Related Party Transactions	6 Months Ended
Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Term loans with Ultrahuman The Centessa Predecessor Group entered into term loan agreements with Ultrahuman Nine and Ultrahuman Ten which are entities with common ownership with the Centessa Predecessor Group and with the Company. The term loans have a stated interest rate of 2% per annum above the Bank of England official rate and the outstanding balances are repayable on demand of the lenders. The Bank of England official rate was 0.10% at June 30, 2020 and 2021, respectively. The outstanding balance of the term loan with Ultrahuman Eleven was forfeited by the lender in February 2020, from which a gain on extinguishment of debt of $264,000 is recognized in the combined statements of operations and comprehensive loss for Centessa Predecessor Group during the six months ended June 30, 2020. The outstanding balance of the term loans with Ultrahuman Nine and Ultrahuman Ten was cancelled in June 2021. During the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, the Centessa Predecessor Group recognized interest expense of $2,500, $5,000, and $1,000, respectively, in connection with the Ultrahuman loans. During the three months ended June 30, 2021 and for the period from January 30, 2021 through June 30, 2021, the Company recognized interest expense of $1,000 and $3,000, respectively, in connection with the loan. Support service agreement with Ultrahuman services The Centessa Predecessor Group entered into a Support Service Agreement with Ultrahuman Limited. Ultrahuman Limited provides scientific and operational consultancy services and other support services. Costs incurred associated with this contract were $0.2 million, $0.3 million, and $48,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. The contract was terminated in connection with the acquisition of the Centessa Subsidiaries. Master services agreements with The Cambridge Partnership Limited The Centessa Predecessor Group entered into Master Services agreements with The Cambridge Partnership Limited for accounting and administrative services. Costs incurred associated with these contracts were $28,000, $52,000, and $17,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within general and administrative expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. David Grainger is a director and shareholder of The Cambridge Partnership and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021. Master services agreements with The Foundry (Cambridge) Limited The Centessa Predecessor Group entered into Master Services agreements with The Foundry (Cambridge) Limited. Costs incurred associated with these contracts were $11,000, $23,000, and $4,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within general and administrative expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. David Grainger is a director and shareholder of The Foundry (Cambridge) Limited and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021. Master Services agreements with RxCelerate Limited The Centessa Predecessor Group entered into Master Services agreements with RxCelerate Limited to provide drug discovery services. Costs incurred associated with this contract were $0.8 million, $2.3 million, and $0.4 million for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. David Grainger is a director and shareholder of RxCelerate Limited and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021. Master Services agreements with RxBiologics Limited The Centessa Predecessor Group entered into Master Services agreements with RxBiologics Limited to provide biologics drug discovery services. Costs incurred associated with this contract were $0, $9,000, and $14,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. William Finlay is a director and shareholder of RxBiologics Limited and was a director of LockBody until he resigned on January 29, 2021. Master Services agreements with Cambridge Protein Works The Centessa Predecessor Group entered into Services agreements with Cambridge Protein Works to provide pure proteins for research and development purposes. Costs incurred associated with this contract were $0, $11,000, and $0 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, and $145,000 for the three months ended June 30, 2021 and for the period from January 30, 2021 through June 30, 2021, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. Jim Huntington is a director and shareholder of Cambridge Protein Works and is the Chief Executive Officer of ApcinteX and Z Factor. Cost Reimbursements During the period from January 30, 2021 through June 30, 2021, the Centessa Successor reimbursed an aggregate of $1.4 million to several shareholders for costs paid on behalf of the Centessa Successor in connection with acquisition of the Centessa Subsidiaries and the sale of the Centessa Successor Series A preferred shares.

The Centessa Predecessor Group entered into term loan agreements with Ultrahuman Nine and Ultrahuman Ten which are entities with common ownership with the Centessa Predecessor Group and with the Company.

The term loans have a stated interest rate of 2% per annum above the Bank of England official rate and the outstanding balances are repayable on demand of the lenders. The Bank of England official rate was 0.10% at June 30, 2020 and 2021, respectively.

The outstanding balance of the term loan with Ultrahuman Eleven was forfeited by the lender in February 2020, from which a gain on extinguishment of debt of $264,000 is recognized in the combined statements of operations and comprehensive loss for

Centessa Predecessor Group during the six months ended June 30, 2020. The outstanding balance of the term loans with Ultrahuman Nine and Ultrahuman Ten was cancelled in June 2021.

During the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, the Centessa Predecessor Group recognized interest expense of $2,500, $5,000, and $1,000, respectively, in connection with the Ultrahuman loans. During the three months ended June 30, 2021 and for the period from January 30, 2021 through June 30, 2021, the Company recognized interest expense of $1,000 and $3,000, respectively, in connection with the loan.

The Centessa Predecessor Group entered into a Support Service Agreement with Ultrahuman Limited. Ultrahuman Limited provides scientific and operational consultancy services and other support services.

Costs incurred associated with this contract were $0.2 million, $0.3 million, and $48,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss. The contract was terminated in connection with the acquisition of the Centessa Subsidiaries.

The Centessa Predecessor Group entered into Master Services agreements with The Cambridge Partnership Limited for accounting and administrative services. Costs incurred associated with these contracts were $28,000, $52,000, and $17,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within general and administrative expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss.

David Grainger is a director and shareholder of The Cambridge Partnership and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021.

The Centessa Predecessor Group entered into Master Services agreements with The Foundry (Cambridge) Limited. Costs incurred associated with these contracts were $11,000, $23,000, and $4,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within general and administrative expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss.

David Grainger is a director and shareholder of The Foundry (Cambridge) Limited and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021.

The Centessa Predecessor Group entered into Master Services agreements with RxCelerate Limited to provide drug discovery services. Costs incurred associated with this contract were $0.8 million, $2.3 million, and $0.4 million for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss.

David Grainger is a director and shareholder of RxCelerate Limited and was a director of Z Factor and Morphogen-IX until he resigned on January 29, 2021.

The Centessa Predecessor Group entered into Master Services agreements with RxBiologics Limited to provide biologics drug discovery services. Costs incurred associated with this contract were $0, $9,000, and $14,000 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, which has been recorded

within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss.

William Finlay is a director and shareholder of RxBiologics Limited and was a director of LockBody until he resigned on January 29, 2021.

The Centessa Predecessor Group entered into Services agreements with Cambridge Protein Works to provide pure proteins for research and development purposes. Costs incurred associated with this contract were $0, $11,000, and $0 for the three and six months ended June 30, 2020 and for the period from January 1, 2021 through January 29, 2021, respectively, and $145,000 for the three months ended June 30, 2021 and for the period from January 30, 2021 through June 30, 2021, which has been recorded within research and development expenses in the unaudited interim consolidated and combined statements of operations and comprehensive loss.

Jim Huntington is a director and shareholder of Cambridge Protein Works and is the Chief Executive Officer of ApcinteX and Z Factor.

During the period from January 30, 2021 through June 30, 2021, the Centessa Successor reimbursed an aggregate of $1.4 million to several shareholders for costs paid on behalf of the Centessa Successor in connection with acquisition of the Centessa Subsidiaries and the sale of the Centessa Successor Series A preferred shares.