Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation and Combination/Consolidation	Basis of Presentation and Consolidation/Combination The accompanying unaudited interim consolidated and combined 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”). In the opinion of management, the accompanying unaudited interim consolidated and combined 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 June 30, 2022 and as of December 31, 2021; •the Company’s results of operations for the three months and six months ended June 30, 2022, for the three months ended June 30, 2021 and the period from January 30, 2021 through June 30, 2021; •the Company’s cash flows for the six months ended June 30, 2022 and the period from January 30, 2021 through June 30, 2021; and •the Predecessor’s results of operations and cash flows for the period from January 1, 2021 through January 29, 2021. Operating results for the Company for the three months and six months ended June 30, 2022 are not necessarily indicative of the results that may be expected for the full year. The unaudited interim consolidated and combined financial statements, presented herein, do not contain all of the required disclosures under U.S. GAAP for annual financial statements. Notes to the financial statements which would substantially duplicate the disclosure contained in the audited financial statements for fiscal 2021 as reported in the 2021 Annual Report have been omitted. Therefore, these unaudited interim consolidated and combined financial statements should be read in conjunction with the annual audited consolidated and combined financial statements and related notes for Centessa Pharmaceuticals plc (Successor) and the Centessa Predecessor Group found in the Form 10-K filed with the SEC. The Company’s unaudited interim consolidated financial statements include the accounts of Centessa Pharmaceuticals plc, its wholly-owned subsidiary, Centessa Pharmaceuticals, Inc. and the wholly-owned Centessa Subsidiaries. The Centessa Predecessor Group’s unaudited interim combined financial statements included the accounts of Z Factor, Morphogen-IX and LockBody. All intercompany accounts and transactions have been eliminated in consolidation and combination.
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.
Use of Estimates	Use of Estimates The preparation of unaudited interim 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 unaudited interim consolidated and combined financial statements and the reported amounts of 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 unaudited interim consolidated and combined financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include share-based compensation assumptions, note purchase agreement assumptions, and accrued research and development expenses.
Property and Equipment, net	Property and Equipment, netProperty 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, which has a useful life of three years, as well as leasehold improvements, which have a useful life of the lesser of the lease term or their useful life. The costs of maintenance and repairs are expensed as incurred. Improvements and betterment that add new functionality or extend the useful life of the asset are capitalized.
Note Purchase Agreement	Note Purchase Agreement In October 2021, the Company entered into a Note Purchase Agreement (the “Note Purchase Agreement”) with Oberland Capital Management LLC (“Oberland Capital”). Under the terms of the Note Purchase Agreement, Oberland Capital will purchase up to $300.0 million of 6-year, interest-only (initial interest rate is 8.0% per annum), senior secured notes (the “Notes”) from the Company including $75.0 million, funded on October 4, 2021, $125.0 million available within 24 months at the Company’s option, and $100.0 million available to fund Mergers and Acquisitions (“M&A”), in-licensing, or other strategic transactions, at the option of the Company and Oberland Capital. In addition to interest payments on the principal, the Company is obligated to pay a milestone payment upon the Company’s first product to obtain regulatory approval and was obligated to pay revenue participation payments, starting on the date of the first commercial sale of lixivaptan. Since the Company’s discontinuation of the development of lixivaptan for the treatment of ADPKD, the revenue participation payment is no longer achievable. The Company evaluated the Notes 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 will be 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 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 Note Purchase 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.
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 convertible preferred shares, stock options, unvested restricted ordinary shares and convertible debt 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.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements On January 1, 2022, the Company adopted ASU No. 2016-02, Leases (“ASC 842”), which requires a lessee to record a right-of-use asset and a corresponding lease liability on the balance sheet for all leases with terms longer than 12 months. As of January 1, 2022, the Company was not party to any significant leases and therefore the adoption of this standard did not have a significant impact as of this adoption date. As permitted in the standards, the Company intends to reflect the adoption of ASC 842 in its annual report on Form 10-K for the year ended December 31, 2022, and in interim periods within the fiscal year ended December 31, 2023.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2022

Basis of Presentation and Combination/Consolidation

Basis of Presentation and Consolidation/Combination

The accompanying unaudited interim consolidated and combined 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”).

In the opinion of management, the accompanying unaudited interim consolidated and combined 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 June 30, 2022 and as of December 31, 2021;

•the Company’s results of operations for the three months and six months ended June 30, 2022, for the three months ended June 30, 2021 and the period from January 30, 2021 through June 30, 2021;

•the Company’s cash flows for the six months ended June 30, 2022 and the period from January 30, 2021 through June 30, 2021; and

•the Predecessor’s results of operations and cash flows for the period from January 1, 2021 through January 29, 2021.

Operating results for the Company for the three months and six months ended June 30, 2022 are not necessarily indicative of the results that may be expected for the full year. The unaudited interim consolidated and combined financial statements, presented herein, do not contain all of the required disclosures under U.S. GAAP for annual financial statements. Notes to the financial statements which would substantially duplicate the disclosure contained in the audited financial statements for fiscal 2021 as reported in the 2021 Annual Report have been omitted. Therefore, these unaudited interim consolidated and combined financial statements should be read in conjunction with the annual audited consolidated and combined financial statements and related notes for Centessa Pharmaceuticals plc (Successor) and the Centessa Predecessor Group found in the Form 10-K filed with the SEC.

The Company’s unaudited interim consolidated financial statements include the accounts of Centessa Pharmaceuticals plc, its wholly-owned subsidiary, Centessa Pharmaceuticals, Inc. and the wholly-owned Centessa Subsidiaries. The Centessa Predecessor Group’s unaudited interim combined financial statements included the accounts of Z Factor, Morphogen-IX and LockBody. All intercompany accounts and transactions have been eliminated in consolidation and combination.

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.

Use of Estimates

The preparation of unaudited interim 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 unaudited interim consolidated and combined financial statements and the reported amounts of 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 unaudited interim consolidated and combined financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include share-based compensation assumptions, note purchase agreement assumptions, and accrued research and development expenses.

Property and Equipment, net

Property and Equipment, netProperty 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, which has a useful life of three years, as well as leasehold improvements, which have a useful life of the lesser of the lease term or their useful life. The costs of maintenance and repairs are expensed as incurred. Improvements and betterment that add new functionality or extend the useful life of the asset are capitalized.

Note Purchase Agreement

In October 2021, the Company entered into a Note Purchase Agreement (the “Note Purchase Agreement”) with Oberland Capital Management LLC (“Oberland Capital”). Under the terms of the Note Purchase Agreement, Oberland Capital will purchase up to $300.0 million of 6-year, interest-only (initial interest rate is 8.0% per annum), senior secured notes (the “Notes”) from the Company including $75.0 million, funded on October 4, 2021, $125.0 million available within 24 months at the Company’s option, and $100.0 million available to fund Mergers and Acquisitions (“M&A”), in-licensing, or other strategic transactions, at the option of the Company and Oberland Capital. In addition to interest payments on the principal, the Company is obligated to pay a milestone payment upon the Company’s first product to obtain regulatory approval and was obligated to pay revenue participation payments, starting on the date of the first commercial sale of lixivaptan. Since the Company’s discontinuation of the development of lixivaptan for the treatment of ADPKD, the revenue participation payment is no longer achievable.

The Company evaluated the Notes 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 will be 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 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 Note Purchase 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.

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 convertible preferred shares, stock options, unvested restricted ordinary shares and convertible debt 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.

Recently Adopted Accounting Pronouncements

On January 1, 2022, the Company adopted ASU No. 2016-02, Leases (“ASC 842”), which requires a lessee to record a right-of-use asset and a corresponding lease liability on the balance sheet for all leases with terms longer than 12 months. As of January 1, 2022, the Company was not party to any significant leases and therefore the adoption of this standard did not have a significant impact as of this adoption date. As permitted in the standards, the Company intends to reflect the adoption of ASC

842 in its annual report on Form 10-K for the year ended December 31, 2022, and in interim periods within the fiscal year ended December 31, 2023.