Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Basis of preparation	2.1. Basis of preparation The accompanying unaudited condensed consolidated interim financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, for interim financial reporting and pursuant to the requirements for reporting on Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain information and disclosures required by U.S. GAAP for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission, or the SEC, on February 27, 2025. In the opinion of management, all adjustments considered necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature. The results for the three and six months ended June 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025, any other interim periods, or any future year or period. The Group previously prepared its consolidated financial statements in accordance with International Financial Reporting Standards as issued by the International Accounting Standards Board when the Group qualified as a foreign private issuer under the rules and regulations of the SEC. In connection with the loss of the Group’s status as a foreign private issuer, the Group is required to report with the SEC on domestic forms and comply with domestic company rules in the United States, including preparation of its financial statements in accordance with U.S. GAAP. The transition to U.S. GAAP was made retrospectively for all periods from the Group’s inception.
Functional and reporting currency	2.2. Functional and reporting currency The reporting currency of the condensed consolidated financial statements is U.S. Dollars, or USD or $. The functional currency of the Group’s subsidiaries reflects the economic environment of their respective operations. All amounts disclosed have been rounded to the nearest thousand, unless otherwise stated. Due to the loss of the Group’s status as a foreign private issuer, effective January 1, 2025, the Group was required as a domestic filer to change its reporting currency of the condensed consolidated financial statements from British pound sterling, or GBP, to USD. The change in reporting currency was applied retrospectively. Condensed consolidated financial statements for all periods have been recast into USD and presented to the nearest thousand dollars.
Principles of consolidation	2.3. Principles of consolidation The condensed consolidated financial information comprises the financial statements of Silence Therapeutics plc and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated on consolidation.
Use of estimates	2.4. Use of estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in the Group’s condensed consolidated financial statements include, but are not limited to, the recognition of revenue and research and development expenses. The Group bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates.
Going concern	2.5. Going concern The Group has incurred recurring losses since inception, including net losses of $55.9 million for the six months ended June 30, 2025. As of June 30, 2025, the Group had accumulated losses of $529.8 million and cash outflows from operating activities for the six months ended June 30, 2025 was $34.1 million. The Group expects to incur operating losses for the foreseeable future as it continues its research and development efforts, seeks to obtain regulatory approval of its product candidates and pursues any future product candidates the Group may develop. To date, the Group has funded its operations through upfront payments and milestones from collaboration agreements, equity offerings and proceeds from private placements, as well as management of expenses and other financing options to support its continued operations. In 2024, the Group raised additional proceeds of $27.7 million before deducting $0.9 million in placement agent fees and other expenses, from sales of American Depositary Shares, or ADSs, under its Open Market Sale Agreement with Jefferies LLC, dated October 15, 2021, or the Sales Agreement,. On February 5, 2024, the Group announced a private placement of 5,714,286 of the ADSs, each representing three ordinary shares, at a price of $21.00 per ADS, with new and existing institutional and accredited investors, or the Private Placement. The aggregate gross proceeds of the Private Placement were $120.0 million before deducting approximately $7.7 million in placement agent fees and other expenses. In 2024, the Group received a $10.0 million milestone payment from the AstraZeneca collaboration and received another $2.0 million in milestone payments from the Hansoh collaboration. As of June 30, 2025, the Group had cash and cash equivalents and short-term investments of $114.2 million. The Group believes that its current cash and cash equivalents are sufficient to fund its operating expenses for at least the next twelve months from the issuance date of these condensed consolidated financial statements. For this reason, the Group continues to adopt the going concern basis in preparing the financial statements. The Group will need to raise additional funding to fund its operation expenses and capital expenditure requirements in relation to its clinical development activities. The Group may seek additional funding through public or private financings, debt financing or collaboration agreements. Specifically, the Group may receive future milestone payments from existing collaboration agreements which will extend the ability to fund operations. However, these future milestone payments are dependent on achievement of certain development or regulatory objectives that may not occur. The inability to obtain future funding could impact; the Group’s financial condition and ability to pursue its business strategies, including being required to delay, reduce or eliminate some of its research and development programs, or being unable to continue operations or unable to continue as a going concern.
Recently Issued Accounting Pronouncements	2.6. Recently Issued Accounting Pronouncements Recently adopted accounting standards There were no accounting standards adopted in the current period. Accounting standards issued but not yet adopted In December 2023, the Financial Accounting Standards Board, or FASB, issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which provides for improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. This guidance is effective for annual periods beginning after December 15, 2024, and should be applied on a prospective basis with the option to apply the standard retrospectively. Early adoption is permitted. This standard will have no impact on the Group’s consolidated financial statements. The Company is currently evaluating the impact to its income tax disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40). Additionally, in January 2025, the FASB issued ASU 2025-01 to clarity the effective date of ASU 2024-03. The amendments in this update require disclosure, in the notes to financial statements, of specified information about certain costs and expenses at each interim and annual reporting period. The amendments are effective for annual periods beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. This guidance should be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Group is currently evaluating the impact of this guidance on its related disclosures.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2025

2.1. Basis of preparation

The accompanying unaudited condensed consolidated interim financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, for interim financial reporting and pursuant to the requirements for reporting on Form 10-Q and Article 10 of Regulation S-X. Accordingly, certain information and disclosures required by U.S. GAAP for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission, or the SEC, on February 27, 2025. In the opinion of management, all adjustments considered necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature. The results for the three and six months ended June 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025, any other interim periods, or any future year or period.

The Group previously prepared its consolidated financial statements in accordance with International Financial Reporting Standards as issued by the International Accounting Standards Board when the Group qualified as a foreign private issuer under the rules and regulations of the SEC. In connection with the loss of the Group’s status as a foreign private issuer, the Group is required to report with the SEC on domestic forms and comply with domestic company rules in the United States, including preparation of its financial statements in accordance with U.S. GAAP. The transition to U.S. GAAP was made retrospectively for all periods from the Group’s inception.

Functional and reporting currency

2.2. Functional and reporting currency

The reporting currency of the condensed consolidated financial statements is U.S. Dollars, or USD or $. The functional currency of the Group’s subsidiaries reflects the economic environment of their respective operations. All amounts disclosed have been rounded to the nearest thousand, unless otherwise stated.

Due to the loss of the Group’s status as a foreign private issuer, effective January 1, 2025, the Group was required as a domestic filer to change its reporting currency of the condensed consolidated financial statements from British pound sterling, or GBP, to USD. The change in reporting currency was applied retrospectively. Condensed consolidated financial statements for all periods have been recast into USD and presented to the nearest thousand dollars.

Principles of consolidation

2.3. Principles of consolidation

The condensed consolidated financial information comprises the financial statements of Silence Therapeutics plc and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated on consolidation.

Use of estimates

2.4. Use of estimates

The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in the Group’s condensed consolidated financial statements include, but are not limited to, the recognition of revenue and research and development expenses. The Group bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates.

Going concern

2.5. Going concern

The Group has incurred recurring losses since inception, including net losses of $55.9 million for the six months ended June 30, 2025. As of June 30, 2025, the Group had accumulated losses of $529.8 million and cash outflows from operating activities for the six months ended June 30, 2025 was $34.1 million.

The Group expects to incur operating losses for the foreseeable future as it continues its research and development efforts, seeks to obtain regulatory approval of its product candidates and pursues any future product candidates the Group may develop.

To date, the Group has funded its operations through upfront payments and milestones from collaboration agreements, equity offerings and proceeds from private placements, as well as management of expenses and other financing options to support its continued operations. In 2024, the Group raised additional proceeds of $27.7 million before deducting $0.9 million in placement agent fees and other expenses, from sales of American Depositary Shares, or ADSs, under its Open Market Sale Agreement with Jefferies LLC, dated October 15, 2021, or the Sales Agreement,. On February 5, 2024, the Group announced a private placement of 5,714,286 of the ADSs, each representing three ordinary shares, at a price of $21.00 per ADS, with new and existing institutional and accredited investors, or the Private Placement. The aggregate gross proceeds of the Private Placement were $120.0 million before deducting approximately $7.7 million in placement agent fees and other expenses. In 2024, the Group received a $10.0 million milestone payment from the AstraZeneca collaboration and received another $2.0 million in milestone payments from the Hansoh collaboration. As of June 30, 2025, the Group had cash and cash equivalents and short-term investments of $114.2 million.

The Group believes that its current cash and cash equivalents are sufficient to fund its operating expenses for at least the next twelve months from the issuance date of these condensed consolidated financial statements. For this reason, the Group continues to adopt the going concern basis in preparing the financial statements.

The Group will need to raise additional funding to fund its operation expenses and capital expenditure requirements in relation to its clinical development activities. The Group may seek additional funding through public or private financings, debt financing or collaboration agreements. Specifically, the Group may receive future milestone payments from existing collaboration agreements which will extend the ability to fund operations. However, these future milestone payments are dependent on achievement of certain development or regulatory objectives that may not occur. The inability to obtain future funding could impact; the Group’s financial condition and ability to pursue its business strategies, including being required to delay, reduce or eliminate some of its research and development programs, or being unable to continue operations or unable to continue as a going concern.

Recently Issued Accounting Pronouncements

2.6. Recently Issued Accounting Pronouncements

Recently adopted accounting standards

There were no accounting standards adopted in the current period.

Accounting standards issued but not yet adopted

In December 2023, the Financial Accounting Standards Board, or FASB, issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which provides for improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. This guidance is effective for annual periods beginning after December 15, 2024, and should be applied on a prospective basis with the option to apply the standard retrospectively. Early adoption is permitted. This standard will have no impact on the Group’s consolidated financial statements. The Company is currently evaluating the impact to its income tax disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40). Additionally, in January 2025, the FASB issued ASU 2025-01 to clarity the effective date of ASU 2024-03. The amendments in this update require disclosure, in the notes to financial statements, of specified information about certain costs and expenses at each interim and annual reporting period. The amendments are effective for annual periods beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. This guidance should be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Group is currently evaluating the impact of this guidance on its related disclosures.