Apexigen (APGN) S-1 22 Feb 23 IPO registration Financial data

Cover Page

Cover Page	12 Months Ended
	Dec. 31, 2022
Document Information [Line Items]
Document Type	S-1
Amendment Flag	false
Entity Registrant Name	Apexigen, Inc.
Entity Central Index Key	0001814140
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)		Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents		$ 14,802,000	$ 23,443,000
Short-term investments		1,997,000	12,917,000
Prepaid expenses and other current assets		2,618,000	1,681,000
Deferred financing costs, current		1,776,000
Total current assets		21,193,000	38,041,000
Property and equipment, net		150,000	245,000
Right-of-use assets		100,000	483,000
Deferred financing costs, non-current		1,036,000
Other assets		376,000	327,000
Total assets		22,855,000	39,096,000
Current liabilities:
Accounts payable		5,343,000	4,487,000
Accrued liabilities		5,359,000	8,488,000
Deferred revenue		5,659,000	3,610,000
Lease liabilities, current portion		106,000	369,000
Total current liabilities		16,467,000	16,954,000
Derivative warrant liabilities		11,000
Lease liabilities, less current portion		0	141,000
Total liabilities		16,478,000	17,095,000
Commitment and contingencies (Note 10)
Stockholders' equity:
Common Stock	[1]	2,000	2,000
Additional paid-in capital		183,168,000	166,727,000
Accumulated deficit		(176,793,000)	(144,724,000)
Accumulated other comprehensive loss		0	(4,000)
Total stockholders' equity		6,377,000	22,001,000
Total liabilities and stockholders' equity		$ 22,855,000	$ 39,096,000
[1]The balance sheet as of December 31, 2021 presented above reflects the retrospective application of recapitalization as if the Transaction had occurred on January 1, 2021. See Note 1, 3, and 7.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,000,000,000	23,563,040
Common stock, shares issued	22,646,015	22,646,015
Common stock, shares outstanding	18,051,592	18,051,592

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 23,035	$ 21,664
General and administrative	9,651	7,293
Total operating expenses	32,686	28,957
Loss from operations	(32,686)	(28,957)
Other income, net	617	41
Net loss	$ (32,069)	$ (28,916)
Net loss per share attributable to common stockholders, Basic	$ 1.62	$ 1.6
Net loss per share attributable to common stockholders, Diluted	$ 1.62	$ 1.6
Weighted-average common shares used to compute net loss per share, Basic	19,787,212	18,034,092
Weighted-average common shares used to compute net loss per share, Diluted	19,787,212	18,034,092
Comprehensive Loss:
Net loss	$ (32,069)	$ (28,916)
Other comprehensive loss
Unrealized gain (loss) on marketable securities	4	(7)
Comprehensive loss	$ (32,065)	$ (28,923)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Restricted Stock Units (RSUs) [Member]	Restricted Stock [Member]	Common Stock [Member]	Common Stock [Member] Restricted Stock Units (RSUs) [Member]	Common Stock [Member] Restricted Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Restricted Stock Units (RSUs) [Member]	Additional Paid-in Capital [Member] Restricted Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Convertible Preferred Stock [Member]
Beginning balance (Shares) at Dec. 31, 2020				17,995,354
Beginning balance at Dec. 31, 2020	$ 49,683			$ 2			$ 165,486			$ (115,808)	$ 3
Balance at the beginning before retroactive application of recapitalization (in Shares) at Dec. 31, 2020												145,130,628
Balance at the beginning before retroactive application of recapitalization at Dec. 31, 2020												$ 158,707
Balance at the beginning before retroactive application of recapitalization (in Shares) at Dec. 31, 2020				30,521,693
Balance at the beginning before retroactive application of recapitalization at Dec. 31, 2020	(109,024)			$ 31			6,750			(115,808)	3
Retroactive application of recapitalization (in Shares)												(145,130,628)
Retroactive application of recapitalization												$ (158,707)
Retroactive application of recapitalization, value	158,707			$ (29)			158,736
Recapitalization Common Stock, Shares				(12,526,339)
Exercise of stock options (Shares)				56,238
Exercise of stock options	98						98
Stock-based compensation	1,143						1,143
Net loss	(28,916)									(28,916)
Other comprehensive gain (loss)	(7)										(7)
Ending balance (Shares) at Dec. 31, 2021												0
Ending balance at Dec. 31, 2021												$ 0
Ending balance (Shares) at Dec. 31, 2021				18,051,592
Ending balance at Dec. 31, 2021	22,001			$ 2			166,727			(144,724)	(4)
Balance at the beginning before retroactive application of recapitalization (in Shares) at Dec. 31, 2021												145,130,628
Balance at the beginning before retroactive application of recapitalization at Dec. 31, 2021												$ 158,707
Balance at the beginning before retroactive application of recapitalization (in Shares) at Dec. 31, 2021				31,070,665
Balance at the beginning before retroactive application of recapitalization at Dec. 31, 2021	(136,706)			$ 31			7,991			(144,724)	(4)
Retroactive application of recapitalization (in Shares)												(145,130,628)
Retroactive application of recapitalization												$ (158,707)
Retroactive application of recapitalization, value	158,707			$ (29)			158,736
Recapitalization Common Stock, Shares				(13,019,073)
Merger and private offering, net, Shares				3,143,464
Merger and private offering	8,468						8,468
Common stock issuance to Lincoln Park	$ 5,410						5,410
Common stock of BCAC				1,266,684
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures					80,668	23,518
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		$ 326	$ 242					$ 326	$ 242
Exercise of stock options (Shares)	75,550			75,550
Exercise of stock options	$ 110						110
Exercise of common stock warrant (in shares)				4,539
Reclassification of preferred stock warrant	2						2
Stock-based compensation	1,883						1,883
Net loss	(32,069)									(32,069)
Other comprehensive gain (loss)	4										4
Ending balance (Shares) at Dec. 31, 2022												0
Ending balance at Dec. 31, 2022												$ 0
Ending balance (Shares) at Dec. 31, 2022				22,646,015
Ending balance at Dec. 31, 2022	$ 6,377			$ 2			$ 183,168			$ (176,793)	$ 0

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Transaction costs amount related to business combination and private offering financing	$ 9,232

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (32,069)	$ (28,916)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	110	105
Stock-based compensation	1,883	1,143
Expense from vesting of restricted stock Units	326	0
Expense from vesting of restricted stock awards	242	0
Accretion of discount and amortization of premiums on marketable securities	(31)	204
Amortization of deferred financing costs	740	0
Change in fair value of derivative warrant liabilities	(78)	0
Change in fair value of liability for common stock to be issued	(205)	0
Non-cash lease expense	401	522
Other	0	6
Changes in current assets and liabilities:
Prepaid expenses and other current assets	(759)	(352)
Other assets	(70)	(168)
Accounts payable	317	841
Accrued expenses	(3,127)	1,521
Deferred revenue	2,049	1,723
Lease liabilities	(422)	(531)
Net cash used in operating activities	(30,693)	(23,902)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(57)	(54)
Purchases of marketable securities	(18,945)	(20,179)
Sales of marketable securities	29,957	42,257
Net cash provided by investing activities	10,955	22,024
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from merger and private offering	18,094	0
Payments of deferred transaction costs	(9,221)	(61)
Proceeds from common stock issuance to Lincoln Park	2,500	0
Payments of Financing Costs	(386)	0
Proceeds from exercise of stock options	110	98
Net cash provided by financing activities	11,097	37
Net decrease in cash and cash equivalents	(8,641)	(1,841)
Cash and cash equivalents, beginning of period	23,443	25,284
Cash and cash equivalents, end of period	14,802	23,443
Supplemental disclosure of non-cash investing and financing activities:
Purchase of equipment included in accounts payable	0	43
Transaction costs in accounts payable and accrued liabilities at period end	0	364
Financing costs in accounts payable and other accrued liabilities	261	0
Common stock issuance to Lincoln Park for commitment fees	2,910	0
Reclassification of warrant	$ 2	$ 0

Organization and Description of

Organization and Description of the Business	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	1. Organization and Description of the Business Description of Business Apexigen, Inc. (“Apexigen” or “we”) is a clinical-stage biopharmaceutical company focused on discovering and developing antibody therapeutics for oncology, with an emphasis on new immuno-oncology agents designed to harness the patient’s immune system to combat and eradicate cancer. Our lead product candidates are sotigalimab (“sotiga” or “APX005M”), which is a CD40 agonist antibody, and APX601, which is a TNFR2 antagonist antibody. We also have out-license out-licensed On March 17, 2022, Brookline Capital Acquisition Corp. (“BCAC”) and Apexigen America, Inc., which was then known as Apexigen, Inc. (“Legacy Apexigen”) entered into a business combination agreement (“Business Combination Agreement”) pursuant to which BCAC and Legacy Apexigen agreed to combine, with the former equityholders of both entities holding equity in the combined public company listed on the Nasdaq Stock Exchange (“Nasdaq”) and with Legacy Apexigen’s existing equityholders owning a majority of the equity in the combined public company. Existing Legacy Apexigen equityholders received equity in the combined public company in the form of common shares, stock options and warrants. Under the Business Combination Agreement, the transaction valued Legacy million on a fully diluted basis, net of exercise proceeds for Legacy Apexigen’s pre-closing The transactions contemplated under the Business Combination Agreement (the “Business Combination”) closed on July 29, 2022 (“Closing” or the “Closing Date”). As a result, the combined public company received approximately non-convertible million in transaction expenses relating to the merger, consisting of banking, legal, and other professional fees. The PIPE investors received an aggregate one-half Legacy Apexigen was incorporated in Delaware in 2010, the year Legacy Apexigen was spun-out spun-out Liquidity and Capital Resources As of December 31, 2022, we had approximately $16.8 million of cash, cash equivalents, and short-term investments and expect to fund our operations into the third quarter of 2023 based on current operations assuming no additional proceeds from our equity line with Lincoln Park or any other potential financing or business development transactions. We have incurred substantial losses and negative cash flows from operations since inception and had an accumulated deficit of We may seek additional funds through the sale and issuance of shares of our common stock in private or public offerings, other equity or debt financings, collaborations, or partnerships with third parties, or other transactions to monetize assets, including our right to receive milestone payments and royalties under our out-license To the extent that we raise additional capital through strategic alliances, licensing arrangements or other monetization transactions with third parties, we may have to relinquish valuable rights to our product candidates, future revenue streams or research programs or grant licenses on terms that may not be favorable to us. If we raise additional capital through public or private equity offerings, the ownership interest of the then-existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we may be subject to covenants limiting or restricting the ability to take specific actions, such as incurring additional debt, making capital expenditures, or declaring dividends.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation We prepare our consolidated financial statements and accompanying notes in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Principles of Consolidation The consolidated financial statements include the accounts of Apexigen and its wholly owned subsidiary. All significant inter-company transactions and balances have been eliminated in consolidation. Emerging Growth Company We are an “emerging growth company,” as defined in Section 2(a) of the Securities Act, as modified by the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”), and may take advantage of certain exemptions from various reporting requirements that are applicable to public companies that are not emerging growth companies. Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934 (the “Exchange Act”)) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts expensed during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to accruals for research and development costs, stock-based compensation, uncertain tax positions and fair values of common stock. We adjust such estimates and assumptions when facts and circumstances dictate. Changes in those estimates resulting from continuing changes in the economic environment will be reflected in the consolidated financial statements in future periods. As future events and their effects cannot be determined with precision, actual results could materially differ from those estimates and assumptions. Segment Reporting We have one operating segment, which is the business of researching, developing and commercializing antibody therapeutics for oncology. Our chief operating decision maker, Chief Executive Officer, manages our operations on an aggregated basis for the purposes of allocating resources and evaluating financial performance. Cash and Cash Equivalents We consider all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and corporate debt securities. The carrying amount of cash equivalents approximates their fair value. Short-Term Investments Short-term investments consist of debt securities with original maturities of greater than three months from the date of purchase but less than one year from the balance sheet date. Such investments are considered available-for-sale Fair Value Measurements We apply fair value accounting to all financial assets and liabilities and non-financial Concentrations of Credit and Other Risks Financial instruments that potentially subject us to a concentration of credit risk consist primarily of cash and cash equivalents and short-term investments. We hold our bank deposits at accredited financial institutions and these deposits may at times exceed insured limits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and cash equivalents to the extent of the amounts held in excess of federally insured limits. We limit our credit risk associated with cash and cash equivalents by placing them with financial institutions we believe are of high quality. We have not experienced any losses on our deposits of cash. Our investment policy limits investments to certain types of securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. As of December 31, 2022 and 2021, we had no off-balance We are subject to a number of risks similar to other early-stage biopharmaceutical companies, including the need to obtain adequate additional funding, possible failure of clinical trials, the need to obtain marketing approval for our product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of our products, and protection of proprietary technology. If we do not successfully develop, obtain regulatory approval for, commercialize or partner our product candidates, we will be unable to generate revenue from product sales or achieve profitability. Property and Equipment, Net Property and equipment are stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. The estimated useful life of laboratory equipment, furniture and fixtures, office equipment, and software ranges from tw Impairment of Long-Lived Assets Our long-lived assets are comprised principally of our property and equipment and right-of-use Deferred Transaction Costs Deferred transaction costs consist of direct legal, accounting, filing and other fees and costs directly attributable to the merger (see Note 3). We capitalized deferred transaction costs prior to the close of the Business Combination and included in prepaid expenses and other current assets. We reclassified the deferred transaction costs related to the Business Combination to additional paid-in million on the consolidated balance sheet as of December 31, 2021. Upon the close of the Business Combination, we reclassified transaction costs million to additional paid-in million in 2022 (see Note 3). Deferred Financing Costs Deferred financing costs consist of direct costs and commitment fees directly attributable to the commencement of the equity line of credit from Lincoln Park Capital Fund, LLC upon closing of the Business Combination (see Note 7). We capitalize deferred financing costs and amortize these costs over 24 months of the equity line of credit. As of December 31, 2022, deferred financing costs totaled $ million. Amortization expense for deferred financing costs was $ million for the year ended December , . Revenue Recognition Under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers We may also earn contingent fees, including milestone payments based on counterparty performance and royalties on sales, from collaborations and other out-license ® respectively. Lease We determine if an arrangement is a lease at inception and if so, we determine whether the lease qualifies as an operating or a finance lease. We include operating lease in operating lease right-of-use We lease our facility under a non-cancelable non-cancellable Research and Development Expenses Research and development costs are expensed as incurred. Research and development expenses are primarily for the development of sotiga, our lead product candidate, as well as APX601 and other preclinical product candidates. Research and development costs consist primarily of external costs related to clinical development, contract manufacturing, preclinical development and discovery as well as personnel costs and allocated overhead, such as rent, equipment, depreciation, and utilities. Personnel costs consist of salaries, employee benefits and stock-based compensation. We estimate external research and development expenses based on the services performed, pursuant to contracts with commercial and academic institutions that conduct and manage research and development services on our behalf. We record the costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued liabilities in the consolidated balance sheets. These costs are a component of our research and development expenses. We accrue these costs based on factors such as the number of patient visits, the number of active patients, the number of patients enrolled, estimates of the work completed and other measures in accordance with agreements established with our third-party service providers under the service agreements. As actual costs become known, we adjust our accrued liabilities. We have not experienced any significant differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed may vary from our estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in significant changes to our accruals could significantly affect our results of operations. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and then expensed as the related goods are delivered or the services are performed. We evaluate such payments for current or long-term classification based on when they will be realized. Common Stock Warrant We record at fair value freestanding puttable or redeemable warrants, or warrants which are not considered to be indexed to our stock and include this amount in accrued expenses on our consolidated balance sheets as of December 31, 2021. On the closing date of the merger (see Note 3), the preferred stock warrant that was outstanding immediately before closing became a common stock warrant. We adjusted the carrying value of such warrant to its estimated fair value at the closing date of the merger based upon the value of our common stock warrant and reclassified estimated fair value at the closing date of the merger from accrued expenses to additional paid-in Public Warrants The public warrants, issued in connection with the BCAC’s initial public offering prior to the merger and the PIPE transaction completed in July 2022, are classified as equity (see Note 8). Derivative Warrant Liabilities We account for the private placement warrants (see Note 8) issued in connection with the initial public offering as derivative warrant liabilities in accordance with FASB ASC Topic 815, “ Derivative and Hedging re-measurement Stock-Based Compensation We measure all equity awards granted to employees and non-employees We use the Black-Scholes option-pricing model to estimate the fair value of equity awards and recognize expense using the straight-line attribution approach. The Black-Scholes option-pricing model requires assumptions to be made related to the expected term of the awards, expected stock priced volatility, risk-free rate for a period that approximates the expected term of the awards and the expected dividend yield. Income Taxes We account for income taxes under the asset and liability method. Under this method, we recognize deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. We measure deferred tax assets and liabilities using enacted tax rates applied to taxable income in the years in which we expect to realize those temporary differences. We recognize the effect on deferred tax assets and liabilities of a change in tax rates as income or loss in the period that includes the enactment date. We establish a valuation allowance, when necessary, to reduce deferred tax assets to the amount we expect to realize. We recognize the financial statement effects of uncertain tax positions when it is more-likely-than-not, Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss, primarily unrealized gains or losses on our marketable securities. Net Loss per Share We calculate basic net loss per share by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is the same as basic net loss per share for each period presented, since the effects of potentially dilutive securities are antidilutive given our net loss. Major Vendor We had a major vendor that accounted for approximately 39.9% and 23.2% of the research and development expenses for the years ended December 31, 2022 and 2021, respectively. The same vendor also accounted for approximately 24.8% and 28.1% of the total accounts payable and accrued liabilities as of December 31, 2022 and 2021, respectively. Moreover, there is another vendor that accounted for approximately 33.6% and 27.7% of the total accounts payable and accrued liabilities as of December 31, 2022 and 2021, respectively, but we did not incur any expenses with this vendor during the years ended December 31, 2022 and 2021. We had an additional vendor in 2021 that accounted for approximately 12.4% of the research and development expenses for the year ended December 31, 2021. The same vendor did not account for a major portion of accounts payable and accrued liabilities as of December 31, 2021. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued Accounting Standards Update (“ASU”) No. 2020-06, 470-20) 815-40), In October 2020, the FASB issued ASU No. 2020-10, Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments off-balance held-to-maturity available-for-sale

Merger

Merger	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Merger	3. Merger On , Legacy Apexigen and BCAC consummated the merger contemplated by the BCA, with Legacy Apexigen surviving the merger or business combination as a wholly-owned subsidiary of BCAC. As part of the consummation of the merger, BCAC changed its name to Apexigen, Inc. and Legacy Apexigen changed its name to Apexigen America, Inc. Upon the closing of the merger, we amended and restated our certificate of incorporation to, among other things, increase the total number of authorized shares of capital stock Immediately prior to the closing of the merger, each issued and outstanding share of Legacy Apexigen’s convertible preferred stock, was converted into shares of common stock based on a one-to-one Upon the consummation of the merger, each share of Legacy Apexigen common stock issued and outstanding was canceled and converted into the right to Outstanding stock options, whether vested or unvested, to purchase shares of Legacy Apexigen’s common stock granted under the 2010 and 2020 Plan (“Legacy Options”) (see Note 9) converted into stock options for shares of our common stock upon the same terms and conditions that were in effect with respect to such stock options immediately prior to the merger, after giving effect to the Exchange Ratio. Outstanding warrants to purchase shares of common stock remained outstanding after the closing of the merger. The warrants became exercisable 30 days after the completion of the merger, subject to other conditions, including with respect to the effectiveness of a registration statement covering the shares of common stock underlying such warrants, and will expire five years after the completion of the Business Combination or earlier upon redemption or liquidation (see Note 2 and Note 8) . In connection with the merger, certain stockholders exercised their right to redeem certain of their outstanding shares for cash, resulting in the redemption o transaction merger paid-in The merger is accounted for as a reverse recapitalization in accordance with U.S. GAAP. Under this method of accounting, BCAC was treated as the “acquired” company for financial reporting purposes. Accordingly, for accounting purposes, the Business Combination was treated as the equivalent of Legacy Apexigen issuing stock for the net assets of BCAC, accompanied by a recapitalization. The net assets of BCAC are stated at historical cost, with no goodwill or intangible assets recorded. Prior to the merger, Legacy Apexigen and BCAC filed separate standalone federal, state, and local income tax returns. As a result of the merger, we will file a consolidated income tax return. Although, for legal purposes, BCAC acquired Legacy Apexigen, and the merger represents a reverse acquisition for federal income tax purposes. BCAC will be the parent of the consolidated group with Legacy Apexigen as a subsidiary, but in the year of the closing of the merger, Legacy Apexigen will file a full-year tax return with BCAC joining in the return the day after the closing date of the merger. Upon closing of the merger million. The following table reconciles the elements of the merger to the consolidated statements of cash flows and the consolidated statement of changes in stockholders’ equity (in thousands): Cash—BCAC’s trust (net of redemption) $ 4,435 Cash—Private offering 14,520 Less: BCAC’s Extension and Working Capital Notes repayment in 2022 (861 ) Proceeds from merger and private offering for the year ended December 31, 2022 18,094 Less: transaction costs paid in 2022 (9,221 ) Net proceeds from merger and private offering for the year ended December 31, 2022 8,873 Less: transaction costs paid in 2021 (11 ) Plus: net assets of BCAC (394 ) Merger and private offering for the years ended December 31, 2022 $ 8,468 The number of shares of common stock issued immediately following the Closing Date was: Common stock, outstanding prior to merger 5,061,592 Less: redemption of BCAC shares (4,618,607 ) Common stock of BCAC 442,985 BCAC Sponsor shares 1,190,979 BCAC Representative shares 57,500 Shares issued in private offering 1,452,000 Business combination and private offering shares 3,143,464 Legacy Apexigen shares 18,147,032 Total shares of common stock immediately after merger 21,290,496 Exercise of Legacy Apexigen common stock warrant 4,539 Shares issued to Lincoln Park (Note 7) 150,000 Total shares of common stock on July 29, 2022 21,445,035 The number of Legacy Apexigen’s shares was determined as follows: Legacy Apexigen Legacy Apexigen Balance as of December 31, 2020 30,521,693 3,126,980 Recapitalization applied to Convertible Preferred Stock outstanding at 145,130,628 14,868,374 Exercise of common stock options—2021 548,972 56,238 Exercise of common stock options—2022 (pre-Closing) 702,074 71,922 Exercise of common stock restricted awards—2022 (pre-Closing) 229,556 23,518 Total Legacy Apexigen shares as of July 29, 2022 177,132,923 18,147,032

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurement	4. Fair Value Measurement We record financial assets and liabilities at fair value. The accounting guidance for fair value provides a framework for measuring fair value, clarifies the definition of fair value and expands disclosures about fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. We categorize assets and liabilities recorded at fair value in the consolidated financial statements based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels are directly related to the amount of subjectivity with the inputs to the valuation of these assets or liabilities as follows: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 2 Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices for identical or similar assets or liabilities 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 assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2022, our cash equivalents consisted of money market funds with less than a three-month maturity. Our short-term investments consisted of U.S. treasury securities, which we recorded as available-for-sale available-for-sale In certain cases where there is limited activity or less transparency around the inputs to valuation, we classify securities as Level 3. Level 3 liabilities consist of derivative warrant liabilities and preferred stock warrant liability. The following tables set forth the financial instruments that we measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 14,671 $ — $ — $ 14,671 U.S. treasury securities 1,997 — — 1,997 Total $ 16,668 $ — $ — $ 16,668 Financial liability: Derivative warrant liabilities $ — $ — $ 11 $ 11 Total $ — $ — $ 11 $ 11 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 18,526 $ — $ — $ 18,526 Commercial paper — 5,498 — 5,498 Corporate debt securities — 4,512 — 4,512 Government debt securities — 1,503 — 1,503 Asset backed securities — 1,404 — 1,404 Total $ 18,526 $ 12,917 $ — $ 31,443 Financial liability: Preferred stock warrant liability $ — $ — $ 2 $ 2 Total $ — $ — $ 2 $ 2 In 2021, the financial liability measured at fair value on a recurring basis is the derivative warrant liabilities and preferred stock warrant liability, a level 3 instrument. The derivative warrant liabilities had a fair value of $11,000 as of December 31, 2022. We estimate the fair value of the derivative warrant liabilities using a Black-Scholes option-pricing model, which assumptions are related to expected stock-price volatility, expected life, risk-free interest rate and dividend yield. We estimate the volatility of our common stock warrants based on historical volatility of select peer company’s common stock that matches the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon The preferred stock warrant liability had a fair value of $2,000 as of December 31, 2021. We option-pricing model, which requires inputs such as the expected volatility based on comparable public companies, the estimated fair value of the preferred stock, and the estimated time to liquidity. On the Closing of the Business Combination, the preferred stock warrant that was outstanding immediately before the Closing became a common stock warrant. We adjusted the carrying value of such warrant to its estimated fair value at the Closing based upon the value of our common stock warrant and reclassified from accrued expenses to additional paid-in The following tables summarize the estimated fair value of our marketable securities and the gross unrealized holding gains and losses (in thousands): December 31, 2022 Unrealized Amortized Gains Losses Estimated Cash and cash equivalents: Cash $ 131 $ — $ — $ 131 Money market funds 14,671 — — 14,671 Total cash and cash equivalents $ 14,802 $ — $ — $ 14,802 Marketable securities: U.S. treasury securities $ 1,997 $ — $ — $ 1,997 Total marketable securities $ 1,997 $ — $ — $ 1,997 December 31, 2021 Unrealized Amortized Gains Losses Estimated Cash and cash equivalents: Cash $ 4,917 $ — $ — $ 4,917 Money market funds 18,526 — — 18,526 Total cash and cash equivalents $ 23,443 $ — $ — $ 23,443 Marketable securities: Commercial paper $ 5,498 $ — $ — $ 5,498 Corporate debt securities 4,515 — (3 ) 4,512 Government debt securities 1,503 — — 1,503 Asset backed securities 1,405 — (1 ) 1,404 Total marketable securities $ 12,921 $ — $ (4 ) $ 12,917

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2022
Balance Sheet Components [Abstract]
Balance Sheet Components	5. Balance Sheet Components Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Prepaid clinical development expenses $ 1,128 $ 776 Prepaid insurance expenses 970 56 Deferred financing costs 261 467 Other prepaid expenses and current assets 259 382 Total prepaid expenses and other current assets 2,618 1,681 Property and Equipment, Net Property and equipment, net consists of the following (in thousands): December 31, 2022 2021 Laboratory equipment $ 909 $ 943 Furniture and fixtures 28 28 Office equipment 25 25 Software 12 12 Total property and equipment 974 1,008 Less: accumulated depreciation (824 ) (763 ) Total property and equipment, net $ 150 $ 245 Depreciation expense for property and equipment was $110,000 and $105,000 for the years ended December 31, 2022 and 2021, respectively. Accrued Liabilities Accrued liabilities consist of the following (in thousands): December 31, 2022 2021 Accrued clinical trial and manufacturing costs $ 4,340 $ 6,472 Accrued personnel costs 497 1,172 Other accrued liabilities 522 844 Total accrued liabilities $ 5,359 $ 8,488

Lease

Lease	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Lease	6. Lease We lease our principal facility under a non-cancelable right-of-use Future minimum lease payments as of December 31, 2022, are as follows (in thousands): Operating Year ending December 31, 2023 $ 106 Total undiscounted future lease payments 106 Less: imputed interest — Total lease liabilities $ 106

Stockholder's Equity

Stockholder's Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	7. Stockholder’s Equity Preferred Stock As discussed in Note 3, Business Combination Prior to the Business Combination, Legacy Apexigen had shares of $0.001 par value Series A-1, A-2, BCA. July 29, 2022 (Closing Date) Convertible Preferred Stock Preferred Exchange Common Series A-1 (pre-combination) 39,196,116 0.102448 4,015,564 Series A-2 (pre-combination) 12,625,343 0.102448 1,293,442 Series B (pre-combination) 14,218,546 0.102448 1,456,662 Series C (pre-combination) 79,090,623 0.102448 8,102,706 Total 145,130,628 14,868,374 As of December , , we are authorized to issue shares of preferred stock with a par value of $ per share. The board of directors (the “Board”) has the authority to issue preferred stock and to determine the rights, privileges, preferences, restrictions, and voting rights of those shares. As of December , , we had shares of preferred stock outstanding. Common Stock The holders of common stock are entitled to one vote per share on all matters to be voted on by the stockholders of Apexigen. Subject to the preferences that may be applicable to any outstanding shares of the convertible preferred stock, the holders of the common stock are entitled to receive ratably such dividends, if any, as the Board may declare. The Board has declared no dividends to date. At December 31, 2022, we had reserved the following shares of common stock for the following purposes: Equity awards issued and outstanding 4,839,554 Equity awards available for future grants 1,065,423 Shares available for Employee Stock Purchase Plan 257,341 Common stock warrants 3,728,821 Total common stock reserved for issuance 9,891,139 Lincoln Park In conjunction with the Business Combination (see Note 1), we entered into a purchase agreement (the “Lincoln Park Purchase Agreement”) and a registration rights agreement (“RRA”) with Lincoln Park in March 2022, which provides that we may sell to Lincoln million of shares (the “Purchase Shares”) of our common stock. The aggregate number of shares that we can sell to Lincoln Park under the Lincoln Park Purchase Agreement may not exceed of the outstanding common stock, subject to certain exceptions set forth in the Lincoln Park Purchase Agreement. On the date of Closing, we issued 150,000 shares of common stock to Lincoln Park as an initial fee for its commitment to purchase shares of our common stock under the Lincoln Park Purchase Agreement. On the date that re-measurement Subject to the terms of the Lincoln Park Purchase Agreement, we have the right, in our sole discretion, to present Lincoln Park with a purchase notice (a “Regular Purchase Notice”), provided that the closing stock price of the common stock on the Nasdaq is not per share. Each Regular Purchase Notice would direct Lincoln Park to purchase million. The Lincoln Park Purchase Agreement provides for a purchase price per Purchase Shares for each Regular Purchase (the “Purchase Price”) equal to the lesser of (i) the lowest sale price of the common stock on the Nasdaq on the purchase date of such shares; and (ii) the average of the three lowest closing sale prices for the common stock traded on the Nasdaq during ten shares. In addition, on any date on which we submit a Regular Purchase Notice for the maximum amount allowed for such a Regular Purchase to Lincoln Park, we also have the right, in our sole discretion, to present Lincoln Park with an accelerated purchase notice (an “Accelerated Purchase Notice”), directing Lincoln Park to purchase an amount of Purchase Shares (an “Accelerated Purchase”), which number of Purchase Shares will not exceed the lesser of (i) 300% of the number of shares purchased pursuant to such Regular Purchase Notice and (ii) 30% of the total volume of shares of the common stock traded on the Nasdaq during the Accelerated Purchase period. The purchase price per Purchase Share for each such Accelerated Purchase will be equal to the lesser of 95% of (i) the volume-weighted average price of the common stock on the Nasdaq during the applicable Accelerated Purchase period on the applicable Accelerated Purchase date; and (ii) the closing sale price of the common stock on the Nasdaq on the applicable Accelerated Purchase date. Lincoln Park has no obligation to purchase shares under the Lincoln Park Purchase Agreement unless we comply with the terms of the RRA. In , we received aggregate proceeds of $ million from Regular Purchases of shares of common stock under the Lincoln Park Purchase Agreement.

Public and Private Warrants

Public and Private Warrants	12 Months Ended
	Dec. 31, 2022
Warrants [Abstract]
Public and Private Warrants	8. Public and Private Warrants Prior to the merger, BCAC issued 2,875,000 shares of public warrants and 123,500 shares of private warrants in connection with the BCAC’s initial public offering. In connection with the PIPE transaction closed on July 29, 2022 (Note 1), we issued 726,000 shares of public warrants. share. Each of these warrants became exercisable on August 28, 2022, which was 30 days after the Closing of the merger ( see Note 3 ), and will expire on the fifth anniversary of the Business Combination, or earlier upon redemption or liquidation. We may call the public warrants for redemption: • in whole or in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption; and • if, and only if, the last reported closing price of the ordinary shares equals or exceeds $18.00 per share for any 20 trading days within a 30-trading If we call the public warrants for redemption, management will have the option to require all holders that wish to exercise the public warrants to do so on a “cashless basis,” as described in the warrant agreement. The private placement warrants are identical to the public warrants, except that none of the private placement warrants will be redeemable so long as they are held by the initial purchasers or any of their permitted transferees. The exercise price and number of shares of common stock issuable upon exercise of the warrants may be adjusted in certain circumstances including in the event of a share dividend, recapitalization, reorganization, merger, or consolidation. However, the warrants will not be adjusted for issuance of common stock at a price below its exercise price.

Equity Plans and Related Equity

Equity Plans and Related Equity Activities	12 Months Ended
	Dec. 31, 2022
Disclosure Text Block Supplement [Abstract]
Equity plans and related equity activities	9. Equity Plans and Related Equity Activities Equity Incentive Plans In December 2010, we adopted the 2010 Stock Incentive Plan and 2010 Equity Incentive Plan, which expired in 2020. In August 2020, we adopted the 2020 Equity Incentive Plan. Upon the close of the merger (see Note 3), we adopted the 2022 Equity Incentive Plan (the 2022 Plan, the 2020 Equity Incentive Plan, the 2010 Stock Incentive Plan and the 2010 Equity Incentive Plan, collectively, the “Plans”). No further grants will be made under the 2020 Equity Incentive Plan. The 2022 Equity Incentive Plan provides for the grant of incentive stock options, non-statutory Initially, the maximum number of shares of common stock that we may issue under the Equity Incentive Plan is shares plus any shares that may be added to the Plan’s reserve if awards from the Equity Incentive Plan or Equity Incentive Plan expire, are canceled or otherwise terminate, up to a maximum of shares added from such expirations, cancellations, and terminations. As of December , , Apexigen had reserved shares of common stock for the issuance of incentive and non-statutory stock options to purchase common stock, stock awards, and restricted stock awards to employees, directors, and consultants under the Plans. The number of shares of common stock reserved for issuance under the Equity Incentive Plan will automatically increase on January of each calendar year, starting on January , through January , , in an amount equal to the lesser of % of the total number of shares of common stock outstanding on the last day of the calendar month before the date of each automatic increase, shares, or such number of shares determined by the administrator of the Plan. The Board determines the period over which options become exercisable and options generally vest over a period. option will become exercisable after the expiration of years from the date of grant. non-statutory In February 2021, we entered into a consulting agreement with a Board member and granted an option (the “Stock Option”) to acquire 20,489 shares of common stock. The Stock Option vests upon the achievement of certain performance milestones and has a ten-y ear Stock Compensation options were vested during the year ended December 31, 2021, and we recognized of stock-based compensation expense in the year ended December 31, 2021. No other performance milestone was achieved as of December 31, 2022. The unrecognized stock-based compensation expense for this option as of December 31, 2022 is approximately $ . In July 2022, we granted restricted stock awards for 23,518 shares of common stock to two former Board members of Legacy Apexigen. The weighted average grant date fair value per restricted stock awards was $10.30 and the fair value of these restricted stock awards is approximately $0.2 million. The restricted stock awards are fully vested upon grant date and $0.2 million was recorded as general and administrative expense during the year ended December 31, 2022. In September 2022, we granted options to purchase 700,000 shares of common stock to our non-executive In October 2022, we granted restricted stock units for 243,618 shares of common stock to various employees. The weighted average grant date fair value per restricted stock units was $2.46 and the fair value of these restricted stock units is approximately $0.6 million. We amortize the fair value of the units on a straight-line basis over its vesting periods. The restricted stock units are 50% vested in December 2022 and 50% vested in June 2023. $0.3 million was recorded as operating expense during the year ended December 31, 2022. Tax related withholdings of restricted stock units was approximately $43,000 during 2022, which equivalent to 42,415 shares of restricted stock units forfeited to cover the tax related withholdings. Equity Stock Purchase Plan In August 2022, we adopted the Apexigen, Inc. 2022 Employee Stock Purchase Plan (the “ESPP”). The ESPP provides eligible employees with a means of acquiring shares of our common stock at a discounted purchase price using their own accumulated payroll deductions. Under the terms of the ESPP, eligible employees can elect to have up to 15% of their eligible compensation, up to a maximum of $25,000 per year, withheld to purchase shares of common stock for a purchase price equal to 85% of the lower of the fair market value per share of common stock on (i) the commencement date of the 24-month The ESPP authorizes the issuance of 257,341 shares of common stock under purchase rights granted to our eligible employees or to eligible employees of any of our designated affiliates. The number of shares of common stock reserved for issuance will automatically increase on January 1 of each calendar year, beginning on January 1, 2023 through January 1, 2032, by the lesser of (1) 1.0% of the total number of shares of common stock outstanding on the last day of the calendar month before the date of the automatic increase, and (2) 536,126 shares; provided that before the date of any such increase, our Board may determine that such increase will be less than the amount set forth in clauses (1) and (2). The initial offering period commenced in November 2022. As of December 31, 2022, no shares of common stock were purchased under the ESPP. There was approximately $39,000 of stock-based compensation expense related to the ESPP recognized during the year ended December 31, 2022. As of December 31, 2022, there was $0.3 million of unrecognized stock-based compensation cost related to ESPP, which we expect to recognize over a weighted average period of 1.9 years. As of December 31, 2022, 257,341 shares were available under the ESPP for future issuance. Stock-Based Compensation Stock-based compensation is included in the consolidated statements of operations and comprehensive loss in research and development and general and administrative expense depending on the nature of the services provided. The following table illustrates stock-based compensation expense related to equity awards granted under the Plans and ESPP recognized for years ended December 31, 2022 and 2021 (in thousands): Year Ended 2022 2021 Research and development $ 583 $ 292 General and administrative 1,300 851 Total stock-based compensation $ 1,883 $ 1,143 As of December 31, 2022, there was $4.2 million of unrecognized stock-based compensation cost related to equity awards granted to employees and others under the Plans and ESPP, which we expect to recognize over a weighted average period of 2.6 years. Summary of Assumptions for Stock Options and ESPP In determining the fair value of the stock options granted and ESPP, we used the Black-Scholes option-pricing model and the following assumptions: Year Ended 2022 2021 Option Grants: Expected term (years) 5.00 - 6.06 5.62 - 10.00 Expected volatility 71% - 86 % 88 % Risk-free interest rate 0.53% - 4.07 % 0.60% - 1.20 % Expected dividend 0 % 0 % ESPP: Expected term (years) 0.50 - 2.00 Expected volatility 83% - 93 % Risk-free interest rate 4.37% - 4.60 % Expected dividend 0 % The assumptions used to determine the fair value of the equity awards are as follows: • Expected volatility: Because our stock is recently traded in an active market, we calculate volatility by using the historical volatilities of the common stock of comparable publicly traded companies. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the equity awards. • Risk-free interest rate: we base the risk-free interest rate from the U.S. Treasury yield curve in effect at the measurement date with maturities approximately equal to the expected term. • Expected term: we determine the expected life of awards granted using the “simplified” method. Under this approach, we presume the expected term to be the mid-point • Expected dividend yield: we have never paid cash dividends on its common stock and do not have plans to pay cash dividends in the future. Therefore, we use an expected dividend yield of zero. Equity Plans’ Activities The following table summarizes the activities under the Plans (in thousands, except share and per share amounts): Awards Number of Weighted Weighted Aggregate Outstanding at December 31, 2021 888,435 3,536,715 $ 2.71 Shares authorized added to 2022 Plan 2,573,405 Shares not return ed (913,842 ) Options Granted (2,097,010 ) 2,097,010 $ 3.18 Options Exercised — (75,550 ) $ 1.45 Options Cancelled 839,156 (839,156 ) $ 2.43 Restricted stock awards granted (23,518 ) 23,518 $ — Restricted stock awards vested — (23,518 ) $ — Restricted stock units granted (243,618 ) 243,618 $ — Restricted stock units vested — (80,668 ) $ — Restricted stock units forfeited 42,415 (42,415 ) $ — Outstanding at December 31, 2022 1,065,423 4,839,554 $ 2.91 6.66 $ 82 Vested and exercisable at December 31, 2022 2,685,009 $ 2.75 4.41 $ — Vested and expected to vest at December 31, 2022 4,824,187 $ 2.91 6.65 $ 82 The weighted average grant date fair value of options granted during 2022 and 2021 was $2.30 and $3.39, respectively. The following table summarizes information about our outstanding options as of December 31, 2022 by range of exercise prices and excludes the 120,535 shares of restricted stock units outstanding as of December 31, 2022: Awards Outstanding Awards Exercisable Range of Number of Weighted- Weighted Number of Weighted- Weighted $ 1.27 3,103,997 6.12 $ 2.08 1,692,935 3.09 $ 1.68 $3.03 to $4.79 1,384,481 7.55 $ 4.38 820,036 6.72 $ 4.13 $6.54 to $7.62 230,541 6.83 $ 6.84 172,038 6.40 $ 6.69 4,719,019 6.58 $ 2.99 2,685,009 4.41 $ 2.75

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Indemnification As permitted under Delaware law and in accordance with our bylaws, we have agreed to indemnify our officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at our request in such capacity. The term of the indemnification period is equal to the officer’s or director’s lifetime. The maximum amount of potential future indemnification is unlimited. However, we currently hold director and officer liability insurance, which limits our exposure and may enable us to recover a portion of any future amounts paid. We believe that the fair value of these indemnification obligations is minimal. Accordingly, we have not recognized any liabilities relating to these obligations for any period presented. We have certain agreements with service providers and other parties with which we do business that contain indemnification provisions pursuant to which we have agreed to indemnify the party against certain types of third-party claims. It is not possible to determine the maximum potential amount under these indemnification agreements due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. Since these agreements were effective after December 31, 2022, there were no payments made by us under these agreements as of December 31, 2022. As of December 31, 2022, there was not a reasonable possibility that we had incurred a material loss with respect to indemnification of such parties. We had not recorded any liability for costs related to indemnification through December 31, 2022. Clinical Collaborations We have entered into a number of collaboration arrangements for the clinical development of sotigalimab with companies and academic and non-profit Upon achievement of certain regulatory and clinical milestones related to the development of sotigalimab in pancreatic cancer, we will be obligated to pay an aggregate of million in cash and shares of common stock. Because we are not currently advancing the development of sotiga in pancreatic cancer, none of these milestones were probable as of December 31, 2022, and no amounts have been recognized. Other No liabilities for loss contingencies arising from claims, assessments, litigation, fines, and penalties and other sources are recorded as it is not probable that a liability has been incurred and the amount cannot be reasonably estimated. Legal costs incurred in connection with loss contingencies are expensed as incurred. We enter into contracts in the normal course of business with contract research organizations for preclinical studies and clinical trials and contract manufacturing organizations for the manufacture of clinical trial materials.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes We recorded no provision for income taxes for the years ended December 31, 2022 and 2021 was zero. We incurred net operating losses for all the periods presented. The effective tax rate of the provision for income taxes differs from the federal statutory rate as follows: Year Ended 2022 2021 Federal statutory income tax rate 21.0 % 21.0 % Permanent differences 0.8 % -0.3 % Other credit 2.3 % 3.2 % Other -0.7 % -0.3 % Change in valuation allowance -23.4 % -23.6 % 0.0 % 0.0 % The components of deferred tax assets and liabilities are as follows (in thousands): Year Ended 2022 2021 Deferred tax assets: Net operating loss carry forwards $ 33,333 $ 27,217 Tax credits 4,702 3,964 Section 174 R&D Capitalization 4,274 — Depreciation and amortization 90 — Stock-based compensation 666 — Other reserves and accruals 1,462 1,334 Gross deferred tax assets 44,527 32,515 Deferred tax liabilities: Depreciation and amortization — (24 ) Right-of-use (21 ) (101 ) Gross deferred tax liabilities (21 ) (125 ) Valuation allowance (44,506 ) (32,390 ) Net deferred tax assets — — Realization of the deferred tax assets depends upon future taxable income. Since the amount and timing of future income are uncertain, the net deferred tax assets as of December 31, 2022 and 2021 have been fully offset by a valuation allowance. The valuation allowance increased by $12.1 million and $6.8 million during the years ended December 31, 2022 and 2021, respectively. As of December 31, 2022, we had federal net operating loss (“NOL”) carryforwards totaling $137.3 million. Of the $137.3 million, $109.0 million related to NOLs generated after December 31, 2017 and are carried forward indefinitely but are subject to an 80% of taxable income limitation, and $28.3 million will begin to expire in 2033. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) permits NOL carryovers and carrybacks to offset 100 % of taxable income for years beginning before 2021. In addition, the CARES Act allows NOLs incurred in 2018, 2019 and 2020 to be carried back to each of the five preceding taxable years. The CARES Act did not have an impact to our NOLs. As of December 31, 2022, the Company had state NOL carryforward of $ million, which will begin to expire in . We also have federal and state research and development tax credits of $ million and $ million, respectively, as of December 31, 2022. The federal research credits will begin to expire in the year 2030, and the state research credits have no expiration date. We qualified for Federal Orphan Drug credit in 2020 and started to claim the credit for tax year 2021. As of December 31, 2022, we have federal Orphan Drug credits of $ million, which will begin to expire in . Our NOL and credit carryforwards may be subject to annual limitations due to ownership change provisions by the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitation may result in the expiration of NOLs and tax credits before utilization. We elected to recognize, if incurred, interest and penalties related to liabilities for uncertain tax positions as a part of income tax expense. We have incurred no such interest and penalties to date. We determine our uncertain tax positions based on whether and how much of a tax benefit taken by us in its tax filings is more likely than not to be sustained upon examination by the relevant income tax authorities. A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in thousands): Year Ended 2022 2021 Gross unrecognized tax benefit at January 1 $ 1,598 $ 1,181 Additions for tax provision taken in the current year 405 417 Gross unrecognized tax benefit at December 31 $ 2,003 $ 1,598 We do not expect the unrecognized tax benefits to change significantly over the next 12 months. We file income tax returns in the U.S. federal jurisdiction and various states jurisdiction. We are subject to examination by the Internal Revenue Service and the st ate jurisdi

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	12. Net Loss Per Share The following outstanding potentially dilutive common stock equivalents have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect: December 31, 2022 2021 Equity awards 4,839,554 3,536,780 Common stock warrants 3,728,821 13,361 Total anti-dilutive securities 8,568,375 3,550,141

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
401(k) Plan	13. 401(k) Plan We have a 401(k) retirement plan that covers all employees. The 401(k) plan provides for voluntary contributions by employees of up to 100% of their eligible compensation, subject to the maximum allowed by law. Apexigen matches employee contributions up to a maximum of 4% of their salary. Apexigen recognized related expense of $177,000 and $139,000 for the years ended December 31, 2022 and 2021, respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events On January 23, 2023, we entered into a Securities Purchase Agreement (the “Purchase Agreement”) with certain institutional and accredited investors (the “Investors”) pursuant to which we issued and sold to the Investors in a private placement (the “Private Placement”) an aggregate of shares of our common stock, par value $ per share (“Common Stock”) and accompanying warrants (the “Warrants”) to purchase an aggregate of additional shares of common stock at a price of $ per share and accompanying Warrant. The exercise price of the Warrants is $ per share. The Warrants are exercisable at any time on or after the date that i s six months following the date of the issuance of the Warrants and will expire five and one-half We also entered into a letter agreement (the “Engagement Agreement”) with the Placement Agent, pursuant to which the Placement Agent agreed to serve as the exclusive placement agent for us in connection with the Private Placement. We agreed to pay the Placement Agent a cash fee equal to 7% of the gross proceeds from the sale of the shares and accompanying Warrants in the Private Placement. The Placement Agent received warrants to purchase up to 99,785 shares of Common Stock (the “Placement Agent Warrants”) on substantially the same terms as the Warrants, except that the Placement Agent Warrants have an exercise price equal to 125% of the price paid by i On January 30, 2023, we received aggregate gross proceeds of $2.8 million before deducting placement agent fees and estimated offering expenses payable by us. We expect the net proceeds from the Private Placement to be used for working capital purposes.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation We prepare our consolidated financial statements and accompanying notes in accordance with accounting principles generally accepted in the United States of America (“GAAP”).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Apexigen and its wholly owned subsidiary. All significant inter-company transactions and balances have been eliminated in consolidation.
Emerging Growth Company	Emerging Growth Company We are an “emerging growth company,” as defined in Section 2(a) of the Securities Act, as modified by the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”), and may take advantage of certain exemptions from various reporting requirements that are applicable to public companies that are not emerging growth companies. Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934 (the “Exchange Act”)) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts expensed during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to accruals for research and development costs, stock-based compensation, uncertain tax positions and fair values of common stock. We adjust such estimates and assumptions when facts and circumstances dictate. Changes in those estimates resulting from continuing changes in the economic environment will be reflected in the consolidated financial statements in future periods. As future events and their effects cannot be determined with precision, actual results could materially differ from those estimates and assumptions.
Segment Reporting	Segment Reporting We have one operating segment, which is the business of researching, developing and commercializing antibody therapeutics for oncology. Our chief operating decision maker, Chief Executive Officer, manages our operations on an aggregated basis for the purposes of allocating resources and evaluating financial performance.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and corporate debt securities. The carrying amount of cash equivalents approximates their fair value.
Short-Term Investments	Short-Term Investments Short-term investments consist of debt securities with original maturities of greater than three months from the date of purchase but less than one year from the balance sheet date. Such investments are considered available-for-sale
Fair Value Measurements	Fair Value Measurements We apply fair value accounting to all financial assets and liabilities and non-financial
Concentrations of Credit and Other Risks	Concentrations of Credit and Other Risks Financial instruments that potentially subject us to a concentration of credit risk consist primarily of cash and cash equivalents and short-term investments. We hold our bank deposits at accredited financial institutions and these deposits may at times exceed insured limits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and cash equivalents to the extent of the amounts held in excess of federally insured limits. We limit our credit risk associated with cash and cash equivalents by placing them with financial institutions we believe are of high quality. We have not experienced any losses on our deposits of cash. Our investment policy limits investments to certain types of securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. As of December 31, 2022 and 2021, we had no off-balance We are subject to a number of risks similar to other early-stage biopharmaceutical companies, including the need to obtain adequate additional funding, possible failure of clinical trials, the need to obtain marketing approval for our product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of our products, and protection of proprietary technology. If we do not successfully develop, obtain regulatory approval for, commercialize or partner our product candidates, we will be unable to generate revenue from product sales or achieve profitability.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost, less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. The estimated useful life of laboratory equipment, furniture and fixtures, office equipment, and software ranges from tw
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Our long-lived assets are comprised principally of our property and equipment and right-of-use
Deferred Transaction Costs	Deferred Transaction Costs Deferred transaction costs consist of direct legal, accounting, filing and other fees and costs directly attributable to the merger (see Note 3). We capitalized deferred transaction costs prior to the close of the Business Combination and included in prepaid expenses and other current assets. We reclassified the deferred transaction costs related to the Business Combination to additional paid-in million on the consolidated balance sheet as of December 31, 2021. Upon the close of the Business Combination, we reclassified transaction costs million to additional paid-in million in 2022 (see Note 3).
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs consist of direct costs and commitment fees directly attributable to the commencement of the equity line of credit from Lincoln Park Capital Fund, LLC upon closing of the Business Combination (see Note 7). We capitalize deferred financing costs and amortize these costs over 24 months of the equity line of credit. As of December 31, 2022, deferred financing costs totaled $ million. Amortization expense for deferred financing costs was $ million for the year ended December , .
Revenue Recognition	Revenue Recognition Under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers We may also earn contingent fees, including milestone payments based on counterparty performance and royalties on sales, from collaborations and other out-license ® respectively.
Lease	Lease We determine if an arrangement is a lease at inception and if so, we determine whether the lease qualifies as an operating or a finance lease. We include operating lease in operating lease right-of-use We lease our facility under a non-cancelable non-cancellable
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Research and development expenses are primarily for the development of sotiga, our lead product candidate, as well as APX601 and other preclinical product candidates. Research and development costs consist primarily of external costs related to clinical development, contract manufacturing, preclinical development and discovery as well as personnel costs and allocated overhead, such as rent, equipment, depreciation, and utilities. Personnel costs consist of salaries, employee benefits and stock-based compensation. We estimate external research and development expenses based on the services performed, pursuant to contracts with commercial and academic institutions that conduct and manage research and development services on our behalf. We record the costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and include these costs in accrued liabilities in the consolidated balance sheets. These costs are a component of our research and development expenses. We accrue these costs based on factors such as the number of patient visits, the number of active patients, the number of patients enrolled, estimates of the work completed and other measures in accordance with agreements established with our third-party service providers under the service agreements. As actual costs become known, we adjust our accrued liabilities. We have not experienced any significant differences between accrued costs and actual costs incurred. However, the status and timing of actual services performed may vary from our estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in significant changes to our accruals could significantly affect our results of operations. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and then expensed as the related goods are delivered or the services are performed. We evaluate such payments for current or long-term classification based on when they will be realized.
Common Stock Warrant	Common Stock Warrant We record at fair value freestanding puttable or redeemable warrants, or warrants which are not considered to be indexed to our stock and include this amount in accrued expenses on our consolidated balance sheets as of December 31, 2021. On the closing date of the merger (see Note 3), the preferred stock warrant that was outstanding immediately before closing became a common stock warrant. We adjusted the carrying value of such warrant to its estimated fair value at the closing date of the merger based upon the value of our common stock warrant and reclassified estimated fair value at the closing date of the merger from accrued expenses to additional paid-in
Public Warrants	Public Warrants The public warrants, issued in connection with the BCAC’s initial public offering prior to the merger and the PIPE transaction completed in July 2022, are classified as equity (see Note 8).
Derivative Warrant Liabilities	Derivative Warrant Liabilities We account for the private placement warrants (see Note 8) issued in connection with the initial public offering as derivative warrant liabilities in accordance with FASB ASC Topic 815, “ Derivative and Hedging re-measurement
Stock-Based Compensation	Stock-Based Compensation We measure all equity awards granted to employees and non-employees We use the Black-Scholes option-pricing model to estimate the fair value of equity awards and recognize expense using the straight-line attribution approach. The Black-Scholes option-pricing model requires assumptions to be made related to the expected term of the awards, expected stock priced volatility, risk-free rate for a period that approximates the expected term of the awards and the expected dividend yield.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method. Under this method, we recognize deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. We measure deferred tax assets and liabilities using enacted tax rates applied to taxable income in the years in which we expect to realize those temporary differences. We recognize the effect on deferred tax assets and liabilities of a change in tax rates as income or loss in the period that includes the enactment date. We establish a valuation allowance, when necessary, to reduce deferred tax assets to the amount we expect to realize. We recognize the financial statement effects of uncertain tax positions when it is more-likely-than-not,
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss, primarily unrealized gains or losses on our marketable securities.
Net Loss per Share	Net Loss per Share We calculate basic net loss per share by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is the same as basic net loss per share for each period presented, since the effects of potentially dilutive securities are antidilutive given our net loss.
Major Vendor	Major Vendor We had a major vendor that accounted for approximately 39.9% and 23.2% of the research and development expenses for the years ended December 31, 2022 and 2021, respectively. The same vendor also accounted for approximately 24.8% and 28.1% of the total accounts payable and accrued liabilities as of December 31, 2022 and 2021, respectively. Moreover, there is another vendor that accounted for approximately 33.6% and 27.7% of the total accounts payable and accrued liabilities as of December 31, 2022 and 2021, respectively, but we did not incur any expenses with this vendor during the years ended December 31, 2022 and 2021. We had an additional vendor in 2021 that accounted for approximately 12.4% of the research and development expenses for the year ended December 31, 2021. The same vendor did not account for a major portion of accounts payable and accrued liabilities as of December 31, 2021.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2020, the FASB issued Accounting Standards Update (“ASU”) No. 2020-06, 470-20) 815-40), In October 2020, the FASB issued ASU No. 2020-10,
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments off-balance held-to-maturity available-for-sale

Merger (Tables)

Merger (Tables)	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Schedule of Reconciliation of Elements of Merger	The following table reconciles the elements of the merger to the consolidated statements of cash flows and the consolidated statement of changes in stockholders’ equity (in thousands): Cash—BCAC’s trust (net of redemption) $ 4,435 Cash—Private offering 14,520 Less: BCAC’s Extension and Working Capital Notes repayment in 2022 (861 ) Proceeds from merger and private offering for the year ended December 31, 2022 18,094 Less: transaction costs paid in 2022 (9,221 ) Net proceeds from merger and private offering for the year ended December 31, 2022 8,873 Less: transaction costs paid in 2021 (11 ) Plus: net assets of BCAC (394 ) Merger and private offering for the years ended December 31, 2022 $ 8,468 The number of shares of common stock issued immediately following the Closing Date was: Common stock, outstanding prior to merger 5,061,592 Less: redemption of BCAC shares (4,618,607 ) Common stock of BCAC 442,985 BCAC Sponsor shares 1,190,979 BCAC Representative shares 57,500 Shares issued in private offering 1,452,000 Business combination and private offering shares 3,143,464 Legacy Apexigen shares 18,147,032 Total shares of common stock immediately after merger 21,290,496 Exercise of Legacy Apexigen common stock warrant 4,539 Shares issued to Lincoln Park (Note 7) 150,000 Total shares of common stock on July 29, 2022 21,445,035 The number of Legacy Apexigen’s shares was determined as follows: Legacy Apexigen Legacy Apexigen Balance as of December 31, 2020 30,521,693 3,126,980 Recapitalization applied to Convertible Preferred Stock outstanding at 145,130,628 14,868,374 Exercise of common stock options—2021 548,972 56,238 Exercise of common stock options—2022 (pre-Closing) 702,074 71,922 Exercise of common stock restricted awards—2022 (pre-Closing) 229,556 23,518 Total Legacy Apexigen shares as of July 29, 2022 177,132,923 18,147,032

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Apexigen measured at fair value on a recurring basis	The following tables set forth the financial instruments that we measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 14,671 $ — $ — $ 14,671 U.S. treasury securities 1,997 — — 1,997 Total $ 16,668 $ — $ — $ 16,668 Financial liability: Derivative warrant liabilities $ — $ — $ 11 $ 11 Total $ — $ — $ 11 $ 11 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 18,526 $ — $ — $ 18,526 Commercial paper — 5,498 — 5,498 Corporate debt securities — 4,512 — 4,512 Government debt securities — 1,503 — 1,503 Asset backed securities — 1,404 — 1,404 Total $ 18,526 $ 12,917 $ — $ 31,443 Financial liability: Preferred stock warrant liability $ — $ — $ 2 $ 2 Total $ — $ — $ 2 $ 2
Summary of fair value of Apexigen's marketable securities and the gross unrealized holding gains and losses	The following tables summarize the estimated fair value of our marketable securities and the gross unrealized holding gains and losses (in thousands): December 31, 2022 Unrealized Amortized Gains Losses Estimated Cash and cash equivalents: Cash $ 131 $ — $ — $ 131 Money market funds 14,671 — — 14,671 Total cash and cash equivalents $ 14,802 $ — $ — $ 14,802 Marketable securities: U.S. treasury securities $ 1,997 $ — $ — $ 1,997 Total marketable securities $ 1,997 $ — $ — $ 1,997 December 31, 2021 Unrealized Amortized Gains Losses Estimated Cash and cash equivalents: Cash $ 4,917 $ — $ — $ 4,917 Money market funds 18,526 — — 18,526 Total cash and cash equivalents $ 23,443 $ — $ — $ 23,443 Marketable securities: Commercial paper $ 5,498 $ — $ — $ 5,498 Corporate debt securities 4,515 — (3 ) 4,512 Government debt securities 1,503 — — 1,503 Asset backed securities 1,405 — (1 ) 1,404 Total marketable securities $ 12,921 $ — $ (4 ) $ 12,917

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2022
Balance Sheet Components [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Prepaid clinical development expenses $ 1,128 $ 776 Prepaid insurance expenses 970 56 Deferred financing costs 261 467 Other prepaid expenses and current assets 259 382 Total prepaid expenses and other current assets 2,618 1,681
Summary of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): December 31, 2022 2021 Laboratory equipment $ 909 $ 943 Furniture and fixtures 28 28 Office equipment 25 25 Software 12 12 Total property and equipment 974 1,008 Less: accumulated depreciation (824 ) (763 ) Total property and equipment, net $ 150 $ 245
Summary of Accrued liabilities	Accrued liabilities consist of the following (in thousands): December 31, 2022 2021 Accrued clinical trial and manufacturing costs $ 4,340 $ 6,472 Accrued personnel costs 497 1,172 Other accrued liabilities 522 844 Total accrued liabilities $ 5,359 $ 8,488

Lease (Tables)

Lease (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Summary of future minimum lease payments	Future minimum lease payments as of December 31, 2022, are as follows (in thousands): Operating Year ending December 31, 2023 $ 106 Total undiscounted future lease payments 106 Less: imputed interest — Total lease liabilities $ 106

Stockholder's Equity (Tables)

Stockholder's Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Schedule of Convertible Preferred Stock	Upon the Closing, the outstanding shares of preferred stock were converted into common stock of Legacy Apexigen, and then into common stock of Apexigen at a ratio of 1:0.102448, the exchange rate established in the BCA. July 29, 2022 (Closing Date) Convertible Preferred Stock Preferred Exchange Common Series A-1 (pre-combination) 39,196,116 0.102448 4,015,564 Series A-2 (pre-combination) 12,625,343 0.102448 1,293,442 Series B (pre-combination) 14,218,546 0.102448 1,456,662 Series C (pre-combination) 79,090,623 0.102448 8,102,706 Total 145,130,628 14,868,374
Summary of Common stock	At December 31, 2022, we had reserved the following shares of common stock for the following purposes: Equity awards issued and outstanding 4,839,554 Equity awards available for future grants 1,065,423 Shares available for Employee Stock Purchase Plan 257,341 Common stock warrants 3,728,821 Total common stock reserved for issuance 9,891,139

Equity Plans and Related Equi_2

Equity Plans and Related Equity Activities (Tables)	12 Months Ended
	Dec. 31, 2022
Disclosure Text Block Supplement [Abstract]
Summary of Stock Based Compensation Expense Related To Stock Options Granted	The following table illustrates stock-based compensation expense related to equity awards granted under the Plans and ESPP recognized for years ended December 31, 2022 and 2021 (in thousands): Year Ended 2022 2021 Research and development $ 583 $ 292 General and administrative 1,300 851 Total stock-based compensation $ 1,883 $ 1,143
Summary of Assumptions for Stock Options and ESPP	In determining the fair value of the stock options granted and ESPP, we used the Black-Scholes option-pricing model and the following assumptions: Year Ended 2022 2021 Option Grants: Expected term (years) 5.00 - 6.06 5.62 - 10.00 Expected volatility 71% - 86 % 88 % Risk-free interest rate 0.53% - 4.07 % 0.60% - 1.20 % Expected dividend 0 % 0 % ESPP: Expected term (years) 0.50 - 2.00 Expected volatility 83% - 93 % Risk-free interest rate 4.37% - 4.60 % Expected dividend 0 %
Summary of Equity Plans Activities	The following table summarizes the activities under the Plans (in thousands, except share and per share amounts): Awards Number of Weighted Weighted Aggregate Outstanding at December 31, 2021 888,435 3,536,715 $ 2.71 Shares authorized added to 2022 Plan 2,573,405 Shares not return ed (913,842 ) Options Granted (2,097,010 ) 2,097,010 $ 3.18 Options Exercised — (75,550 ) $ 1.45 Options Cancelled 839,156 (839,156 ) $ 2.43 Restricted stock awards granted (23,518 ) 23,518 $ — Restricted stock awards vested — (23,518 ) $ — Restricted stock units granted (243,618 ) 243,618 $ — Restricted stock units vested — (80,668 ) $ — Restricted stock units forfeited 42,415 (42,415 ) $ — Outstanding at December 31, 2022 1,065,423 4,839,554 $ 2.91 6.66 $ 82 Vested and exercisable at December 31, 2022 2,685,009 $ 2.75 4.41 $ — Vested and expected to vest at December 31, 2022 4,824,187 $ 2.91 6.65 $ 82
Summary of Outstanding Options	The following table summarizes information about our outstanding options as of December 31, 2022 by range of exercise prices and excludes the 120,535 shares of restricted stock units outstanding as of December 31, 2022: Awards Outstanding Awards Exercisable Range of Number of Weighted- Weighted Number of Weighted- Weighted $ 1.27 3,103,997 6.12 $ 2.08 1,692,935 3.09 $ 1.68 $3.03 to $4.79 1,384,481 7.55 $ 4.38 820,036 6.72 $ 4.13 $6.54 to $7.62 230,541 6.83 $ 6.84 172,038 6.40 $ 6.69 4,719,019 6.58 $ 2.99 2,685,009 4.41 $ 2.75

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of reconciliation of effective tax rate of the provision for income taxes	The effective tax rate of the provision for income taxes differs from the federal statutory rate as follows: Year Ended 2022 2021 Federal statutory income tax rate 21.0 % 21.0 % Permanent differences 0.8 % -0.3 % Other credit 2.3 % 3.2 % Other -0.7 % -0.3 % Change in valuation allowance -23.4 % -23.6 % 0.0 % 0.0 %
Summary of components of the deferred tax assets and liabilities	The components of deferred tax assets and liabilities are as follows (in thousands): Year Ended 2022 2021 Deferred tax assets: Net operating loss carry forwards $ 33,333 $ 27,217 Tax credits 4,702 3,964 Section 174 R&D Capitalization 4,274 — Depreciation and amortization 90 — Stock-based compensation 666 — Other reserves and accruals 1,462 1,334 Gross deferred tax assets 44,527 32,515 Deferred tax liabilities: Depreciation and amortization — (24 ) Right-of-use (21 ) (101 ) Gross deferred tax liabilities (21 ) (125 ) Valuation allowance (44,506 ) (32,390 ) Net deferred tax assets — —
Summary of unrecognized tax benefits roll forward	A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in thousands): Year Ended 2022 2021 Gross unrecognized tax benefit at January 1 $ 1,598 $ 1,181 Additions for tax provision taken in the current year 405 417 Gross unrecognized tax benefit at December 31 $ 2,003 $ 1,598

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Summary of diluted net loss per share for the periods presented due to their anti-dilutive effect	The following outstanding potentially dilutive common stock equivalents have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect: December 31, 2022 2021 Equity awards 4,839,554 3,536,780 Common stock warrants 3,728,821 13,361 Total anti-dilutive securities 8,568,375 3,550,141

Organization and Description _2

Organization and Description of the Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 29, 2022	Dec. 31, 2022	Mar. 17, 2022	Dec. 31, 2021
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Business acquisition, transaction costs		$ 9,200		$ 11,000
Cash, cash equivalents and short term investments		16,800
Accumulated deficit		$ 176,793		$ 144,724
Paid off extension and working capital notes	$ 900
PIPE Investment [Member]
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Business acquisition, transaction costs	9,200
Sale of stock consideration received on transaction	19,000
Proceeds from sale maturity and collections of investments	$ 14,500
Number of shares issued in transaction	1,452,000
Sale of stock, price per share	$ 10
Number of securities called by each warrant or right	1
Exercise price of warrants or rights	$ 11.5
Number of days commences for share purchase after the closing and terminating on the five-year anniversary	30 days
PIPE Investment [Member] | Cash [Member]
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Assets held in trust	$ 4,500
Business Combination Agreement [Member] | Combined Company [Member]
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Transaction value			$ 205,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2022 USD ($) Segment shares	Dec. 31, 2021 USD ($)
Deferred revenue	$ 5,659,000	$ 3,610,000
Number of operating segments | Segment	1
Concentration risk, credit risk off balance sheet amount	$ 0	0
Business acquisition, transaction costs	9,200,000	11,000,000
Deferred financing costs	2,800,000
Amortization expense for deferred financing costs	700,000
Derivative warrant liabilities	11,000
Change in fair value of derivative warrant liabilities	$ 78,000
Common Stock Warrants [Member]
Class of Warrant or Right, Outstanding | shares	4,321
Minimum [Member] | Laboratory Equipment [Member]
Property plant and equipment useful life	2 years
Minimum [Member] | Furniture and Fixtures [Member]
Property plant and equipment useful life	2 years
Minimum [Member] | Office Equipment [Member]
Property plant and equipment useful life	2 years
Minimum [Member] | Software Development [Member]
Property plant and equipment useful life	2 years
Maximum [Member] | Laboratory Equipment [Member]
Property plant and equipment useful life	5 years
Maximum [Member] | Furniture and Fixtures [Member]
Property plant and equipment useful life	5 years
Maximum [Member] | Office Equipment [Member]
Property plant and equipment useful life	5 years
Maximum [Member] | Software Development [Member]
Property plant and equipment useful life	5 years
Prepaid Expenses and Other Current Assets [Member]
Deferred transaction costs		$ 500,000

Merger - Schedule of Reconcilia

Merger - Schedule of Reconciliation of Elements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Cash—BCAC's trust (net of redemption)	$ 4,435
Cash—Private offering	14,520
Less: BCAC's Extension and Working Capital Notes repayment in 2022	(861)
Proceeds from Merger and private offering for the year ended December 31, 2022	18,094	$ 0
Less: transaction costs paid	(9,200)	$ (11,000)
Legacy Apexigen [Member]
Business Acquisition [Line Items]
Less: BCAC's Extension and Working Capital Notes repayment in 2022	900
Less: transaction costs paid	(9,221)
Net proceeds from merger and private offering for the year ended December 31, 2022	8,873
Less: transaction costs paid in 2021	(11)
Plus: net assets of BCAC	(394)
Merger and private offering for the years ended December 31, 2022	$ 8,468

Merger - Schedule of Number of

Merger - Schedule of Number of Legacy Apexigen Shares (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2020
Business Acquisition [Line Items]
Exercise of common stock options (Shares)	75,550
Legacy Apexigen [Member]
Business Acquisition [Line Items]
Common stock,shares	177,132,923	30,521,693
Recapitalization applied to Convertible Preferred Stock outstanding at December 31, 2020		145,130,628
Common Stock Shares effected for Exchange Ratio	18,147,032	3,126,980
Recapitalization applied to Convertible Preferred Stock outstanding at December 31, 2020 (Ratio)		14,868,374
Legacy Apexigen [Member] | Twenty Twenty Two Stock Options [Member]
Business Acquisition [Line Items]
Exercise of common stock options (Shares)	702,074
Exercise of common stock restricted awards—2022 (pre-Closing)	229,556
Exercise of common stock options (Ratio)	71,922
Exercise of common stock restricted awards—2022 (pre-Closing) (Ratio)	23,518
Legacy Apexigen [Member] | Twenty Twenty One Stock Options [Member]
Business Acquisition [Line Items]
Exercise of common stock options (Shares)	548,972
Exercise of common stock options (Ratio)	56,238

Merger - Schedule of Number o_2

Merger - Schedule of Number of Common Stock Issued Following the Business Combination (Details) - shares	12 Months Ended
	Dec. 31, 2022	Jul. 29, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Common stock, outstanding prior to Merger	18,051,592	14,868,374	18,051,592
Total shares of common stock on July 29, 2022	18,051,592	14,868,374	18,051,592
Legacy Apexigen [Member]
Business Acquisition [Line Items]
Common stock, outstanding prior to Merger	5,061,592	21,445,035
Less: redemption of BCAC shares	(4,618,607)
Common stock of BCAC	442,985
BCAC Sponsor shares	1,190,979
BCAC Representative shares	57,500
Shares issued in private offering	1,452,000
Business Combination and private offering shares	3,143,464
Legacy Apexigen shares	18,147,032
Total shares of common stock immediately after Merger	21,290,496
Exercise of Legacy Apexigen common stock warrant	4,539
Shares issued to Lincoln Park (Note 7)	150,000
Total shares of common stock on July 29, 2022	5,061,592	21,445,035

Merger - Additional Information

Merger - Additional Information (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Jul. 29, 2022 $ / shares shares
Business Acquisition [Line Items]
Common stock, shares authorized | shares	1,000,000,000	23,563,040
Common stock, par value | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares authorized | shares	20,000,000
Preferred stock, par value | $ / shares	$ 0.0001
Proceeds from common stock issuance to Lincoln Park	$ 2,500	$ 0
Repayment of working capital notes	(861)
Proceeds from Business Combination and PIPE financing before offsetting	18,094	0
Offering costs	$ 9,221	$ 61
Legacy Apexigen [Member]
Business Acquisition [Line Items]
Business acquisition, effective date	Jul. 29, 2022
Common stock, shares authorized | shares			1,000,000,000
Common stock, par value | $ / shares			$ 0.0001
Preferred stock, shares authorized | shares			20,000,000
Preferred stock, par value | $ / shares			$ 0.0001
Convertible preferred stock converted into common stock | shares	145,130,628
Exchange Ratio	0.102448
Repayment of working capital notes	$ 900
Business combination, direct and incremental costs related Costs	$ 9,200
Legacy Apexigen [Member] | PIPE Investment [Member]
Business Acquisition [Line Items]
Shares redeemed (in shares) | shares	4,618,607
Gross Common Stock Redemption Payments	$ 47,200
Exercise of common stock warrant (in shares) | shares	1,452,000
Sale of Stock, Price Per Share | $ / shares	$ 10
Proceeds from common stock issuance to Lincoln Park	$ 14,500
Proceeds from Business Combination and PIPE financing before offsetting	19,000
Offering costs	$ 9,200
Apexigen [Member]
Business Acquisition [Line Items]
Authorized shares of capital stock | shares			1,020,000,000

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Change in fair value of derivative warrant liabilities	$ 78,000
Description of the valuation input used	Black-Scholes option-pricing model	Black-Scholes
Share based compensation by share based payment arrangement dividend rate	0%	0%
Preferred Stock Warrant Liability [Member]
Change in fair value of derivative warrant liabilities		$ 2,000,000
Derivative Warrant Liabilities [Member]
Change in fair value of derivative warrant liabilities	$ 11,000,000

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Apexigen measured at fair value on a recurring basis (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financial assets:
Assets, Fair Value Disclosure	$ 16,668	$ 31,443
Financial liability:
Financial Liabilities Fair Value Disclosure	11	2
Preferred stock warrant liability [Member]
Financial liability:
Financial Liabilities Fair Value Disclosure		2
Derivative Warrant Liabilities [Member]
Financial liability:
Financial Liabilities Fair Value Disclosure	11
Money market funds [Member]
Financial assets:
Assets, Fair Value Disclosure	14,671	18,526
U.S. treasury securities [Member]
Financial assets:
Assets, Fair Value Disclosure	1,997
Commercial paper [Member]
Financial assets:
Assets, Fair Value Disclosure		5,498
Corporate debt securities [Member]
Financial assets:
Assets, Fair Value Disclosure		4,512
Government debt securities [Member]
Financial assets:
Assets, Fair Value Disclosure		1,503
Asset backed securities [Member]
Financial assets:
Assets, Fair Value Disclosure		1,404
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Assets, Fair Value Disclosure	16,668	18,526
Financial liability:
Financial Liabilities Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Money market funds [Member]
Financial assets:
Assets, Fair Value Disclosure	14,671	18,526
Fair Value, Inputs, Level 1 [Member] | U.S. treasury securities [Member]
Financial assets:
Assets, Fair Value Disclosure	1,997
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Assets, Fair Value Disclosure		12,917
Fair Value, Inputs, Level 2 [Member] | Commercial paper [Member]
Financial assets:
Assets, Fair Value Disclosure		5,498
Fair Value, Inputs, Level 2 [Member] | Corporate debt securities [Member]
Financial assets:
Assets, Fair Value Disclosure		4,512
Fair Value, Inputs, Level 2 [Member] | Government debt securities [Member]
Financial assets:
Assets, Fair Value Disclosure		1,503
Fair Value, Inputs, Level 2 [Member] | Asset backed securities [Member]
Financial assets:
Assets, Fair Value Disclosure		1,404
Fair Value, Inputs, Level 3 [Member]
Financial liability:
Financial Liabilities Fair Value Disclosure	11	2
Fair Value, Inputs, Level 3 [Member] | Preferred stock warrant liability [Member]
Financial liability:
Financial Liabilities Fair Value Disclosure		$ 2
Fair Value, Inputs, Level 3 [Member] | Derivative Warrant Liabilities [Member]
Financial liability:
Financial Liabilities Fair Value Disclosure	$ 11

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of fair value of Apexigen's marketable securities and the gross unrealized holding gains and losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 1,997	$ 12,921
Unrealized Gains	0	0
Unrealized Losses	0	(4)
Estimated Fair Value	1,997	12,917
U.S. treasury securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,997
Unrealized Gains	0
Unrealized Losses	0
Estimated Fair Value	1,997
Commercial paper [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		5,498
Unrealized Gains		0
Unrealized Losses		0
Estimated Fair Value		5,498
Corporate debt securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		4,515
Unrealized Gains		0
Unrealized Losses		(3)
Estimated Fair Value		4,512
Government debt securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		1,503
Unrealized Gains		0
Unrealized Losses		0
Estimated Fair Value		1,503
Asset backed securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		1,405
Unrealized Gains		0
Unrealized Losses		(1)
Estimated Fair Value		1,404
Cash [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	131	4,917
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	131	4,917
Money market funds [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	14,671	18,526
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	14,671	18,526
Total cash and cash equivalents [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	14,802	23,443
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	$ 14,802	$ 23,443

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid clinical development expenses	$ 1,128	$ 776
Prepaid insurance expenses	970	56
Deferred financing costs	261	467
Other prepaid expenses and current assets	259	382
Total prepaid expenses and other current assets	$ 2,618	$ 1,681

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 974	$ 1,008
Less: accumulated depreciation	(824)	(763)
Total property and equipment, net	150	245
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	909	943
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	28	28
Office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	25	25
Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 12	$ 12

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Accrued liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Accrued Liabilities [Line Items]
Accrued clinical trial and manufacturing costs	$ 4,340	$ 6,472
Accrued personnel costs	497	1,172
Other accrued liabilities	522	844
Total accrued liabilities	$ 5,359	$ 8,488

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Components [Abstract]
Depreciation expense for property and equipment	$ 110,000	$ 105,000

Lease - Additional Information

Lease - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease agreement lease term	2023-03
Operating lease, weighted average discount rate, percent	5.05%
Right-of-use assets	$ 100	$ 483
Lease liability	106	500
Rent Expense	$ 400	$ 600

Lease - Summary of future minim

Lease - Summary of future minimum lease payments (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lessee, Operating Lease, Liability, to be Paid [Abstract]
Year ending December 31, 2023	$ 106
Total undiscounted future lease payments	106
Less: imputed interest	0
Total lease liabilities	$ 106	$ 500

Stockholder's Equity - Schedule

Stockholder's Equity - Schedule of Convertible Preferred Stock (Detail)	Jul. 29, 2022 shares	Dec. 31, 2022 shares	Dec. 31, 2021 shares
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	145,130,628	0
Common stock, shares outstanding	14,868,374	18,051,592	18,051,592
Series A One Convertible Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	39,196,116
Exchange Ratio	0.102448
Common stock, shares outstanding	4,015,564
Series A Two Convertible Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	12,625,343
Exchange Ratio	0.102448
Common stock, shares outstanding	1,293,442
Series B Convertible Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	14,218,546
Exchange Ratio	0.102448
Common stock, shares outstanding	1,456,662
Series C Convertible Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Preferred stock, shares outstanding	79,090,623
Exchange Ratio	0.102448
Common stock, shares outstanding	8,102,706

Stockholder's Equity - Addition

Stockholder's Equity - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Jul. 29, 2022
Class of Stock [Line Items]
Preferred stock, par value		$ 0.0001
Preferred stock, shares authorized		20,000,000
Preferred stock, shares outstanding		0		145,130,628
Change in fair value of liability for common stock to be issued		$ (205,000)	$ 0
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, par value		$ 0.001
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, par value		0.001
Series A One Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, par value		0.001
Series A Two Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, par value		$ 0.001
Lincoln Park Capital Fund [Member]
Class of Stock [Line Items]
Number Of Trading Days For Determining Share Price		90 days
Change in fair value of liability for common stock to be issued		$ 205,000
Common Stock Liability		1,400,000
Stock Issued During Period, Value, Other		$ 1,000,000
Sale of Stock, Number of Shares Issued in Transaction		500,000
Accelerated Share Repurchases, Cash or Stock Settlement		300% of the number of shares purchased pursuant to such Regular Purchase Notice and (ii) 30% of the total volume of shares of the common stock traded on the Nasdaq during the Accelerated Purchase period. The purchase price per Purchase Share for each such Accelerated Purchase will be equal to the lesser of 95% of (i) the volume-weighted average price of the common stock on the Nasdaq during the applicable Accelerated Purchase period on the applicable Accelerated Purchase date; and (ii) the closing sale price of the common stock on the Nasdaq on the applicable Accelerated Purchase date. Lincoln Park has no obligation to purchase shares under the Lincoln Park Purchase Agreement unless we comply with the terms of the RRA.
Proceeds FromPurchase Of Common Stock		$ 2,500,000
Purchase of common stock		616,684
Lincoln Park Capital Fund [Member] | Commitment Shares [Member]
Class of Stock [Line Items]
Stock Issued During Period, Value, Other		$ 1,500,000
Sale of Stock, Number of Shares Issued in Transaction		150,000
Lincoln Park Capital Fund [Member] | Commitment Shares [Member] | Maximum [Member]
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	500,000	500,000
Lincoln Park Capital Fund [Member] | Purchase Share [Member]
Class of Stock [Line Items]
Maximum amount of purchase of cs		$ 50,000,000
Nasdaq Capital [Member]
Class of Stock [Line Items]
Number Of Trading Days For Determining Share Price		10 days
Sale of stock, price per share		$ 3
Lincoln Park Purchase Agreement [Member] | Common Stock [Member]
Class of Stock [Line Items]
Ownership percentage		4.99%

Stockholder's Equity - Summary

Stockholder's Equity - Summary of Common Stock (Detail)	Dec. 31, 2022 shares
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance	9,891,139
Equity awards issued and outstanding [Member]
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance	4,839,554
Equity awards available for future grants [Member]
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance	1,065,423
Shares Available For Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance	257,341
Common Stock Warrants [Member]
Class of Stock [Line Items]
Common stock, capital shares reserved for future issuance	3,728,821

Public and Private Warrants - A

Public and Private Warrants - Additional Information (Details)		12 Months Ended
	Jul. 29, 2022 shares	Dec. 31, 2022 Item $ / shares shares
Public Warrants [Member]
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding		3,601,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares		$ 11.5
Redemption price per public warrant (in dollars per share) | $ / shares		0.01
Warrant redemption condition minimum share price | $ / shares		$ 18
Threshold trading days for redemption of public warrants		30 days
Number of consecutive trading days for determining share price triggering warrant redemption		30 days
Threshold consecutive trading days for redemption of public warrants | Item		20
Public Warrants [Member] | BCAC Initial Public Offering [Member]
Class of Warrant or Right [Line Items]
Class of warrants or rights, warrants issued during period	2,875,000
Public Warrants [Member] | PIPE Transaction [Member]
Class of Warrant or Right [Line Items]
Class of warrants or rights, warrants issued during period	726,000
Private Placement Warrants [Member]
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding		123,500
Private Placement Warrants [Member] | BCAC Initial Public Offering [Member]
Class of Warrant or Right [Line Items]
Class of warrants or rights, warrants issued during period	123,500

Equity Plans and Related Equi_3

Equity Plans and Related Equity Activities - Summary of Assumptions for Stock Options and ESPP (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected volatility		88%
Expected dividend	0%	0%
Equity Stock Purchase Plan [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected dividend	0%
Minimum [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (years)	5 years	5 years 7 months 13 days
Expected volatility	71%
Risk-free interest rate	0.53%	0.60%
Minimum [Member] | Equity Stock Purchase Plan [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (years)	6 months
Expected volatility	83%
Risk-free interest rate	4.37%
Maximum [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (years)	6 years 21 days	10 years
Expected volatility	86%
Risk-free interest rate	4.07%	1.20%
Maximum [Member] | Equity Stock Purchase Plan [Member]
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (years)	2 years
Expected volatility	93%
Risk-free interest rate	4.60%

Equity Plans and Related Equi_4

Equity Plans and Related Equity Activities - Summary of Equity Plans' Activities (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2022	Jul. 31, 2022	Dec. 31, 2022
Restricted stock awards vested
Awards Available to Grant , Beginning balance			888,435
Shares authorized added to 2022 Plan			2,573,405
Shares not returned to plan			(913,842)
Options Granted			(2,097,010)
Options Cancelled			839,156
Awards Available to Grant , Ending balance			1,065,423
Number of Awards Outstanding , Beginning balance			3,536,715
Options Granted			2,097,010
Options Exercised			(75,550)
Options Cancelled			(839,156)
Number of Awards Outstanding , Ending balance			4,839,554
Vested and exercisable			2,685,009
Vested and expected			4,824,187
Weighted Average Exercise Price , Beginning balance			$ 2.71
Options Granted			3.18
Options Exercised			1.45
Options Cancelled			2.43
Weighted Average Exercise Price , Ending balance			2.91
Vested and exercisable			2.75
Vested and expected			$ 2.91
Weighted Average Remaining Contractual Terms (Years)			6 years 7 months 28 days
Vested and exercisable , Weighted Average Remaining Contractual Terms (Years)			4 years 4 months 28 days
Vested and expected , Weighted Average Remaining Contractual Terms (Years)			6 years 7 months 24 days
Aggregate Intrinsic Value			$ 82
Vested and expected , Aggregate Intrinsic Value			$ 82
Restricted Stock [Member]
Restricted stock awards vested
Restricted stock awards granted			(23,518)
Options Granted		23,518
Restricted stock awards granted			23,518
Restricted stock units vested			(23,518)
Restricted Stock Units (RSUs) [Member]
Restricted stock awards vested
Restricted stock awards granted			(243,618)
Restricted stock units forfeited			42,415
Restricted stock awards granted	243,618		243,618
Restricted stock units vested			(80,668)
Restricted stock units forfeited			(42,415)

Equity Plans and Related Equi_5

Equity Plans and Related Equity Activities - Summary of Stock Based Compensation Expense Related To Stock Options Granted (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 1,883	$ 1,143
Research and development [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	583	292
General and administrative [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 1,300	$ 851

Equity Plans and Related Equi_6

Equity Plans and Related Equity Activities - Summary of Outstanding options (Detail)	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Awards | shares	4,719,019
Weighted- Average Remaining Contractual Term (Years)	6 years 6 months 29 days
Weighted Average Exercise Price per Share	$ 2.99
Number of Awards | shares	2,685,009
Weighted- Average Remaining Contractual Term (Years)	4 years 4 months 28 days
Weighted Average Exercise Price per Share	$ 2.75
One Point Seven To Two Point Six Five [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Awards | shares	3,103,997
Weighted- Average Remaining Contractual Term (Years)	6 years 1 month 13 days
Weighted Average Exercise Price per Share	$ 2.08
Number of Awards | shares	1,692,935
Weighted- Average Remaining Contractual Term (Years)	3 years 1 month 2 days
Weighted Average Exercise Price per Share	$ 1.68
Range of Exercise Price	1.27
Range of Exercise Price	$ 2.65
Three Point Zero Three To Four Point Seven Nine [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Awards | shares	1,384,481
Weighted- Average Remaining Contractual Term (Years)	7 years 6 months 18 days
Weighted Average Exercise Price per Share	$ 4.38
Number of Awards | shares	820,036
Weighted- Average Remaining Contractual Term (Years)	6 years 8 months 19 days
Weighted Average Exercise Price per Share	$ 4.13
Range of Exercise Price	3.03
Range of Exercise Price	$ 4.79
Six Point Five Four To Seven Point Six Two [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of Awards | shares	230,541
Weighted- Average Remaining Contractual Term (Years)	6 years 9 months 29 days
Weighted Average Exercise Price per Share	$ 6.84
Number of Awards | shares	172,038
Weighted- Average Remaining Contractual Term (Years)	6 years 4 months 24 days
Weighted Average Exercise Price per Share	$ 6.69
Range of Exercise Price	6.54
Range of Exercise Price	$ 7.62

Equity Plans and Related Equi_7

Equity Plans and Related Equity Activities - Additional Information (Detail) - USD ($)	1 Months Ended							3 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Oct. 31, 2022	Sep. 30, 2022	Aug. 31, 2022	Jul. 31, 2022	Feb. 28, 2022	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, nonvested award, cost not yet recognized, amount		$ 60,000							$ 60,000
Share-based compensation arrangements by share-based payment award, options, grants in period, weighted average exercise price									$ 3.18
Share-based payment arrangement, expense									$ 1,883,000	$ 1,143,000
Payment, tax withholding, share-based payment arrangement									$ 43,000
Share-based compensation arrangement by share-based payment award, options, grants in period, gross									2,097,010
Share-based compensation arrangement by share-based payment award, number of shares authorized		2,573,405							2,573,405
Common stock, capital shares reserved for future issuance		9,891,139							9,891,139
Share-based compensation arrangement by share-based payment award, award vesting period									4 years
Share-based compensation arrangement by share-based payment award, description									The term of an incentive stock option (“ISO”) granted to a 10% stockholder will not exceed five years from the date of the grant. The exercise price of an ISO and non-statutory stock option (“NSO”) will not be less than 100% of the estimated fair value of the shares on the date of grant, respectively, and the exercise price of an ISO and NSO granted to a 10% stockholder will not be less than 110% of the estimated fair value of the shares on the date of grant.
share-based compensation arrangement by share-based payment award, options, vested, number of shares								5,122
Non Executive Board [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price				$ 2.65
Equity Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, nonvested award, cost not yet recognized, amount		$ 300,000							$ 300,000
Share-based payment arrangement, expense									$ 39,000
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition									1 year 10 months 24 days
Share-based compensation arrangement by share-based payment award, number of shares authorized					257,341
Common stock, capital shares reserved for future issuance		257,341							257,341
share-based compensation arrangement by share-based payment award, maximum employee subscription rate					15%
share based compensation arrangement by share based payment award maximum employee subscription amount					$ 25,000
Share-based compensation arrangement by share-based payment award, purchase price of common stock, percent					85%
Share-based compensation arrangement by share-based payment award, expiration period					24 months
Equity incentive plan description					The number of shares of common stock reserved for issuance will automatically increase on January 1 of each calendar year, beginning on January 1, 2023 through January 1, 2032, by the lesser of (1) 1.0% of the total number of shares of common stock outstanding on the last day of the calendar month before the date of the automatic increase, and (2) 536,126 shares; provided that before the date of any such increase, our Board may determine that such increase will be less than the amount set forth in clauses (1) and (2).
Stock Option Plans and Equity Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, nonvested award, cost not yet recognized, amount		$ 4,200,000							$ 4,200,000
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition									2 years 7 months 6 days
Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangements by share-based payment award, options, grants in period, weighted average exercise price									$ 2.3	$ 3.39
Share-based payment arrangement, expense									$ 300,000
Two Thousand Twenty Two Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized		2,573,405							2,573,405
Common stock, capital shares reserved for future issuance		3,216,756							3,216,756
Annual increase in shares reserved for issuance as a percentage of common shares outstanding		5%							5%
Two Thousand and Ten Equity Incentive Plan or Two Thousand And Twenty Equity Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, expirations in period									3,461,319
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-Based payment award, equity instruments other than options, non vested, number		120,535							120,535
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value			$ 2.46
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value			$ 600,000
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period			243,618						243,618
Restricted Stock Units (RSUs) [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting of award under share-based payment arrangement.		50%
Restricted Stock Units (RSUs) [Member] | Subsequent Event [Member] | Share-Based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting of award under share-based payment arrangement.	50%
Equity Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangements by share-based payment award, options, grants in period, weighted average exercise price									$ 1.96
Share-based payment arrangement, expense									$ 100,000
Share-based compensation arrangement by share-based payment award, options, vested in period, fair value									1,300,000
Share-based compensation arrangement by share-based payment award, shares purchased for award							20,489
Share based compensation arrangement by share based payment option agreement period							10 years
Share-based compensation arrangement by share-based payment award, terms of award				3 years
Equity Option [Member] | Two Thousand Twenty Two Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, grants in period, gross				700,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense									$ 200,000
Share-based compensation arrangement by share-based payment award, options, grants in period, gross						23,518
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value									$ 10.3
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value									$ 200,000
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period									23,518
Incentive Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance		5,904,977							5,904,977
Percentage of stock option granted to stockholder									10%
Nonstatutory Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of the estimated fair value of the shares on the date of grant									110%
Nonstatutory Stock Option [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of the estimated fair value of the shares on the date of grant									100%
Repriced Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense								$ 20,000
Vesting Of Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock, Shares Issued Net of Shares for Tax Withholdings									42,415

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Clinical Collabaration [Member]
Other Commitments [Line Items]
Other Commitment	$ 9.5

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Tax Rate of the Provision For Income Taxes (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	21%	21%
Permanent differences	0.80%	(0.30%)
Other credit	2.30%	3.20%
Other	(0.70%)	(0.30%)
Change in valuation allowance	(23.40%)	(23.60%)
Effective tax rate	0%	0%

Income Taxes - Summary of Compo

Income Taxes - Summary of Components of the Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carry forwards	$ 33,333	$ 27,217
Tax credits	4,702	3,964
Section 174 R&D Capitalization	4,274	0
Depreciation and amortization	90	0
Stock-based compensation	666	0
Other reserves and accruals	1,462	1,334
Gross deferred tax assets	44,527	32,515
Deferred tax liabilities:
Depreciation and amortization	0	(24)
Right-of-use assets	(21)	(101)
Gross deferred tax liabilities	(21)	(125)
Valuation allowance	(44,506)	(32,390)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits Roll Forward (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Uncertainties [Abstract]
Gross unrecognized tax benefit at January 1	$ 1,598	$ 1,181
Additions for tax provision taken in the current year	405	417
Gross unrecognized tax benefit at December 31	$ 2,003	$ 1,598

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Mar. 27, 2020	Dec. 31, 2017
Valuation allowance inreased amount during the period	$ 12.1	$ 6.8
Operating Loss Carry forwards Expiration year	2035 years
Coronavirus Aid, Relief, and Economic Security Act [Member]
Percentage of operating loss carryforwards to offset taxable income			100%
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax credit carryforward amount	$ 3.7
Domestic Tax Authority [Member] | Federal Orphan Drug credits [Member]
Tax credit carryforward amount	$ 0.9
Tax Credit Carryforward Expiration Year	2041 years
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	$ 64.6
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax credit carryforward amount	2.5
U.s. Federal Tax uthority [Member]
Operating Loss Carryforwards	$ 137.3
U.s. Federal Tax uthority [Member] | Indefinite [Member]
Operating Loss Carryforwards				$ 109
Operating loss carryforwards, limitations on use	80
U.s. Federal Tax uthority [Member] | Two Thousand And Thirty Three [Member]
Operating Loss Carryforwards	$ 28.3
Operating Loss Carry forwards Expiration year	2033 years

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Diluted Net Loss Per Share for the Periods Presented Due To Their Anti-Dilutive Effect (Detail) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	8,568,375	3,550,141
Equity awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	4,839,554	3,536,780
Common stock warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	3,728,821	13,361

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Maximum voluntary Contributions Per Employee, Percent	100%
Employer Matching Contribution, Percent of Match	4%
Labor and Related Expense	$ 177,000	$ 139,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jan. 30, 2023	Jan. 23, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Common stock, par or stated value per share			$ 0.0001	$ 0.0001
Proceeds from issuance of Private Placement			$ 14,520
Common Stock [Member]
Subsequent Event [Line Items]
Stock issued during period, shares, new issues			4,539
Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from issuance of Private Placement	$ 2,800
Subsequent Event [Member] | Placement Agent Warrants [Member]
Subsequent Event [Line Items]
Class of warrant or right, exercise price of warrants or rights		$ 1.75
Percentage of placement agent cash fee		7%
Number of common stock into which the class of warrant or right may be converted		99,785
Percentage of exercise price over issue price		125%
Subsequent Event [Member] | Purchase Agreement [Member]
Subsequent Event [Line Items]
Class of warrant or right, period from which warrants or rights exercisable			6 months
Warrants and rights outstanding, term		5 years 6 months
Subsequent Event [Member] | Purchase Agreement [Member] | Private Placement [Member]
Subsequent Event [Line Items]
Class of warrant or right, exercise price of warrants or rights		$ 1.4
Stock issued during period, shares, new issues		1,995,708
Number of common stock into which the class of warrant or right may be converted		1,995,708
Subsequent Event [Member] | Purchase Agreement [Member] | Private Placement [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Common stock, par or stated value per share		$ 0.0001
Subsequent Event [Member] | Purchase Agreement [Member] | Private Placement [Member] | Warrant [Member]
Subsequent Event [Line Items]
Sale of stock, price per share		$ 1.4