Centessa Pharmaceuticals (CNTA) 10-K 28 Mar 24 2023 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2023	Mar. 19, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Entity Transition Report	false
Entity File Number	001-40445
Entity Registrant Name	CENTESSA PHARMACEUTICALS PLC
Entity Incorporation, State or Country Code	X0
Entity Tax Identification Number	98-1612294
Entity Address, Address Line One	3rd Floor
Entity Address, Address Line Two	1 Ashley Road
Entity Address, Address Line Three	Altrincham
Entity Address, City or Town	Cheshire
Entity Address, Postal Zip Code	WA14 2DT
Entity Address, Country	GB
Country Region	+1
City Area Code	617)
Local Phone Number	468-5770
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
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 Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 310,787,000
Entity Common Stock, Shares Outstanding		100,305,850
Entity Central Index Key	0001847903
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Ordinary shares
Document Information [Line Items]
Title of 12(b) Security	Ordinary shares, nominal value £0.002 per share
Trading Symbol	CNTA
Security Exchange Name	NASDAQ
American Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	American Depositary Shares, each representing one ordinary share, nominal value £0.002 per share
Trading Symbol	CNTA
Security Exchange Name	NASDAQ

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	KPMG LLP
Auditor Location	Boston, MA
Auditor Firm ID	185

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 128,030	$ 393,644
Short-term investments	128,519	0
Tax incentive receivable	37,818	24,166
Prepaid expenses and other current assets	20,725	19,937
Total current assets	315,092	437,747
Property and equipment, net	1,039	1,168
Operating lease right-of-use assets	11,914	0
Deferred tax asset	29,647	3,512
Other non-current assets	2,554	1,880
Total assets	360,246	444,307
Current liabilities:
Accounts payable	11,815	13,836
Accrued expenses and other current liabilities	27,570	24,502
Total current liabilities	39,385	38,338
Long term debt	75,700	69,800
Operating lease liabilities	8,888	0
Other noncurrent liabilities	29	0
Total liabilities	124,002	108,138
Commitments and contingencies (Note 7)
Shareholders’ equity
Ordinary shares: £0.002 nominal value: 152,500,000 shares authorized; 98,774,827 shares issued and outstanding at December 31, 2023; 94,843,391 shares issued and outstanding at December 31, 2022	273	265
Additional paid-in capital	987,423	939,261
Accumulated other comprehensive income (loss)	1,493	(1,497)
Accumulated deficit	(752,945)	(601,860)
Total shareholders’ equity	236,244	336,169
Total liabilities and shareholders’ equity	$ 360,246	$ 444,307

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - £ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Common stock, nominal value (in pound sterling per share)	£ 0.002	£ 0.002
Common stock, shares authorized (in shares)	152,500,000	152,500,000
Common stock, shares issued (in shares)	98,774,827	94,843,391
Common Stock, shares outstanding (in shares)	98,774,827	94,843,391

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
License and other revenue	$ 6,853	$ 0
Operating expenses:
Research and development	124,405	155,083
General and administrative	53,731	55,200
Change in fair value of contingent value rights	0	1,980
Loss from operations	(171,283)	(212,263)
Interest income	10,476	244
Interest expense	(9,906)	(7,277)
Other (expense) income, net	(5,428)	2,342
Loss before income taxes	(176,141)	(216,954)
Income tax benefit	(25,056)	(747)
Net loss	(151,085)	(216,207)
Other comprehensive income (loss):
Foreign currency translation adjustments	1,700	(2,185)
Unrealized gain on available for sale securities, net of taxes of $0.4 million	1,290	0
Total comprehensive loss	$ (148,095)	$ (218,392)
Net loss per ordinary share - basic (in dollars per share)	$ (1.57)	$ (2.31)
Net loss per ordinary share - diluted (in dollars per share)	$ (1.57)	$ (2.31)
Weighted average ordinary shares outstanding - basic (in shares)	96,177,578	93,400,513
Weighted average ordinary shares outstanding - diluted (in shares)	96,177,578	93,400,513

Consolidated Statements of Op_2

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Income Statement [Abstract]
Unrealized gain on available for sale securities, tax	$ 0.4

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Ordinary shares	Additional paid-in capital	Accumulated other comprehensive (loss) income	Accumulated deficit
Ordinary shares, beginning balance (in shares) at Dec. 31, 2021		89,988,228
Beginning balance at Dec. 31, 2021	$ 491,554	$ 252	$ 876,267	$ 688	$ (385,653)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of ordinary shares (in shares)		3,938,423
Issuance of ordinary shares	37,748	$ 10	37,738
Stock option exercises (in shares)		205,107
Stock option exercises	799	$ 1	798
Share-based compensation expense	24,965		24,965
Vesting of ordinary shares (in shares)		853,013
Vesting of ordinary shares	0	$ 2	(2)
Shares withheld to pay employee withholding tax on share based compensation (in shares)		(141,380)
Shares withheld to pay employee withholding tax on share based compensation	(505)		(505)
Foreign currency translation adjustments	(2,185)			(2,185)
Unrealized gain on available for sale securities, net of tax of $0.4 million	0
Net loss	$ (216,207)				(216,207)
Ordinary shares, ending balance (in shares) at Dec. 31, 2022	94,843,391	94,843,391
Ending balance at Dec. 31, 2022	$ 336,169	$ 265	939,261	(1,497)	(601,860)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of ordinary shares (in shares)		3,040,816
Issuance of ordinary shares	$ 20,807	$ 7	20,800
Stock option exercises (in shares)	70,197	70,197
Stock option exercises	$ 310		310
Share-based compensation expense	29,392		29,392
Vesting of ordinary shares (in shares)		1,194,665
Vesting of ordinary shares	0	$ 1	(1)
Shares withheld to pay employee withholding tax on share based compensation (in shares)		(374,242)
Shares withheld to pay employee withholding tax on share based compensation	(2,339)		(2,339)
Foreign currency translation adjustments	1,700			1,700
Unrealized gain on available for sale securities, net of tax of $0.4 million	1,290			1,290
Net loss	$ (151,085)				(151,085)
Ordinary shares, ending balance (in shares) at Dec. 31, 2023	98,774,827	98,774,827
Ending balance at Dec. 31, 2023	$ 236,244	$ 273	$ 987,423	$ 1,493	$ (752,945)

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Statement of Stockholders' Equity [Abstract]
Unrealized gain on available for sale securities, tax	$ 0.4

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (151,085)	$ (216,207)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	29,392	24,965
Depreciation and amortization	810	131
Change in fair value of financial instruments	5,900	(3,920)
Change in deferred taxes	(26,529)	(2,857)
Changes in operating assets and liabilities:
Tax incentive receivable	(12,092)	(11,711)
Prepaid expenses and other assets	(1,364)	(3,732)
Operating leases, net	(1,883)	0
Accounts payable	(2,722)	6,351
Accrued expenses and other liabilities	(797)	6,261
Other, net	28	173
Net cash used in operating activities	(160,342)	(200,546)
Cash flows from investing activities:
Purchases of investments in marketable securities	(264,910)	0
Proceeds from redemption of investments in marketable securities	138,075	0
Purchase of property and equipment	(169)	(1,137)
Other, net	0	206
Net cash used in investing activities	(127,004)	(931)
Cash flows from financing activities:
Proceeds from issuance of shares under ATM program, net of issuance costs	20,807	0
Proceeds from option exercises	310	718
Other, net	0	(261)
Net cash provided by financing activities	21,117	457
Effect of exchange rate on cash and cash equivalents	615	(418)
Net decrease in cash and cash equivalents	(265,614)	(201,438)
Cash and cash equivalents at beginning of period	393,644	595,082
Cash and cash equivalents at end of period	128,030	393,644
Supplemental disclosure:
Interest paid	9,906	7,277
Income taxes paid	2,943	1,299
Operating lease payments reducing operating lease liabilities	1,178	0
Right-of-use assets obtained in exchange for operating lease liabilities	9,711	0
Non-cash investing and financing activities:
Issuance of ordinary shares to settle outstanding contingent value rights	$ 0	$ 39,680

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Centessa Pharmaceuticals plc (“Centessa” or “the Company”) is a clinical-stage pharmaceutical company that aims to discover, develop and ultimately deliver medicines that are transformational for patients. Centessa was incorporated on October 26, 2020 as a limited liability company under the laws of England and Wales. In connection with the IPO in June 2021, the Company re-registered Centessa Pharmaceuticals Limited as an English public limited company and renamed it as Centessa Pharmaceuticals plc. Risks and Liquidity The Company is subject to risks common to other life science companies in early stages of development including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development of new technological innovations by its competitors, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing and compliance with government regulations, in the markets in which the Company is seeking approvals, including FDA regulations. If the Company does not successfully advance its programs into and through human clinical trials and/or enter into collaborations for its programs and commercialize any of its product candidates, it may be unable to produce product revenue or achieve profitability. The Company has incurred losses and negative cash flows from operations since inception and the Company had an accumulated deficit o f $752.9 million as of December 31, 2023. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of the product candidates currently in development by the Centessa Subsidiaries. Substantial additional capital will be needed by the Company to fund its operations (including those of the Centessa Subsidiaries) and to develop its product candidates. In October 2021, the Company entered into a Note Purchase Agreement with Oberland Capital Management LLC (“Oberland Capital”). As of December 31, 2023, in addition to the principal amount of senior secured notes already funded on October 4, 2021 of $75.0 million, Oberland Capital will purchase up to $75.0 million through September 2024 at the Company’s option, and up to $100.0 million to fund Mergers and Acquisitions (“M&A”), in-licensing, or other strategic transactions, at the option of the Company and Oberland Capital (See - Note 6 "Debt" ). On July 12, 2022, the Securities and Exchange Commission (“SEC”) declared effective the Company’s filed shelf registration statement on Form S-3 (“Shelf”), which covers the offering, issuance and sale of an amount up to $350.0 million in the aggregate of the Company’s ordinary shares, American Depository Shares representing ordinary shares, debt securities, warrants, and/or units or any combination thereof. The Company entered into a Sales Agreement, dated January 27, 2023, by and between Centessa Pharmaceuticals plc and Leerink Partners LLC (formerly SVB Securities LLC). As sales agent, Leerink Partners LLC will provide for the issuance and sale by the Company of up to $125.0 million of its ordinary shares represented by American Depository Shares from time to time in “at-the-market” offerings under the Shelf (“ATM Program”). As of December 31, 2023, the Company has sold 3,040,816 ordinary shares under the ATM Program, resulting in net proceeds to us of approximately $20.8 million. Additionally, in January 2024, we sold 1,250,000 ordinary shares under the ATM Program, resulting in net proceeds to us of about $9.7 million. The Company expects its existing cash, cash equivalents and short-term investments as of December 31, 2023 of $256.5 million

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) promulgated by the Financial Accounting Standards Board (“FASB”). All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying consolidated financial statements include all normal and recurring adjustments (which consist primarily of accruals, estimates and assumptions that impact the financial statements) considered necessary to present fairly: • the Company’s financial position as of December 31, 2023 and December 31, 2022; and • the Company’s results of operations and cash flows for the years ended December 31, 2023 and December 31, 2022. Emerging Growth Company and Smaller Reporting Company The Company is an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act (“JOBS Act”) enacted in April 2012. For so long as we remain an emerging growth company, we are permitted and intend to rely on certain exemptions from various public company reporting requirements, including not being required to have our internal control over financial reporting audited by our independent registered public accounting firm pursuant to Section 404(b) of the Sarbanes-Oxley Act of 2002, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and any golden parachute payments not previously approved. We will remain an emerging growth company until the earlier to occur of (1) the last day of the fiscal year that is five years following the closing of our initial public offering, (2) the last day of the fiscal year in which we have total annual gross revenues of at least $1.235 billion, (3) the last day of the fiscal year in which we are deemed to be a “large accelerated filer,” under the rules of the U.S. Securities and Exchange Commission, or SEC, which means the market value of our equity securities that is held by non-affiliates exceeds $700 million as of the prior June 30th after we have been subject to the SEC’s periodic reporting requirements for at least twelve calendar months and have filed at least one annual report, and (4) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period. In addition, the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. This provision allows an emerging growth company to delay the adoption of some accounting standards until those standards would otherwise apply to private companies. We are electing to utilize the extended transition period and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for emerging growth companies. We are also a “smaller reporting company” as defined in the Securities Exchange Act of 1934 (the “Exchange Act”) because our annual revenue was less than $100.0 million during the most recently completed fiscal year and the market value of our voting and non-voting ordinary shares held by non-affiliates was less than $560.0 million on June 30, 2023. Even after we no longer qualify as an emerging growth company, we may still qualify as a “smaller reporting company” if the market value of our ordinary shares held by non-affiliates is below $250 million (or $700 million if our annual revenue is less than $100 million) as of June 30 in any given year. As a smaller reporting company, we are eligible for scaled disclosure relief from certain Regulation S-X and Regulation S-K requirements. The Company adopted the scaled disclosures in this annual report on Form 10-K. Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts, certificate of deposits, money market funds and U.S. Treasury securities. Short Term Investments The Company invests its excess cash in cash deposits, U.S. Treasury securities and SEC-registered money market funds. Securities with original maturities of three months or less when purchased are included in Cash and cash equivalents. The Company considers investments with original maturities greater than three months and remaining maturities less than one year to be short-term investments. As of December 31, 2023, all investments in U.S. Treasury securities were classified as available-for-sale securities, which are recorded at fair value. Unrealized holding gains and losses on available-for-sale securities are reported net of related income taxes in accumulated other comprehensive income until realized. Purchase premiums and discounts are amortized to interest income over the terms of the related securities. Concentrations of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and short-term investments. The Company’s cash, cash equivalents and short-term investments are held by financial institutions primarily in the United States and the United Kingdom. Amounts on deposit may at times exceed federally insured limits. Management believes that the financial institutions are financially sound, and accordingly, the Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Segments Operating segments are defined as components of an enterprise with separate discrete information available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. We view our operations and manage our business as one segment. Reclassifications Certain amounts in the prior period financial statements have been reclassified to conform to the presentation of the current period financial statements. These reclassifications had no effect on previously reported net loss or comprehensive loss. Foreign Currency Translation The Company’s financial statements are presented in U.S. dollars (“USD”), the reporting currency of the Company. The functional currency of Centessa Pharmaceuticals plc is USD and the functional currency of the Centessa Subsidiaries is their respective local currency. Income and expenses have been translated into USD at average monthly exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the balance sheets dates and equity accounts at their respective historical rates. The resulting translation gain and loss adjustments are recorded directly as a separate component of shareholders’ equity as other comprehensive (loss) income. Transactions denominated in a currency other than the functional currency are remeasured based upon the exchange rate at the date of remeasurement with the resulting gain or loss included in the accompanying consolidated statements of operations and comprehensive loss within Other income (expense), net. The aggregate foreign currency transaction gain or loss is included in the results of operations. For the year ended December 31, 2023, the Company recorded a net foreign currency transaction gain of $0.8 million, while for the year ended December 31, 2022, it recorded a net loss of $2.8 million. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the consolidated financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include accrued research and development expenses, the note purchase agreement, share-based compensation, leases and tax-related matters. Property and Equipment, net Property and equipment are recorded at cost and are depreciated using the straight-line method over the estimated useful lives of the respective assets. Property and equipment includes computer equipment, furniture and office equipment, which have a useful life of three Depreciation expense for the years ended December 31, 2023 and December 31, 2022 was $298 thousand and $131 thousand respectively. Capitalized software as a service costs representing costs incurred during the application development stage are included in “Other non-current assets” and the corresponding current portion, in “Prepaid expenses and other current assets” and is amortized using the straight line method over 5 years. Costs incurred during the preliminary project stage and the post-implementation-operation stage are expensed as incurred. Hosting fees associated with the hosting as a service arrangement are expensed on a straight line basis over the term of the hosting arrangement. Amortization expense for the year ended December 31, 2023 was $0.5 million. Leases In accordance with ASU No. 2016-02, Leases (“ASC 842”) , the Company assesses whether an arrangement is a lease, or contains a lease at the inception of the arrangement. When an arrangement contains a lease, the Company categorizes leases with contractual terms longer than twelve months as either operating or finance. Finance leases are generally those leases that allow us to substantially utilize or pay for the entire asset over its estimated life. Assets acquired under finance leases are recorded in “Property and equipment, net.” All other leases are categorized as operating leases. The Company records right-of use ("ROU") assets and lease obligations for its finance and operating leases, which are initially recognized based on the discounted future lease payments over the term of the lease. As the rate implicit in the Company's leases may not be easily determinable, the Company uses its incremental borrowing rate to calculate the present value of the sum of the lease payments. Lease terms may include options to extend or terminate the lease. The Company will include such options in determining the lease term when it is reasonably certain that the Company will exercise such options. Operating and finance lease ROU assets are recognized net of any lease prepayments and incentives. The Company elected the practical expedient to not separate lease and non-lease components and, accordingly, accounts for them as a single lease component. Operating lease expense is recognized on a straight-line basis over the lease term. Finance lease expense is recognized based on the effective-interest method over the lease term. The Company elected not to recognize ROU assets and lease obligations for any short-term leases, which are defined as leases with an initial term of 12 months or less. Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the estimated fair value of the asset. As of December 31, 2023, the Company believes that no revision of the remaining useful lives or write-down of long-lived assets is required. Fair Value Measurement Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, prepaid expense and accounts payable, are shown at cost, which approximates fair value due to the short-term nature of these instruments. The Company follows the provisions of FASB ASC Topic 820, Fair Value Measurement , for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities. Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Note Purchase Agreement In October 2021, the Company entered into a Note Purchase Agreement (the “NPA”) with Oberland Capital. As described in further detail in Note 6 - "Debt" , as of December 31, 2023, in addition to a secured note in the principal amount of $75 million, which was funded on October 4, 2021, Oberland Capital has agreed to purchase tranches of secured notes in the aggregate principal amount of up to $175 million, including up to $75 million through September 2024, at the Company’s option ; and up to $100 million at any time at the Company’s and Purchasers’ option, to be used to finance certain permitted acquisitions as described in the NPA. In addition, the Company is obligated to pay a Milestone payment equal to 30% of the aggregate principal amount issued under the Notes by the Company upon regulatory approval of any drug candidate. The Company evaluated the notes under the NPA and determined that the notes include embedded derivatives that would otherwise require bifurcation as derivative liabilities. Neither the debt instrument nor any embedded features are required to be classified as equity. Therefore, the hybrid financial instrument comprised of the debt host and the embedded derivative liability may be accounted for under the fair value option. The Company elected to carry the notes at fair value, and the debt instrument is outside the scope of ASC 480, Distinguishing Liabilities from Equity , and thus is classified as a liability under ASC 470, Debt , in the Company’s financial statements. As the Company has elected to account for the notes under the fair value option, debt issuance costs were immediately expensed. The fair value of the notes under the NPA represents the present value of estimated future payments, including interest, principal as well as estimated payments that are contingent upon the achievement of specified milestones. The fair value of the notes is based on the cumulative probability of the various estimated payments. The fair value measurement is based on significant Level 3 unobservable inputs such as the probability of achieving the milestones, anticipated timelines, probability and timing of an early redemption of all obligations under the agreement and the discount rate. Any changes in the fair value of the liability in each reporting period are recognized in the consolidated statement of operations and comprehensive loss until it is settled. License and other revenue The Company recognizes revenues from collaboration, license or other research or sale arrangements when or as performance obligations are satisfied. For milestone payments, the Company assesses, at contract inception, whether the milestones are considered probable of being achieved. If it is probable that a significant revenue reversal will occur, the Company will not record revenue until the uncertainty has been resolved. Milestone payments that are contingent upon regulatory approval are not considered probable until the approvals are obtained as it is outside of the control of the Company. If it is probable that significant revenue reversal will not occur, the Company will estimate the milestone payments using the most likely amount method. The Company reassesses the milestones each reporting period to determine the probability of achievement. Any potential consideration received in the form of royalty or sales-based milestones will be recorded when the customer’s subsequent sales or usages occur. Collaborative Arrangements The Company enters into collaborative arrangements to develop and commercialize intellectual property. These arrangements typically involve two (or more) parties who are active participants in the collaboration and are exposed to significant risks and rewards dependent on the commercial success of the activities. These collaborations usually involve various activities by one or more parties, including research and development, marketing and selling and distribution. Often, these collaborations require upfront, milestone and royalty or profit share payments, contingent upon the occurrence of certain future events linked to the success of the asset in development. Amounts due to collaborative partners related to development activities are generally reflected as research and development expense. Research and Development Expenses and Accruals All research and development costs are expensed in the period incurred and consist primarily of salaries, payroll taxes, employee benefits, stock-based compensation charges for those individuals involved in research and development efforts, external research and development costs incurred under agreements with contract research organizations and consultants to conduct and support the Company’s ongoing clinical trials. The Company has entered into various research and development contracts with clinical research organizations, clinical development and manufacturing organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred. Payments made in advance of performance are reflected in the accompanying balance sheets as prepaid expenses, while payments made after performance are reflected as accrued liabilities in the accompanying balance sheets. The Company records accruals for estimated costs incurred for ongoing research and development activities. When recording accruals for ongoing research and development activities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Nonrefundable advance payments for goods and services, including fees for process development or manufacturing and distribution of clinical supplies that will be used in future research and development activities, are recognized as expense in the period that the related goods are consumed or services are performed. Milestone payments within the Company’s licensing arrangements are recognized when achievement of the milestone is deemed probable to occur. To the extent products are commercialized and future economic benefit has been established, commercial milestones that become probable are capitalized and amortized over the estimated remaining useful life of the intellectual property. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. Research and Development Tax Incentives The Company participates in research tax incentive programs that are granted to companies by the United Kingdom tax authorities in order to encourage them to conduct technical and scientific research. Expenditures that meet the required criteria are eligible to receive a tax credit that is reimbursed in cash, upon surrender of loss carryforwards. Estimates of the amount of the cash refund expected to be received are determined at each reporting period and recorded as reductions to research and development expenses. The Company recorded research and development tax incentives of $24.3 million and $12.6 million during the years ended December 31, 2023 and December 31, 2022, respectively. The Company may not be able to continue to claim the most beneficial payable research and development tax credits in the future if it ceased to qualify as a small or medium enterprise, based on size criteria concerning employee headcount, turnover and gross assets. In addition, unless its subsidiaries qualify for an exemption, there are limitations to how much tax incentive can be claimed. This limitation is calculated as the total of the Company's relevant expenditure on employees in the period, multiplied by 300%, plus £20,000. Share-Based Compensation The Company measures share-based awards, including restricted shares, restricted stock units and stock options, at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. Subsequent to the IPO, the Company determines the fair value of share-based compensation awards using the market closing price of the Company’s ADSs on the date of grant. F orfeitures of stock options are recognized in the period the forfeiture occurs. The Company uses the Black-Scholes option pricing model to value its stock option awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For share price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option. The estimated annual dividend yield is 0% because the Company has not historically paid and does not expect for the foreseeable future to pay a dividend on its ordinary shares. Retirement Plans The Company provided defined contribution plans to its employees beginning in 2021. In the U.S., the primary plan sponsored by the Company is a safe harbor, 401k plan with a 4% employer match, no waiting period and immediate vesting on the match. In the UK, the primary plan sponsored by the Company is a money purchase plan, which requires a minimum 8% contribution, including a minimum employer contributio n of 4% and employee contribution of 4% in 2022. The Company recorded charges of $0.6 million under these plans during the year ended December 31, 2023 and $0.7 million during the year ended December 31, 2022. Income Taxes The Company follows the asset and liability method of accounting for income taxes under ASC 740, Income Taxes . Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company regularly assesses its ability to realize its deferred tax assets. Assessing the realization of deferred tax assets requires significant judgment. In determining whether its deferred tax assets are more likely than not realizable, the Company evaluated all available positive and negative evidence, and weighed the evidence based on its objectivity. After consideration of the evidence, the Company believes it would more likely than not be able to utilize existing loss carryforwards and research and development tax credits to offset future income in the United States. The operating entity in the United States has a history of cumulative net profits as it carries out services for other entities in the group. ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception. Net Loss Per Ordinary Share Basic loss per ordinary share is computed by dividing net loss by the aggregate weighted-average number of ordinary shares outstanding. Diluted loss per ordinary share includes the effect, if any, from the potential exercise or conversion of securities, such as stock options, unvested restricted ordinary shares and restricted stock units which would result in the issuance of incremental ordinary shares. For diluted net loss per ordinary share, the weighted-average number of ordinary shares is the same for basic net loss per ordinary share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The following potentially dilutive securities have been excluded from the computation of diluted weighted-average ordinary shares outstanding, as they would be anti-dilutive. Year Ended Year Ended Unvested ordinary shares 310,052 599,421 Restricted stock units 1,949,463 1,804,760 Stock options 16,069,015 14,688,996 18,328,530 17,093,177

Revenue

Revenue	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue	Revenue On November 24, 2023, the Company entered an out-license agreement with AnaptysBio, Inc. Under the license agreement, Centessa granted to AnaptysBio an exclusive license to manufacture, develop, register, sell, commercialize or otherwise exploit the licensed compound CBS004 and its related backup antibodies. In exchange, Centessa received a one-time non-refundable upfront cash payment of approximately $7 million for the license as well as for transferred manufactured supply of CBS004 and related backup antibodies. Centessa is eligible to receive an additional development milestone payment and a low single-digit royalties on global net sales upon the first commercial sale through to the expiration of any regulatory exclusivity. The Company recorded the upfront fee it received as license and other revenue in the year ended December 31, 2023. As of December 31, 2023, the Company concluded it was not probable that a significant reversal in cumulative revenue recognized related to the additional development milestone will not occur and therefore did not record any potential additional revenue related to the development milestone. The Company will reevaluate the transaction price at the end of each reporting period as uncertain events are resolved, or as other changes in circumstances occur. Any potential royalty will be recorded if or when the customer’s subsequent sales occur.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The following fair value hierarchy table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis (amounts in thousands): Fair value measurement at reporting date using Quoted prices Significant Significant December 31, 2023 Assets Money Market fund $ 28,339 $ — $ — U.S. Treasury securities $ 128,519 $ — $ — Liabilities Note Purchase Agreement $ — $ — $ 75,700 Fair value measurement at reporting date using Quoted prices Significant Significant December 31, 2022 Liabilities Note Purchase Agreement $ — $ — $ 69,800 We classify our investments in available-for-sale U.S. Treasury securities and the money market fund into Level 1 of the ASC Topic 820 hierarchy because fair values represent quoted market prices for identical or comparable instruments. The following represents the amortized cost bases and fair values of the Company’s U.S. Treasury securities and its money market fund as of December 31, 2023 (amounts in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money Market fund, included in Cash and cash equivalents $ 28,339 $ — $ — $ 28,339 U.S. Treasury securities, included in: Short-term investments 126,835 1,684 — 128,519 Total U.S. Treasury securities $ 126,835 $ 1,684 $ — $ 128,519 For the Company's financial instruments measured at fair value on a recurring basis using significant unobservable inputs (Level 3), the following table provides a reconciliation of the beginning and ending balances for each category therein (amounts in thousands): Contingent Value Rights Note Purchase Agreement Balance at January 1, 2022 $ 37,700 $ 75,700 Change in fair value 1,980 (5,900) Settlements (39,680) — Balance at December 31, 2022 $ — $ 69,800 Change in fair value — 5,900 Balance at December 31, 2023 $ — $ 75,700 The fair value of the Note Purchase Agreement represents the present value of estimated future payments, including interest, principal as well as estimated payments that are contingent upon the achievement of specified milestones. The fair value of the notes is based on the cumulative probability of the various estimated payments. The fair value measurement is based on significant Level 3 unobservable inputs such as the probability of achieving the milestones, anticipated timelines, probability and timing of an early redemption of all obligations under the agreement and the discount rate. Any changes in the fair value of the liability are recognized in the consolidated statement of operations and comprehensive loss until it is settled. For the year ended December 31, 2023, the Company recorded an unrealized loss of $5.9 million, while in the year ended December 31, 2022, it recorded an unrealized gain of $5.9 million. The unrealized loss in 2023 reflected the accretion of discount and a lower discount rate primarily from a decline in credit spreads. The unrealized gain in 2022 was largely driven by a higher discount rate due to a higher risk free rate and an increase in credit spreads in 2022.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Prepaid expenses and other current assets consist of the following (amounts in thousands): December 31, December 31, Research and development costs $ 16,123 $ 11,321 Insurance related costs 1,651 2,788 Value added tax receivable 1,330 2,557 Other 1,621 3,271 $ 20,725 $ 19,937 Accrued expenses and other current liabilities consist of the following (amounts in thousands): December 31, December 31, Research and development costs $ 18,814 $ 10,795 Personnel related expenses 6,733 7,264 Professional fees 1,072 4,171 Income tax liability 112 1,582 Other 839 690 $ 27,570 $ 24,502 Property and equipment, net consisted of the following (amounts in thousands): December 31, December 31, Computer equipment $ 734 $ 442 Office furniture 724 — Office equipment 43 — Construction in progress — 890 Property and equipment, at cost 1,501 1,332 Less: Accumulated depreciation (462) (164) Property and equipment, net $ 1,039 $ 1,168

Debt

Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	Debt Debt as of December 31, 2023 and December 31, 2022 (in thousands): December 31, December 31, Note Purchase Agreement $ 75,700 $ 69,800 Note Purchase Agreement On October 1, 2021 (the “Signing Date”), the Company, as issuer, and certain of the Company’s wholly owned subsidiaries, as guarantors (the “Guarantors”), entered into a Note Purchase Agreement (the “NPA”) with Oberland Capital Management LLC (the “Purchasers”) and Cocoon SA LLC (the “Agent”), an affiliate of Oberland Capital Management LLC, as agent for the Purchasers. On February 11, 2022, on November 7, 2022 and on June 23, 2023, the Company, the Guarantors, the Purchasers and the Agent agreed to certain amendments to the Note Purchase Agreement, memorialized in the “Amendment”, the “Second Amendment”, and the “Third Amendment” respectively. The Note Purchase Agreement, collectively with the amendments, is hereinafter referred to as the NPA. As of December 31, 2023, in addition to a secured note in the principal amount of $75 million, which was funded on October 4, 2021 (the “First Purchase Date”), the Purchasers have agreed to purchase tranches of secured notes in the aggregate principal amount of up to $175 million, including up to $75 million through September 2024, at the Company’s option ; and up to $100 million at any time at the Company’s and Purchasers’ option, to be used to finance certain permitted acquisitions as described in the NPA. The notes under the NPA will mature on the six-year anniversary of the First Purchase Date, unless earlier accelerated under the terms of the NPA. At maturity, the Company must repay the outstanding principal amount of the Notes, together with any accrued and unpaid interest thereon and other outstanding obligations thereunder. Interest is payable quarterly during the term of the Notes at a rate per annum equal to the sum of (a) the greater of (i) the Secured Overnight Financing Rate (“SOFR”) (which may be subject to replacement as contemplated by the NPA) and (ii) 0.25%; plus (b) 7.75% (which percentage is subject to adjustment as described in the NPA); provided that the interest rate shall never be less than 8.00%. The average interest rate over the year ended December 31, 2023 was 13.0% per annum compared with an average interest rate of 9.6% per annum over the year ended December 31, 2022. The Company’s obligations under the facility are secured by a first priority security interest in all assets of the Company and Guarantors, subject to variation in accordance with local law with respect to assets held by the Company and the Guarantors outside of the United States. Upon the first regulatory approval of any of the Company’s product candidates by either the FDA or the European Medicines Agency (“EMA”), the Company is obligated to pay the Purchasers an amount equal to 30% of the aggregate principal amount issued under the Notes by the Company (the “Milestone Payment”). The Milestone Payment shall be paid in quarterly installments over five years beginning on the earlier of (i) the date of the first commercial sale following such regulatory approval; and (ii) the six month anniversary of such regulatory approval. The Milestone Payment is triggered one time only, and applies only to the Company’s first product to obtain regulatory approval. The Company may redeem all, but not less than all, of the outstanding notes (if any) and pay all other outstanding obligations under the NPA. On the applicable date, the Company shall repurchase the notes by paying an amount of up to (i) 175% of the principal amount issued under the notes if such repurchase occurs on or prior to the third anniversary of the First Purchase Date, (ii) 185% of the principal amount issued under the notes if such repurchase occurs between the third and sixth anniversaries of the First Purchase Date, and (iii) 205% of the principal amount issued under the notes if such repurchase occurs thereafter, in each case less specified deductions and exclusions described in the NPA, including amounts paid by the Company to the Purchasers in respect of certain asset sale or strategic transactions, the interest payments and the Milestone Payments (the “Final Payment Amount”). As of December 31, 2023, the cumulative payments under the NPA, including interest payments, totaled $18.7 million. Conversely, the Purchasers may require the Company to redeem any outstanding notes by payment of the Final Payment Amount upon a sale, divestment or transfer of all or substantially all assets of the Company in a transaction or series of transactions or a change of control of the Company, a material breach of the NPA and related transaction documents, an event of default under the NPA or the tenth anniversary of the First Purchase Date (or such earlier date as described in the NPA). In addition, upon certain asset sales and similar strategic transactions by the Company with respect to its own or its subsidiaries’ assets or businesses as described in the NPA (other than a change of control described above), the Purchasers may require the Company to pay an amount in cash equal to up to 75% of the Net Proceeds (as defined in the NPA) received from such asset sales, subject to a $100 million deductible such that the Purchaser Agent will not collect any repurchase amounts until $100 million has been received by the Company from such sale event (the “Deductible”). The NPA contains customary affirmative and negative covenants, including with respect to notice obligations, limitations on new indebtedness, liens, investments and transactions with affiliates of the Company, restrictions on the payment of dividends, maintenance of collateral accounts in the amount of 90% of the aggregate outstanding principal amount of all issued notes, maintenance of insurance and addition of new subsidiaries as obligors. It also contains customary representations and warranties in favor of the Purchasers and the Agent and customary events of default, which may cause the obligations of the Company to be accelerated. Such events include among others, failure to make payments when due, breach of covenants, insolvency, a cross-default to other indebtedness, a judgment event of default, and delisting of the Company’s securities from the Nasdaq Global Select Market.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments As of December 31, 2023, the Company had non-cancellable commitments for purchase of clinical materials, contract manufacturing, maintenance, and committed funding of up to $61.1 million, of which the Company expects to pay $45.1 million within one year and the remaining $16.0 million over one to five years. The amount and timing of these payments vary depending on the rate of progress of development. Future clinical trial expenses have not been included within the purchase commitments because they are contingent on enrollment in clinical trials and the activities required to be performed by the clinical sites. Leases On February 7, 2022, the Company entered into an operating lease for its new U.S. corporate headquarters in Boston, Massachusetts (the “Boston Lease”). After a build out of the space, the Boston Lease commenced on March 31, 2023. The 10-year Boston Lease is for 18,922 square feet with a fixed annual rent of approximately $1.6 million commencing in 2023 and escalating to approximately $1.9 million by year 10 . The Boston Lease required the Company to issue a letter of credit in the amount of $0.7 million in favor of the landlord. The Company may, at its discretion, extend the Boston Lease for one extension term of five years. As of December 31, 2023, the Company has recognized an operating lease right-of-use asset, net of $11.9 million, including capitalized leasehold improvements that will be owned by the landlord, prepayments of rent, and a corresponding lease liability of $9.4 million . On October 11, 2023, the Company entered into a five-year agreement to sublet 4,242 square feet of the Boston Lease, which may be extended at subtenant’s option. The following table provides balance sheet information related to leases as of December 31, 2023 (amounts in thousands): December 31, 2023 Assets: Operating lease, right-of-use asset $ 11,914 Liabilities: Current portion of operating lease liabilities $ 505 Operating lease liabilities, net of current portion 8,888 Total operating lease liabilities $ 9,393 In calculating the present value of the lease payments, the Company elected to utilize its incremental borrowing rate based on the original term of the lease. The following table summarizes supplemental information related to leases as of December 31, 2023 (amount in thousands): December 31, 2023 Weighted-average remaining lease term 9.0 years Weighted-average discount rate 11.97 % The components of the Company’s lease costs and sublease income are classified on its consolidated statements of operations as follows (amounts in thousands): Year Ended Year Ended Operating lease cost $ 1,498 $ — Variable lease cost 53 66 Short term lease cost 26 131 Sublease income (58) — Total operating lease cost $ 1,519 $ 197 Future lease payments under non-cancelable operating leases and expected sublease income as of December 31, 2023 were as follows (amounts in thousands): Operating Leases Sublease Income Year ending: 2024 $ 1,602 $ 348 2025 1,634 355 2026 1,667 362 2027 1,700 369 2028 1,734 376 Thereafter 7,289 — Total undiscounted amounts $ 15,626 $ 1,810 Less: Imputed interest (6,233) Present value of lease liabilities $ 9,393 Less: current portion (505) Lease liabilities, net of current portion $ 8,888 Licensing and Collaborative Arrangements The Company is party to licensing and collaboration arrangements to develop and commercialize intellectual property. As of December 31, 2023, the Company had no licensing and collaborative arrangement milestone obligations recorded on its balance sheet. License Agreement with Heptares Limited in connection with Orexin Program The Company is party to a license, assignment, and research services agreement with Heptares Therapeutics Limited (“Heptares”), relating to certain specific molecules with, among other criteria, the primary mode of action of an orexin agonist or orexin positive modulator (“Molecules”). Under the agreement, Heptares assigned to the Company all of Heptares’ right, title, and interest in and to intellectual property that is already in existence and that is developed as a result of the agreement that relates solely to Molecules or products that contain Molecules (“Products”), including all rights to obtain patent or similar protection throughout the world for such intellectual property and to take any and all actions regarding past infringements of existing intellectual property. Additionally, Heptares granted to the Company an exclusive, sublicensable (subject to certain terms) license to make, import, export, use, sell, or offer for sale, including to development, commercialization, registration, modification, enhancement, improvement, manufacturing, holding, keeping or disposing of Molecules and Products. Heptares must not by itself or through a third party (other than a single company) exploit, use or dispose of ( inter alia ) any product in the field of orexin agonism and orexin positive modulation for the duration of the agreement and for three years thereafter. In consideration for the assignment and license, the Company is to pay Heptares a royalty in the low single-digits on net sales of Products (subject to limitations in certain scenarios). Royalties are on a Product-by-Product and country-by country basis. Payments shall commence with the first commercial sale of such product in a country and shall continue until the later of: (a) the duration of regulatory exclusivity in the country; or (b) ten years after the first commercial sale. Further, the Company is responsible for all development costs incurred by itself or Heptares in the performance of the research program (within the confines of the research budget). Additionally, the Company must pay Heptares, on a Molecule-by-Molecule basis, development milestone payments in the aggregate of a low double-digit number in the millions of pounds sterling. Milestone payments are payable once per Molecule. The Company anticipates paying between the low single digits millions of pounds sterling to low double digit millions of pounds sterling in the next twelve months. The Company may terminate the agreement at any time following the expiration or termination of the research program. In addition, customary termination rights exist for both parties for breach and insolvency. In the event of termination, all licenses automatically terminate. The term of the agreement is until the later of: (i) the expiration of the last to expire patent within the licensed intellectual property; (ii) the expiration of the royalty term; and (iii) the fifteenth anniversary of the effective date. Upon expiration, with respect to any given Molecule, the license granted to the Company shall become perpetual, irrevocable, and fully-paid up. Other License and Collaboration Agreements The Company is a party to other license and collaboration agreements to develop and commercialize intellectual property in addition to the agreement discussed above. In aggregate, Centessa is obligated to make up to $5.2 million and $15.0 million in development and commercial milestone payments, respectively, related to these other agreements. Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. Legal charges incurred in connection with contingencies and litigation are expensed as incurred. Litigation On September 28, 2022 (“Original Complaint”), the Company and certain of its current and former officers were named as defendants in a proposed class-action lawsuit filed in the United States District Court for the Central District of California. The complaint generally alleges that the Company violated Sections 10(b) and 20(a) and Sections 11 and 15 of the Securities Act of 1933, as amended (the “Securities Act”) by allegedly making materially false and/or misleading statements, as well as allegedly failing to disclose material adverse facts relating to the safety profile and future clinical and commercial prospects of each of its lixivaptan and ZF874 programs, which caused the Company’s securities to trade at artificially inflated prices. On October 12, 2022, by order, the lawsuit was transferred to the United States District Court for the Southern District of New York. On February 10, 2023, an amended complaint was filed (“Amended Complaint”) in which our IPO underwriters were added as co-defendants. A number of the claims set forth in the Original Complaint have been abandoned including with respect to intentional fraud theory and claims pursuant to Sections 10(b) or 20(a) of the Securities Exchange Act of 1934. The only claims alleged in the Amended Complaint are violations of Sections 11 and 15 of the Securities Act based on alleged misstatements in the S-1 filed by the Company in connection with its Initial Public Offering. The Amended Complaint also abandoned any claims concerning ZF874 and focuses entirely on lixivaptan. The Amended Complaint seeks damages and attorneys’ fees, among other things. On August 23, 2023, the Company submitted its motion to dismiss all claims, which remains pending. The Company believes this lawsuit is without merit and intends to defend the case vigorously. Litigation is subject to inherent uncertainty and a court could ultimately rule against the Company. In addition, the defense of litigation and related matters are costly and may divert the attention of the Company’s management and other resources that would otherwise be engaged in other activities. The Company has not recorded an estimate of the possible loss associated with this legal proceeding due to the uncertainties related to both the likelihood and the amount of any possible loss or range of loss.

Share-based Compensation

Share-based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Share-based Compensation	Share-based Compensation Centessa Pharmaceuticals plc Stock Option and Incentive Plan In January 2021, the Company’s board of directors approved the 2021 Stock Option and Incentive Plan (the “2021 Plan”). The 2021 Plan provides for the granting of ordinary shares, incentive stock options, non-qualified stock options, restricted share awards, and/or share appreciation rights to employees, directors, and other persons, as determined by the Company’s board of directors. The number of shares authorized under the 2021 Plan was increased in May 2021 at the time of the IPO, whereby the total number of shares authorized under the 2021 Plan was 20,026,816. Beginning on January 1, 2022 and each January 1 thereafter, the number of Shares reserved and available for issuance under the 2021 Plan shall be cumulatively increased by 5% of the number of Shares issued and outstanding on the immediately preceding December 31, or such lesser number as the board of directors may determine. Remaining shares available for future grants as of December 31, 2023 were 8,252,636. Share-based Compensation Expense The Company recorded share-based compensation expense in the following expense categories in the consolidated statements of operations and comprehensive loss (amounts in thousands): Year Ended Year Ended Research and development $ 13,221 $ 11,954 General and administrative 16,171 13,011 $ 29,392 $ 24,965 Stock Options The following table summarizes stock option activity for the year ended December 31, 2023: Number of Shares Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (in millions) Balance at January 1, 2023 14,688,996 $ 7.88 8.5 years Granted 3,542,700 4.48 Exercised (70,197) 4.41 Forfeited (2,092,484) 8.37 Balance at December 31, 2023 16,069,015 $ 7.09 7.9 years $ 29.0 Exercisable at December 31, 2023 8,417,959 $ 7.41 7.5 years $ 13.4 Vested and expected to vest at December 31, 2023 16,069,015 $ 7.09 7.9 years $ 29.0 The Company’s stock options vest based on the terms in each award agreement, generally over four-year periods, and have a contractual term of ten years. As of December 31, 2023, the total unrecognized compensation expense related to unvested stock option awards was $30.7 million, which the Company expects to recognize over a weighted-average period of 2.0 years. Based on the trading price of $7.96 per ADS, which was the closing price as of December 31, 2023, the aggregate intrinsic value of options as of December 31, 2023 was $29.0 million. The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below: Year Ended Year Ended Weighted-average grant date fair value of options $3.22 $5.38 Expected term (in years) 6.02 6.01 Expected stock price volatility 78.3% 76.4% Risk-free interest rate 3.8% 2.2% Expected dividend yield 0% 0% The Company uses the Black-Scholes option pricing model to value its stock option awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For share price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option. Forfeitures of stock options are recognized in the period the forfeiture occurs. Restricted Share Awards and Units In connection with the acquisition of the Centessa Subsidiaries, the Company issued 379,905 ordinary shares subject to future vesting under its Restricted Stock Awards program. For the period subsequent to the acquisition through December 31, 2023, the Company issued an additional 833,897 ordinary shares subject to future vesting to an employee. The fair value of the awards are based upon the estimated fair value of the Company’s ordinary shares at the time of grant. The Board, following the recommendations of the Company’s Compensation Committee, grants service-based restricted stock unit awards under the Company’s Stock Incentive Plan to certain executive officers and employees of the Company to encourage employee retention. Periodic grants are made at fair market value, representing the NASDAQ market close quoted price on the day of the grant. The following table summarizes ordinary share activity related to the restricted stock programs for the year ended December 31, 2023: Restricted Stock Awards Restricted Stock Units Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Unvested at January 1, 2023 599,421 1,804,760 Granted — n/a 1,443,381 $ 3.87 Vested (289,369) (905,297) Forfeited — (393,381) Unvested at December 31, 2023 310,052 1,949,463 Unrecognized compensation expense at December 31, 2023 ($ in thousands) $ 5,708 $ 7,765 Expected weighted average recognition period 1.3 years 1.9 years Centessa Pharmaceuticals plc 2021 Employee Share Purchase Plan In January 2021, the Company’s board of directors approved the 2021 Employee Share Purchase Plan (the “2021 ESPP”). The initial number of shares reserved for issuance under the 2021 ESPP was 860,000. On January 1, 2022 and each January 1 thereafter, the number of Shares reserved and available for issuance under the ESPP shall be cumulatively increased by a number of shares equal to the lesser of: (i) 1% of the number of Shares issued and outstanding on the immediately preceding December 31; (ii) two times the initial number of shares reserved or (iii) such number of Shares as determined by the board of directors. Remaining shares reserved as of December 31, 2023 were 2,708,315.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Master Services agreements with drug discovery companies affiliated with David Grainger, former Chief Innovation Officer The Company has entered into Master Services agreements with certain drug discovery companies affiliated with David Grainger, who served as the Company’s Chief Innovation Officer in October 2021 through December 31, 2023. These companies include RxCelerate Limited, RxBiologics Limited and The Foundry (Cambridge) Limited, of which David Grainger is a director and shareholder. The Company incurred research and development costs associated with these contracts as follows in the consolidated statements of operations and comprehensive loss (amounts in thousands): Year Ended Year Ended Research and development $ 5,360 $ 7,373

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities were as follows (amounts in thousands): December 31, December 31, Deferred tax assets: Tax loss carryforwards $ 77,435 $ 73,097 Capitalized research and development 14,440 15,624 Research and development credits 10,488 7,174 Other 3,246 1,467 Total deferred tax assets 105,609 97,362 Valuation allowance (73,239) (93,850) Deferred tax assets, net of allowance 32,370 3,512 Deferred tax liabilities: Other (2,723) — Net deferred tax assets $ 29,647 $ 3,512 The Company regularly assesses its ability to realize its deferred tax assets. Assessing the realization of deferred tax assets requires significant judgment. In determining whether its deferred tax assets are more likely than not realizable, the Company evaluated all available positive and negative evidence, and weighed the evidence based on its objectivity. After consideration of the evidence, including the Company's history of cumulative net losses in the U.K., the Company has concluded that it is more likely than not that the Company will not realize the benefits of its U.K. deferred tax assets and accordingly the Company has provided a valuation allowance for the full amount of the net deferred tax assets in the U.K. The Company has considered the history of cumulative net profits in an operating entity in the United States, which carries out services for other entities in the group, and estimated that entity’s future taxable income and concluded that it is more likely than not that the Company will realize the benefits of the deferred tax assets in that entity, and has not provided a valuation allowance against the net deferred tax assets in that entity. For the year ended December 31, 2023 , the valuation allowance decreased by $20.6 million, primarily reflecting the release of a valuation allowance following an internal reorganization of subsidiaries in the U.S. in 2023 . For the year ended December 31, 2022, the valuation allowance increased by $44.8 million . Components of the Company’s pre-tax loss are as follows (amounts in thousands): Year Ended Year Ended Loss before tax: UK $ (187,643) $ (173,476) Non-UK 11,502 (43,478) Total $ (176,141) $ (216,954) The income tax (benefit) expense consists of the following (amounts in thousands): December 31, December 31, Federal - U.S. Current $ 1,237 $ 1,575 Deferred (26,272) (2,464) State - U.S. Current 233 534 Deferred (256) (392) Foreign Current 2 — Deferred — — Income tax (benefit) expense $ (25,056) $ (747) A reconciliation of the United Kingdom (“UK”) income tax rate to the Company’s effective tax rate is as follows: Year Ended Year Ended Statutory tax rate benefit 24 % 19 % Non-deductible share-based compensation (4) % (2) % Other non-deductible expenses (2) % (1) % Enhanced UK research and development expenses 10 % 7 % Losses surrendered for UK research tax incentive (28) % (7) % UK non-taxable research and development incentive 3 % 1 % U.S. research & development tax credits 1 % 1 % Change in tax rate — % 2 % Effect of overseas tax rates — % 3 % Unrecognized tax benefits (1) % — % Return to provision adjustments 2 % — % Release of U.S. valuation allowance 15 % — % Increase in valuation allowance (6) % (23) % Effective income tax rate 14 % — % The following table summarizes carryforwards of federal and local net operating losses (NOL) and research tax credits (amounts in thousands): December 31, December 31, UK $ 278,989 $ 225,662 U.S. $ 45,484 $ 48,523 France $ — $ 25,474 UK income tax returns from 2021 remain open for examination and UK NOLs do not expire. In the U.S., income tax returns from 2020 and later remain open for examination and unutilized U.S. NOLs and credit carryforwards are subject to examination until utilized. If not utilized prior to the specified dates, U.S. federal NOLs totaling $3.2 million and a U.S. R&D tax credit carryforward of $10.5 million would expire starting in 2036 and $39.3 million of U.S. state NOLs would expire beginning in 2036. Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”) provides for limitation on the use of net operating loss and research and development tax credit carryforwards following certain ownership changes (as defined in Code) that could limit the Company’s ability to utilize these carryforwards, in relation to its principal operating unit in the U.S. Pursuant to Section 382 of the Code, an ownership change occurs when the stock ownership of a 5% stockholder increases by more than 50% over a three-year testing period. The Company’s U.S. entities may have experienced various ownership changes, as defined by the Code, as a result of past financings and may in the future experience an ownership change. Accordingly, the Company’s ability to utilize the aforementioned carryforwards may be limited. A reconciliation of gross unrecognized tax benefits, as of December 31, 2023 and 2022 is as follows (amounts in thousands): 2023 2022 Gross unrecognized tax benefits at beginning of period $ — $ — Increase related to current year tax positions 2,614 — Gross unrecognized tax benefits at end of period $ 2,614 $ —

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net loss	$ (151,085)	$ (216,207)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	12 Months Ended
	Dec. 31, 2023 shares	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Karen Anderson [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On November 23, 2023, Karen Anderson, our Chief People Officer, adopted a trading arrangement for the sale of the Company's ADSs, or a Rule 10b5-1 Trading Plan, that is intended to satisfy the affirmative defense conditions of Securities Exchange Act Rule 10b5-1(c). Ms. Anderson's Rule 10b5-1 Trading Plan, which has a plan end date of August 15, 2024, provides for the sale of up to 90,000 ADSs pursuant to the terms of the plan.
Name	Karen Anderson
Title	Chief People Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	November 23, 2023
Arrangement Duration	266 days
Aggregate Available	90,000	90,000

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) promulgated by the Financial Accounting Standards Board (“FASB”). All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying consolidated financial statements include all normal and recurring adjustments (which consist primarily of accruals, estimates and assumptions that impact the financial statements) considered necessary to present fairly: • the Company’s financial position as of December 31, 2023 and December 31, 2022; and • the Company’s results of operations and cash flows for the years ended December 31, 2023 and December 31, 2022.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts, certificate of deposits, money market funds and U.S. Treasury securities.
Short Term Investments	Short Term Investments The Company invests its excess cash in cash deposits, U.S. Treasury securities and SEC-registered money market funds. Securities with original maturities of three months or less when purchased are included in Cash and cash equivalents. The Company considers investments with original maturities greater than three months and remaining maturities less than one year to be short-term investments.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and short-term investments. The Company’s cash, cash equivalents and short-term investments are held by financial institutions primarily in the United States and the United Kingdom. Amounts on deposit may at times exceed federally insured limits. Management believes that the financial institutions are financially sound, and accordingly, the Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.
Segments	Segments Operating segments are defined as components of an enterprise with separate discrete information available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. We view our operations and manage our business as one segment.
Reclassifications	Reclassifications Certain amounts in the prior period financial statements have been reclassified to conform to the presentation of the current period financial statements. These reclassifications had no effect on previously reported net loss or comprehensive loss.
Foreign Currency Translation	Foreign Currency Translation The Company’s financial statements are presented in U.S. dollars (“USD”), the reporting currency of the Company. The functional currency of Centessa Pharmaceuticals plc is USD and the functional currency of the Centessa Subsidiaries is their respective local currency. Income and expenses have been translated into USD at average monthly exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the balance sheets dates and equity accounts at their respective historical rates. The resulting translation gain and loss adjustments are recorded directly as a separate component of shareholders’ equity as other comprehensive (loss) income.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the consolidated financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include accrued research and development expenses, the note purchase agreement, share-based compensation, leases and tax-related matters.
Property and Equipment, net	Property and Equipment, net Property and equipment are recorded at cost and are depreciated using the straight-line method over the estimated useful lives of the respective assets. Property and equipment includes computer equipment, furniture and office equipment, which have a useful life of three
Leases	Leases In accordance with ASU No. 2016-02, Leases (“ASC 842”) , the Company assesses whether an arrangement is a lease, or contains a lease at the inception of the arrangement. When an arrangement contains a lease, the Company categorizes leases with contractual terms longer than twelve months as either operating or finance. Finance leases are generally those leases that allow us to substantially utilize or pay for the entire asset over its estimated life. Assets acquired under finance leases are recorded in “Property and equipment, net.” All other leases are categorized as operating leases. The Company records right-of use ("ROU") assets and lease obligations for its finance and operating leases, which are initially recognized based on the discounted future lease payments over the term of the lease. As the rate implicit in the Company's leases may not be easily determinable, the Company uses its incremental borrowing rate to calculate the present value of the sum of the lease payments. Lease terms may include options to extend or terminate the lease. The Company will include such options in determining the lease term when it is reasonably certain that the Company will exercise such options. Operating and finance lease ROU assets are recognized net of any lease prepayments and incentives. The Company elected the practical expedient to not separate lease and non-lease components and, accordingly, accounts for them as a single lease component. Operating lease expense is recognized on a straight-line basis over the lease term. Finance lease expense is recognized based on the effective-interest method over the lease term. The Company elected not to recognize ROU assets and lease obligations for any short-term leases, which are defined as leases with an initial term of 12 months or less.
Long-Lived Assets	Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the estimated fair value of the asset. As of December 31, 2023, the Company believes that no revision of the remaining useful lives or write-down of long-lived assets is required.
Fair Value Measurement	Fair Value Measurement Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, prepaid expense and accounts payable, are shown at cost, which approximates fair value due to the short-term nature of these instruments. The Company follows the provisions of FASB ASC Topic 820, Fair Value Measurement , for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities. Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).
Note Purchase Agreement	Note Purchase Agreement In October 2021, the Company entered into a Note Purchase Agreement (the “NPA”) with Oberland Capital. As described in further detail in Note 6 - "Debt" , as of December 31, 2023, in addition to a secured note in the principal amount of $75 million, which was funded on October 4, 2021, Oberland Capital has agreed to purchase tranches of secured notes in the aggregate principal amount of up to $175 million, including up to $75 million through September 2024, at the Company’s option ; and up to $100 million at any time at the Company’s and Purchasers’ option, to be used to finance certain permitted acquisitions as described in the NPA. In addition, the Company is obligated to pay a Milestone payment equal to 30% of the aggregate principal amount issued under the Notes by the Company upon regulatory approval of any drug candidate. The Company evaluated the notes under the NPA and determined that the notes include embedded derivatives that would otherwise require bifurcation as derivative liabilities. Neither the debt instrument nor any embedded features are required to be classified as equity. Therefore, the hybrid financial instrument comprised of the debt host and the embedded derivative liability may be accounted for under the fair value option. The Company elected to carry the notes at fair value, and the debt instrument is outside the scope of ASC 480, Distinguishing Liabilities from Equity , and thus is classified as a liability under ASC 470, Debt , in the Company’s financial statements. As the Company has elected to account for the notes under the fair value option, debt issuance costs were immediately expensed. The fair value of the notes under the NPA represents the present value of estimated future payments, including interest, principal as well as estimated payments that are contingent upon the achievement of specified milestones. The fair value of the notes is based on the cumulative probability of the various estimated payments. The fair value measurement is based on significant Level 3 unobservable inputs such as the probability of achieving the milestones, anticipated timelines, probability and timing of an early redemption of all obligations under the agreement and the discount rate. Any changes in the fair value of the liability in each reporting period are recognized in the consolidated statement of operations and comprehensive loss until it is settled.
License and other revenue	License and other revenue The Company recognizes revenues from collaboration, license or other research or sale arrangements when or as performance obligations are satisfied. For milestone payments, the Company assesses, at contract inception, whether the milestones are considered probable of being achieved. If it is probable that a significant revenue reversal will occur, the Company will not record revenue until the uncertainty has been resolved. Milestone payments that are contingent upon regulatory approval are not considered probable until the approvals are obtained as it is outside of the control of the Company. If it is probable that significant revenue reversal will not occur, the Company will estimate the milestone payments using the most likely amount method. The Company reassesses the milestones each reporting period to determine the probability of achievement. Any potential consideration received in the form of royalty or sales-based milestones will be recorded when the customer’s subsequent sales or usages occur.
Collaborative Arrangements	Collaborative Arrangements The Company enters into collaborative arrangements to develop and commercialize intellectual property. These arrangements typically involve two (or more) parties who are active participants in the collaboration and are exposed to significant risks and rewards dependent on the commercial success of the activities. These collaborations usually involve various activities by one or more parties, including research and development, marketing and selling and distribution. Often, these collaborations require upfront, milestone and royalty or profit share payments, contingent upon the occurrence of certain future events linked to the success of the asset in development. Amounts due to collaborative partners related to development activities are generally reflected as research and development expense.
Research and Development Expenses and Accruals and Tax Incentives	Research and Development Expenses and Accruals All research and development costs are expensed in the period incurred and consist primarily of salaries, payroll taxes, employee benefits, stock-based compensation charges for those individuals involved in research and development efforts, external research and development costs incurred under agreements with contract research organizations and consultants to conduct and support the Company’s ongoing clinical trials. The Company has entered into various research and development contracts with clinical research organizations, clinical development and manufacturing organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred. Payments made in advance of performance are reflected in the accompanying balance sheets as prepaid expenses, while payments made after performance are reflected as accrued liabilities in the accompanying balance sheets. The Company records accruals for estimated costs incurred for ongoing research and development activities. When recording accruals for ongoing research and development activities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Nonrefundable advance payments for goods and services, including fees for process development or manufacturing and distribution of clinical supplies that will be used in future research and development activities, are recognized as expense in the period that the related goods are consumed or services are performed. Milestone payments within the Company’s licensing arrangements are recognized when achievement of the milestone is deemed probable to occur. To the extent products are commercialized and future economic benefit has been established, commercial milestones that become probable are capitalized and amortized over the estimated remaining useful life of the intellectual property. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. Research and Development Tax Incentives The Company participates in research tax incentive programs that are granted to companies by the United Kingdom tax authorities in order to encourage them to conduct technical and scientific research. Expenditures that meet the required criteria are eligible to receive a tax credit that is reimbursed in cash, upon surrender of loss carryforwards. Estimates of the amount of the cash refund expected to be received are determined at each reporting period and recorded as reductions to research and development expenses. The Company recorded research and development tax incentives of $24.3 million and $12.6 million during the years ended December 31, 2023 and December 31, 2022, respectively. The Company may not be able to continue to claim the most beneficial payable research and development tax credits in the future if it ceased to qualify as a small or medium enterprise, based on size criteria concerning employee headcount, turnover and gross assets. In addition, unless its subsidiaries qualify for an exemption, there are limitations to how much tax incentive can be claimed. This limitation is calculated as the total of the Company's relevant expenditure on employees in the period, multiplied by 300%, plus £20,000.
Share-Based Compensation	Share-Based Compensation The Company measures share-based awards, including restricted shares, restricted stock units and stock options, at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. Subsequent to the IPO, the Company determines the fair value of share-based compensation awards using the market closing price of the Company’s ADSs on the date of grant. F orfeitures of stock options are recognized in the period the forfeiture occurs. The Company uses the Black-Scholes option pricing model to value its stock option awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For share price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option.
Retirement Plans	Retirement Plans The Company provided defined contribution plans to its employees beginning in 2021. In the U.S., the primary plan sponsored by the Company is a safe harbor, 401k plan with a 4% employer match, no waiting period and immediate vesting on the match. In the UK, the primary plan sponsored by the Company is a money purchase plan, which requires a minimum 8% contribution, including a minimum employer contributio n of 4% and employee contribution of 4% in
Income Taxes	Income Taxes The Company follows the asset and liability method of accounting for income taxes under ASC 740, Income Taxes . Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. The Company regularly assesses its ability to realize its deferred tax assets. Assessing the realization of deferred tax assets requires significant judgment. In determining whether its deferred tax assets are more likely than not realizable, the Company evaluated all available positive and negative evidence, and weighed the evidence based on its objectivity. After consideration of the evidence, the Company believes it would more likely than not be able to utilize existing loss carryforwards and research and development tax credits to offset future income in the United States. The operating entity in the United States has a history of cumulative net profits as it carries out services for other entities in the group. ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception.
Net Loss Per Ordinary Share	Net Loss Per Ordinary Share Basic loss per ordinary share is computed by dividing net loss by the aggregate weighted-average number of ordinary shares outstanding. Diluted loss per ordinary share includes the effect, if any, from the potential exercise or conversion of securities, such as stock options, unvested restricted ordinary shares and restricted stock units which would result in the issuance of incremental ordinary shares. For diluted net loss per ordinary share, the weighted-average number of ordinary shares is the same for basic net loss per ordinary share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted-Average Ordinary Shares Outstanding	The following potentially dilutive securities have been excluded from the computation of diluted weighted-average ordinary shares outstanding, as they would be anti-dilutive. Year Ended Year Ended Unvested ordinary shares 310,052 599,421 Restricted stock units 1,949,463 1,804,760 Stock options 16,069,015 14,688,996 18,328,530 17,093,177

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following fair value hierarchy table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis (amounts in thousands): Fair value measurement at reporting date using Quoted prices Significant Significant December 31, 2023 Assets Money Market fund $ 28,339 $ — $ — U.S. Treasury securities $ 128,519 $ — $ — Liabilities Note Purchase Agreement $ — $ — $ 75,700 Fair value measurement at reporting date using Quoted prices Significant Significant December 31, 2022 Liabilities Note Purchase Agreement $ — $ — $ 69,800
Schedule of Debt Securities, Fair Value of U.S. Treasury Securities and Money Market Fund	The following represents the amortized cost bases and fair values of the Company’s U.S. Treasury securities and its money market fund as of December 31, 2023 (amounts in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money Market fund, included in Cash and cash equivalents $ 28,339 $ — $ — $ 28,339 U.S. Treasury securities, included in: Short-term investments 126,835 1,684 — 128,519 Total U.S. Treasury securities $ 126,835 $ 1,684 $ — $ 128,519
Reconciliation of the Redemption Feature Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs	For the Company's financial instruments measured at fair value on a recurring basis using significant unobservable inputs (Level 3), the following table provides a reconciliation of the beginning and ending balances for each category therein (amounts in thousands): Contingent Value Rights Note Purchase Agreement Balance at January 1, 2022 $ 37,700 $ 75,700 Change in fair value 1,980 (5,900) Settlements (39,680) — Balance at December 31, 2022 $ — $ 69,800 Change in fair value — 5,900 Balance at December 31, 2023 $ — $ 75,700

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 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 (amounts in thousands): December 31, December 31, Research and development costs $ 16,123 $ 11,321 Insurance related costs 1,651 2,788 Value added tax receivable 1,330 2,557 Other 1,621 3,271 $ 20,725 $ 19,937
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (amounts in thousands): December 31, December 31, Research and development costs $ 18,814 $ 10,795 Personnel related expenses 6,733 7,264 Professional fees 1,072 4,171 Income tax liability 112 1,582 Other 839 690 $ 27,570 $ 24,502
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (amounts in thousands): December 31, December 31, Computer equipment $ 734 $ 442 Office furniture 724 — Office equipment 43 — Construction in progress — 890 Property and equipment, at cost 1,501 1,332 Less: Accumulated depreciation (462) (164) Property and equipment, net $ 1,039 $ 1,168

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Debt	Debt as of December 31, 2023 and December 31, 2022 (in thousands): December 31, December 31, Note Purchase Agreement $ 75,700 $ 69,800

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Balance Sheet Information Related to Leases	The following table provides balance sheet information related to leases as of December 31, 2023 (amounts in thousands): December 31, 2023 Assets: Operating lease, right-of-use asset $ 11,914 Liabilities: Current portion of operating lease liabilities $ 505 Operating lease liabilities, net of current portion 8,888 Total operating lease liabilities $ 9,393
Schedule of Lease, Cost	The following table summarizes supplemental information related to leases as of December 31, 2023 (amount in thousands): December 31, 2023 Weighted-average remaining lease term 9.0 years Weighted-average discount rate 11.97 % The components of the Company’s lease costs and sublease income are classified on its consolidated statements of operations as follows (amounts in thousands): Year Ended Year Ended Operating lease cost $ 1,498 $ — Variable lease cost 53 66 Short term lease cost 26 131 Sublease income (58) — Total operating lease cost $ 1,519 $ 197
Schedule of Lessee, Operating Lease, Liability, Maturity	Future lease payments under non-cancelable operating leases and expected sublease income as of December 31, 2023 were as follows (amounts in thousands): Operating Leases Sublease Income Year ending: 2024 $ 1,602 $ 348 2025 1,634 355 2026 1,667 362 2027 1,700 369 2028 1,734 376 Thereafter 7,289 — Total undiscounted amounts $ 15,626 $ 1,810 Less: Imputed interest (6,233) Present value of lease liabilities $ 9,393 Less: current portion (505) Lease liabilities, net of current portion $ 8,888

Share-based Compensation (Table

Share-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Share-based Compensation Expense	The Company recorded share-based compensation expense in the following expense categories in the consolidated statements of operations and comprehensive loss (amounts in thousands): Year Ended Year Ended Research and development $ 13,221 $ 11,954 General and administrative 16,171 13,011 $ 29,392 $ 24,965
Summary of Stock Option Activity	The following table summarizes stock option activity for the year ended December 31, 2023: Number of Shares Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value (in millions) Balance at January 1, 2023 14,688,996 $ 7.88 8.5 years Granted 3,542,700 4.48 Exercised (70,197) 4.41 Forfeited (2,092,484) 8.37 Balance at December 31, 2023 16,069,015 $ 7.09 7.9 years $ 29.0 Exercisable at December 31, 2023 8,417,959 $ 7.41 7.5 years $ 13.4 Vested and expected to vest at December 31, 2023 16,069,015 $ 7.09 7.9 years $ 29.0
Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards	The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below: Year Ended Year Ended Weighted-average grant date fair value of options $3.22 $5.38 Expected term (in years) 6.02 6.01 Expected stock price volatility 78.3% 76.4% Risk-free interest rate 3.8% 2.2% Expected dividend yield 0% 0%
Summary of Replacement Equity Award Activity	The following table summarizes ordinary share activity related to the restricted stock programs for the year ended December 31, 2023: Restricted Stock Awards Restricted Stock Units Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Unvested at January 1, 2023 599,421 1,804,760 Granted — n/a 1,443,381 $ 3.87 Vested (289,369) (905,297) Forfeited — (393,381) Unvested at December 31, 2023 310,052 1,949,463 Unrecognized compensation expense at December 31, 2023 ($ in thousands) $ 5,708 $ 7,765 Expected weighted average recognition period 1.3 years 1.9 years

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The Company incurred research and development costs associated with these contracts as follows in the consolidated statements of operations and comprehensive loss (amounts in thousands): Year Ended Year Ended Research and development $ 5,360 $ 7,373

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities were as follows (amounts in thousands): December 31, December 31, Deferred tax assets: Tax loss carryforwards $ 77,435 $ 73,097 Capitalized research and development 14,440 15,624 Research and development credits 10,488 7,174 Other 3,246 1,467 Total deferred tax assets 105,609 97,362 Valuation allowance (73,239) (93,850) Deferred tax assets, net of allowance 32,370 3,512 Deferred tax liabilities: Other (2,723) — Net deferred tax assets $ 29,647 $ 3,512
Schedule of Income before Income Tax, Domestic and Foreign	Components of the Company’s pre-tax loss are as follows (amounts in thousands): Year Ended Year Ended Loss before tax: UK $ (187,643) $ (173,476) Non-UK 11,502 (43,478) Total $ (176,141) $ (216,954)
Schedule of Components of Income Tax Provision	The income tax (benefit) expense consists of the following (amounts in thousands): December 31, December 31, Federal - U.S. Current $ 1,237 $ 1,575 Deferred (26,272) (2,464) State - U.S. Current 233 534 Deferred (256) (392) Foreign Current 2 — Deferred — — Income tax (benefit) expense $ (25,056) $ (747)
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the United Kingdom (“UK”) income tax rate to the Company’s effective tax rate is as follows: Year Ended Year Ended Statutory tax rate benefit 24 % 19 % Non-deductible share-based compensation (4) % (2) % Other non-deductible expenses (2) % (1) % Enhanced UK research and development expenses 10 % 7 % Losses surrendered for UK research tax incentive (28) % (7) % UK non-taxable research and development incentive 3 % 1 % U.S. research & development tax credits 1 % 1 % Change in tax rate — % 2 % Effect of overseas tax rates — % 3 % Unrecognized tax benefits (1) % — % Return to provision adjustments 2 % — % Release of U.S. valuation allowance 15 % — % Increase in valuation allowance (6) % (23) % Effective income tax rate 14 % — %
Summary of Operating Loss Carryforwards and Research Tax Credits	The following table summarizes carryforwards of federal and local net operating losses (NOL) and research tax credits (amounts in thousands): December 31, December 31, UK $ 278,989 $ 225,662 U.S. $ 45,484 $ 48,523 France $ — $ 25,474
Schedule of Gross Unrecognized Tax Benefits	A reconciliation of gross unrecognized tax benefits, as of December 31, 2023 and 2022 is as follows (amounts in thousands): 2023 2022 Gross unrecognized tax benefits at beginning of period $ — $ — Increase related to current year tax positions 2,614 — Gross unrecognized tax benefits at end of period $ 2,614 $ —

Organization and Description _2

Organization and Description of Business (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2024	Dec. 31, 2023	Jan. 27, 2023	Dec. 31, 2022	Jul. 12, 2022	Oct. 04, 2021
Subsidiary, Sale of Stock [Line Items]
Accumulated deficit		$ 752,945		$ 601,860
Cash and cash equivalents and short-term investments		$ 256,500
Sufficient funding term (at least)		12 months
At-the-market
Subsidiary, Sale of Stock [Line Items]
Sale of stock, maximum consideration receivable			$ 125,000		$ 350,000
Shares sold in offering (in shares)		3,040,816
Aggregate net proceeds in connection with the IPO and subsequent exercise of the underwriter's options		$ 20,800
At-the-market | Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Shares sold in offering (in shares)	1,250,000
Aggregate net proceeds in connection with the IPO and subsequent exercise of the underwriter's options	$ 9,700
Oberland Capital
Subsidiary, Sale of Stock [Line Items]
Note purchase agreement, value		175,000
Note purchase agreement, amount available for funding at the option of the company and counterparty		100,000
Oberland Capital | Second Purchase Note
Subsidiary, Sale of Stock [Line Items]
Note purchase agreement, value		75,000				$ 75,000
Oberland Capital | First Purchase Note
Subsidiary, Sale of Stock [Line Items]
Note purchase agreement, value		$ 75,000				$ 75,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Segments (Details)	12 Months Ended
	Dec. 31, 2023 segment
Accounting Policies [Abstract]
Number of operating segments	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Foreign Currency Translation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Foreign currency transaction gain (loss)	$ 0.8	$ (2.8)

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 298	$ 131
Capitalized computer software, amortization	$ 500
Computer equipment, furniture and office equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	3 years
Computer equipment, furniture and office equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	7 years
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment useful life	5 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Note Purchase Agreement (Details) - USD ($) $ in Millions	Dec. 31, 2023	Oct. 04, 2021
Debt Instrument [Line Items]
Note purchase agreement, milestone payment, percent of aggregate principal amount issued	30%
Oberland Capital
Debt Instrument [Line Items]
Note purchase agreement, value	$ 175
Note purchase agreement, amount available for funding at the option of the company and counterparty	100
Oberland Capital | First Purchase Note
Debt Instrument [Line Items]
Note purchase agreement, value	$ 75	$ 75

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Research and Development Tax Incentives (Details) € in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 USD ($)
Accounting Policies [Abstract]
Research and development tax credit | $	$ 24.3		$ 12.6
Research and development tax credit limitation, expenditure on employees multiple	300%	300%
Research and development tax credit limitation, expenditure on employees additional Value | €		€ 20

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Share-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0%	0%

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Defined contribution plan, employer matching contribution, percent of match	4%
Defined contribution plan, minimum contribution, percent	8%
Defined contribution plan, minimum employer contribution, percent	4%
Defined contribution plan, minimum employee contribution, percent	4%
Defined contribution plan, charges	$ 0.6	$ 0.7

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted-Average Ordinary Shares Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted weighted-average ordinary shares outstanding (in shares)	18,328,530	17,093,177
Unvested ordinary shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted weighted-average ordinary shares outstanding (in shares)	310,052	599,421
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted weighted-average ordinary shares outstanding (in shares)	1,949,463	1,804,760
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted weighted-average ordinary shares outstanding (in shares)	16,069,015	14,688,996

Revenue (Details)

Revenue (Details) $ in Millions	Nov. 24, 2023 USD ($)
AnaptsyBio, Inc. | License
Disaggregation of Revenue [Line Items]
Upfront cash payment received	$ 7

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
U.S. Treasury securities
Assets
U.S. Treasury securities	$ 128,519
Quoted prices in active markets for identical assets (Level 1) | Fair Value, Recurring
Liabilities
Note Purchase Agreement	0	$ 0
Quoted prices in active markets for identical assets (Level 1) | Fair Value, Recurring | U.S. Treasury securities
Assets
U.S. Treasury securities	128,519
Quoted prices in active markets for identical assets (Level 1) | Fair Value, Recurring | Money Market fund
Assets
Money Market fund	28,339
Significant other observable inputs (Level 2) | Fair Value, Recurring
Liabilities
Note Purchase Agreement	0	0
Significant other observable inputs (Level 2) | Fair Value, Recurring | U.S. Treasury securities
Assets
U.S. Treasury securities	0
Significant other observable inputs (Level 2) | Fair Value, Recurring | Money Market fund
Assets
Money Market fund	0
Significant unobservable inputs (Level 3) | Fair Value, Recurring
Liabilities
Note Purchase Agreement	75,700	$ 69,800
Significant unobservable inputs (Level 3) | Fair Value, Recurring | U.S. Treasury securities
Assets
U.S. Treasury securities	0
Significant unobservable inputs (Level 3) | Fair Value, Recurring | Money Market fund
Assets
Money Market fund	$ 0

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Schedule of Debt Securities, Fair Value of U.S. Treasury Securities and Money Market Fund (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Money Market fund, included in Cash and cash equivalents, amortized cost	$ 128,030	$ 393,644
Money Market fund
Debt Securities, Available-for-Sale [Line Items]
Money Market fund, included in Cash and cash equivalents, amortized cost	28,339
Money Market fund, included in Cash and cash equivalents, fair value	28,339
U.S. Treasury securities
Debt Securities, Available-for-Sale [Line Items]
U.S. Treasury securities, amortized cost	126,835
U.S. Treasury securities, gross unrealized gains	1,684
U.S. Treasury securities, gross unrealized losses	0
U.S. Treasury securities, fair value	128,519
U.S. Treasury securities | Short-term investments
Debt Securities, Available-for-Sale [Line Items]
U.S. Treasury securities, amortized cost	126,835
U.S. Treasury securities, gross unrealized gains	1,684
U.S. Treasury securities, gross unrealized losses	0
U.S. Treasury securities, fair value	$ 128,519

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Reconciliation of the Redemption Feature Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Contingent Value Rights
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	$ 37,700
Change in fair value	0	1,980
Settlements		(39,680)
Ending balance	0	0
Note Purchase Agreement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	69,800	75,700
Change in fair value	5,900	(5,900)
Settlements		0
Ending balance	$ 75,700	$ 69,800

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Note Purchase Agreement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) in fair value measurement	$ (5.9)	$ 5.9

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development costs	$ 16,123	$ 11,321
Insurance related costs	1,651	2,788
Value added tax receivable	1,330	2,557
Other	1,621	3,271
Prepaid expenses and other current assets	$ 20,725	$ 19,937

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development costs	$ 18,814	$ 10,795
Personnel related expenses	6,733	7,264
Professional fees	1,072	4,171
Income tax liability	112	1,582
Other	839	690
Accrued expenses and other current liabilities	$ 27,570	$ 24,502

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 1,501	$ 1,332
Less: Accumulated depreciation	(462)	(164)
Property and equipment, net	1,039	1,168
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	734	442
Office furniture
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	724	0
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	43	0
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 0	$ 890

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Note Purchase Agreement
Debt Instrument [Line Items]
Long-term debt, gross	$ 75,700	$ 69,800

Debt - Note Purchase Agreement

Debt - Note Purchase Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Oct. 04, 2021
Debt Instrument [Line Items]
Debt instrument, term	6 years
Debt instrument, reference rate	7.75%
Weighted average interest rate	13%	9.60%
Milestone payment, percent of aggregate principal amount issued under the notes	30%
Milestone payment, period	5 years
Cumulative payments under note purchase agreement, including interest	$ 18.7
Note purchase agreement, deductible amount due to company	$ 100
Note purchase agreement, percent of aggregate outstanding principal amount, cash balance required	90%
Oberland Capital
Debt Instrument [Line Items]
Note purchase agreement, value	$ 175
Note purchase agreement, amount available for funding at the option of the company and counterparty	$ 100
Secured Overnight Financing Rate (SOFR) [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.25%
Note Purchase Agreement
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	75%
Note Purchase Agreement | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	175%
Note Purchase Agreement | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	185%
Note Purchase Agreement | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	205%
First Purchase Note | Oberland Capital
Debt Instrument [Line Items]
Note purchase agreement, value	$ 75		$ 75
Second Purchase Note | Oberland Capital
Debt Instrument [Line Items]
Note purchase agreement, value	$ 75		$ 75
Interest Only, Senior Secured Notes | Oberland Capital | Senior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate floor	8%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)		12 Months Ended
	Oct. 11, 2023 ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Feb. 07, 2022 USD ($) ft² option
Lessee, Lease, Description [Line Items]
Purchase obligation		$ 61,100,000
Purchase obligation, to be paid within one year		45,100,000
Purchase obligation, to be paid, over one to five years		16,000,000
Lease term				10 years
Area of real estate property | ft²				18,922
Rent expense		1,600,000
Rent expense, year 10		1,900,000
Letter of credit outstanding				$ 700,000
Number of options to extend | option				1
Lease, renewal term				5 years
Operating lease right-of-use assets		11,914,000	$ 0
Operating lease liabilities		9,393,000
Period of sublease agreement	5 years
Number of square feet to sublease | ft²	4,242
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Lessee, Lease, Description [Line Items]
Maximum aggregate development and regulatory milestone payments		0
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Orexia
Lessee, Lease, Description [Line Items]
Maximum aggregate development milestone payments		5,200,000
Maximum aggregate commercial milestone payments		$ 15,000,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Heptares
Lessee, Lease, Description [Line Items]
Period after contractual agreement ends		3 years
Period after first commercial sale		10 years

Commitments and Contingencies_2

Commitments and Contingencies - Balance Sheet Information Related to Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Operating lease, right-of-use asset	$ 11,914	$ 0
Liabilities:
Current portion of operating lease liabilities	$ 505
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other current liabilities
Operating lease liabilities, net of current portion	$ 8,888	$ 0
Total operating lease liabilities	$ 9,393

Commitments and Contingencies_3

Commitments and Contingencies - Cash Flow, Supplemental Disclosures (Details)	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Weighted-average remaining lease term	9 years
Weighted-average discount rate	11.97%

Commitments and Contingencies_4

Commitments and Contingencies - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,498	$ 0
Variable lease cost	53	66
Short term lease cost	26	131
Sublease income	(58)	0
Total operating lease cost	$ 1,519	$ 197

Commitments and Contingencies_5

Commitments and Contingencies - Future Lease Payments under Non-Cancelable Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Operating Leases
2024	$ 1,602
2025	1,634
2026	1,667
2027	1,700
2028	1,734
Thereafter	7,289
Total undiscounted amounts	15,626
Less: Imputed interest	(6,233)
Total operating lease liabilities	9,393
Less: current portion	(505)
Operating lease liabilities	8,888	$ 0
Sublease Income
2024	348
2025	355
2026	362
2027	369
2028	376
Thereafter	0
Total undiscounted amounts	$ 1,810

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended	35 Months Ended
	Jan. 01, 2022	Jan. 31, 2021	Dec. 31, 2023	Dec. 31, 2023	May 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested stock option awards			$ 30,700	$ 30,700
Share price (in dollars per share)			$ 7.96	$ 7.96
Aggregate intrinsic value of options			$ 29,000	$ 29,000
2021 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for equity incentive plan (in shares)					20,026,816
Percent of additional shares authorized each year			5%
Shares available for grant (in shares)			8,252,636	8,252,636
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Contractual term			10 years
Unrecognized compensation expense recognition period			2 years
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense recognition period			1 year 3 months 18 days
Share-based payment awards issued in period (in shares)		379,905
Restricted Stock Awards | Share-based Payment Arrangement, Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment awards issued in period (in shares)				833,897
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense recognition period			1 year 10 months 24 days
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved for future issuance (in shares)		860,000	2,708,315	2,708,315
Share-based compensation, percentage of outstanding stock maximum	1%
Multiplier for initial number of shares reserved	2

Share-based Compensation - Summ

Share-based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation expense recognized	$ 29,392	$ 24,965
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation expense recognized	13,221	11,954
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation expense recognized	$ 16,171	$ 13,011

Share-based Compensation - Su_2

Share-based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Shares
Beginning balance (in shares)	14,688,996
Granted (in shares)	3,542,700
Exercised (in shares)	(70,197)
Forfeited (in shares)	(2,092,484)
Ending balance (in shares)	16,069,015	14,688,996
Exercisable at end of period (in shares)	8,417,959
Vested and expected to vest at end of period (in shares)	16,069,015
Weighted-Average Exercise Price Per Share
Beginning balance (in dollars per share)	$ 7.88
Granted (in dollars per share)	4.48
Exercised (in dollars per share)	4.41
Forfeited (in dollars per share)	8.37
Ending balance (in dollars per share)	7.09	$ 7.88
Exercisable at end of period (in dollars per share)	7.41
Vested and expected to vest as end of period (in dollars per share)	$ 7.09
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, weighted-average remaining contractual term	7 years 10 months 24 days	8 years 6 months
Options exercisable, weighted-average remaining contractual term	7 years 6 months
Options vested and expected to vest, weighted-average remaining contractual term	7 years 10 months 24 days
Options outstanding, aggregate intrinsic value	$ 29,000
Options exercisable, aggregate intrinsic value	13,400
Options vested and expected to vest, aggregate intrinsic value	$ 29,000

Share-based Compensation - Sche

Share-based Compensation - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of options (in dollars per share)	$ 3.22	$ 5.38
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 7 days	6 years 3 days
Expected stock price volatility	78.30%	76.40%
Risk-free interest rate	3.80%	2.20%
Expected dividend yield	0%	0%

Share-based Compensation - Su_3

Share-based Compensation - Summary of Replacement Equity Award Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Restricted Stock Awards
Number of Shares
Unvested beginning balance (in shares)	599,421
Granted (in shares)	0
Vested (in shares)	(289,369)
Forfeited (in shares)	0
Unvested ending balance (in shares)	310,052
Unrecognized compensation expense excluding options | $	$ 5,708
Unrecognized compensation expense recognition period	1 year 3 months 18 days
Restricted stock units
Number of Shares
Unvested beginning balance (in shares)	1,804,760
Granted (in shares)	1,443,381
Vested (in shares)	(905,297)
Forfeited (in shares)	(393,381)
Unvested ending balance (in shares)	1,949,463
Unrecognized compensation expense excluding options | $	$ 7,765
Unrecognized compensation expense recognition period	1 year 10 months 24 days
Weighted-Average Grant Date Fair Value Per Share
Granted (in dollars per share) | $ / shares	$ 3.87

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Research and development	$ 124,405	$ 155,083
Master Service Agreements | Related Party
Related Party Transaction [Line Items]
Research and development	$ 5,360	$ 7,373

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Tax loss carryforwards	$ 77,435	$ 73,097
Capitalized research and development	14,440	15,624
Research and development credits	10,488	7,174
Other	3,246	1,467
Total deferred tax assets	105,609	97,362
Valuation allowance	(73,239)	(93,850)
Deferred tax assets, net of allowance	32,370	3,512
Deferred tax liabilities:
Other	(2,723)	0
Net deferred tax assets	$ 29,647	$ 3,512

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)	$ (20,600)	$ 44,800
Unrecognized tax benefits	2,614	$ 0	$ 0
Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	10,500
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration	3,200
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration	$ 39,300

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) before Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
UK	$ (187,643)	$ (173,476)
Non-UK	11,502	(43,478)
Loss before income taxes	$ (176,141)	$ (216,954)

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Federal - U.S.
Current	$ 1,237	$ 1,575
Deferred	(26,272)	(2,464)
State - U.S.
Current	233	534
Deferred	(256)	(392)
Foreign
Current	2	0
Deferred	0	0
Income tax (benefit) expense	$ (25,056)	$ (747)

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Statutory tax rate benefit	24%	19%
Non-deductible share-based compensation	(4.00%)	(2.00%)
Other non-deductible expenses	(2.00%)	(1.00%)
Enhanced UK research and development expenses	10%	7%
Losses surrendered for UK research tax incentive	(28.00%)	(7.00%)
UK non-taxable research and development incentive	3%	1%
U.S. research & development tax credits	1%	1%
Change in tax rate	0%	2%
Effect of overseas tax rates	0%	3%
Unrecognized tax benefits	(1.00%)	0%
Return to provision adjustments	2%	0%
Release of U.S. valuation allowance	0.15	0
Increase in valuation allowance	(6.00%)	(23.00%)
Effective income tax rate	14%	0%

Income Taxes - Summary of Opera

Income Taxes - Summary of Operating Loss Carryforwards and Research Tax Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
UK
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards and research tax credits	$ 278,989	$ 225,662
U.S.
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards and research tax credits	45,484	48,523
France
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards and research tax credits	$ 0	$ 25,474

Income Taxes - Schedule of Gros

Income Taxes - Schedule of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits at beginning of period	$ 0	$ 0
Increase related to current year tax positions	2,614	0
Gross unrecognized tax benefits at end of period	$ 2,614	$ 0