Ambrx Biopharma 10-Q 13 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Nov. 07, 2023
Document Information [Line Items]
Document Type	10-Q
Entity Registrant Name	Ambrx Biopharma, Inc.
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Securities Act File Number	000-56600
Entity Central Index Key	0001990550
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	93-2892120
Document Quarterly Report	true
Document Transition Report	false
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Address, Address Line One	10975 North Torrey Pines Road
Entity Address, City or Town	La Jolla
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92037
Entity Address, Country	US
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	AMAM
Security Exchange Name	NASDAQ
City Area Code	858
Local Phone Number	875-2400
Entity Common Stock, Shares Outstanding		63,150,244

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 225,262	$ 55,610
Restricted cash	665	831
Marketable debt securities, available-for-sale, current portion	0	28,873
Accounts receivable, net	122	376
Prepaid expenses and other current assets	7,769	4,893
Total current assets	233,818	90,583
Marketable debt securities, available-for-sale, net of current portion	0	16,793
Property and equipment, net	2,999	3,044
Right-of-use assets, net	9,569	10,968
Intangible assets, net	24,778	25,250
Other long-term assets	336	339
Total assets	271,500	146,977
Current liabilities:
Accounts payable	5,141	3,205
Accrued liabilities	10,805	11,314
Operating lease liabilities, current portion	1,915	1,734
Deferred revenue, current portion	407	407
Total current liabilities	18,268	16,660
Operating lease liabilities, net of current portion	8,608	10,245
Deferred tax liabilities	880	880
Deferred revenue, net of current portion	1,342	1,342
Total liabilities	29,098	29,127
Commitments and contingencies (Note 7)
Shareholders' Equity (Deficit):
Ordinary shares, as converted (Note 1), par value $0.0001;135,714,285 and 71,428,571 shares authorized at September 30, 2023 and December 31, 2022, respectively; 63,006,294 and 38,636,441 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	6	4
Additional paid-in capital	590,931	410,776
Accumulated other comprehensive loss	(790)	(1,302)
Accumulated deficit	(347,745)	(291,628)
Total shareholders' equity	242,402	117,850
Total liabilities and shareholders' equity	$ 271,500	$ 146,977

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Common Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Common Stock, Shares Authorized	135,714,285	71,428,571
Common Stock, Shares, Issued	63,006,294
Common Stock, Shares, Outstanding		38,636,441

Consolidated Statements of Oper

Consolidated Statements of Operations and comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues	$ 53	$ 1,597	$ 1,200	$ 4,509
Operating expenses:
Research and development	16,269	12,443	40,412	45,209
General and administrative	9,410	5,095	21,616	14,488
Impairment of intangible assets	0	0	0	9,660
Total operating expenses	25,679	17,538	62,028	69,357
Loss from operations	(25,626)	(15,941)	(60,828)	(64,848)
Other income (expense), net:
Investment income, net	2,400	509	4,379	732
Interest income (expense), net	326	(10)	727	(975)
Other income (expense), net	59	(126)	131	(250)
Total other income (expense), net	2,785	373	5,237	(493)
Loss before income taxes	(22,841)	(15,568)	(55,591)	(65,341)
Provision for income taxes	(148)	0	(526)	(1,716)
Net loss	$ (22,989)	$ (15,568)	$ (56,117)	$ (67,057)
Net loss per ordinary share,as converted (Note 1) , basic	$ (0.37)	$ (0.4)	$ (1.03)	$ (1.74)
Net loss per ordinary share,as converted (Note 1) , diluted	$ (0.37)	$ (0.4)	$ (1.03)	$ (1.74)
Weighted-average ordinary shares, as converted (Note 1)used to compute net loss per share, basic	62,250,431	38,618,354	54,444,428	38,600,716
Weighted-averageordinary shares, as converted (Note 1) used to compute net loss per share, diluted	62,250,431	38,618,354	54,444,428	38,600,716
Other comprehensive loss, net of tax:
Net loss	$ (22,989)	$ (15,568)	$ (56,117)	$ (67,057)
Changes in comprehensive loss before reclassifications	23	(360)	(16)	(577)
Amounts reclassified from accumulated other comprehensive loss	140	0	528	0
Total other comprehensive income (loss)	163	(360)	512	(577)
Comprehensive loss	$ (22,826)	$ (15,928)	$ (55,605)	$ (67,634)

Condensed Consolidated Statemen

Condensed Consolidated Statements of Changes In Shareholders' Equity - USD ($) $ in Thousands	Total	Ordinary Shares [Member]	Additional Paid-In-Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2021	$ 189,967	$ 4	$ 404,385	$ (790)	$ (213,632)
Beginning balance (in shares) at Dec. 31, 2021		38,588,629
Share-based compensation	5,067		5,067
Issuance of ordinary shares for cash	102		102
Issuance of ordinary shares for cash (in shares)		29,705
Change in unrealized loss on marketable debt securities available-for-sale	(577)			(577)
Net loss	(67,057)				(67,057)
Ending balance at Sep. 30, 2022	127,502	$ 4	409,554	(1,367)	(280,689)
Ending balance (in shares) at Sep. 30, 2022		38,618,334
Beginning balance at Jun. 30, 2022	141,892	$ 4	408,016	(1,007)	(265,121)
Beginning balance (in shares) at Jun. 30, 2022		38,618,334
Share-based compensation	1,538		1,538
Change in unrealized loss on marketable debt securities available-for-sale	(360)			(360)
Net loss	(15,568)				(15,568)
Ending balance at Sep. 30, 2022	127,502	$ 4	409,554	(1,367)	(280,689)
Ending balance (in shares) at Sep. 30, 2022		38,618,334
Beginning balance at Dec. 31, 2022	117,850	$ 4	410,776	(1,302)	(291,628)
Beginning balance (in shares) at Dec. 31, 2022		38,636,441
Share-based compensation	8,187		8,187
Issuance of ordinary shares for cash through registered direct offering with a related party, net of issuance costs	74,663	$ 1	74,662
Issuance of ordinary shares for cash through registered direct offering with a related party, net of issuance costs (in shares)		5,384,063
Issuance of ordinary shares for cash through an at-the-market offering, net of issuance costs	77,780	$ 1	77,779
Issuance of ordinary shares for cash through an at-the-market offering, net of issuance costs (in shares)		16,575,826
Issuance of ordinary shares upon option exercises for cash	$ 18,070		18,070
Issuance of ordinary shares upon option exercises for cash (in shares)	2,299,251	2,299,251
Issuance of ordinary shares for services	$ 1,457		1,457
Issuance of ordinary shares for services (in shares)		110,713
Change in unrealized loss on marketable debt securities available-for-sale	512			512
Net loss	(56,117)				(56,117)
Ending balance at Sep. 30, 2023	242,402	$ 6	590,931	(790)	(347,745)
Ending balance (in shares) at Sep. 30, 2023		63,006,294
Beginning balance at Jun. 30, 2023	250,380	$ 6	576,083	(953)	(324,756)
Beginning balance (in shares) at Jun. 30, 2023		61,746,762
Share-based compensation	4,154		4,154
Issuance of ordinary shares upon option exercises for cash	10,028		10,028
Issuance of ordinary shares upon option exercises for cash (in shares)		1,219,532
Issuance of ordinary shares for services	666		666
Issuance of ordinary shares for services (in shares)		40,000
Change in unrealized loss on marketable debt securities available-for-sale	163			163
Net loss	(22,989)				(22,989)
Ending balance at Sep. 30, 2023	$ 242,402	$ 6	$ 590,931	$ (790)	$ (347,745)
Ending balance (in shares) at Sep. 30, 2023		63,006,294

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (56,117)	$ (67,057)
Noncash adjustments reconciling net loss to cash flows from operating activities:
Loss on impairment of intangible assets	0	9,660
Share-based compensation expense	9,644	5,067
Noncash lease expense	2,048	2,048
Depreciation and amortization	642	537
Realized loss on sales of marketable debt securities, available-for-sale	528	0
Amortization of intangible assets	472	895
Accretion/amortization of discounts/premiums on marketable debt securities	(328)	(290)
Loss on disposal of property and equipment	0	6
Changes in operating assets and liabilities:
Accounts receivable, net	254	430
Prepaid and other current assets and other long-term assets	(2,874)	(1,174)
Accounts payable	2,420	3,364
Accrued liabilities	422	(5,611)
Deferred revenue	0	(2,355)
Operating lease liabilities	(2,105)	(1,492)
Net cash used in operating activities	(44,994)	(55,972)
Cash flows from investing activities:
Purchases of marketable debt securities, available-for-sale	(40,645)	(75,431)
Sales of marketable debt securities, available-for-sale	60,725	1,982
Maturities of marketable debt securities, available-for-sale	25,900	10,000
Purchases of property and equipment	(1,081)	(1,007)
Net cash provided by (used in) investing activities	44,899	(64,456)
Cash flows from financing activities:
Proceeds from short-term bridge loan	0	166,000
Repayment of short-term bridge loan	0	(166,000)
Proceeds from directors and officers insurance premium financing agreement	0	1,831
Payments of directors and officers insurance premium financing agreement	(932)	(364)
Proceeds from issuance of ordinary shares for cash, net of issuance costs	77,780	0
Issuance of ordinary shares for cash through registered direct offering with a related party, net of issuance costs	74,663	0
Issuance of ordinary shares for cash pursuant to option exercises and employee stock purchase programs	18,070	103
Payments of costs for the issuance of ordinary shares	0	(136)
Net cash provided by (used in) financing activities	169,581	1,434
Net increase (decrease) in cash, cash equivalents and restricted cash	169,486	(118,994)
Cash, cash equivalents and restricted cash, beginning of period	56,441	170,906
Cash, cash equivalents and restricted cash, end of period	225,927	51,912
Supplemental information:
Cash paid for interest	0	963
Cash paid for income taxes	1	312
Noncash investing and financing activities:
Property and equipment costs in accounts payable and accrued liabilities	$ 7	$ 66

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business Ambrx Biopharma, Inc., a Delaware corporation (“Ambrx” or the “Company”), is a clinical-stage biologics company focused on discovering and developing a novel class of engineered precision biologics using its proprietary expanded genetic code technology platform that allows it to incorporate, in a site-specific manner, synthetic amino acids into proteins within living cells. Ambrx commenced its operations in the United States in January 2003 through Ambrx, Inc., a Delaware corporation (“Ambrx US”). In May 2015, Ambrx Biopharma Cayman, Inc. (formerly known as Ambrx Biopharma Inc.) incorporated under the laws of the Cayman Islands (“Ambrx Cayman”) and became the ultimate holding company through a series of transactions. In October 2023, Ambrx became the ultimate holding company through the Merger (as defined below). On September 11, 2023, the board of directors of Ambrx Cayman unanimously approved the merger (the “Merger”) of Ambrx Merger Sub Inc. (“Merger Sub”), a Cayman Islands exempted company and newly-formed direct wholly owned subsidiary of Ambrx, with and into Ambrx Cayman, with Ambrx Cayman surviving the Merger as a direct wholly owned subsidiary of Ambrx, on the terms of and subject to the conditions of the Agreement and Plan of Merger, dated as of September 11, 2023, by and among Ambrx, Merger Sub and Ambrx Cayman (the “Merger Agreement”). The Merger was approved by the shareholders of Ambrx Cayman at its extraordinary general meeting of shareholders held on October 10, 2023. Each ordinary share, par value $ 0.0001 per share, of Ambrx Cayman (“ordinary share”) issued and outstanding immediately prior to the effective time of the Merger (including ordinary shares underlying the outstanding American Depositary Shares (“ADSs”)), was automatically converted into one-seventh (1/7) of one duly issued, fully paid and non-assessable share of common stock, par value $ 0.0001 per share, of Ambrx (“common stock”). Each ADS represented seven ordinary shares, therefore, each ADS holder was entitled to receive one share of common stock for each ADS held immediately prior to the effective time of the Merger. As a result of the Merger, Ambrx became the successor issuer to Ambrx Cayman. As a result of the Merger, shareholders of Ambrx Cayman became stockholders of Ambrx, and the rights of such stockholders are now defined by Delaware General Corporation Law, the Amended and Restated Certificate of Incorporation of Ambrx and the Amended and Restated Bylaws of Ambrx. Pursuant to the Merger Agreement, the directors and executive officers of Ambrx immediately following consummation of the Merger are the same individuals who were directors and executive officers of Ambrx Cayman immediately prior to the Merger. As of October 11, 2023, the total amount of authorized capital stock of Ambrx was increased to 251,000,000 shares of capital stock, which consists of 250,000,000 shares of common stock and 1,000,000 shares of Ambrx preferred stock, par value $ 0.0001 per share (“preferred stock”). Immediately prior to the effective time of the Merger, there were 441,044,212 ordinary shares issued and outstanding, which were automatically converted into 63,006,294 shares of common stock. In connection with the Merger, Ambrx Cayman and JPMorgan Chase Bank, N.A. (“JPM”) mutually agreed to, among other things, terminate the deposit agreement dated June 17, 2021 (the “Deposit Agreement”), by and between Ambrx Cayman and JPM, as depositary and holders and beneficial owners of Ambrx Cayman’s ADSs, and Ambrx Cayman’s ADS program was terminated upon approval of the Merger (the “ADS Program Termination”) on October 11, 2023. In connection with the ADS Program Termination, Ambrx Cayman agreed to pay JPM approximately $ 1.9 million in accordance with the terms of the Deposit Agreement and pursuant to an adjusted fee letter between Ambrx Cayman and JPM, dated October 24, 2023. The ADS Program Termination fees will be recorded during the fourth quarter of 2023. On the terms of and subject to the conditions of the Merger Agreement, each option to purchase ordinary shares outstanding immediately prior to the effective time of the Merger was converted into an option to acquire a number of shares of common stock at (a) an adjusted exercise price determined by multiplying (x) the per share exercise price of options to acquire ordinary shares as of immediately prior to the effective time of the Merger by (y) seven, and rounding the resulting exercise price up to the nearest whole cent, and (b) an adjusted number of shares determined by dividing (x) the number of ordinary shares subject to such option as of immediately prior to the effective time of the Merger by (y) seven (and rounding the resulting number down to the nearest whole number of shares of common stock) (each such resulting option, a “Converted Option”). Each Converted Option is subject to substantially equivalent terms and conditions as were applicable to such corresponding option to purchase ordinary shares that was outstanding immediately prior to the effective time of the Merger. In addition, each award of restricted share units representing the right to receive ordinary shares outstanding immediately prior to the effective time of the Merger was converted into an award of restricted stock units representing the right to receive a number of shares of common stock determined by dividing (x) the number of ordinary shares subject to such award of restricted share units as of immediately prior to the effective time of the Merger by (y) seven (and rounding the resulting number down to the nearest whole number of shares of common stock) (each such resulting award of restricted stock units, a “Converted RSU Award”). Each Converted RSU award is subject to substantially equivalent terms and conditions as were applicable to such corresponding award of restricted share units representing the right to receive ordinary shares that was outstanding immediately prior to the effective time of the Merger. As of the date of these condensed consolidated financial statements, Ambrx Cayman owned 100 % of Ambrx US; Shanghai Ambrx Biopharma Company Limited, a company incorporated in China (“Ambrx Shanghai”); and Biolaxy Pharmaceutical Hong Kong Limited, a company incorporated in Hong Kong (“Ambrx HK”). Ambrx US, based in San Diego, California, owned 100 % of Ambrx Australia Pty Limited, a company incorporated in Australia (“Ambrx AU”). All ordinary share, option to purchase ordinary shares and restricted stock unit amounts, including per share amounts, presented in these consolidated financial statements have been adjusted to reflect the retroactive effect of the conversion of each ordinary share into one-seventh (1/7) of one share of common stock, the Converted Options and the Converted RSU Awards, as the case may be, as a result of the Merger. When used in these financial statements, the terms “Ambrx,” or the “Company,” refer to Ambrx Cayman and its consolidated subsidiaries prior to the closing on October 11, 2023 of the Merger and Ambrx Biopharma, Inc. (formerly New Ambrx Biopharma Inc.), a Delaware corporation, and its consolidated subsidiaries, on and after the closing on October 11, 2023 of the Merger, unless otherwise specified or the context otherwise requires. Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Company’s condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. The Company’s operating currency is the U.S. dollar. Unaudited Interim Financial Information The interim condensed consolidated financial statements are unaudited. These unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and following the requirements of the United States Securities and Exchange Commission (the “SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. In management’s opinion, the unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position, its results of operations, equity activities and its cash flows for the periods presented. These statements do not include all disclosures required by U.S. GAAP and should be read in conjunction with the Company’s audited consolidated financial statements and notes for the fiscal year ended December 31, 2022, contained in the Company’s Annual Report on Form 10-K filed by the Company with the SEC on March 30, 2023 (the “Annual Report”). The results for the three and nine months ended September 30, 2023, are not necessarily indicative of the results expected for the full fiscal year or any other future interim or annual period. Liquidity and Capital Resources The Company has incurred net operating losses and negative cash flows from operations since its incorporation in 2015 and had an accumulated deficit of $ 347.7 million as of September 30, 2023. As of September 30, 2023, the Company had cash and cash equivalents of $ 225.3 million. Management believes its existing financial resources are sufficient to continue operating activities for at least 12 months past the issuance date of these condensed consolidated financial statements. Future capital requirements will depend on many factors, including the timing and extent of spending on research and development (“R&D”) activities and market acceptance of the Company’s products, if approved. Until such time the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through public or private equity or debt financings or other capital sources, which may include strategic collaborations or other arrangements with third parties. However, the Company may be unable to raise additional funds or enter into such other agreements or arrangements when needed on favorable terms, or at all. If the Company is unable to raise capital or enter into such agreements as and when needed, the Company may have to significantly delay, scale back or discontinue the development or commercialization of one or more of its product candidates. Insufficient liquidity may also require the Company to relinquish rights to product candidates at an earlier stage of development or on less favorable terms than the Company would otherwise choose. The Company’s ability to raise additional funds may be adversely impacted by potential worsening global macroeconomic and geopolitical conditions and disruptions to, and volatility in, the credit and financial markets in the United States and worldwide, including from the COVID-19 pandemic and related variants, the ongoing conflict between Ukraine and Russia, the ongoing conflict between Israel and Hamas, and recent disruption in access to bank deposits and lending commitments due to bank failures earlier this year.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies There have been no material changes to the Company’s significant accounting policies from those described in the notes to the audited consolidated financial statements of the Company contained in the Annual Report. Risks and Uncertainties Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to the valuation of share-based awards and marketable debt securities, available-for-sale (“MDS”), the discount rate used in estimating the present value of the right-of-use (“ROU”) assets and lease liabilities, the useful lives of property and equipment and intangible assets, the recoverability of long-lived assets, clinical trial accruals, periods over which revenue should be recognized, deferred income taxes and related valuation allowances, and the assessment of the Company’s ability to fund its operations for at least the next 12 months from the date of issuance of these condensed consolidated financial statements. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Estimates are assessed each reporting period and updated to reflect current information. As future events and their effects cannot be determined with precision, actual results may materially differ from those estimates or assumptions. Due to recent disruptions in access to bank deposits and lending commitments associated with bank failures, the COVID-19 pandemic and macroeconomic and geopolitical conditions, there has been uncertainty and disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of September 30, 2023. While there was no material impact to the Company’s condensed consolidated financial statements as of and for the three and nine months ended September 30, 2023 , these estimates may change, as new events occur and additional information is obtained, which could materially impact the Company’s condensed consolidated financial statements in future reporting periods. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, MDS, and accounts receivable which are generally not collateralized. Deposits in the Company’s checking and money market accounts are maintained in federally insured financial institutions and are subject to federally insured limits or limits set by the Securities Investor Protection Corporation. In addition, the Company maintains cash and cash equivalents in foreign bank accounts, which are not federally insured. The Company attempts to minimize credit risk associated with its cash and cash equivalents by periodically evaluating the credit quality of its primary financial institutions. The Company’s investment portfolio is maintained in accordance with its investment policy, which is designed to preserve capital, safeguard funds and limit exposure to risk. While the Company maintains cash deposits in Federal Deposit Insurance Corporation insured financial institutions in excess of federally insured limits, it does not believe that it is exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has not experienced any losses on such accounts. During the three months ended September 30, 2023, revenues from the Company’s top customer represented 100 % of total revenues. During the three months ended September 30, 2022 , revenues from the Company’s top three customers represented 66.2 %, 14.9 % and 13.6 % of total revenues, respectively. During the nine months ended September 30, 2023, revenues from the Company’s top customer represented 91.7 % of total revenues. During the nine months ended September 30, 2022, revenues from the Company’s top two customers represented 78.6 % and 13.7 % of total revenues, respectively. As of September 30, 2023, billed accounts receivable for the top customer represented 100 % of total billed receivables. As of December 31, 2022, billed accounts receivable for the top two customers represented 78.4 % and 11.8 % of total billed receivables, respectively. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of readily available cash in checking accounts, U.S. government securities, certificates of deposit, money market funds and other marketable securities with original maturities of three months or less. The following table provides a reconciliation of cash, cash equivalents and restricted cash, reported within the condensed consolidated statements of cash flows (in thousands): For the Nine Months 2023 2022 Cash and cash equivalents $ 225,262 $ 51,081 Restricted cash 665 831 Total cash, cash equivalents, and restricted cash presented in the $ 225,927 $ 51,912 As of September 30, 2023 and 2022 , the Company’s restricted cash consists of cash related to the Company’s clinical trials. Accounts Receivable, Net Accounts receivable, net, are recorded net of any allowance for current expected credit losses measured based on historical experience, current conditions, and reasonable and supportable forecasts. As of September 30, 2023 and December 31, 2022 , the Company has determined an allowance for expected credit losses is not material. Intangible Assets, Net The Company records its intangible assets based on their fair values at the date of acquisition. The Company’s finite lived intangible assets related to acquired technologies has estimated remaining useful lives between approximately 2.3 to 11.3 years as of September 30, 2023, and three to 12 years as of December 31, 2022. Amortization expense for the Company’s finite lived intangible assets is charged to research and development expense in the condensed consolidated statements of operations and comprehensive loss on a straight-line basis over the assets’ estimated useful lives. Impairment losses on finite-lived intangible assets are recorded when indicators of impairment are present and the undiscounted cash flows estimated to be generated by those assets are less than the assets’ carrying amount. If such assets are considered impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets. In the first quarter of 2022, the Company received a Notice of Termination of Collaboration and License agreement (“Relaxin”) between Bristol-Myers Squibb Company (“BMS”) and the Company (the “Relaxin Agreement”) from BMS to be effective three months from receipt of the notification. Due to this termination notice and the Company’s determination that the asset had no alternative future use, the Company concluded the net carrying value of the BMS Relaxin intangible asset was greater than its estimated fair value and therefore recorded an impairment charge of $ 2.5 million. In the second quarter of 2022, the Company received verbal notification from BMS of its intent to terminate the Collaboration and License Agreement (“FGF-21”) between BMS and the Company (the “FGF-21 Agreement”), which was followed by a formal notification on July 18, 2022 to be effective three months from receipt of the formal notification date. Due to this termination notice and the Company’s determination that the asset had no alternative future use, the Company concluded the net carrying value of the BMS FGF-21 intangible asset was greater than its estimated fair value and therefore recorded an impairment charge of $ 7.2 million. The Company’s intangible assets also include acquired in-process research and development (“IPR&D”) from a business combination, which is recognized as an indefinite lived intangible asset until completion or abandonment of the related R&D activities. When the related R&D activity is completed, the IPR&D intangible asset is reclassified as a finite-lived intangible asset and amortized over the remaining useful life. The Company’s acquired IPR&D is tested for impairment annually or more frequently if events or changes in circumstances between annual tests indicate that the asset may be impaired. While the Company’s current and historical operating losses and negative cash flows are possible indicators of impairment, management believes future cash flows to be generated by its remaining long-lived assets support the carrying value. There were no impairment charges recognized during the three and nine months ended September 30, 2023 . Net Loss Per Ordinary Share, As Converted (Note 1) Basic net loss per ordinary share is calculated by dividing the net loss by the weighted-average number of ordinary shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per ordinary share is computed by dividing the weighted-average number of ordinary shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, potentially dilutive securities are excluded from the calculation of diluted net loss per share because their effect was anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented. For the periods presented, the following table presents potentially dilutive securities, excluded from the computation of diluted net loss per ordinary share: Three and Nine Months Ended September 30, 2023 2022 Outstanding stock options, as converted (Note 1) 6,790,557 5,516,952 Outstanding RSUs, as converted (Note 1) 612,258 — Total 7,402,815 5,516,952 Share-Based Compensation The Company accounts for share-based compensation under the provisions of ASC Topic 718, Compensation—Stock Compensation . The Company estimates the fair value of each option award on the date of grant using the Black-Scholes option pricing model. The fair value of restricted stock units (“RSU”) is based on the closing price of the Company’s common stock on the date of grant. The Company recognizes share-based compensation expense on a straight-line basis based upon the grant date fair value. The Company recognizes the effect of forfeitures in compensation cost in the period that the award was forfeited. See Note 11—Share-Based Compensation for information on the assumptions used in determining the grant date fair value of option awards. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standards setting bodies that are adopted as of the specified effective date. The Company believes the impact of recently issued standards and any issued but not yet effective standards will not have a material impact on its condensed consolidated financial statements upon adoption.

Balance Sheets Details

Balance Sheets Details	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheets Details	3. Balance Sheet Details Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): September 30, December 31, Prepaid R&D costs (1) $ 3,721 $ 1,476 Tax receivable 2,235 1,506 Prepaid insurance and service contracts 1,008 1,424 Other 805 487 Total $ 7,769 $ 4,893 __________ (1) Includes $ 79 and $ 14 of prepaid R&D costs due to related parties as of September 30, 2023 and December 31, 2022 , respectively. Property and Equipment, Net Property and equipment, net, consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 8,084 $ 7,559 Computers, software and office equipment 523 512 Leasehold improvements 506 467 Office furniture and fixtures 130 123 9,243 8,661 Accumulated depreciation and amortization ( 6,244 ) ( 5,617 ) Total $ 2,999 $ 3,044 Depreciation and amortization expense related to property and equipment totaled $ 0.2 million for each of the three months ended September 30, 2023 and 2022, and $ 0.6 million and $ 0.5 million for the nine months ended September 30, 2023 and 2022, respectively. Accrued Liabilities Accrued liabilities consist of the following (in thousands): September 30, December 31, Accrued R&D costs (1) $ 3,997 $ 4,069 Accrued compensation 3,536 3,494 Accrued audit, tax and filing fees 2,252 1,703 Accrued directors and officers insurance premium (2) — 926 Accrued other 1,020 1,122 Total $ 10,805 $ 11,314 __________ (1) Includes $ 114 and $ 99 of accrued R&D costs due to related parties as of September 30, 2023 and December 31, 2022 , respectively. (2) Represents the remaining balance due at December 31, 2022 under the Company’s insurance premium financing agreement, which was payable in equal monthly installments through May 2023 and bore interest at approximately 3.4 % per annum. Accumulated Other Comprehensive Loss The following table provides a reconciliation of the components of accumulated other comprehensive loss for the three and nine months ended September 30, 2023 (in thousands): Three Months Ended Nine Months Ended Foreign Currency Items Unrealized Gains and Losses on MDS Total Foreign Currency Items Unrealized Gains and Losses on MDS Total Balance at beginning of period $ ( 790 ) $ ( 163 ) $ ( 953 ) $ ( 790 ) $ ( 512 ) $ ( 1,302 ) Changes in comprehensive loss — 23 23 — ( 16 ) ( 16 ) Amounts reclassified from — 140 140 — 528 528 Total other comprehensive income — 163 163 — 512 512 Balance at end of period $ ( 790 ) $ — $ ( 790 ) $ ( 790 ) $ — $ ( 790 ) The following table provides a reconciliation of the components of accumulated other comprehensive loss for the three and nine months ended September 30, 2022 (in thousands): Three Months Ended Nine Months Ended Foreign Currency Items Unrealized Losses on MDS Total Foreign Currency Items Unrealized Losses on MDS Total Balance at beginning of period $ ( 790 ) $ ( 217 ) $ ( 1,007 ) $ ( 790 ) $ — $ ( 790 ) Changes in comprehensive loss — ( 360 ) ( 360 ) — ( 577 ) ( 577 ) Total other comprehensive loss — ( 360 ) ( 360 ) — ( 577 ) ( 577 ) Balance at end of period $ ( 790 ) $ ( 577 ) $ ( 1,367 ) $ ( 790 ) $ ( 577 ) $ ( 1,367 )

Intangible Assets, Net

Intangible Assets, Net	9 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	4. Intangible Assets, Net Intangible assets, net, consist of the following (in thousands, except years): As of September 30, 2023 Weighted- Gross Accumulated Intangible Acquired technologies 8.3 $ 7,410 $ ( 3,572 ) $ 3,838 IPR&D 20,940 — $ 20,940 Total $ 28,350 $ ( 3,572 ) $ 24,778 Intangible assets, net, consist of the following (in thousands, except years): As of December 31, 2022 Weighted- Gross Impairment (1) Accumulated Intangible Acquired technologies 8.8 $ 24,330 $ ( 9,660 ) $ ( 10,360 ) $ 4,310 IPR&D 20,940 — — $ 20,940 Total $ 45,270 $ ( 9,660 ) $ ( 10,360 ) $ 25,250 __________ (1) Includes the impairment of BMS Relaxin and BMS FGF-21 intangible assets, as more fully described within the Intangible Assets, Net subsection of Note 2—Summary of Significant Accounting Policies . These intangible asset impairments are presented in the condensed consolidated statements of operations and comprehensive loss as impairment of intangible assets within operating activities. Amortization expense related to intangible assets totaled $ 0.2 million in each of the three months ended September 30, 2023 and 2022 , and $ 0.5 million and $ 0.9 million for the nine months ended September 30, 2023 and 2022 , respectively.

Marketable Debt Securities, Ava

Marketable Debt Securities, Available-for-Sale	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Debt Securities, Available-for-Sale	5. Marketable Debt Securities, Available-for-Sale There were no investments classified as MDS as of September 30, 2023. The following table summarizes the Company’s MDS as of December 31, 2022 (in thousands, except years): Weighted Amortized Unrealized Unrealized Fair Classified as current assets: Commercial paper 1 or less $ 15,803 $ 1 $ ( 23 ) $ 15,781 Certificates of deposit 1 or less 7,500 2 ( 25 ) 7,477 U.S. government securities 1 or less 5,001 — ( 30 ) 4,971 Corporate bonds 1 or less 646 — ( 2 ) 644 Total Marketable debt securities, 1 or less $ 28,950 $ 3 $ ( 80 ) $ 28,873 Classified as non-current assets: U.S. government securities 1.4 $ 6,979 $ — $ ( 184 ) $ 6,795 Corporate bonds 1.5 6,824 — ( 192 ) 6,632 Asset backed securities 1.8 2,999 — ( 45 ) 2,954 Non-U.S. government securities 1.5 423 — ( 11 ) 412 Total Marketable debt securities, available- 1.5 $ 17,225 $ — $ ( 432 ) $ 16,793 Total 0.7 $ 46,175 $ 3 $ ( 512 ) $ 45,666 As of December 31, 2022 , the Company had $ 0.2 million of accrued interest on MDS included in prepaid expenses and other current assets in the condensed consolidated balance sheets. The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of December 31, 2022, aggregated by investment category for MDS that had been in a continuous loss position for less than 12 months and for more than 12 months (in thousands): Less than 12 months More than 12 months Estimated Gross Estimated Gross December 31, 2022 Commercial paper $ 12,803 $ ( 22 ) $ — $ — U.S. government securities 11,765 ( 216 ) — — Corporate bonds 7,276 ( 193 ) — — Certificates of deposit 2,975 ( 25 ) — — Asset backed securities 2,954 ( 45 ) — — Non-U.S. government securities 412 ( 11 ) — — Total $ 38,185 $ ( 512 ) $ — $ — Investment income, net Investment income, net, which includes income from the Company’s MDS as well as investments in money market funds and other securities included in cash equivalents, consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Interest and dividend income $ 195 $ 218 $ 764 $ 365 Accretion/amortization of discounts/premiums 2,345 291 4,143 367 Realized (losses) gains, net ( 140 ) — ( 528 ) — Investment income, net $ 2,400 $ 509 $ 4,379 $ 732

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. Fair Value Measurements The following table presents the Company’s financial assets measured at fair value on a recurring basis as of September 30, 2023 (in thousands): Total Level 1 Level 2 Level 3 Cash equivalents: U.S. government securities $ 178,937 $ — $ 178,937 $ — Certificates of deposit 24,000 — 24,000 — Money market funds 17,137 17,137 — — Total cash equivalents $ 220,074 $ 17,137 $ 202,937 $ — The following table presents the Company’s financial assets measured at fair value on a recurring basis as of December 31, 2022 (in thousands): Total Level 1 Level 2 Level 3 Cash equivalents: Certificates of deposit $ 24,000 $ — $ 24,000 $ — Commercial paper 15,352 — 15,352 $ — Money market funds 12,743 12,743 — — Total cash equivalents $ 52,095 $ 12,743 $ 39,352 $ — Marketable debt securities, available-for-sale: Commercial paper $ 15,781 $ — $ 15,781 $ — Certificates of deposit 7,477 — 7,477 — U.S. government securities 4,971 — 4,971 — Corporate bonds 644 — 644 — Total Marketable debt securities, available-for-sale $ 28,873 $ — $ 28,873 $ — Marketable debt securities, available-for-sale, net of U.S. government securities $ 6,795 $ — $ 6,795 $ — Corporate bonds 6,632 — 6,632 — Asset backed securities 2,954 — 2,954 — Non-U.S. government securities 412 — 412 — Total Marketable debt securities, available-for-sale, $ 16,793 $ — $ 16,793 $ — As of and for the periods ended September 30, 2023 and December 31, 2022 , the Company had no assets or liabilities measured on a non-recurring basis, and no liabilities measured at fair value on a recurring basis. During the nine months ended September 30, 2023 and the year ended December 31, 2022 , there were no transfers into or out of Level 3 of the fair value hierarchy.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Litigation From time to time, the Company may be involved in various lawsuits, legal proceedings, or claims that arise in the ordinary course of business. Management believes there are no claims or actions pending against the Company as of September 30, 2023 which will have, individually or in the aggregate, a material adverse effect on its business, liquidity, financial position, or results of operations. Litigation, however, is subject to inherent uncertainties, and an adverse result in these or other matters may arise from time to time that may harm the Company’s business. Indemnification In accordance with the Company’s amended and restated memorandum and articles of association, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving in such capacity. There have been no claims to date, and the Company has a directors and officers liability insurance policy that may enable it to recover a portion of any amounts paid for future claims.

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Lessee Disclosure [Abstract]
Leases	8. Leases The Company has operating leases for its corporate offices and certain equipment. The leases have remaining lease terms of approximately less than one to four years. During the nine months ended September 30, 2023 and the year ended December 31, 2022, the Company did not acquire any new ROU assets or lease liabilities. The components of lease expense consist of the following (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Operating lease expenses R&D: Operating lease costs $ 546 $ 553 $ 1,647 $ 1,666 Variable lease costs (1) 325 312 1,110 763 Operating lease expenses G&A: Operating lease costs 135 129 398 379 Variable lease costs (1) 94 59 282 160 Total operating leases expense $ 1,100 $ 1,053 $ 3,437 $ 2,968 ____________ (1) Includes short-term lease costs which are immaterial. Supplemental cash flow information related to leases is as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Cash paid for amounts included in Operating cash flows used for operating $ 701 $ 689 $ 2,105 $ 1,492 Weighted-average remaining lease term in years 4.2 5.2 4.2 5.2 Weighted-average discount rate 7.63 % 7.63 % 7.63 % 7.63 %

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2023
Convertible Preferred Ordinary Shares And Ordinary Shares [Abstract]
Shareholders' Equity	9. Shareholders' Equity Ordinary Shares In June 2021, Ambrx Cayman completed its initial public offering of ADSs. Each ADS represented seven ordinary shares of Ambrx Cayman. As a result of the Merger described in Note 1 , each ordinary share issued and outstanding immediately prior to the effective time of the Merger (including ordinary shares underlying the outstanding ADSs), were automatically converted into one-seventh (1/7) of one duly issued, fully paid and non-assessable share of common stock. All ordinary shares and per share amounts presented in these condensed consolidated financial statements have been adjusted to reflect the retroactive effect of the automatic conversion of each ordinary share into one-seventh (1/7) of one share of common stock as a result of the Merger. Securities Purchase Agreement On May 23, 2023, the Company entered into a securities purchase agreement with a related party, pursuant to which the Company offered and sold 5,384,063 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, at a selling price of $ 13.93 per ordinary share, as converted to reflect the exchange ratio effectuated in the Merger, for gross proceeds of approximately $ 75.0 million, less expenses of approximately $ 0.3 million, for net proceeds of approximately $ 74.7 million. There were no underwriting or placement agent fees associated with this offering. The offering price of $ 13.93 per ordinary share, as converted to reflect the exchange ratio effectuated in the Merger, was based on the 5‑day trailing variable weighted-average price of the Company’s ADSs immediately prior to the agreement date. Upon the satisfaction of all closing conditions, the offering closed on June 27, 2023. At-the-Market Offering Agreement On July 29, 2022, the Company entered into a sales agreement with Cowen and Company LLC, pursuant to which the Company was able to offer and sell ordinary shares having an aggregate offering price of up to $ 80.0 million (the “ATM Program”). During the first quarter of 2023, the Company issued and sold 16,575,826 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, at an average selling price of $ 4.83 per share, as converted to reflect the exchange ratio effectuated in the Merger, for gross proceeds of approximately $ 80.0 million, less sales commissions and expenses of approximately $ 2.2 million, for net proceeds of approximately $ 77.8 million. Accordingly, as of March 10, 2023, the ATM Program is complete. Other Share Issuances During the three and nine months ended September 30, 2023, the Company issued a total of 40,000 and 110,713 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, respectively, valued at $ 0.7 million and $ 1.5 million, respectively, to service providers in lieu of cash. Amended and Restated Certificate of Incorporation On October 11, 2023, the Company filed an Amended and Restated Certificate of Incorporation, pursuant to which, among other things, the Company’s authorized capital stock was increased to 251,000,000 shares of capital stock, which consists of 250,000,000 shares of common stock and 1,000,000 shares of preferred stock. The number of authorized shares of any class may be increased or decreased by an amendment to the Company’s certificate of incorporation proposed by its board of directors and approved by a majority of voting shares voted on the issue at the meeting at which a quorum exists.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenues	10. Revenues During the three and nine months ended September 30, 2023 and 2022, the Company recognized revenue over time under each of its R&D Agreements as its performance obligations were satisfied. Variable consideration, such as development and regulatory milestones previously constrained is recognized to the extent a significant revenue reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Revenue recognized was earned under the Company’s R&D Agreements and is summarized below based on the nature of payment type (in thousands): Three Months Ended Nine Months Ended Timing of Transfer of Goods or Services 2023 2022 2023 2022 Over time: Reimbursements $ 53 $ 216 $ 94 $ 384 License fees — 693 — 2,140 R&D services — 688 6 1,985 Point in time: Milestones — — 1,100 — Total revenues $ 53 $ 1,597 $ 1,200 $ 4,509 During the nine months ended September 30, 2023 , the Company recognized milestone revenue of $ 1.1 million from performance obligations satisfied (or partially satisfied) pursuant to an agreement with BMS. The Company did no t recognize any revenue from performance obligations satisfied (or partially satisfied) during the three and nine months ended September 30, 2022. Remaining Performance Obligations and Deferred Revenue As of September 30, 2023, the Company had no unsatisfied remaining performance obligations for minimum full-time equivalent (“FTE”) services under its R&D Agreements. In each of the periods ended September 30, 2023 and December 31, 2022, the Company had deferred revenue of $ 1.7 million, which was primarily related to (i) the combined performance obligation for transfer of the Company’s license and R&D services and (ii) conducting R&D activities which are a separate performance obligation in the Company’s contracts pursuant to research plans under the R&D agreements. The Company anticipates that the remaining performance obligations as of September 30, 2023 will be satisfied over the next 3.5 to four years . Zhejiang Medicine Co. Ltd. (“ZMC”) In June 2013, the Company entered into a co-development and license agreement with ZMC to develop and commercialize ARX788 (the “ZMC Agreement”). In March 2019, the ZMC Agreement was transferred to NovoCodex Biopharmaceutical Ltd (“NovoCodex”), a subsidiary of ZMC. Under the ZMC Agreement, both companies will continue the development of ARX788. ZMC is responsible, at its sole expense, for making commercially reasonable efforts to develop, obtain regulatory approval for and commercialize the licensed products in China and fund the development of the product in Australia or other jurisdictions approved by a joint steering committee through Phase 1 clinical trials. ZMC will receive commercial rights in China while Ambrx retains commercial rights outside of China and will receive low double-digit tiered royalties on sales of the product in China. Under the terms of the ZMC Agreement, as amended, ZMC received an exclusive right and license for the prevention, and treatment of human diseases and conditions associated with αHer2 with the right to grant sublicenses under the Company’s existing patents and know how. Under the agreement, the Company is entitled to receive tiered royalties as high as mid-teens range on aggregate net sales of ARX788 in the People’s Republic of China (“PRC”). The Company will be entitled to receive these royalties until the later of the expiration of the applicable patent rights or 20 years after the first commercial sale of the product in the PRC. In addition, the Company is obligated to pay royalties in a mid-single digit to low-teens percentage range of any sublicensing profit that the Company may receive outside of the PRC, depending on what phase of clinical development has been completed at the time of transfer, or a low single digit percentage range on any net sales that the Company or its successors may receive from sales of ARX788 outside of the PRC, if the market authorization of ARX788 is based on Phase 1 clinical data obtained during the Company’s collaboration with ZMC. BeiGene Ltd. (“BeiGene”) In March 2019, the Company entered into a collaboration and exclusive license agreement with BeiGene for the development and commercialization of next-generation biologics drugs (the “BeiGene Agreement”) and received an upfront license payment to fund the initial discovery and research activities of $ 10.0 million. Under the terms of the BeiGene Agreement, BeiGene will have worldwide rights to develop and commercialize any drug products resulting from the collaboration. BeiGene may terminate the BeiGene Agreement upon three months ’ written notice. The Company or BeiGene may terminate the BeiGene Agreement for cause for safety reasons or upon other party’s material breach that remains uncured after receipt of notice thereof, or upon certain bankruptcy or insolvency proceedings. The Company may also terminate the BeiGene Agreement for cause due to BeiGene’s failure to use commercially reasonable efforts in the development and commercialization of products. In November 2022, the Company received notification from BeiGene of its intent to terminate the HER-3 anti-body drug conjugate (“ADC”) research program, effective January 23, 2023 (the “BeiGene Notification”). Prior to receipt of the BeiGene Notification, deferred revenue would have been recognized through February 2023. However, the BeiGene Notification resulted in a re-evaluation of the measure of progress for the program and the Company accelerating revenue recognition associated with the remaining deferred revenue as of the notification date. In March 2023, the Company and BeiGene extended the initial research term for an additional two years . NovoCodex Biopharmaceuticals Ltd. (“NovoCodex”) In October 2019, the Company entered into a co-development and commercialization agreement with NovoCodex, a majority owned company of ZMC to develop and commercialize Ambrx’s internally developed site-specific ADCs (the “NovoCodex Agreement”), and received an upfront, non-refundable, and non-creditable payment of $ 2.0 million. The license to the Company’s intellectual property and R&D services performed by the Company until the initial manufacturing run or technology transfer are combined as a single performance obligation. R&D services performed after the initial manufacturing run or technology transfer are considered to represent a separate performance obligation. NovoCodex may terminate the NovoCodex Agreement upon six months written notice. The Company or NovoCodex may terminate the NovoCodex Agreement for cause for safety reasons or upon other party’s material breach that remains uncured after receipt of notice thereof, or upon certain bankruptcy or insolvency proceedings. The Company may also terminate the NovoCodex Agreement for cause due to NovoCodex’s failure to use commercially reasonable efforts in the development and commercialization of products. Under the terms of the NovoCodex Agreement, NovoCodex is responsible for developing and commercializing ARX305 in China while Ambrx is responsible for developing and commercializing ARX305 outside of China. NovoCodex will fund global development activities through the end of Phase 1 clinical trials. The Company is eligible to receive payments for R&D services for a minimum of one FTE based on the annual rate defined in the agreement. In addition, the Company is eligible to receive milestone payments upon achievement of certain clinical development milestones. During the fourth quarter of 2022, the Company recognized milestone revenue of $ 1.0 million upon dosing of the first patient with ARX305 pursuant to the NovoCodex Agreement. The Company is also eligible to receive tiered royalties on a product-by-product basis on aggregate worldwide net sales of each product. NovoCodex is also eligible to share in a portion of ARX305 product sales outside of China. In the event the Company transfers or licenses the Phase 1 clinical data to a third party, NovoCodex is entitled to royalties on aggregate net sales of ARX305 outside of China. Since inception and through September 30, 2023, the Company has identified two performance obligations for all promises under the NovoCodex Agreement. Accordingly, the Company recognizes revenue for the transaction price based upon efforts or inputs to satisfy its performance obligations relative to the total expected inputs. Due to the uncertainty in the achievement of the development milestones, the variable consideration associated with these future milestone payments has been fully constrained (excluded) from the transaction price until such time that the Company concludes that it is probable that a significant reversal of previously recognized revenue will not occur. These estimates are re-assessed at each reporting period. Sino Biopharmaceutical Co., Ltd. (“Sino Biopharma”) In January 2020, the Company entered into a co-development and license agreement with Sino Biopharma pursuant to which the Company (i) assigned to Sino Biopharma existing and future patent rights in the People’s Republic of China (inclusive of Hong Kong, Macau and Taiwan, the Sino Territory) to ARX822 and ARX102 (each a preclinical compound) and (ii) granted exclusive rights and licenses in the Sino Territory to develop and manufacture ARX822 and ARX102 (the “Sino Agreement”). Sino Biopharma is solely responsible, at its own expense, for marketing, selling, offering for sale, distributing, promoting and otherwise commercializing the products in the Sino Territory and costs associated with Investigational New Drug (“IND”) enabling activities and for providing the Company with study drug for up to 100 patients enrolled in a Phase 1 clinical trial for each of ARX822 and ARX102, if any. Sino Biopharma may terminate the Sino Agreement upon six-months ’ written notice. Under the terms of the Sino Agreement, the Company received an upfront payment of $ 10.0 million, which is no longer subject to refund. The Company is also eligible to receive milestone payments upon achievement of certain potential development and regulatory milestones for each program. In the fourth quarter of 2022, Sino completed its IND enabling activities associated with ARX102, at which time the Company fully recognized all previously deferred revenue associated with this compound. In 2022, at Sino’s request the Company has temporarily suspended development of ARX822. Since inception and through September 30, 2023, the Company has identified one performance obligation per each preclinical compound for all promises under the agreement. Accordingly, the Company recognizes revenue for the transaction price based upon efforts or inputs to satisfy its performance obligations relative to the total expected inputs. Due to the uncertainty in the achievement of the development and regulatory milestones, the variable consideration associated with these future milestone payments has been fully constrained (excluded) from the transaction price until such time that the Company concludes that it is probable that a significant reversal of previously recognized revenue will not occur. These estimates are re-assessed at each reporting period. Contract Assets and Liabilities Contract balances are as follows (in thousands): September 30, December 31, Receivables, included in accounts receivable, net $ 122 $ 376 Contract liabilities, included in deferred revenue, current and $ 1,749 $ 1,749

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Share-Based Compensation	11. Share-Based Compensation Share-based compensation expense was as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Share-based compensation expense: Stock options $ 3,212 $ 1,538 $ 6,908 $ 5,067 RSUs 942 — 1,279 — Issuance of ordinary shares for 666 — 1,457 — $ 4,820 $ 1,538 $ 9,644 $ 5,067 Share-based compensation expense Research and development $ 1,665 $ 921 $ 4,383 $ 3,143 General and administrative 3,155 617 5,261 1,924 $ 4,820 $ 1,538 $ 9,644 $ 5,067 Stock Options The following table summarizes option activity for the periods presented, excluding options granted and canceled as part of the option repricing discussed below: Total Weighted- Aggregate Weighted- Outstanding at December 31, 2022 5,587,892 $ 7.76 $ 1,088 5.4 Granted 4,042,803 $ 10.70 Exercised ( 2,299,251 ) $ 7.86 Forfeited/expired ( 540,887 ) $ 7.01 Outstanding at September 30, 2023 6,790,557 $ 7.02 $ 39,113 8.4 Vested and exercisable at 1,582,502 $ 2.18 $ 15,198 7.7 Cash proceeds received from stock option exercises during the nine months ended September 30, 2023 totaled $ 18.1 million. The total intrinsic value of stock options exercised during the nine months ended September 30, 2023 was $ 12.5 million. There were no option exercises during the nine months ended September 30, 2022. As of September 30, 2023, unrecognized compensation cost related to outstanding stock options was $ 34.6 million, which is expected to be recognized over a remaining weighted-average term of 2.9 years. The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of option grants were as follows: For the Nine Months Ended September 30, 2023 2022 Expected term (in years) 5.9 5.9 Risk-free interest rate 3.9 % 2.3 % Expected volatility 86.9 % 80.2 % Dividend yield — — Weighted-average grant date fair value. $ 7.95 $ 2.92 Option Repricing On January 27, 2023, the compensation committee of the board of directors of the Company approved an option repricing program (the “Option Repricing”) to permit the Company to reprice all underwater options to purchase the Company’s common stock held by its employees (including an officer of the Company), non-employee directors and consultants providing services as of January 27, 2023. Under the Option Repricing, options with an exercise price above $ 1.96 per ordinary share, as converted to reflect the exchange ratio effectuated in the Merger, representing an aggregate of 2,612,044 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, or approximately 53.2 % of the total options outstanding as of January 27, 2023, were amended to reduce such exercise price to $ 1.96 per ordinary share, as converted to reflect the exchange ratio effectuated in the Merger. The Option Repricing resulted in additional compensation expense of $ 1.2 million, including $ 0.1 million and $ 0.8 million that was recognized in the Company’s condensed consolidated statements of operations and comprehensive loss during the three and nine months ended September 30, 2023, respectively. Restricted Stock Units The following table summarizes RSU activity for the periods presented: Number of Weighted- Non-vested balance at December 31, 2022 — $ — Granted 612,258 $ 9.70 Non-vested balance at September 30, 2023 612,258 $ 9.70 As of September 30, 2023, unrecognized compensation costs related to non-vested RSUs was $ 4.7 million, which is expected to be recognized over a remaining weighted-average term of 2.4 years. Employee Share Purchase Plan During the nine months ended September 30, 2022, there were 29,705 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, issued pursuant to the Company’s employee stock purchase plan (the “ESPP”) for gross proceeds in each period of approximately $ 0.1 million. No ordinary shares were issued during the three months ended September 30, 2022. The ESPP was suspended indefinitely, effective December 16, 2022, and as such, as of September 30, 2023 and December 31, 2022 , there was no unrecognized share-based compensation expense related to the ESPP.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions In the ordinary course of business, the Company has related party transactions with affiliates of a noncontrolling shareholder. The following tables present the Company’s activities with affiliates of the noncontrolling shareholders (in thousands): September 30, December 31, Balances: Prepaid R&D expenses $ 79 $ 14 Accounts payable $ 82 $ 352 Accrued liabilities $ 114 $ 99 Three Months Ended Nine Months Ended 2023 2022 2023 2022 Activity: Amounts paid $ 152 $ 90 $ 662 $ 359 R&D expense recognized $ 248 $ 207 $ 342 $ 676 As more fully described within the Securities Purchase Agreement subsection of Note 9, Shareholders’ Equity , during the second quarter of 2023, the Company entered into a securities purchase agreement with a significant shareholder, pursuant to which the Company issued 5,384,063 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, for net proceeds of approximately $ 74.7 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Risk and Uncertainties	Risks and Uncertainties
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to the valuation of share-based awards and marketable debt securities, available-for-sale (“MDS”), the discount rate used in estimating the present value of the right-of-use (“ROU”) assets and lease liabilities, the useful lives of property and equipment and intangible assets, the recoverability of long-lived assets, clinical trial accruals, periods over which revenue should be recognized, deferred income taxes and related valuation allowances, and the assessment of the Company’s ability to fund its operations for at least the next 12 months from the date of issuance of these condensed consolidated financial statements. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Estimates are assessed each reporting period and updated to reflect current information. As future events and their effects cannot be determined with precision, actual results may materially differ from those estimates or assumptions. Due to recent disruptions in access to bank deposits and lending commitments associated with bank failures, the COVID-19 pandemic and macroeconomic and geopolitical conditions, there has been uncertainty and disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of September 30, 2023. While there was no material impact to the Company’s condensed consolidated financial statements as of and for the three and nine months ended September 30, 2023 , these estimates may change, as new events occur and additional information is obtained, which could materially impact the Company’s condensed consolidated financial statements in future reporting periods.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, MDS, and accounts receivable which are generally not collateralized. Deposits in the Company’s checking and money market accounts are maintained in federally insured financial institutions and are subject to federally insured limits or limits set by the Securities Investor Protection Corporation. In addition, the Company maintains cash and cash equivalents in foreign bank accounts, which are not federally insured. The Company attempts to minimize credit risk associated with its cash and cash equivalents by periodically evaluating the credit quality of its primary financial institutions. The Company’s investment portfolio is maintained in accordance with its investment policy, which is designed to preserve capital, safeguard funds and limit exposure to risk. While the Company maintains cash deposits in Federal Deposit Insurance Corporation insured financial institutions in excess of federally insured limits, it does not believe that it is exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has not experienced any losses on such accounts. During the three months ended September 30, 2023, revenues from the Company’s top customer represented 100 % of total revenues. During the three months ended September 30, 2022 , revenues from the Company’s top three customers represented 66.2 %, 14.9 % and 13.6 % of total revenues, respectively. During the nine months ended September 30, 2023, revenues from the Company’s top customer represented 91.7 % of total revenues. During the nine months ended September 30, 2022, revenues from the Company’s top two customers represented 78.6 % and 13.7 % of total revenues, respectively. As of September 30, 2023, billed accounts receivable for the top customer represented 100 % of total billed receivables. As of December 31, 2022, billed accounts receivable for the top two customers represented 78.4 % and 11.8 % of total billed receivables, respectively.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of readily available cash in checking accounts, U.S. government securities, certificates of deposit, money market funds and other marketable securities with original maturities of three months or less. The following table provides a reconciliation of cash, cash equivalents and restricted cash, reported within the condensed consolidated statements of cash flows (in thousands): For the Nine Months 2023 2022 Cash and cash equivalents $ 225,262 $ 51,081 Restricted cash 665 831 Total cash, cash equivalents, and restricted cash presented in the $ 225,927 $ 51,912 As of September 30, 2023 and 2022 , the Company’s restricted cash consists of cash related to the Company’s clinical trials.
Accounts Receivable, Net	Accounts Receivable, Net Accounts receivable, net, are recorded net of any allowance for current expected credit losses measured based on historical experience, current conditions, and reasonable and supportable forecasts. As of September 30, 2023 and December 31, 2022 , the Company has determined an allowance for expected credit losses is not material.
Intangible Assets	Intangible Assets, Net The Company records its intangible assets based on their fair values at the date of acquisition. The Company’s finite lived intangible assets related to acquired technologies has estimated remaining useful lives between approximately 2.3 to 11.3 years as of September 30, 2023, and three to 12 years as of December 31, 2022. Amortization expense for the Company’s finite lived intangible assets is charged to research and development expense in the condensed consolidated statements of operations and comprehensive loss on a straight-line basis over the assets’ estimated useful lives. Impairment losses on finite-lived intangible assets are recorded when indicators of impairment are present and the undiscounted cash flows estimated to be generated by those assets are less than the assets’ carrying amount. If such assets are considered impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets. In the first quarter of 2022, the Company received a Notice of Termination of Collaboration and License agreement (“Relaxin”) between Bristol-Myers Squibb Company (“BMS”) and the Company (the “Relaxin Agreement”) from BMS to be effective three months from receipt of the notification. Due to this termination notice and the Company’s determination that the asset had no alternative future use, the Company concluded the net carrying value of the BMS Relaxin intangible asset was greater than its estimated fair value and therefore recorded an impairment charge of $ 2.5 million. In the second quarter of 2022, the Company received verbal notification from BMS of its intent to terminate the Collaboration and License Agreement (“FGF-21”) between BMS and the Company (the “FGF-21 Agreement”), which was followed by a formal notification on July 18, 2022 to be effective three months from receipt of the formal notification date. Due to this termination notice and the Company’s determination that the asset had no alternative future use, the Company concluded the net carrying value of the BMS FGF-21 intangible asset was greater than its estimated fair value and therefore recorded an impairment charge of $ 7.2 million. The Company’s intangible assets also include acquired in-process research and development (“IPR&D”) from a business combination, which is recognized as an indefinite lived intangible asset until completion or abandonment of the related R&D activities. When the related R&D activity is completed, the IPR&D intangible asset is reclassified as a finite-lived intangible asset and amortized over the remaining useful life. The Company’s acquired IPR&D is tested for impairment annually or more frequently if events or changes in circumstances between annual tests indicate that the asset may be impaired. While the Company’s current and historical operating losses and negative cash flows are possible indicators of impairment, management believes future cash flows to be generated by its remaining long-lived assets support the carrying value. There were no impairment charges recognized during the three and nine months ended September 30, 2023 .
Net Loss Per Ordinary Share, As Converted	Net Loss Per Ordinary Share, As Converted (Note 1) Basic net loss per ordinary share is calculated by dividing the net loss by the weighted-average number of ordinary shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per ordinary share is computed by dividing the weighted-average number of ordinary shares and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. For purposes of the diluted net loss per share calculation, potentially dilutive securities are excluded from the calculation of diluted net loss per share because their effect was anti-dilutive and therefore, basic and diluted net loss per share were the same for all periods presented. For the periods presented, the following table presents potentially dilutive securities, excluded from the computation of diluted net loss per ordinary share: Three and Nine Months Ended September 30, 2023 2022 Outstanding stock options, as converted (Note 1) 6,790,557 5,516,952 Outstanding RSUs, as converted (Note 1) 612,258 — Total 7,402,815 5,516,952
Share-Based Compensation	Share-Based Compensation The Company accounts for share-based compensation under the provisions of ASC Topic 718, Compensation—Stock Compensation . The Company estimates the fair value of each option award on the date of grant using the Black-Scholes option pricing model. The fair value of restricted stock units (“RSU”) is based on the closing price of the Company’s common stock on the date of grant. The Company recognizes share-based compensation expense on a straight-line basis based upon the grant date fair value. The Company recognizes the effect of forfeitures in compensation cost in the period that the award was forfeited. See Note 11—Share-Based Compensation for information on the assumptions used in determining the grant date fair value of option awards.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standards setting bodies that are adopted as of the specified effective date. The Company believes the impact of recently issued standards and any issued but not yet effective standards will not have a material impact on its condensed consolidated financial statements upon adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash, reported within the condensed consolidated statements of cash flows (in thousands): For the Nine Months 2023 2022 Cash and cash equivalents $ 225,262 $ 51,081 Restricted cash 665 831 Total cash, cash equivalents, and restricted cash presented in the $ 225,927 $ 51,912
Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share	For the periods presented, the following table presents potentially dilutive securities, excluded from the computation of diluted net loss per ordinary share: Three and Nine Months Ended September 30, 2023 2022 Outstanding stock options, as converted (Note 1) 6,790,557 5,516,952 Outstanding RSUs, as converted (Note 1) 612,258 — Total 7,402,815 5,516,952

Balance Sheets Details (Tables)

Balance Sheets Details (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Prepaid expenses and other current assets	Prepaid expenses and other current assets consist of the following (in thousands): September 30, December 31, Prepaid R&D costs (1) $ 3,721 $ 1,476 Tax receivable 2,235 1,506 Prepaid insurance and service contracts 1,008 1,424 Other 805 487 Total $ 7,769 $ 4,893 __________ (1) Includes $ 79 and $ 14 of prepaid R&D costs due to related parties as of September 30, 2023 and December 31, 2022 , respectively.
Schedule of property and equipment	Property and equipment, net, consist of the following (in thousands): September 30, December 31, Laboratory equipment $ 8,084 $ 7,559 Computers, software and office equipment 523 512 Leasehold improvements 506 467 Office furniture and fixtures 130 123 9,243 8,661 Accumulated depreciation and amortization ( 6,244 ) ( 5,617 ) Total $ 2,999 $ 3,044
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, December 31, Accrued R&D costs (1) $ 3,997 $ 4,069 Accrued compensation 3,536 3,494 Accrued audit, tax and filing fees 2,252 1,703 Accrued directors and officers insurance premium (2) — 926 Accrued other 1,020 1,122 Total $ 10,805 $ 11,314 (1) Includes $ 114 and $ 99 of accrued R&D costs due to related parties as of September 30, 2023 and December 31, 2022 , respectively. Represents the remaining balance due at December 31, 2022 under the Company’s insurance premium financing agreement, which was payable in equal monthly installments through May 2023 and bore interest at approximately 3.4 % per annum.
Schedule of Reconciliation of Components of Accumulated Other Comprehensive Loss	The following table provides a reconciliation of the components of accumulated other comprehensive loss for the three and nine months ended September 30, 2023 (in thousands): Three Months Ended Nine Months Ended Foreign Currency Items Unrealized Gains and Losses on MDS Total Foreign Currency Items Unrealized Gains and Losses on MDS Total Balance at beginning of period $ ( 790 ) $ ( 163 ) $ ( 953 ) $ ( 790 ) $ ( 512 ) $ ( 1,302 ) Changes in comprehensive loss — 23 23 — ( 16 ) ( 16 ) Amounts reclassified from — 140 140 — 528 528 Total other comprehensive income — 163 163 — 512 512 Balance at end of period $ ( 790 ) $ — $ ( 790 ) $ ( 790 ) $ — $ ( 790 ) The following table provides a reconciliation of the components of accumulated other comprehensive loss for the three and nine months ended September 30, 2022 (in thousands): Three Months Ended Nine Months Ended Foreign Currency Items Unrealized Losses on MDS Total Foreign Currency Items Unrealized Losses on MDS Total Balance at beginning of period $ ( 790 ) $ ( 217 ) $ ( 1,007 ) $ ( 790 ) $ — $ ( 790 ) Changes in comprehensive loss — ( 360 ) ( 360 ) — ( 577 ) ( 577 ) Total other comprehensive loss — ( 360 ) ( 360 ) — ( 577 ) ( 577 ) Balance at end of period $ ( 790 ) $ ( 577 ) $ ( 1,367 ) $ ( 790 ) $ ( 577 ) $ ( 1,367 )

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	9 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets, net, consist of the following (in thousands, except years): As of September 30, 2023 Weighted- Gross Accumulated Intangible Acquired technologies 8.3 $ 7,410 $ ( 3,572 ) $ 3,838 IPR&D 20,940 — $ 20,940 Total $ 28,350 $ ( 3,572 ) $ 24,778 Intangible assets, net, consist of the following (in thousands, except years): As of December 31, 2022 Weighted- Gross Impairment (1) Accumulated Intangible Acquired technologies 8.8 $ 24,330 $ ( 9,660 ) $ ( 10,360 ) $ 4,310 IPR&D 20,940 — — $ 20,940 Total $ 45,270 $ ( 9,660 ) $ ( 10,360 ) $ 25,250 __________ (1) Includes the impairment of BMS Relaxin and BMS FGF-21 intangible assets, as more fully described within the Intangible Assets, Net subsection of Note 2—Summary of Significant Accounting Policies . These intangible asset impairments are presented in the condensed consolidated statements of operations and comprehensive loss as impairment of intangible assets within operating activities.

Marketable Debt Securities, A_2

Marketable Debt Securities, Available-for-Sale (Tables)	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-Sale Securities Reconciliation	The following table summarizes the Company’s MDS as of December 31, 2022 (in thousands, except years): Weighted Amortized Unrealized Unrealized Fair Classified as current assets: Commercial paper 1 or less $ 15,803 $ 1 $ ( 23 ) $ 15,781 Certificates of deposit 1 or less 7,500 2 ( 25 ) 7,477 U.S. government securities 1 or less 5,001 — ( 30 ) 4,971 Corporate bonds 1 or less 646 — ( 2 ) 644 Total Marketable debt securities, 1 or less $ 28,950 $ 3 $ ( 80 ) $ 28,873 Classified as non-current assets: U.S. government securities 1.4 $ 6,979 $ — $ ( 184 ) $ 6,795 Corporate bonds 1.5 6,824 — ( 192 ) 6,632 Asset backed securities 1.8 2,999 — ( 45 ) 2,954 Non-U.S. government securities 1.5 423 — ( 11 ) 412 Total Marketable debt securities, available- 1.5 $ 17,225 $ — $ ( 432 ) $ 16,793 Total 0.7 $ 46,175 $ 3 $ ( 512 ) $ 45,666
Schedule of Gross Unrealized Losses and Fair Values on Debt Securities Classified as Available-for Sale	The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of December 31, 2022, aggregated by investment category for MDS that had been in a continuous loss position for less than 12 months and for more than 12 months (in thousands): Less than 12 months More than 12 months Estimated Gross Estimated Gross December 31, 2022 Commercial paper $ 12,803 $ ( 22 ) $ — $ — U.S. government securities 11,765 ( 216 ) — — Corporate bonds 7,276 ( 193 ) — — Certificates of deposit 2,975 ( 25 ) — — Asset backed securities 2,954 ( 45 ) — — Non-U.S. government securities 412 ( 11 ) — — Total $ 38,185 $ ( 512 ) $ — $ —
Summary of Investment Income, Net	Investment income, net, which includes income from the Company’s MDS as well as investments in money market funds and other securities included in cash equivalents, consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Interest and dividend income $ 195 $ 218 $ 764 $ 365 Accretion/amortization of discounts/premiums 2,345 291 4,143 367 Realized (losses) gains, net ( 140 ) — ( 528 ) — Investment income, net $ 2,400 $ 509 $ 4,379 $ 732

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the Company’s financial assets measured at fair value on a recurring basis as of September 30, 2023 (in thousands): Total Level 1 Level 2 Level 3 Cash equivalents: U.S. government securities $ 178,937 $ — $ 178,937 $ — Certificates of deposit 24,000 — 24,000 — Money market funds 17,137 17,137 — — Total cash equivalents $ 220,074 $ 17,137 $ 202,937 $ — The following table presents the Company’s financial assets measured at fair value on a recurring basis as of December 31, 2022 (in thousands): Total Level 1 Level 2 Level 3 Cash equivalents: Certificates of deposit $ 24,000 $ — $ 24,000 $ — Commercial paper 15,352 — 15,352 $ — Money market funds 12,743 12,743 — — Total cash equivalents $ 52,095 $ 12,743 $ 39,352 $ — Marketable debt securities, available-for-sale: Commercial paper $ 15,781 $ — $ 15,781 $ — Certificates of deposit 7,477 — 7,477 — U.S. government securities 4,971 — 4,971 — Corporate bonds 644 — 644 — Total Marketable debt securities, available-for-sale $ 28,873 $ — $ 28,873 $ — Marketable debt securities, available-for-sale, net of U.S. government securities $ 6,795 $ — $ 6,795 $ — Corporate bonds 6,632 — 6,632 — Asset backed securities 2,954 — 2,954 — Non-U.S. government securities 412 — 412 — Total Marketable debt securities, available-for-sale, $ 16,793 $ — $ 16,793 $ —

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2023
Lessee Disclosure [Abstract]
Summary of Components of Operating Lease Expense	The components of lease expense consist of the following (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Operating lease expenses R&D: Operating lease costs $ 546 $ 553 $ 1,647 $ 1,666 Variable lease costs (1) 325 312 1,110 763 Operating lease expenses G&A: Operating lease costs 135 129 398 379 Variable lease costs (1) 94 59 282 160 Total operating leases expense $ 1,100 $ 1,053 $ 3,437 $ 2,968 ____________ Includes short-term lease costs which are immaterial.
Summary of Supplemental cash flow information related to leases	Supplemental cash flow information related to leases is as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Cash paid for amounts included in Operating cash flows used for operating $ 701 $ 689 $ 2,105 $ 1,492 Weighted-average remaining lease term in years 4.2 5.2 4.2 5.2 Weighted-average discount rate 7.63 % 7.63 % 7.63 % 7.63 %

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Revenue recognized was earned under the Company’s R&D Agreements and is summarized below based on the nature of payment type (in thousands): Three Months Ended Nine Months Ended Timing of Transfer of Goods or Services 2023 2022 2023 2022 Over time: Reimbursements $ 53 $ 216 $ 94 $ 384 License fees — 693 — 2,140 R&D services — 688 6 1,985 Point in time: Milestones — — 1,100 — Total revenues $ 53 $ 1,597 $ 1,200 $ 4,509
Contract with Customer, Contract Asset, Contract Liability, and Receivable	Contract balances are as follows (in thousands): September 30, December 31, Receivables, included in accounts receivable, net $ 122 $ 376 Contract liabilities, included in deferred revenue, current and $ 1,749 $ 1,749

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Share-based Compensation Expense	Share-based compensation expense was as follows (in thousands): Three Months Ended Nine Months Ended 2023 2022 2023 2022 Share-based compensation expense: Stock options $ 3,212 $ 1,538 $ 6,908 $ 5,067 RSUs 942 — 1,279 — Issuance of ordinary shares for 666 — 1,457 — $ 4,820 $ 1,538 $ 9,644 $ 5,067 Share-based compensation expense Research and development $ 1,665 $ 921 $ 4,383 $ 3,143 General and administrative 3,155 617 5,261 1,924 $ 4,820 $ 1,538 $ 9,644 $ 5,067
Summary of Option Activity Excluding Options Granted and Canceled as Part of Option Repricing	The following table summarizes option activity for the periods presented, excluding options granted and canceled as part of the option repricing discussed below: Total Weighted- Aggregate Weighted- Outstanding at December 31, 2022 5,587,892 $ 7.76 $ 1,088 5.4 Granted 4,042,803 $ 10.70 Exercised ( 2,299,251 ) $ 7.86 Forfeited/expired ( 540,887 ) $ 7.01 Outstanding at September 30, 2023 6,790,557 $ 7.02 $ 39,113 8.4 Vested and exercisable at 1,582,502 $ 2.18 $ 15,198 7.7
Summary Of Share Based Payment Award Stock Options Valuation Assumptions	The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of option grants were as follows: For the Nine Months Ended September 30, 2023 2022 Expected term (in years) 5.9 5.9 Risk-free interest rate 3.9 % 2.3 % Expected volatility 86.9 % 80.2 % Dividend yield — — Weighted-average grant date fair value. $ 7.95 $ 2.92
Summary of RSU Activity	The following table summarizes RSU activity for the periods presented: Number of Weighted- Non-vested balance at December 31, 2022 — $ — Granted 612,258 $ 9.70 Non-vested balance at September 30, 2023 612,258 $ 9.70

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Summary of activities with affiliates of the non controlling shareholders	The following tables present the Company’s activities with affiliates of the noncontrolling shareholders (in thousands): September 30, December 31, Balances: Prepaid R&D expenses $ 79 $ 14 Accounts payable $ 82 $ 352 Accrued liabilities $ 114 $ 99 Three Months Ended Nine Months Ended 2023 2022 2023 2022 Activity: Amounts paid $ 152 $ 90 $ 662 $ 359 R&D expense recognized $ 248 $ 207 $ 342 $ 676 As more fully described within the Securities Purchase Agreement subsection of Note 9, Shareholders’ Equity , during the second quarter of 2023, the Company entered into a securities purchase agreement with a significant shareholder, pursuant to which the Company issued 5,384,063 ordinary shares, as converted to reflect the exchange ratio effectuated in the Merger, for net proceeds of approximately $ 74.7 million.

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands				1 Months Ended
	Oct. 24, 2023 USD ($)	Oct. 11, 2023 $ / shares shares	Sep. 11, 2023 $ / shares	Jun. 30, 2021	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, par value per share | $ / shares					$ 0.0001	$ 0.0001
Common stock shares authorized					135,714,285	71,428,571
Retained earnings accumulated deficit | $					$ (347,745)	$ (291,628)
Cash and cash equivalents | $					225,262	55,610	$ 51,081
Non-current marketable debt securities | $					$ 0	$ 16,793
Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Termination fees | $	$ 1,900
Ambrx Cayman [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Ordinary share, par value per share | $ / shares			$ 0.0001
Ambrx Cayman [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Ordinary shares issued		441,044,212
Ordinary shares outstanding		441,044,212
Ambrx HoldCo [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, par value per share | $ / shares			$ 0.0001
Shares conversion ratio			0.143	0.143
Ambrx HoldCo [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Shares conversion ratio		0.143
Common stock shares authorized		250,000,000
Preferred stock shares authorized		1,000,000
Preferred stock, par or stated value per share | $ / shares		$ 0.0001
Conversion of common stock		63,006,294
Ambrx HoldCo [Member] | Maximum [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Shares authorized		251,000,000
Shangai Ambrx Biomedical Company Limited [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Equity method investment ownership percentage					100%
Biolaxy Pharmaceutical Hongkong Limited [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Equity method investment ownership percentage					100%
Ambrx Austrailia Pty Limited [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Equity method investment ownership percentage					100%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)		3 Months Ended			9 Months Ended		12 Months Ended
	Feb. 03, 2022	Sep. 30, 2023	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Antidilutive securities excluded from computation of Earnings per share, Amount		7,402,815			5,516,952
Impairment of intangible assets		$ 0	$ 0		$ 0	$ 9,660,000	$ 9,660,000
Impairment of Intangible Assets, Indefinite-Lived (Excluding Goodwill)		$ 0			$ 0
BMS Relax in Agreement [Member]
Impairment of intangible assets	$ 2,500,000
BMS FGF-21 Agreement [Member]
Impairment of intangible assets				$ 7,200,000
Technology-Based Intangible Assets [Member]
Impairment of intangible assets							$ 9,660,000
Maximum [Member] | Technology-Based Intangible Assets [Member]
Finite Lived Intangible Asset Remaining Useful Life		11 years 3 months 18 days			11 years 3 months 18 days		12 years
Minimum [Member] | Technology-Based Intangible Assets [Member]
Finite Lived Intangible Asset Remaining Useful Life		2 years 3 months 18 days			2 years 3 months 18 days		3 years
Share-based Payment Arrangement, Option [Member]
Antidilutive securities excluded from computation of Earnings per share, Amount		6,790,557			5,516,952
Customer From Top Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage		100%			91.70%
Customer From Top Customer [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration risk, percentage					100%
First Customer From Top Three Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage			66.20%
Second Customer From Top Three Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage			14.90%
Third Customer From Top Three Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage			13.60%
First Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage						78.60%
First Customer [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration risk, percentage							78.40%
Second Customer [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration risk, percentage						13.70%
Second Customer [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration risk, percentage							11.80%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 225,262	$ 55,610	$ 51,081
Restricted cash	665	831	831
Total cash, cash equivalents, and restricted cash presented in the condensed consolidated statements of cash flows	$ 225,927	$ 56,441	$ 51,912	$ 170,906

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share (Detail) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of Earnings per share, Amount	7,402,815	5,516,952
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of Earnings per share, Amount	6,790,557	5,516,952
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of Earnings per share, Amount	612,258

Balance Sheets Details - Schedu

Balance Sheets Details - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid R&D costs	$ 3,721	$ 1,476
Tax receivable	2,235	1,506
Prepaid insurance and service contracts	1,008	1,424
Other	805	487
Total	$ 7,769	$ 4,893

Balance Sheets Details - Sche_2

Balance Sheets Details - Schedule of Prepaid Expenses and Other Current Assets (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid R&D costs due to related parties	$ 79	$ 14

Balance Sheets Details - Sche_3

Balance Sheets Details - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 9,243	$ 8,661
Accumulated depreciation and amortization	(6,244)	(5,617)
Total	2,999	3,044
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	8,084	7,559
Computers, software and office equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	523	512
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	506	467
Office furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 130	$ 123

Balance Sheets Details - Additi

Balance Sheets Details - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and amortization expense	$ 0.2	$ 0.2	$ 0.6	$ 0.5

Balance Sheets Details - Sche_4

Balance Sheets Details - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued R&D costs	$ 3,997	$ 4,069
Accrued compensation	3,536	3,494
Accrued audit, tax and filing fees	2,252	1,703
Accrued directors and officers insurance premium financing obligation		926
Accrued other	1,020	1,122
Total	$ 10,805	$ 11,314

Balance Sheets Details - Sche_5

Balance Sheets Details - Schedule of Accrued Liabilities (Parenthetical) (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Line Items]
Accrued research and development costs related party	$ 114	$ 99
Insurance Premium Financing Agreement [Member]
Payables and Accruals [Line Items]
Debt instrument interest rate during period	3.40%

Balance Sheets Details - Sche_6

Balance Sheets Details - Schedule of Reconciliation of Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 250,380	$ 141,892	$ 117,850	$ 189,967
Changes in comprehensive loss before reclassifications	23	(360)	(16)	(577)
Amounts reclassified from accumulated other comprehensive loss	140	0	528	0
Total other comprehensive income (loss)	163	(360)	512	(577)
Ending balance	242,402	127,502	242,402	127,502
Foreign Currency Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(790)	(790)	(790)	(790)
Ending balance	(790)	(790)	(790)	(790)
Unrealized Gains and Losses on Marketable Debt Securities, Available-for-sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(163)	(217)	(512)
Changes in comprehensive loss before reclassifications	23	(360)	(16)	(577)
Amounts reclassified from accumulated other comprehensive loss	140		528
Total other comprehensive income (loss)	163	(360)	512	(577)
Ending balance		(577)		(577)
Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(953)	(1,007)	(1,302)	(790)
Changes in comprehensive loss before reclassifications	23	(360)	(16)	(577)
Amounts reclassified from accumulated other comprehensive loss	140		528
Total other comprehensive income (loss)	163	(360)	512	(577)
Ending balance	$ (790)	$ (1,367)	$ (790)	$ (1,367)

Intangible Assets, Net - Schedu

Intangible Assets, Net - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 28,350		$ 28,350		$ 45,270
Impairment of intangible assets	0	$ 0	0	$ (9,660)	(9,660)
Accumulated Amortization	(3,572)		(3,572)		(10,360)
Intangible Assets, Net	24,778		24,778		25,250
IPR&D [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	20,940		20,940		20,940
Impairment of intangible assets					0
Accumulated Amortization	0		0		0
Intangible Assets, Net	$ 20,940		$ 20,940		$ 20,940
Acquired technologies [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	8 years 3 months 18 days		8 years 3 months 18 days		8 years 9 months 18 days
Gross Carrying Amount	$ 7,410		$ 7,410		$ 24,330
Impairment of intangible assets					(9,660)
Accumulated Amortization	(3,572)		(3,572)		(10,360)
Intangible Assets, Net	$ 3,838		$ 3,838		$ 4,310

Intangible Assets Net - Additio

Intangible Assets Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 200	$ 200	$ 472	$ 895

Marketable Debt Securities, A_3

Marketable Debt Securities, Available-for-Sale - Schedule of Available-for-Sale Securities Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	8 months 12 days
Amortized Costs	$ 46,175,000
Gross Unrealized Gains	3,000
Gross Unrealized Losses	(512,000)
Fair Value	45,666,000	$ 0
Due Greater than 90 Days and Less than One Year [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Costs	28,950,000
Gross Unrealized Gains	3,000
Gross Unrealized Losses	(80,000)
Fair Value	$ 28,873,000
Due Greater than 90 Days and Less than One Year [Member] | Maximum [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year
Due Greater than 90 Days and Less than One Year [Member] | US Government Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Costs	$ 5,001,000
Gross Unrealized Losses	(30,000)
Fair Value	$ 4,971,000
Due Greater than 90 Days and Less than One Year [Member] | US Government Debt Securities [Member] | Maximum [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year
Due Greater than 90 Days and Less than One Year [Member] | Commercial Paper [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Costs	$ 15,803,000
Gross Unrealized Gains	1,000
Gross Unrealized Losses	(23,000)
Fair Value	$ 15,781,000
Due Greater than 90 Days and Less than One Year [Member] | Commercial Paper [Member] | Maximum [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year
Due Greater than 90 Days and Less than One Year [Member] | Certificates of Deposit [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Costs	$ 7,500,000
Gross Unrealized Gains	2,000
Gross Unrealized Losses	(25,000)
Fair Value	$ 7,477,000
Due Greater than 90 Days and Less than One Year [Member] | Certificates of Deposit [Member] | Maximum [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year
Due Greater than 90 Days and Less than One Year [Member] | Corporate Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Costs	$ 646,000
Gross Unrealized Losses	(2,000)
Fair Value	$ 644,000
Due Greater than 90 Days and Less than One Year [Member] | Corporate Debt Securities [Member] | Maximum [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year
Due One to Two Years [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year 6 months
Amortized Costs	$ 17,225,000
Gross Unrealized Losses	(432,000)
Fair Value	$ 16,793,000
Due One to Two Years [Member] | US Government Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year 4 months 24 days
Amortized Costs	$ 6,979,000
Gross Unrealized Losses	(184,000)
Fair Value	$ 6,795,000
Due One to Two Years [Member] | Corporate Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year 6 months
Amortized Costs	$ 6,824,000
Gross Unrealized Losses	(192,000)
Fair Value	$ 6,632,000
Due One to Two Years [Member] | Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year 9 months 18 days
Amortized Costs	$ 2,999,000
Gross Unrealized Losses	(45,000)
Fair Value	$ 2,954,000
Due One to Two Years [Member] | Non US Government Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Weighted-Average Remaining Contractual Life (In Years)	1 year 6 months
Amortized Costs	$ 423,000
Gross Unrealized Losses	(11,000)
Fair Value	$ 412,000

Marketable Debt Securities, A_4

Marketable Debt Securities, Available-for-Sale - Additional Information (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Investments	$ 0	$ 45,666,000
Interest receivable		$ 200,000

Marketable Debt Securities, A_5

Marketable Debt Securities, Available-for-Sale - Schedule of Gross Unrealized Losses and Fair Values on Debt Securities Classified as Available-for Sale (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	$ 38,185
Less than 12 Months, Gross Unrealized Losses	(512)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
Commercial Paper [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	12,803
Less than 12 Months, Gross Unrealized Losses	(22)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
US Government Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	11,765
Less than 12 Months, Gross Unrealized Losses	(216)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
Corporate Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	7,276
Less than 12 Months, Gross Unrealized Losses	(193)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
Certificates of Deposit [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	2,975
Less than 12 Months, Gross Unrealized Losses	(25)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	2,954
Less than 12 Months, Gross Unrealized Losses	(45)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	0
Debt Security, Government, Non-US [Member]
Debt Securities, Available-for-Sale [Line Items]
Less than 12 Months, Estimated Fair Value	412
Less than 12 Months, Gross Unrealized Losses	(11)
More than 12 Months, Estimated Fair Value	0
More than 12 Months, Gross Unrealized Losses	$ 0

Marketable Debt Securities, A_6

Marketable Debt Securities, Available-for-Sale - Summary of Investment Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investment Income, Interest and Dividend [Abstract]
Interest and dividend income	$ 195	$ 218	$ 764	$ 365
Accretion/amortization of discounts/premiums	2,345	291	4,143	367
Realized (losses) gains, net	(140)	0	(528)	0
Investment income, net	$ 2,400	$ 509	$ 4,379	$ 732

Fair Value Measurements - Sched

Fair Value Measurements - Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Current	$ 0	$ 28,873
Debt Securities, Available-for-Sale, Noncurrent	0	16,793
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		52,095
Cash Equivalents, Fair Value Disclosure	220,074
Debt Securities, Available-for-Sale, Current		28,873
Debt Securities, Available-for-Sale, Noncurrent		16,793
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		12,743
Cash Equivalents, Fair Value Disclosure	17,137
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		39,352
Cash Equivalents, Fair Value Disclosure	202,937
Debt Securities, Available-for-Sale, Current		28,873
Debt Securities, Available-for-Sale, Noncurrent		16,793
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0
Cash Equivalents, Fair Value Disclosure	0
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | US Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	178,937
Debt Securities, Available-for-Sale, Current		4,971
Debt Securities, Available-for-Sale, Noncurrent		6,795
Fair Value, Recurring [Member] | US Government Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | US Government Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	178,937
Debt Securities, Available-for-Sale, Current		4,971
Debt Securities, Available-for-Sale, Noncurrent		6,795
Fair Value, Recurring [Member] | US Government Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	24,000	24,000
Debt Securities, Available-for-Sale, Current		7,477
Fair Value, Recurring [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Debt Securities, Available-for-Sale, Current		0
Fair Value, Recurring [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	24,000	24,000
Debt Securities, Available-for-Sale, Current		7,477
Fair Value, Recurring [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Debt Securities, Available-for-Sale, Current		0
Fair Value, Recurring [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		15,352
Debt Securities, Available-for-Sale, Current		15,781
Fair Value, Recurring [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0
Debt Securities, Available-for-Sale, Current		0
Fair Value, Recurring [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		15,352
Debt Securities, Available-for-Sale, Current		15,781
Fair Value, Recurring [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure		0
Debt Securities, Available-for-Sale, Current		0
Fair Value, Recurring [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	17,137	12,743
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	17,137	12,743
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	$ 0	0
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Current		644
Debt Securities, Available-for-Sale, Noncurrent		6,632
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Current		644
Debt Securities, Available-for-Sale, Noncurrent		6,632
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Current		0
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		2,954
Fair Value, Recurring [Member] | Asset-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Asset-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		2,954
Fair Value, Recurring [Member] | Asset-Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Non US Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		412
Fair Value, Recurring [Member] | Non US Government Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		0
Fair Value, Recurring [Member] | Non US Government Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		412
Fair Value, Recurring [Member] | Non US Government Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale, Noncurrent		$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Recurring [Member]
Liabilities, fair value disclosure	$ 0	$ 0
Fair value liability, transfers out of level 3	0	0
Fair Value, Nonrecurring [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	$ 0	$ 0

Leases - Summary of Components

Leases - Summary of Components of Operating Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessee, Lease, Description [Line Items]
Total operating leases expense	$ 1,100	$ 1,053	$ 3,437	$ 2,968
Operating lease expenses R&D [Member]
Lessee, Lease, Description [Line Items]
Operating lease costs	546	553	1,647	1,666
Variable lease costs	325	312	1,110	763
Operating lease expenses G&A [Member]
Lessee, Lease, Description [Line Items]
Operating lease costs	135	129	398	379
Variable lease costs	$ 94	$ 59	$ 282	$ 160

Leases - Summary of Supplementa

Leases - Summary of Supplemental cash flow information related to leases (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$ 701	$ 689	$ 2,105	$ 1,492
Weighted-average remaining lease term in years	4 years 2 months 12 days	5 years 2 months 12 days	4 years 2 months 12 days	5 years 2 months 12 days
Weighted-average discount rate	7.63%	7.63%	7.63%	7.63%

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail)					1 Months Ended	3 Months Ended			9 Months Ended
	Oct. 11, 2023 shares	Sep. 11, 2023 $ / shares	May 23, 2023 USD ($) $ / shares shares	Jul. 29, 2022 USD ($)	Jun. 30, 2021	Sep. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) shares	Mar. 31, 2023 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 shares	Dec. 31, 2022 USD ($) $ / shares shares
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Common stock shares outstanding											38,636,441
Commission on sale of common stock | $			$ 300,000
Stock issued during period, value, issued for services | $						$ 666,000			$ 1,457,000
Ordinary shares						63,006,294			63,006,294
Ordinary shares value | $						$ 6,000			$ 6,000		$ 4,000
Common stock shares authorized						135,714,285			135,714,285		71,428,571
Common Stock, Par or Stated Value Per Share | $ / shares						$ 0.0001			$ 0.0001		$ 0.0001
Issuance of ordinary shares									2,299,251
Ambrx HoldCo [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares conversion ratio		0.143			0.143
Common Stock, Par or Stated Value Per Share | $ / shares		$ 0.0001
Ambrx HoldCo [Member] | Subsequent Event [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares conversion ratio	0.143
Common stock shares authorized	250,000,000
Preferred stock shares authorized	1,000,000
Maximum [Member] | Ambrx HoldCo [Member] | Subsequent Event [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares authorized	251,000,000
Amended and Restated Certificate of Incorporation
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Common stock shares authorized	250,000,000
Preferred stock shares authorized	1,000,000
Amended and Restated Certificate of Incorporation | Maximum [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares authorized	251,000,000
Common Stock [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Stock shares issued during the period shares										29,705
Shares issued and sold during the period shares							5,384,063
Stock issued during period, shares, issued for services						40,000			110,713
Issuance of ordinary shares						1,219,532			2,299,251
ATM Offering Program [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Average stock price per share | $ / shares								$ 4.83
Gross proceeds from issuance of common stock including sales commissions | $								$ 80,000,000
Commission on sale of common stock | $								2,200,000
Net proceeds from the issuance of common stock | $								$ 77,800,000
ATM Offering Program [Member] | Maximum [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Aggregate offering price | $				$ 80,000,000
ATM Offering Program [Member] | Common Stock [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares issued and sold during the period shares								16,575,826
Securities Purchase Agreement [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Average stock price per share | $ / shares			$ 13.93
Gross proceeds from issuance of common stock including sales commissions | $			$ 75,000,000
Net proceeds from the issuance of common stock | $			74,700,000
Underwriting and placement agent fees | $			$ 0
Securities Purchase Agreement [Member] | Maximum [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Shares issued and sold during the period shares			5,384,063
Securities Purchase Agreement [Member] | Common Stock [Member]
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Average stock price per share | $ / shares			$ 13.93
Net proceeds from the issuance of common stock | $							$ 74,700,000
Other Share Issuances [Member] | Common Stock [Member] | Issuance of Ordinary Shares for Services
Convertible Preferred Ordinary Shares And Ordinary Shares [Line Items]
Stock issued during period, shares, issued for services						40,000			110,713
Stock issued during period, value, issued for services | $						$ 700,000			$ 1,500,000

Revenues - Schedule of Revenue

Revenues - Schedule of Revenue Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 53	$ 1,597	$ 1,200	$ 4,509
License Fees [Member] | Over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	0	693		2,140
Reimbursements [Member] | Over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	53	216	94	384
Milestones [Member] | Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	0	0	1,100	0
Research And Development Services [Member] | Over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 0	$ 688	$ 6	$ 1,985

Revenues - Additional Informati

Revenues - Additional Information (Detail)	1 Months Ended				3 Months Ended			9 Months Ended
	Mar. 31, 2023	Jan. 31, 2020 USD ($) Patients	Oct. 31, 2019 USD ($) FullTimeEquivalentServices	Mar. 31, 2019 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax					$ 53,000		$ 1,597,000	$ 1,200,000	$ 4,509,000
Revenue from performance obligations of the previous period recognized							0		0
Deferred Revenue					$ 1,700,000	$ 1,700,000		$ 1,700,000
Bigene Limited [Member]
Disaggregation of Revenue [Line Items]
Upfront payment received towards license fees				$ 10,000,000
Bigene Limited [Member] | Collaboration and Exclusive License Agreement [Member]
Disaggregation of Revenue [Line Items]
Notice period to be given by the counterparty for the termination of the license agreement				3 months
Initial research term extension period	2 years
Novocodex [Member] | Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax						$ 1,000,000
Novocodex [Member] | Development and Commercialization Agreement [Member]
Disaggregation of Revenue [Line Items]
Upfront payment received towards license fees			$ 2,000,000
Notice period to be given by the counterparty for the termination of the license agreement			6 months
Sino Biopharmaceutical Limited [Member] | Development and Commercialization Agreement [Member]
Disaggregation of Revenue [Line Items]
Upfront payment received towards license fees		$ 10,000,000
Notice period to be given by the counterparty for the termination of the license agreement								6 months
Sino Biopharmaceutical Limited [Member] | Development and Commercialization Agreement [Member] | Phase One Clinical Trial for Products ARX Eight Twenty Two and Arx One Hundred and Two [Member]
Disaggregation of Revenue [Line Items]
Total number of patients for which the drug study detail is to be given by the counterparties | Patients		100
Minimum [Member]
Disaggregation of Revenue [Line Items]
Remaining performance obligations remaining satisfaction period					3 years 6 months			3 years 6 months
Minimum [Member] | Novocodex [Member] | Development and Commercialization Agreement [Member]
Disaggregation of Revenue [Line Items]
Number of full time equivalent services to be performed for receiving research and development related amount | FullTimeEquivalentServices			1
Maximum [Member]
Disaggregation of Revenue [Line Items]
Remaining performance obligations remaining satisfaction period					4 years			4 years
Milestones [Member] | Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax					$ 0		$ 0	$ 1,100,000	$ 0
Milestones [Member] | BMS Relax in Agreement [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax					$ 1,100,000			$ 1,100,000

Revenues - Schedule of the Cont

Revenues - Schedule of the Contract Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Receivables, included in accounts receivable, net	$ 122	$ 376
Contract liabilities included in deferred revenue, current and deferred revenue net of current portion	$ 1,749	$ 1,749

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 4,820	$ 1,538	$ 9,644	$ 5,067
Employee Stock Option
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	3,212	1,538	6,908	5,067
RSUs
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	942	0	1,279	0
Issuance of Ordinary Shares for Services
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	666	0	1,457	0
Research and Development Expense [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	1,665	921	4,383	3,143
General and Administrative [Member]
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated share based compensation expense	$ 3,155	$ 617	$ 5,261	$ 1,924

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Option Activity Excluding Options Granted and Canceled as Part of Option Repricing (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Beginning balance, Total Options | shares	5,587,892
Total Options, Granted | shares	4,042,803
Total Options, Exercised | shares	(2,299,251)
Top Options, Forfeited/expired | shares	(540,887)
Ending balance, Total Options | shares	6,790,557	5,587,892
Vested and exercisable share | shares	1,582,502
Beginning balance, Weighted Average Exercise Price | $ / shares	$ 7.76
Weighted Average Exercise Price, Granted | $ / shares	10.7
Weighted Average Exercise Price, Exercised | $ / shares	7.86
Weighted Average Exercise Price, Forfeited/expired | $ / shares	7.01
Ending balance, Weighted Average Exercise Price | $ / shares	7.02	$ 7.76
Weighted Average Exercise Price, Vested and Exercisable | $ / shares	$ 2.18
Aggregate Intrinsic Value, Outstanding | $	$ 39,113	$ 1,088
Aggregate Intrinsic Value, Vested and Exercisable | $	$ 15,198
Weighted Average Remaining Contractual Term, Outstanding	8 years 4 months 24 days	5 years 4 months 24 days
Weighted Average Remaining Contractual Life, Vested and Exercisable	7 years 8 months 12 days

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 27, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expected to be recognized over a remaining weighted-average term				2 years 10 months 24 days
Issuance of ordinary shares upon option exercises for cash (in shares)				2,299,251
Share-based payment award, options, exercises in period				$ 12,500,000
Allocated share based compensation expense		$ 4,820,000	$ 1,538,000	$ 9,644,000	$ 5,067,000
Weighted average exercise price, granted				$ 10.7
Stock shares issued during the period on exercise of stock options					0
Aggregate Intrinsic Value, Outstanding		39,113,000		$ 39,113,000		$ 1,088,000
Share based payment arrangement nonvested award cost not yet recognized period for recognition		34,600,000		$ 34,600,000
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition				2 years 10 months 24 days
Shares issued during the period, Value					102,000
Share-based compensation expense				$ 9,644,000	5,067,000
Proceeds from stock options exercised				18,100,000
Total intrinsic value of stock options exercised				12,500,000
Employee Stock Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Allocated share based compensation expense		3,212,000	1,538,000	$ 6,908,000	$ 5,067,000
Weighted average grant date fair values				$ 7.95	$ 2.92
RSUs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expected to be recognized over a remaining weighted-average term				2 years 4 months 24 days
Allocated share based compensation expense		942,000	$ 0	$ 1,279,000	$ 0
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition				2 years 4 months 24 days
Unrecognized compensation costs related to non-vested RSUs		4,700,000		$ 4,700,000
Option Repricing Program [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Allocated share based compensation expense				1,200,000
Ordinary shares repriced shares outstanding	2,612,044
exercise price	$ 1.96
Weighted average exercise price, granted	$ 1.96
Ordinary shares repriced as a percentage of options outstanding	53.20%
Option Repricing Program [Member] | Statements of Operations and Comprehensive Loss [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Allocated share based compensation expense		$ 100,000		800,000
Employee Share Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock shares issued during the period shares			0		29,705
Shares issued during the period, Value					$ 100,000
Share-based compensation expense				$ 0		$ 0

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Share Based Payment Award Stock Options Valuation Assumptions (Detail) - Employee Stock Option - $ / shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (in years)	5 years 10 months 24 days	5 years 10 months 24 days
Risk-free interest rate	3.90%	2.30%
Expected volatility	86.90%	80.20%
Weighted average grant date fair values	$ 7.95	$ 2.92

Share-Based Compensation - Su_4

Share-Based Compensation - Summary of RSU Activity (Detail) - RSUs	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Units, Granted | shares	612,258
Number of Units, Non-vested Ending Balance | shares	612,258
Weighted-Average Grant Date Fair Value Non-vested, Granted | $ / shares	$ 9.7
Weighted-Average Grant Date Fair Value Non-vested, Ending Balance | $ / shares	$ 9.7

Related Party Transactions - Su

Related Party Transactions - Summary of Activities with Affiliates of the Non Controlling Shareholders (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Related Party Transaction [Line Items]
Prepaid R&D expenses	$ 79		$ 79		$ 14
Accounts payable	$ 82		$ 82		$ 352
Accounts Payable, Related Party, Type [Extensible Enumeration]	Accounts Payable, Current		Accounts Payable, Current		Accounts Payable, Current
Accrued liabilities	$ 114		$ 114		$ 99
Amounts paid	152	$ 90	662	$ 359
R&D expense recognized	$ 248	$ 207	$ 342	$ 676

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended
	May 23, 2023	Jun. 30, 2023
Securities Purchase Agreement [Member]
Related Party Transaction [Line Items]
Net proceeds from the issuance of common stock	$ 74.7
Ordinary Shares
Related Party Transaction [Line Items]
Number of ordinary shares sold		5,384,063
Ordinary Shares | Securities Purchase Agreement [Member]
Related Party Transaction [Line Items]
Net proceeds from the issuance of common stock		$ 74.7