments to certain types of instruments such as money market funds, debt securities issued by the U.S. government and its agencies, corporate debt securities, commercial paper as well as asset-backed securities, and places restrictions on the credit ratings, maturities and concentration by type and issuer. The Company has not experienced any losses on its deposits of cash, cash equivalents and investments. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the U.S. Food and Drug Administration, or FDA, and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized on a straight-line basis over the shorter of the term of the lease, or the useful life of the assets. Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in the consolidated statement of operations. Maintenance and repairs are charged to the consolidated statement of operations as incurred.
Leases	Leases On January 1, 2021, the Company adopted Accounting Standards Update No. 2016-02, Leases, Topic 842, or Accounting Standards Codification (ASC) 842, using the alternative modified transition method, which applies the standard as of the adoption date. Results and disclosure requirements for reporting periods beginning after January 1, 2021 are presented under ASC 842. The Company determines if an arrangement contains a lease at inception. For arrangements where the Company is the lessee, leases are included in operating or finance lease right-of-use, or ROU, assets; current operating or finance lease liabilities; and non-current operating or finance lease liabilities. Lease ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. ROU assets also include any initial direct costs incurred and any lease payments made on or before the lease commencement date, less lease incentives received. The Company uses its incremental borrowing rate based on the information available at the commencement date in determining the lease liabilities as the Company’s leases generally do not provide an implicit rate. The incremental borrowing rate is reevaluated upon a lease modification. The Company considered information available at the adoption date of ASC 842 to determine the incremental borrowing rate for leases in existence as of this date. Lease terms may include options to extend or terminate the lease when the Company is reasonably certain that the option will be exercised. Lease expense for operating leases is recognized on a straight-line basis over the lease term. For finance leases, ROU assets are amortized on a straight-line basis over the shorter of the expected useful life or the lease term, and the carrying amount of the lease liability is adjusted to reflect interest, which is recorded in interest expense. The Company elected to apply each of the practical expedients described in ASC 842 which allow companies (i) not to reassess prior conclusions on whether any expired or existing contracts are or contain a lease, lease classification, and initial direct costs, (ii) combine lease and non-lease components for all underlying assets groups, and (iii) not recognize ROU assets or lease liabilities for short term leases. A short-term lease is a lease that, at the commencement date, has a lease term of 12 months or less and does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. The Company has no t recorded impairment of any long-lived assets.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of the Company’s financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC 820, Fair Value Measurements and Disclosures. ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels: Level 1—Observable inputs, such as quoted prices in active markets; Level 2—Inputs, other than the quoted prices in active markets, which are observable either directly or indirectly such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life; and Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company classifies money market funds and U.S. treasury securities as Level 1 within the fair value hierarchy as the fair value is based on quoted prices. The Company classifies its investments in U.S. government agency securities, corporate debt securities, commercial paper, and asset-backed securities as Level 2 within the fair value hierarchy as the fair value is estimated by third-party pricing sources using quoted prices for identical or similar instruments in markets that are not active and industry-standard model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to benchmark yields, reported trades and broker/dealer quotes. Where applicable the market approach utilizes prices and information from market transactions for similar or identical assets.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs consist of payments made to secure commitments under certain debt financing arrangements. These amounts are recognized as interest expense over the period of the financing arrangement using the effective interest method. If the financing arrangement is canceled or forfeited, or if the utility of the arrangement to the Company is otherwise compromised, these costs are recognized as interest expense immediately. The Company’s consolidated financial statements present debt issuance costs related to a recognized debt liability as a direct reduction from the carrying amount of that debt liability.
Convertible Preferred Stock	Convertible Preferred Stock The Company records convertible preferred stock net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its organization documents unless the holders of convertible preferred stock have converted their convertible preferred stock into common stock. Convertible preferred stock is classified outside of stockholders’ equity (deficit) on the accompanying consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. Upon the consummation of the Company’s initial public offering in July 2020, all shares of convertible preferred stock outstanding and accrued cumulative dividends automatically converted into 23,934,533 shares of common stock.
Revenue Recognition	Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. No such revenue was earned in either 2021 or 2022. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, Revenue from Contracts with Customers , the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of ASC 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.
Cost of Services for Related-Party Revenue	Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying consolidated statements of operations.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, stock-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed.
Asset Acquisition Including Acquired In-Process Research and Development Expenses	Asset Acquisition including Acquired In-Process Research and Development Expenses When determining whether a transaction gives rise to an acquisition of a business or asset group, the Company applies a screening test to determine whether substantially all of the fair value of the gross assets acquired in the transaction is concentrated in a single identifiable asset or group of similar identifiable assets. If so, then the assets are not considered a business and the transaction is accounted for as an asset acquisition. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the asset or group of assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions or transactions to license intellectual property. In an asset acquisition, the cost allocated to acquired in-process research and development (IPR&D) with no alternative future use is recognized as an expense on the acquisition date. When a transaction is accounted for as an asset acquisition, an in-process research and development, or IPR&D asset is only capitalized if it has an alternative future use other than in a particular research and development project. Otherwise, amounts allocated to IPR&D that have no alternative use are expensed. Upfront and milestone payments made related to an asset acquisition are accrued for and expensed when the achievement of the milestone is considered probable.
Clinical and Contract Manufacturing Accruals	Clinical and Contract Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from its clinical and non-clinical studies and other third-party vendors. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. Through December 31, 2022 , there have been no material differences from the Company’s accrued estimated expenses to the actual clinical trial expenses. However, variations in the assumptions used to estimate accruals, including, but not limited to, the number of patients enrolled, the rate of patient enrollment, the actual services performed, and related costs may vary from the Company’s estimates, resulting in adjustments to clinical trial expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect its financial position and results of operations.
Stock-based Compensation Expense	Stock-based Compensation Expense The Company incurs stock-based compensation expense primarily from stock options, restricted stock units, and ESPP purchase rights. The Company estimates the fair value of stock options granted to employees, directors and non-employees and ESPP purchase rights using the Black-Scholes option-pricing model. The Black-Scholes model requires the input of subjective assumptions, including expected volatility, expected dividend yield, expected term, risk-free rate of return and the estimated fair value of the underlying common stock on the date of grant. Prior to the Company’s initial public offering, the fair value of the common stock underlying the stock-based awards was determined on each grant date by the board of directors, with input from management, considering the most recently available third-party valuation of common shares. The grant-date fair value of restricted stock units is the fair value of the underlying stock on the award’s grant date. The Company uses the straight-line method to allocate compensation expense to reporting periods over the requisite service period, which is generally the vesting period. The Company accounts for the effect of forfeitures as they occur.
Segment Reporting	Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s long-lived assets are located in the United States.
Foreign Currency Transactions	Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and recorded in other expense, net, and were immaterial for the years December 31, 2022, 2021 and 2020 .
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statements of operations in the period that includes the enactment date. Deferred income taxes comprise the impact of temporary differences between assets and liabilities recognized for financial reporting purposes and the amounts recognized for income tax reporting purposes, net operating loss carryforwards, and other tax credits measured by applying currently enacted tax laws. A valuation allowance is provided when necessary to reduce deferred tax assets to an amount that is more likely than not to be realized . If the Company determines that it would be able to realize its deferred tax assets in the future in excess of their net recorded amount, it would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on investments for all periods presented.
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented.
Recent Accounting Pronouncements	Recent Accounting Pronouncements None.
Series B Preferred Stock
Convertible Preferred Stock Warrant Liability	Series B Convertible Preferred Stock Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred stock. Freestanding warrants for the Company’s convertible preferred stock that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement at the end of every period until the earlier of the exercise of the warrants or the completion of a liquidation event, including the completion of an initial public offering. Upon exercise, the Series B convertible preferred stock warrant liability would be reclassified to additional paid-in capital, with any change in fair value recognized as a component of other expense, net. Following the Company’s initial public offering, the warrants were automatically converted to warrants to purchase shares of common stock. The Company revalued the Series B convertible preferred stock warrants as of the completion of the initial public offering and reclassified the outstanding preferred stock warrant liability balance to additional paid-in capital with no further re-measurement required as common stock warrants are considered permanent equity.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Financial Assets Measured at Fair Value on Recurring Basis	The following table presents the Company’s financial assets that are measured at fair value on a recur ring basis by level within the fair value hierarchy as of December 31, 2022 and 2021 (in thousands): December 31, 2022 Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash equivalents Money market funds Level 1 $ 36,690 $ — $ — $ 36,690 U.S. government agency securities Level 2 3,484 — — 3,484 Short-term investments U.S. Treasury securities Level 1 73,058 3 ( 438 ) 72,623 U.S. government agency securities Level 2 16,227 36 — 16,263 Corporate debt securities Level 2 56,318 — ( 367 ) 55,951 Commercial paper Level 2 62,087 — — 62,087 Asset-backed securities Level 2 10,512 — ( 51 ) 10,461 Long-term investments U.S. Treasury securities Level 1 5,242 2 — 5,244 U.S. government agency securities Level 2 9,760 — ( 15 ) 9,745 Asset-backed securities Level 2 1,725 — ( 15 ) 1,710 Total $ 275,103 $ 41 $ ( 886 ) $ 274,258 December 31, 2021 Fair Value Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 357,181 $ — $ — $ 357,181
Schedule of Fair Value of Available for Sale Investments by Classification	The fair value of cash equivalents and available-for-sale investments by classification included in the consolidated balance sheets was as follows as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Cash and cash equivalents $ 40,174 $ 357,181 Short-term investments 217,385 — Long-term investments 16,699 — Total $ 274,258 $ 357,181
Schedule of Fair Value of Available-for-Sale Investments by Contractual Maturity	The fair value of cash equivalents and available-for-sale investments by contractual maturity was as follows as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Maturing in one year or less $ 257,559 $ 357,181 Maturing after one year through five years 16,699 — Total $ 274,258 $ 357,181

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Schedule of Components of Property and Equipment	The following table presents the components of property and equipment, net as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Leasehold improvements $ 2,360 $ 229 Laboratory equipment 1,422 324 Computer hardware and software 344 241 Furniture and fixtures 166 166 Property and equipment, gross 4,292 960 Less: accumulated depreciation ( 403 ) ( 63 ) Property and equipment, net $ 3,889 $ 897
Schedule of Components of Other Assets, Net	The following table presents the components of other assets, net as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Long-term prepaid clinical expenses $ 7,264 $ 6,694 Operating lease right-of-use assets 5,626 1,829 Long-term prepaid contract manufacturing costs 1,456 2,854 Finance lease right-of-use assets 298 746 Deposits 144 144 Accrued interest receivable 78 — Restricted cash 66 — Total other assets $ 14,932 $ 12,267
Components of Accrued Expenses and Other Current Liabilities	The following table presents the components of accrued expenses and other current liabilities as of December 31, 2022 and 2021 (in thousands): December 31, December 31, 2022 2021 Accrued clinical and nonclinical study costs $ 5,485 $ 4,119 Accrued contract manufacturing 5,249 693 Accrued compensation and related expenses 3,708 3,294 Accrued property and equipment 2,110 27 Accrued professional fees 835 790 Operating lease liabilities, current 755 313 Finance lease liabilities, current 286 429 Other 174 236 Total accrued expenses and other current liabilities $ 18,602 $ 9,901

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Schedule of Maturities of Operating and Finance Lease Liabilities	The following table presents the maturities and balance sheet information of the Company’s operating and finance lease liabilities as of December 31, 2022 (in thousands, except lease term and discount rate): December 31, 2022 Operating Leases Finance Leases 2023 $ 1,240 $ 288 2024 1,267 — 2025 1,305 — 2026 1,187 — 2027 912 — Thereafter 2,069 — Total lease payments 7,980 288 Less: imputed interest ( 1,957 ) ( 2 ) Total lease liabilities $ 6,023 $ 286 Lease liabilities: current (i) $ 765 $ 286 Lease liabilities: non-current (ii) 5,258 — Total lease liabilities $ 6,023 $ 286 Weighted average remaining lease term (in years) 6.3 0.7 Weighted average discount rate 8.4 % 1.7 % (i) Current lease liabilities are presented within accrued expenses and other current liabilities and payable and accrued liabilities due to related party on the consolidated balance sheets and includes a nominal amount due to Tallac Therapeutics, Inc. for an operating lease. Refer to Note 11 “Related-Party Transactions” for additional discussion. (ii) Non-current lease liabilities are presented within other non-current liabilities on the consolidated balance sheet.
Components of Lease Costs	The following table presents the components of lease costs for the years ended December 31, 2022 and 2021 (in thousands): Year Ended December 31, 2022 2021 Operating lease cost $ 1,159 $ 360 Variable lease cost and other, net (i) 262 84 Short-term lease cost 88 — Finance lease cost: Amortization of right-of-use assets 447 369 Interest 9 13 Total lease costs $ 1,965 $ 826 (i) The variable lease cost and other, net is comprised primarily of common area maintenance charges for the operating lease, which are dependent on usage. These costs are classified as operating lease expense due to the election to not separate lease and non-lease components. These costs were not included within the measurement of the Company’s operating lease ROU assets and operating lease liabilities.
Supplemental Cash Flow Disclosures for Cash Paid for Leases	The following table presents the supplemental cash flow disclosures for cash paid for the years ended December 31, 2022 and 2021 (in thousands): Year Ended December 31, 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 933 $ 243 Operating cash flows from finance leases $ 8 $ 11 Financing cash flows from finance leases $ 388 $ 281 Right-of-use asset acquired under leases Operating leases $ 4,613 $ 1,780 Finance leases $ — $ 776

Term Loan (Tables)

Term Loan (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Schedule of Future Maturities Under the Loan Agreement	As of December 31, 2022, the future maturities under the Loan Agreement are as follows (in thousands): December 31, 2022 2023 $ — 2024 — 2025 435 2026 5,217 2027 4,948 Total future maturities 10,600 Less: current portion of term loan — Total term loan, net of current portion 10,600 Less: unamortized debt issuance costs ( 993 ) Less: unaccreted final payment costs ( 218 ) Term loan, non-current, net $ 9,389

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Common Stock Reserved for Future Issuance	Common stock reserved for future issuance as of December 31, 2022 consists of the following: December 31, 2022 Stock options issued and outstanding 6,196,848 Stock options authorized for future issuance 2,932,309 Employee Stock Purchase Plan shares authorized for future issuance 1,147,986 Restricted stock issued and outstanding 820,326 Total 11,097,469

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Summary of Shares Available for Grant	The following table provides a summary of shares available for grant under the 2020 Plan: Amended and Restated 2020 Equity Incentive Plan Shares available for grant at December 31, 2021 3,407,898 Authorized 1,623,483 Granted ( 2,385,984 ) Canceled/forfeited 286,912 Shares available for grant at December 31, 2022 2,932,309
Summary of Share Option Activity	The following table provides a summary of stock option activity under the 2020 Plan and related information: Outstanding Options Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2021 5,128,639 $ 23.91 8.28 $ 49,745 Granted 1,481,234 10.89 Exercised ( 171,838 ) 3.30 Canceled/forfeited ( 241,187 ) 44.58 Outstanding at December 31, 2022 6,196,848 $ 20.56 7.78 $ 19,872 Exercisable at December 31, 2022 3,663,358 $ 14.73 7.03 $ 18,824
Schedule of Fair Value of Each Option Grant Using Black-Scholes Option-Pricing Model	The fair value of each option grant during the years ended December 31, 2022, 2021 and 2020 was estimated with the following assumptions:   Year Ended December 31,   2022 2021 2020 Expected term (in years)  5.3 - 6.1  5.3 - 6.1  5.8 - 6.1 Risk-free interest rate  1.6 % - 4.4 %  0.8 % - 1.4 %  0.3 % - 0.8 % Expected dividend rate  -  -  - Expected stock price volatility  81.9 % - 84.7 %  79.7 % - 86.9 %  78.7 % - 89.0 %
Summary of Restricted Stock Unit Activity	The following table provides a summary of restricted stock unit activity under the 2020 Plan and related information: Outstanding RSUs Number of RSUs Weighted- Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Unvested as of December 31, 2021 15,075 $ 58.56 1.83 $ 324 Granted 904,750 13.55 Vested ( 53,774 ) 14.71 Canceled/forfeited ( 45,725 ) 16.55 Unvested as of December 31, 2022 820,326 $ 14.13 1.68 $ 9,245
Summary of Share-Based Compensation Expense	Stock-based compensation expense includes stock options and restricted stock units and has been reported in the Company’s consolidated statements of operations as follows (in thousands): Year Ended December 31, 2022 2021 2020 Research and development $ 10,741 $ 5,211 $ 2,551 General and administrative 13,098 8,703 2,885 Total $ 23,839 $ 13,914 $ 5,436

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule Components of Loss Before Income Taxes	The U.S. domestic and international components of pre-tax loss for the years ending December 31, 2022, 2021 and 2020 are as follows (in thousands): Year Ended December 31, 2022 2021 2020 United States $ ( 111,360 ) $ ( 30,565 ) $ ( 9,457 ) International ( 12,058 ) ( 52,919 ) ( 36,042 ) Loss before income taxes $ ( 123,418 ) $ ( 83,484 ) $ ( 45,499 )
Schedule of Income Tax Provision (Benefit)	The federal and state provision (benefit) for income taxes consist of the following (in thousands): Year Ended December 31, 2022 2021 2020 Current provision for income taxes: Federal $ 64 $ ( 21 ) $ 239 State — — 2 International — — — Total current 64 ( 21 ) 241 Deferred tax provision: Federal — — — State — — — International — — — Total deferred — — — Provision (benefit) for income taxes $ 64 $ ( 21 ) $ 241
Schedule of Statutory and Effective Income Tax Rate Reconciliation	A reconciliation of the U.S. federal statutory income tax rate to the effective tax for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): Year Ended December 31, 2022 2021 2020 At federal statutory income tax rate $ ( 25,918 ) $ ( 17,532 ) $ ( 9,555 ) State income taxes ( 2,659 ) ( 105 ) ( 3,098 ) Stock-based compensation 2,368 ( 4,031 ) ( 5 ) Research & Development credits ( 1,779 ) ( 2,131 ) ( 512 ) Change in valuation allowance 9,067 11,476 5,710 Other 36 172 321 Foreign rate differential 18,949 11,032 7,380 Prior period true ups — 1,098 — Provision (benefit) for income taxes $ 64 $ ( 21 ) $ 241
Schedule of Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets as of December 31, 2022 and 2021 are as follows (in thousands): December 31, 2022 2021 Deferred tax assets: Loss carryforwards $ 16,319 $ 15,407 Research & other credits 8,435 5,325 Other 14 16 Accrued expenses 1,860 529 Stock options 3,860 1,530 Lease Liabilities 1,323 542 Capitalized R&D 1,702 — Total deferred tax assets 33,513 23,349 Deferred tax liabilities: Fixed assets 215 73 Lease ROU assets 1,244 541 Prepaid expenses 252 — Total deferred tax liabilities 1,711 614 Valuation allowance ( 31,802 ) ( 22,735 ) Net deferred tax assets $ — $ —
Summary of Net Operating Loss and Tax Credit Carryforwards	Net operating losses and tax credit carryforwards as of December 31, 2022 are as follows (in thousands): Amount Expiration Years Net operating losses, federal (Post December 31, 2017) $ 46,835 Do Not Expire Net operating losses, state $ 68,993 2038 - 2040 Tax credits, federal $ 5,978 2039 - 2042 Tax credits, state $ 4,177 N/A Net operating losses, foreign $ 4,554 N/A
Schedule of Unrecognized Tax Benefits	The Company has the following activity relating to unrecognized tax benefits (in thousands): Year Ended December 31, 2022 2021 2020 Balance at beginning of year $ 1,217 $ 842 $ 692 Additions/reversals based on tax positions of prior years 13 ( 69 ) ( 64 ) Additions based on tax positions related to the current year 443 494 240 Lapses in statutes of limitations ( 12 ) ( 50 ) ( 26 ) Balance at end of year $ 1,661 $ 1,217 $ 842

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Year Ended December 31, 2022 2021 2020 Numerator: Net loss $ ( 123,482 ) $ ( 83,463 ) $ ( 45,740 ) Less: cumulative preferred dividends allocated to — — ( 5,202 ) Net loss attributable to common stockholders $ ( 123,482 ) $ ( 83,463 ) $ ( 50,942 ) Denominator: Weighted-average shares of common stock 40,699,612 40,308,050 18,485,343 Net loss per share attributable to common stockholders, $ ( 3.03 ) $ ( 2.07 ) $ ( 2.76 )
Summary of Outstanding Potentially Dilutive Securities Were Excluded from Computation of Diluted Net Loss Per Share	The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share for the years ended December 31, 2022, 2021 and 2020, because including them would have been anti-dilutive: Year Ended December 31, 2022 2021 2020 Common stock subject to repurchase — — 63 Stock options issued and outstanding 6,196,848 5,128,639 4,857,308 Restricted stock issued and outstanding 820,326 15,075 — Employee Stock Purchase Plan estimated shares issuable — — — Total 7,017,174 5,143,714 4,857,371

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Summary of Other Contractual Obligations and Other Commitments from Manufacturing and Service Contracts	We have other contractual obligations and other commitments from manufacturing and service contracts, which are presented as follows as of December 31, 2022 (in thousands): December 31, 2022 Total 2023 2024-2025 2026-2027 Thereafter Manufacturing and service contracts 10,953 9,590 1,323 40 — Total $ 10,953 $ 9,590 $ 1,323 $ 40 $ —

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jul. 08, 2020	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jul. 31, 2020 shares	Jul. 21, 2020 shares
Significant Accounting Policies [Line Items]
Other income (expense), net		$ (260,000)	$ (20,000)	$ (1,339,000)
Reverse stock split, description		On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806 reverse split of its common stock and convertible preferred stock.
Reverse stock split, conversion ratio	0.151961827
Impairment charges		$ 0
Number of operating segment | Segment		1
Revenue		$ 0	0	1,182,000
Initial Public Offering | Common Stock
Significant Accounting Policies [Line Items]
Convertible shares converted in to common stock | shares					23,934,533	23,934,533
Revision of Prior Period, Reclassification, Adjustment
Significant Accounting Policies [Line Items]
Other income (expense), net			100,000	100,000
Interest income			$ 100,000	100,000
Interest expense				800,000
Other expense, net				$ 800,000

Acquisition of Assets and Own_2

Acquisition of Assets and Ownership - Additional Information (Details) - ScalmiBio, Inc - USD ($)		12 Months Ended
	Oct. 04, 2021	Dec. 31, 2021	Oct. 04, 2022
Business Acquisition [Line Items]
Business acquisition, initial payment in cash	$ 4,500,000
Retention milestone payment			$ 2,000,000
Business acquisition, date of acquisition	Oct. 04, 2021
Maximum milestones amount payable on clinical development acquired technology	$ 35,000,000
Business acquisition, percentage of voting interests acquired	31.70%		31.70%
Repayment of note and accrued interest	$ 87,000
Acquisition related costs		$ 200,000
Research and Development
Business Acquisition [Line Items]
Acquisition related costs		$ 4,700,000

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Fair Value	$ 274,258	$ 357,181
Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	275,103
Unrealized Gains	41
Unrealized Losses	(886)
Fair Value	274,258
Money Market Funds | Level 1 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	36,690	357,181
Fair Value	36,690	$ 357,181
U.S. Government Agency Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	3,484
Fair Value	3,484
Short Term Investment U.S. Treasury Securities | Level 1 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	73,058
Unrealized Gains	3
Unrealized Losses	(438)
Fair Value	72,623
Short Term Investment U.S. Government Agency Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	16,227
Unrealized Gains	36
Fair Value	16,263
Short Term Investment Corporate Debt Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	56,318
Unrealized Losses	(367)
Fair Value	55,951
Short Term Investment Commercial Paper | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	62,087
Fair Value	62,087
Short Term Investment Asset-Backed Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	10,512
Unrealized Losses	(51)
Fair Value	10,461
Long Term Investment U.S. Treasury Securities | Level 1 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	5,242
Unrealized Gains	2
Fair Value	5,244
Long-term Investment U.S. Government Agency Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	9,760
Unrealized Losses	(15)
Fair Value	9,745
Long Term Investment Asset-Backed Securities | Level 2 | Fair Value on Recurring Basis
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,725
Unrealized Losses	(15)
Fair Value	$ 1,710

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assets and liabilities transfers amount	$ 0	$ 0
Fair value assets transferred into level 3	0	0
Fair value assets transferred out of level 3	0	0
Fair value liabilities transferred into level 3	0	0
Fair value liabilities transferred out of level 3	0	0
Accrued interest receivable, investment	$ 1,000,000	$ 0
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Prepaid Expense and Other Assets, Current	Prepaid Expense and Other Assets, Current
Bank account cash	$ 8,600,000	$ 6,500,000
Allowance for credit losses	0	0
Fair value of securities, continuous unrealized loss position for more than 12 months	0	0
Impairment losses on available-for-sale investments	0	0
Fair Value on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial liabilities fair value disclosure	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Schedule of Fair Value of Available for Sale Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total available-for-sale investments	$ 274,258	$ 357,181
Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents available for sale	40,174	$ 357,181
Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short term investments available for sale	217,385
Long-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long term investments available for sale	$ 16,699

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Schedule of Fair Value of Available-for-sale Investments by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale, Fair Value, Fiscal Year Maturity [Abstract]
Maturing in one year or less	$ 257,559	$ 357,181
Maturing after one year through five years	16,699
Total available-for-sale investments	$ 274,258	$ 357,181

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 4,292	$ 960
Less: accumulated depreciation	(403)	(63)
Property and equipment, net	3,889	897
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,360	229
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,422	324
Computer Hardware and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	344	241
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 166	$ 166

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2020
Schedule Of Balance Sheet Components [Line Items]
Depreciation	$ 0.3	$ 0.2

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Components of Other Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Operating lease right-of-use assets	$ 5,626	$ 1,829
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total other assets	Total other assets
Finance lease right-of-use assets	$ 298	$ 746
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total other assets	Total other assets
Deposits	$ 144	$ 144
Accrued interest receivable	78
Restricted cash	66
Total other assets	14,932	12,267
Long-term Prepaid Clinical Expenses
Property Plant And Equipment [Line Items]
Long-term prepaid expenses	7,264	6,694
Long-term Prepaid Contract Manufacturing Costs
Property Plant And Equipment [Line Items]
Long-term prepaid expenses	$ 1,456	$ 2,854

Balance Sheet Components - Comp

Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Accrued clinical and nonclinical study costs	$ 5,485	$ 4,119
Accrued contract manufacturing	5,249	693
Accrued compensation and related expenses	3,708	3,294
Accrued property and equipment	2,110	27
Accrued professional fees	835	790
Operating lease liabilities, current	$ 755	$ 313
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total accrued expenses and other current liabilities	Total accrued expenses and other current liabilities
Finance lease liabilities, current	$ 286	$ 429
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total accrued expenses and other current liabilities	Total accrued expenses and other current liabilities
Other	$ 174	$ 236
Total accrued expenses and other current liabilities	$ 18,602	$ 9,901

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 28, 2022 USD ($) ft²	May 31, 2021 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Lessee Lease Description [Line Items]
Operating lease ROU assets			$ 5,626	$ 1,829
Option to extend term			no
Total lease payment			$ 7,980
Finance lease ROU assets			$ 298	$ 746
Office Space at 323 Allerton Avenue, South San Francisco, California
Lessee Lease Description [Line Items]
Lessee, operating lease commencing end date		Jun. 06, 2021
Lessee operating lease expiration date		Aug. 31, 2026
Operating lease ROU assets		$ 2,000
Area of operating lease | ft²		10,000
Operating lease, description			Company entered into a lease agreement for approximately 10,000 square feet of office space located in South San Francisco, California. The lease commenced on June 6, 2021 and expires on August 31, 2026. The lease does not provide an option to extend after it expires. The total lease payments for the life of the lease are approximately $2.0 million.
Existence of option to extend		false
Option to extend term		no
Office and Laboratory Space Located In Palo Alto, California
Lessee Lease Description [Line Items]
Area of operating lease | ft²	11,074
Existence of option to extend	true
Lease operating lease expiration period	2030-02
Lessee operating lease renewal term	2 years
Lease operating lease commencement period	2022-02
Lease operating lease commencement period for second premises	2022-04
Annual base rent	$ 800
Percentage of increase of annual rent	3%
Lessee operating lease leasehold improvements	$ 2,100
Lessee operating lease leasehold improvements additional payments	$ 1,500
Annual interest rate of additional payments over life of lease	7%
Total lease payment	$ 6,900
Letter of credit	100
Restricted cash deposits	$ 100
Option to extend term			The lease provides for an option to extend for two years after expiration

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating and Finance Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2023	$ 1,240
2024	1,267
2025	1,305
2026	1,187
2027	912
Thereafter	2,069
Total lease payments	7,980
Less: imputed interest	(1,957)
Operating lease liabilities	6,023
Lease liabilities: current	765
Lease liabilities: non-current	$ 5,258
Operating lease, liability, noncurrent, statement of financial position [extensible list]	Other non-current liabilities
Total lease liabilities	$ 6,023
Weighted average remaining lease term (in years)	6 years 3 months 18 days
Weighted average discount rate	8.40%
Finance Lease, Liability, Payment, Due [Abstract]
2023	$ 288
Total lease payments	288
Less: imputed interest	(2)
Finance lease liabilities	286
Finance lease liabilities, current	286	$ 429
Total lease liabilities	$ 286
Weighted average remaining lease term (in years)	8 months 12 days
Weighted average discount rate	1.70%

Leases - Components of Lease Co

Leases - Components of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease cost	$ 1,159	$ 360
Variable lease cost and other, net	262	84
Short-term lease cost	88
Finance lease cost, Amortization of right-of-use assets	447	369
Finance lease cost, Interest	9	13
Total lease costs	$ 1,965	$ 826

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Disclosures for Cash Paid for Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating cash flows from operating leases	$ 933	$ 243
Operating cash flows from finance leases	8	11
Financing cash flows from finance leases	388	281
Right-of-use asset acquired under leases
Operating leases	$ 4,613	1,780
Finance leases		$ 776

Term Loan - Additional Informat

Term Loan - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 20, 2019
Debt Instrument [Line Items]
Issuance of term loan		$ 10,000,000
SVB-WestRiver Loan Agreement
Debt Instrument [Line Items]
Term loan, principal amount					$ 6,000,000
Increase in fair value of warrant liability				$ 8,000
SVB-WestRiver Loan Agreement | Compound Derivative Liability
Debt Instrument [Line Items]
Fair value of compound derivative liability		51,000
Increase in fair value of compound derivative liability				$ 658,000
SVB-WestRiver Loan Agreement | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrant liability converted into common stock		400,000
Oxford-SVB Loan Agreement
Debt Instrument [Line Items]
Issuance of term loan	$ 9,300,000
Draw an additional loan	$ 50,000,000
Interest rate terms	Borrowings under the Loan Agreement bear interest at a floating rate per annum equal to the greater of (i) 1-month term Secured Overnight Financing Rate, or SOFR, and (ii) 2.33%, plus 6.25%. The minimum per annum interest rate is 8.58%.
Maturity date	Oct. 01, 2027
Incremental prepayment amount	$ 10,000,000
Percentage of fee amount paid upon final payment	6%
Debt default rate	5%
Interest expense		$ 200,000
deduction of debt issuance costs	$ 700,000
Oxford-SVB Loan Agreement | Term Loan
Debt Instrument [Line Items]
Interest expense			$ 0
Outstanding debt			$ 0
Oxford-SVB Loan Agreement | Fixed Rate
Debt Instrument [Line Items]
Basis spread rate	6.25%
Oxford-SVB Loan Agreement | Base Rate
Debt Instrument [Line Items]
Basis spread rate	8.58%
Oxford-SVB Loan Agreement | Tranche A
Debt Instrument [Line Items]
Issuance of term loan	$ 10,000,000
Draw an additional loan	40,000,000
Oxford-SVB Loan Agreement | Tranche B
Debt Instrument [Line Items]
Available borrowing capacity upon achievement of milestones	12,500,000
Oxford-SVB Loan Agreement | Tranche C
Debt Instrument [Line Items]
Available borrowing capacity upon achievement of milestones	12,500,000
Oxford-SVB Loan Agreement | Tranche D
Debt Instrument [Line Items]
Available borrowing capacity at lender's discretion	25,000,000
Oxford-SVB Loan Agreement | Maximum | Secured Term Loan Facility
Debt Instrument [Line Items]
Term loan, principal amount	$ 100,000,000
Oxford-SVB Loan Agreement | Minimum
Debt Instrument [Line Items]
Basis spread rate	2.33%
Oxford-SVB Loan Agreement | Minimum | Term Loan | Intellectual Property
Debt Instrument [Line Items]
Outstanding balance of loan threshold at which Intellectual Property becomes collateral	$ 75,000,000

Term Loan - Schedule of Future

Term Loan - Schedule of Future Maturities Under the Loan Agreement (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Long-Term Debt, Fiscal Year Maturity [Abstract]
2025	$ 435
2026	5,217
2027	4,948
Total future maturities	10,600
Less: current portion of term loan	0
Total term loan, net of current portion	10,600
Less: unamortized debt issuance costs	(993)
Less: unaccreted final payment costs	218
Term loan, non-current, net	$ 9,389

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Jul. 21, 2020	Jul. 20, 2020	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2020	Dec. 31, 2021	Jul. 31, 2020
Class Of Stock [Line Items]
Common stock, shares authorized	1,000,000,000			1,000,000,000		1,000,000,000
Common stock, par value	$ 0.001			$ 0.001		$ 0.001
Preferred stock, par value	$ 0.001
Common stock, shares outstanding				40,861,386		40,587,067
Underwriting discounts and commissions paid					$ 3,848
Common Stock
Class Of Stock [Line Items]
Issuance of common stock in connection with equity offerings, net of underwriter discounts and issuance costs, shares					12,512,000
Initial Public Offering | Common Stock
Class Of Stock [Line Items]
Issuance of common stock in connection with equity offerings, net of underwriter discounts and issuance costs, shares	9,775,000
Net proceeds from initial public offering	$ 169,500
Underwriting discounts and commissions paid	13,000
Payment for offering related expense	$ 3,200
Convertible shares converted in to common stock	23,934,533						23,934,533
Follow-on Public Offering | Common Stock
Class Of Stock [Line Items]
Issuance of common stock in connection with equity offerings, net of underwriter discounts and issuance costs, shares			2,737,000
Net proceeds from initial public offering			$ 194,900
Underwriting discounts and commissions paid			12,500
Payment for offering related expense			$ 700
Undesignated Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares authorized	100,000,000
Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, cumulative dividends percentage				6%
Accrued cumulative dividends on the Series A, Series B and Series C convertible preferred stock		$ 18,000
Cumulative preferred stock dividend convertible shares issued upon conversion		2,564,759
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Shares original issue price				$ 6.58
Series B and C Convertible Preferred Stock
Class Of Stock [Line Items]
Shares original issue price				$ 9.4972

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2022 shares
Class Of Stock [Line Items]
Common stock reserved for future issuance	11,097,469
Stock Options Issued and Outstanding
Class Of Stock [Line Items]
Common stock reserved for future issuance	6,196,848
Stock Options Authorized for Future Issuance
Class Of Stock [Line Items]
Common stock reserved for future issuance	2,932,309
Employee Stock Purchase Plan Shares Authorized for Future Issuance
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,147,986
Restricted Stock Issued and Outstanding
Class Of Stock [Line Items]
Common stock reserved for future issuance	820,326

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)			1 Months Ended	12 Months Ended
	Jan. 01, 2022	Jan. 01, 2021	Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2015	Apr. 01, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance				11,097,469
Unvested early exercised options				0
Stock-based compensation expenses				$ 23,839,000	$ 13,914,000	$ 5,436,000
Total intrinsic value of options exercised				$ 1,700,000	$ 48,100,000	$ 4,400,000
Weighted-average grant-date fair value per share				$ 7.88	$ 42.29	$ 7.74
Unrecognized share-based compensation expense				$ 52,400,000
Unrecognized share-based compensation expense, weighted-average period				2 years 6 months
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			400,000	1,147,986
Percentage of eligible compensation withheld			15%
Share-based compensation, authorized amount			$ 25,000
Share-based compensation, number of shares authorized			3,000
Share-based Compensation, lower of closing price, percentage			85%
Maximum percentage of additional shares reserved for future issuance				1%
Number of additional shares reserved for future issuance	405,871	398,445
Number of shares purchased				56,330
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant-date fair value per share, restricted stock units granted				$ 13.55	$ 58.56
Restricted stock units granted				904,750		0
Unrecognized share-based compensation expense				$ 9,800,000
Unrecognized share-based compensation expense, weighted-average period				3 years 2 months 12 days
Maximum | ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares reserved for future issuance				800,000
2015 Share Award Scheme | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share option granted during the period							2,143,117
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of permitted issuance of share option								4,379,139
2020 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			7,874,862
Share options, maximum term				10 years
Share options, service period				4 years
Maximum percentage of additional shares reserved for future issuance				4%
2020 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares reserved for future issuance				4,000,000
Stock Option Modification
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expenses				$ 0	$ 0	$ 1,700,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Shares Available for Grant (Details) - 2020 Plan	12 Months Ended
	Dec. 31, 2022 shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares Available to Grant Balance	3,407,898
Shares Available to Grant, Authorized	1,623,483
Shares Available to Grant, Granted	(2,385,984)
Shares Available to Grant, Canceled/forfeited	286,912
Shares Available to Grant Balance	2,932,309

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Number of Options, Balance	5,128,639
Number of Options, Granted	1,481,234
Number of Options, Exercised	(171,838)
Number of Options, Canceled/forfeited	(241,187)
Number of Options, Balance	6,196,848	5,128,639
Number of Options, Exercisable at December 31, 2022	3,663,358
Weighted Average Exercise Price, Balance	$ 23.91
Weighted Average Exercise Price, Granted	10.89
Weighted Average Exercise Price, Exercised	3.30
Weighted Average Exercise Price, Canceled/forfeited	44.58
Weighted Average Exercise Price, Balance	20.56	$ 23.91
Weighted Average Exercise Price, Exercisable at December 31, 2022	$ 14.73
Weighted Average Remaining Contractual Life (Years), Outstanding Options	7 years 9 months 10 days	8 years 3 months 10 days
Weighted Average Remaining Contractual Life (Years), Outstanding Options Exercisable	7 years 10 days
Outstanding Options Aggregate Intrinsic Value, Balance	$ 19,872	$ 49,745
Outstanding Options Aggregate Intrinsic Value, Exercisable	$ 18,824

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Fair Value of Each Option Grant Using Black-Scholes Option-Pricing Model (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.60%	0.80%	0.30%
Risk-free interest rate, maximum	4.40%	1.40%	0.80%
Expected dividend rate	0%	0%	0%
Expected stock price volatility, minimum	81.90%	79.70%	78.70%
Expected stock price volatility, maximum	84.70%	86.90%	89%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years 3 months 18 days	5 years 9 months 18 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	6 years 1 month 6 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Balance	15,075
Number of RSUs, Granted	904,750		0
Number of RSUs, Vested	(53,774)
Number of RSUs, Canceled/forfeited	(45,725)
Number of RSUs, Balance	820,326	15,075
Weighted-Average Grant Date Fair Value, Balance	$ 58.56
Weighted-Average Grant Date Fair Value, Granted	13.55	$ 58.56
Weighted-Average Grant Date Fair Value, Vested	14.71
Weighted-Average Grant Date Fair Value, Canceled/forfeited	16.55
Weighted-Average Grant Date Fair Value, Balance	$ 14.13	$ 58.56
Weighted Average Remaining Contractual Life (Years), Balance	1 year 8 months 4 days	1 year 9 months 29 days
Aggregate Intrinsic Value, Balance	$ 9,245	$ 324

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 23,839	$ 13,914	$ 5,436
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	10,741	5,211	2,551
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 13,098	$ 8,703	$ 2,885

Income Taxes - Domestic and Int

Income Taxes - Domestic and International Components of Pre-Tax Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
United States	$ (111,360)	$ (30,565)	$ (9,457)
International	(12,058)	(52,919)	(36,042)
Loss before income taxes	$ (123,418)	$ (83,484)	$ (45,499)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current provision for income taxes:
Federal	$ 64	$ (21)	$ 239
State			2
Total current	64	(21)	241
Deferred tax provision:
Provision (benefit) for income taxes	$ 64	$ (21)	$ 241

Income Taxes - Schedule of Stat

Income Taxes - Schedule of Statutory and Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
At federal statutory income tax rate	$ (25,918)	$ (17,532)	$ (9,555)
State income taxes	(2,659)	(105)	(3,098)
Stock-based compensation	2,368	(4,031)	(5)
Research & Development credits	(1,779)	(2,131)	(512)
Change in valuation allowance	9,067	11,476	5,710
Other	36	172	321
Foreign rate differential	18,949	11,032	7,380
Prior period true ups		1,098
Provision (benefit) for income taxes	$ 64	$ (21)	$ 241

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Loss carryforwards	$ 16,319	$ 15,407
Research & other credits	8,435	5,325
Other	14	16
Accrued expenses	1,860	529
Stock options	3,860	1,530
Lease Liabilities	1,323	542
Capitalized R&D	1,702
Total deferred tax assets	33,513	23,349
Deferred tax liabilities:
Fixed assets	215	73
Lease ROU assets	1,244	541
Prepaid expenses	252
Total deferred tax liabilities	1,711	614
Valuation allowance	(31,802)	(22,735)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Deferred tax assets, increase in valuation allowance	$ 9,100,000	$ 11,400,000
Unrecognized tax benefits	1,661,000	1,217,000	$ 842,000	$ 692,000
Recognized interest and penalties expense (benefit) related to unrecognized tax benefits	$ 0	$ 0	$ 0

Income Taxes - Schedule of Net

Income Taxes - Schedule of Net Operating Losses and Tax Credit Carryforwards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Federal
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Net operating losses	$ 46,835
Tax credits	$ 5,978
Federal | Minimum
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Tax credits, Expiration Years	2039
Federal | Maximum
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Tax credits, Expiration Years	2042
State
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Net operating losses	$ 68,993
Tax credits	$ 4,177
State | Minimum
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Net operating losses, Expiration Years	2038
State | Maximum
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Net operating losses, Expiration Years	2040
Foreign
Net Operating Loss And Tax Credit Carryforwards [Line Items]
Net operating losses	$ 4,554

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 1,217	$ 842	$ 692
Additions/reversals based on tax positions of prior years	13	(69)	(64)
Additions based on tax positions related to the current year	443	494	240
Lapses in statutes of limitations	(12)	(50)	(26)
Balance at end of year	$ 1,661	$ 1,217	$ 842

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) $ in Thousands			1 Months Ended		12 Months Ended
	Oct. 04, 2022 USD ($)	Jul. 01, 2020	Jul. 31, 2020 USD ($)	Jun. 30, 2018	Dec. 31, 2022 USD ($) Investor	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 04, 2021
Related Party Transaction [Line Items]
Related-party revenue					$ 0	$ 0	$ 1,182
Research and development costs					$ 98,400	60,170	28,961
ScalmiBio, Inc
Related Party Transaction [Line Items]
Research and development costs	$ 600
Business acquisition, percentage of voting interests acquired	31.70%							31.70%
Retention milestone payment	$ 2,000
Tallac Therapeutics | Lab Equipment and Other Assets
Related Party Transaction [Line Items]
Proceeds from transfer of assets			$ 600
Research and Development Services Agreement | Tollnine
Related Party Transaction [Line Items]
Number of company's investors who are investors in related party as well | Investor					2
Related-party revenue					$ 0	0	1,200
Initial term of agreement with related party				3 years
Markup cost in percentage				10%
Research and Development Services Agreement | Tallac Therapeutics
Related Party Transaction [Line Items]
Initial term of agreement with related party		4 years
Markup cost in percentage		10%
Agreement automatically renewal additional term unless terminated		1 year
Research and development costs					600	800	$ 600
Collaboration Agreement | Tallac Therapeutics
Related Party Transaction [Line Items]
Research and development costs					7,800	2,800
Accrued expenses due					$ 1,600	$ 1,400

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (123,482)	$ (83,463)	$ (45,740)
Less: cumulative preferred dividends allocated to preferred stockholders			(5,202)
Net loss attributable to common stockholders	$ (123,482)	$ (83,463)	$ (50,942)
Denominator:
Weighted-average shares of common stock used to compute net loss per share attributable to common stockholders, basic	40,699,612	40,308,050	18,485,343
Weighted-average shares of common stock used to compute net loss per share attributable to common stockholders, diluted	40,699,612	40,308,050	18,485,343
Net loss per share attributable to common stockholders, basic	$ (3.03)	$ (2.07)	$ (2.76)
Net loss per share attributable to common stockholders, diluted	$ (3.03)	$ (2.07)	$ (2.76)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Summary of Outstanding Potentially Dilutive Securities Were Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,017,174	5,143,714	4,857,371
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share			63
Stock Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	6,196,848	5,128,639	4,857,308
Restricted Stock Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	820,326	15,075

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2015 USD ($)	Dec. 31, 2022 USD ($) Litigation	Dec. 31, 2021 USD ($) Litigation	Dec. 31, 2020 Litigation
Commitments And Contingencies [Line Items]
Guarantee obligations		$ 10,953,000
Number of pending or threatened litigation | Litigation		0	0	0
Future purchase obligations		$ 10,953,000
Master Service Agreement
Commitments And Contingencies [Line Items]
Initial term of agreement	3 years
Renewal periods of agreement	1 year
Future purchase obligations	$ 11,000,000
Indemnification Agreement
Commitments And Contingencies [Line Items]
Guarantee obligations		0
Stanford Junior University | Exclusive Equity Agreement
Commitments And Contingencies [Line Items]
Nonrefundable license royalty and patent expenses			$ 100,000
Clinical and regulatory milestones payments			5,000,000
Milestone payments related to clinical and regulatory		0	200,000
Selexis SA | Commercial License Agreement
Commitments And Contingencies [Line Items]
Clinical and regulatory milestones payments			1,200,000
Milestone payments related to clinical and regulatory		0	$ 100,000
Crystal Bioscience Inc | Commercial Antibody Agreement
Commitments And Contingencies [Line Items]
Clinical and regulatory milestones payments		11,100,000
Milestone payments related to clinical and regulatory		$ 300,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Other Contractual Obligations and Other Commitments from Manufacturing and Service Contracts (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Manufacturing and service contracts, Total	$ 10,953
Manufacturing and service contracts, 2023	9,590
Manufacturing and service contracts, 2024 - 2025	1,323
Manufacturing and service contracts, 2026 - 2027	40
Contractual Obligation, Total	10,953
Contractual Obligation, 2023	9,590
Contractual Obligation, 2024 - 2025	1,323
Contractual Obligation, 2026 - 2027	$ 40