Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

You should read the following discussion and analysis of our financial condition and results of operations together with our consolidated financial statements and the related notes thereto appearing elsewhere in this Annual Report. Historically, we qualified as a foreign private issuer (as defined in Rule 405 of Regulation C under the Securities Act and Rule 3b-4 under the Exchange Act) and prepared our financial statements in accordance with IFRS as issued by the IASB. On June 30, 2024, the last day of our second fiscal quarter, we determined that we no longer qualified as a foreign private issuer under Rule 3b-4(c) of the Exchange Act. As a result, beginning January 1, 2025, we are required to report with the SEC on domestic forms and comply with domestic company rules in the United States. Therefore, we have now become a domestic issuer and are required under current SEC rules to prepare our financial statements in accordance with U.S. GAAP, as opposed to IFRS. The transition to U.S. GAAP from IFRS was made retrospectively for all periods from our inception. The following discussion is based on our financial information prepared in accordance with U.S. GAAP and regulations of the SEC. Some of the information contained in this discussion and analysis or set forth elsewhere in this Annual Report, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. You should review the section titled “Risk Factors” for a discussion of important factors that could cause actual results to differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis, as well as the section titled “Special Note Regarding Forward-Looking Statements.”

We maintain our books and records in pounds sterling, our results are subsequently translated to U.S. dollars, and we prepare our consolidated financial statements in accordance with U.S. GAAP. All references in this Annual Report to “$” are to U.S. dollars and all references to “£” are to pounds sterling. Our Consolidated Balance Sheets as of December 31, 2024, 2023 and 2022 have been translated from pounds sterling into U.S. dollars at the rate of £1.00 to $1.25, £1.00 to $1.27 and £1.00 to $1.21, respectively. Our Consolidated Statements of Operations and Comprehensive Loss and Cash Flows for the years ended December 31, 2024, 2023 and 2022 have been translated from pounds sterling to U.S. dollars at the rate of £1.00 to $1.28, £1.00 to $1.25 and £1.00 to $1.24, respectively. These translations should not be considered representations that any such amounts have been, could have been or could be converted into U.S. dollars at that or any other exchange rate as of that or any other date.

Overview

Silence Therapeutics plc (“we”, “us”, “our”, “the Company” or “Silence”) is a biotechnology company focused on discovering and developing novel molecules incorporating short interfering ribonucleic acid, or siRNA, to inhibit the expression of specific target genes thought to play a role in the pathology of diseases with significant unmet medical need. Our siRNA molecules are designed to harness the body’s natural mechanism of RNA interference, or RNAi, by specifically binding to and degrading messenger RNA, or mRNA, molecules that encode specific targeted disease-associated proteins in a cell. By degrading the message that encodes the disease-associated protein, the production of that protein is reduced, and its level of activity is lowered. In the field of RNAi therapeutics, this reduction of disease-associated protein production and activity is referred to as “gene silencing.” Our proprietary mRNAi GOLDTM (GalNAc Oligonucleotide Discovery) platform consists of siRNA product candidates designed to precisely target and ‘silence’ specific disease-associated genes in the liver. Using our mRNAi GOLDTM platform, we have generated siRNA product candidates both for our internal development pipeline as well as for out-licensed programs with third-party collaborators. Our wholly owned pipeline is currently focused in three therapeutic areas of high unmet need: cardiovascular disease, hematology and rare diseases.

Divesiran (SLN124) is our wholly owned siRNA product candidate designed to inhibit TMPRSS6 expression in the liver. TMPRSS6 is a negative regulator of hepcidin, the body's master regulator of iron metabolism, including its absorption, distribution and storage. Divesiran has shown preclinical potential in several hematological disorders and proof-of-mechanism in a Phase 1 healthy volunteer study. Divesiran is currently being evaluated in the SANRECO Phase 2 clinical trial in polycythemia vera, or PV, patients. We believe divesiran has the potential to be the first-in-class siRNA in PV. PV is a rare, myeloproliferative neoplasm – a type of blood cancer - characterized by the excessive production of red blood cells, often resulting in elevated hematocrit, or HCT, levels. Elevated HCT above 45-percent is associated with a four-times higher rate of death from cardiovascular or thrombotic events. PV is associated with a range of burdensome symptoms including fatigue, cognitive disturbance and pruritis and additionally, longer term can transform to myelofibrosis and Acute Myeloid Leukemia. The aim of treatment is to maintain HCT less than 45%, a level that is associated with a reduced incidence of thrombosis and CV-associated death. The current standard of care

includes repeated phlebotomies to reduce HCT and/or cytoreductive agents to reduce red blood cell production. There are currently no approved therapies that specifically target red blood cells and HCT.By silencing TMPRSS6 in PV patients, divesiran aims to increase hepcidin production and release by liver hepatocytes, leading to the restriction of iron to the bone marrow and, thus, reducing the excessive production of red blood cells, a process dependent on availability of iron. In December 2024, we presented positive interim results from the Phase 1 portion of the SANRECO clinical trial at the American Society of Hematology, or ASH, annual meeting. Interim results showed divesiran substantially reduced phlebotomy requirements and lowered HCT levels following infrequent dosing in a range of PV patients. Divesiran has been well tolerated to-date with no dose-limiting toxicities. In December 2024, we also announced the first subject has been dose in the Phase 2 portion of the SANRECO clinical trial, which is currently underway. Full enrollment in the Phase 2 clinical trial is anticipated by year-end 2025. The U.S. Food and Drug Administration, or FDA, has granted divesiran Fast Track and orphan drug designations for PV. In December 2024, the European Commission, or EC, granted divesiran orphan drug designation for PV in Europe.

Zerlasiran (SLN360) is our wholly owned siRNA product candidate designed to lower the body's production of apolipoprotein(a), a key component of lipoprotein(a), or Lp(a), that has been associated with an increased risk of cardiovascular events. Zerlasiran works by targeting messenger RNA required to translate the LPA gene into particles of Lp(a), effectively ‘silencing’ the gene to reduce Lp(a) production. High Lp(a), defined as 125nmol/L or higher, is a genetically determined cardiovascular risk factor affecting at least 20% of the world’s population and is associated with a high risk of heart attack, stroke and aortic stenosis. Unlike low-density lipoprotein, or LDL, Lp(a) levels are predominantly genetically determined, typically by age five, and unaffected by diet or lifestyle. There are currently no approved medicines that selectively lower Lp(a). Lp(a) levels can be measured by a simple blood test and while there is no generalized consensus on Lp(a) risk thresholds, growing evidence supports three main levels: Low or Normal (less than 75 nmol/L), Elevated (75 nmol/L to 124 nmol/L) and High (125 nmol/L or higher). A recent US based registry study in over 16,000 individuals showed that there is substantial risk of major cardiovascular events in individuals with elevated levels below the current accepted risk threshold of 125 nmol/L. Guidelines from the European Atherosclerosis Society, or EAS, and Canadian Cardiovascular Society, or CCS, suggest at least one test in an adult lifetime. The American College of Cardiology, or ACC, and American Heart Association, or AHA, recommend testing for those with a family history of premature atherosclerotic cardiovascular disease, or ASCVD, or personal history of ASCVD. In Phase 1 and Phase 2 clinical trials, zerlasiran substantially lowered Lp(a) levels in ASCVD patients with persisting effects following infrequent dosing and was well tolerated with no major safety concerns. We are engaged in global partnership discussions for potential Phase 3 development and future commercialization.

In addition to our wholly owned clinical pipeline, we have a third siRNA product candidate from our GOLD platform in Phase 1 development in an undisclosed indication through our collaboration with AstraZeneca. We believe the potential for our GOLD platform to address disease-associated genes in the liver is substantial and are progressing several undisclosed preclinical programs that have shown promising results. We are committed to maximizing our GOLD platform by advancing a pipeline of both wholly owned and partnered programs.

Recent Developments

Zerlasiran (Cardiovascular Disease)

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In November 2024, we presented end-of-treatment data from the Phase 2 clinical trial of zerlasiran in ASCVD patients with high Lp(a) during the Late-Breaking Science Session of the AHA Annual Meeting in Chicago, Illinois. These data were simultaneously published in the Journal of the American Medical Association, or JAMA. Study results showed zerlasiran was well tolerated and produced significant time-averaged Lp(a) reductions following infrequent dosing with effects persisting 60 weeks following the first dose.

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During the fourth quarter 2024, we received positive regulatory feedback from the FDA and European Medicines Agency, or EMA, on the Phase 3 cardiovascular (CV) outcomes study design for zerlasiran in patients with elevated Lp(a) and at high risk of a CV event.

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During the fourth quarter 2024, we progressed core Phase 3 readiness activities for zerlasiran, including the scale-up of product supply to enable the full start-up of the Phase 3 CVOT study in the first half of

2025. Partnering discussions for this program are ongoing; timing for Phase 3 initiation is dependent on partnership.

Divesiran (Polycythemia Vera)

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In December 2024, we presented additional results from the Phase 1 open-label portion of the SANRECO clinical trial of divesiran in PV patients at the American Society of Hematology, or ASH, Annual Meeting in San Diego, California. Data presented at ASH were consistent with initial results presented in June 2024 and showed divesiran was well tolerated and substantially reduced phlebotomy frequency and lowered hematocrit levels following infrequent dosing in PV patients.

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In December 2024, we announced the first subject has been dosed in the Phase 2 randomized, double-blind portion of the SANRECO clinical trial of divesiran in PV patients. Full enrollment is anticipated by year-end 2025.

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In December 2024, the European Commission EC granted divesiran orphan drug designation for PV in Europe. Divesiran also has FDA Fast Track and orphan drug designation for PV in the United States.

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In February 2025, we completed follow-up in the SANRECO Phase 1 clinical trial of divesiran in PV patients. Phase 1 data presentations are planned for medical congresses in 2025.

Other mRNAi GOLD Pipeline Updates

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A Phase 1 clinical trial of SLN312 (licensed to AstraZeneca) is ongoing.

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A Phase 1 clinical trial of SLN548, our wholly owned siRNA for complement-mediated diseases, is planned for the second half of 2025.

We have incurred significant operating losses and expect to continue to incur significant expenses and operating losses for the near future. These net losses were $45.3 million, $54.2 million and $50.3 million, for the years ended December 31, 2024, 2023 and 2022, respectively. As of December 31, 2024, our accumulated deficit was $474.0 million. We expect to continue to incur significant and increasing expenses and to incur operating losses for the foreseeable future, as we advance our product candidates through preclinical and clinical development and seek regulatory approvals, manufacture drug product and drug supply, maintain and expand our intellectual property portfolio, as well as hire additional personnel, pay for further accounting, audit, legal, regulatory and consulting services, and pay costs associated with maintaining compliance with Nasdaq listing rules and the requirements of the U.S. Securities and Exchange Commission, or SEC, director and officer liability insurance, investor and public relations activities and other expenses associated with operating as a public company.

Collaboration Agreement with AstraZeneca

In March 2020, we entered into a collaboration agreement with AstraZeneca to discover, develop and commercialize siRNA therapeutics for the treatment of cardiovascular, renal, metabolic and respiratory diseases. Under this agreement, AstraZeneca made an upfront cash payment to us of $20.0 million in May 2020. AstraZeneca made an additional unconditional cash payment to us of $40.0 million which was received in May 2021. In March 2020, an affiliate of AstraZeneca also subscribed for 4,276,580 new ordinary shares for an aggregate subscription price of $20.0 million.

The collaboration covers five targets initially, with AstraZeneca having the option to extend the collaboration to a further five targets. AstraZeneca has agreed to pay us $10.0 million upon the exercise of each option to collaborate on an additional target. In May 2023, AstraZeneca nominated the first product candidate under our collaboration, triggering a $10.0 million option fee to us to advance development on an undisclosed program. In February 2024, AstraZeneca initiated a Phase 1 clinical trial for this undisclosed program which triggered another $10.0 million milestone payment to us. In March 2024, we completed our obligations for the second product candidate under the collaboration. For each target selected, we will be eligible to receive up to $140.0 million in potential milestone payments upon the achievement of milestones relating to the initiation of specified clinical trials, the acceptance of specified regulatory filings and the first commercial sale in specified jurisdictions. For each target selected, we will also be eligible to receive up to $250.0 million in potential commercial milestone payments, upon the achievement of specified annual net sales levels, as well as tiered royalties as a percentage of net sales ranging from the high single digits to the low double digits.

Collaboration Agreement with Mallinckrodt

In July 2019, we entered into a collaboration agreement with Mallinckrodt to develop and commercialize RNAi drug targets designed to silence the complement cascade in complement-mediated disorders. In connection with the execution of this agreement, Mallinckrodt made an upfront cash payment to us of $20.0 million. Under a separate subscription agreement, Cache Holdings Limited, a wholly owned subsidiary of Mallinckrodt, concurrently subscribed for 5,062,167 new ordinary shares for an aggregate subscription price of $5.0 million. Under the agreement, we granted Mallinckrodt an exclusive worldwide license to our C3 targeting program, SLN501, with options to license two additional undisclosed complement-mediated disease targets from us. In July 2020, Mallinckrodt exercised options on the two additional complement targets.

In March 2023, we reacquired exclusive worldwide rights from Mallinckrodt to the two undisclosed preclinical complement targets. Under the terms of the modified agreement, we did not make any upfront payment to get the two assets back and will potentially pay future success-based milestones and low single digit royalties on net sales if the projects advance. SLN501, the C3 targeting program, remained under the original collaboration agreement. In March 2024, Mallinckrodt notified us that they will not pursue further development of SLN501 following the completion of the phase 1 clinical trial. This completion also concludes all required development activities and commitments under the collaboration.

Collaboration Agreement with Hansoh

On October 15, 2021, we announced a collaboration agreement with Hansoh, one of the leading biopharmaceutical companies in China, to develop siRNAs for three undisclosed targets leveraging our proprietary mRNAi GOLDTM platform. Under the terms of the agreement, we retain exclusive rights to the first two targets in all territories except the China Region (Greater China, Hong Kong, Macau and Taiwan). Hansoh has the exclusive option to license rights to those two targets in the China Region following the completion of phase 1 studies. We will be responsible for all activities up to option exercise and will retain responsibility for development outside the China region post phase 1 studies. Hansoh will also have the exclusive option to license global rights to a third target at the point of IND filing. Hansoh will be responsible for all development activities post option exercise for the third target. Hansoh made a $16 million upfront payment to us in December 2021. We achieved our first $2 million research milestone payment in the Hansoh collaboration in April 2022. In 2023, we achieved two additional preclinical milestones and received $4 million from the collaboration. In 2024, we achieved an additional preclinical milestone and received $2 million from the collaboration.

Components of Results of Operations

Revenue

We do not have any approved products. Accordingly, we have not generated any revenue from product sales, and we do not expect to generate any revenue from the sale of any products unless and until we obtain regulatory approvals for, and commercialize any of, our product candidates. In the future, we will seek to generate revenue primarily from product sales and, potentially, regional or global strategic collaborations with third parties.

Under our collaboration agreement with Mallinckrodt, we received an upfront cash payment of $20.0 million in 2019 and are eligible to receive specified development, regulatory and commercial milestone payments. We received a milestone payment of $2.0 million during the year ended December 31, 2020. In February 2021, we initiated work on the third complement target which triggered another $2 million research milestone payment. In April 2021, we also received $2 million for the second research milestone related to the first complement 3 target. During the year ended December 31, 2022, we received milestone payments totaling $3.0 million. During the years ended December 31, 2023 and 2024 we received no milestone payments. In addition to these potential payments, Mallinckrodt has agreed to fund some of our research personnel and preclinical development costs. We recognize the upfront payment, milestone payments, payments for personnel costs and other research funding payments over time.

In March 2023, we reacquired exclusive worldwide rights to two preclinical siRNA assets under our Mallinckrodt collaboration, which resulted in a modification of the agreement. No additional performance obligations were identified as a result of the modification as there were no additional goods or services to be provided by us and the modification resulted in the partially satisfied performance obligations relating to the two reacquired targets becoming fully satisfied as we were no longer obligated to develop these targets. SLN501, the C3 targeting program, remained under the original Mallinckrodt collaboration through March 2024. We have accounted for the modification as if it were part of the existing contract as the remaining services to be delivered form part of a single performance obligation that is partially satisfied at the date of contract modification. The effect of the contract modification was that the consideration originally received for the two preclinical siRNA assets was reallocated to SLN501. We have recognized the effect of the contract modification on the measure of progress towards complete satisfaction of the SLN501 performance obligation and recognized an adjustment to revenue at the date of the contract modification on a cumulative catch-up basis. We recognized $10.0 million on the contract modification date. In relation to the reacquired targets, the two preclinical siRNA assets were recognized at fair value. The fair value of those assets has been determined to be nil. Under the modification, we agreed to pay future success-based milestones and low single digit royalties on net sales if the projects advance. We will recognize these variable success-based milestones as an intangible asset at cost when triggered. Any royalties payable will be expensed in cost of sales.

In March 2024, Mallinckrodt notified us that it will not pursue further development of the SLN501 program following the completion of the Phase 1 clinical trial. The completion of the Phase 1 clinical trial also represented the conclusion of all required development activities and commitments under the terms of the Mallinckrodt Collaboration. During the year ended December 31, 2024, we recognized a total of $0.6 million in revenue under our agreement with Mallinckrodt.

Under our collaboration agreement with AstraZeneca, we received an upfront cash payment of $20.0 million and an additional payment of $40.0 million in May 2021. We are also eligible to receive specified development and commercial milestone payments as well as tiered royalties on net sales, if any. During the year ended December 31, 2023, we received milestone payments totaling $10.0 million. During the year ended December 31, 2024, we received milestone payments totaling $10.0 million. We recognize the upfront payment and milestone payments over time. During the year ended December 31, 2024, we recognized a total of $18.0 million in revenue under the AstraZeneca agreement.

We entered into a collaboration agreement with Hansoh on October 15, 2021. We received a $16 million upfront payment to us in December 2021. We are eligible to receive up to $1.3 billion in additional development, regulatory and commercial milestones. We will also receive royalties tiered from low double-digit to mid-teens on Hansoh net product sales. During the year ended December 31, 2023, we achieved milestone payments totaling $4.0 million. During the year ended December 31, 2024, we achieved milestone payments totaling $2.0 million related to the Hansoh collaboration. We recognize the upfront payment and milestone payments over time.

In December 2024, Hansoh notified us that it will not pursue further development under the Hansoh Collaboration. This represented the conclusion of all required development activities and commitments under the terms of the Hansoh Collaboration. During the year ended December 31, 2024, we recognized a total of $24.6 million in revenue under this agreement.

In December 2018, we entered into a settlement and license agreement with Alnylam Pharmaceuticals Inc., or Alnylam, pursuant to which we settled outstanding patent litigation with Alnylam related to its RNAi product ONPATTRO. As part of the settlement, we license specified patents to Alnylam, and Alnylam pays us a tiered royalty of up to one percent of net sales of ONPATTRO in the European Union. We were eligible to receive these royalties until December 2023. We invoice Alnylam quarterly in arrears based on sales data for that quarter as reported to us by Alnylam. Royalty revenue is recognized based on the level of sales when the related sales occur. During the year ended December 31, 2024, we recognized a total of $0.1 million in royalty income from Alnylam.

Cost of sales

Cost of sales consists of research and development expenditure that is directly related to work carried out on revenue generating contracts. This includes salary costs that are apportioned based on time spent by employees working on these contracts as well as costs of materials and costs incurred under agreements with CROs.

Operating Expenses

We classify our operating expenses into two categories: research and development costs and general and administrative expenses. Personnel costs, including salaries, benefits, bonuses and share-based payment expenses, comprise a significant component of each of these expense categories. We allocate expenses associated with personnel costs based on the function performed by the respective employees.

Research and Development Costs

The largest component of our total operating expenses since inception has been costs related to our research and development activities, including the preclinical and clinical development of our product candidates. We expense research and development costs as they are incurred and classify them as contracted development, personnel and other.

Our contracted development costs primarily consist of:

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costs incurred under agreements with CROs and investigative sites that conduct our preclinical studies and clinical trials;

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costs related to manufacturing active pharmaceutical ingredients and drug products for our preclinical studies and clinical trials; and

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costs for materials used for in-house research and development activities.

Our personnel research and development expense primarily consists of:

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salaries and personnel-related costs, including bonuses, benefits, recruitment costs and any share-based payment expenses, for our personnel performing research and development activities or managing those activities that have been out-sourced; and

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consultants’ costs associated with target selection, preclinical and clinical research activities, and the progression of programs towards clinical trials.

Our other research and development costs primarily consists of

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costs of related facilities, equipment and other overhead expenses that are considered directly attributable to research and development; and

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depreciation of capital assets used for research and development activities.

The successful development of our product candidates is highly uncertain. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. Accordingly, we expect research and development costs to increase significantly for the foreseeable future as programs progress.

The duration, costs and timing of clinical trials and development of our product candidates will depend on a variety of factors, including:

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the scope, rate of progress, results and expenses of our ongoing and future clinical trials, preclinical studies and research and development activities;

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the potential need for additional clinical trials or preclinical studies requested by regulatory authorities;

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potential uncertainties in clinical trial enrollment rates or drop-out or discontinuation rates of patients;

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competition with other drug development companies in, and the related expense of, identifying and enrolling patients in our clinical trials and contracting with third-party manufacturers for the production of the drug product needed for our clinical trials;

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the achievement of milestones requiring payments under in-licensing agreements, if any;

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any significant changes in government regulation;

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the terms and timing of any regulatory approvals;

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the ability to market, commercialize and achieve market acceptance for any of our product candidates, if they are approved.

We have not historically tracked research and development expenses on a program-by-program basis for our preclinical product candidates.

General and Administrative Expenses

General and administrative expenses consist of personnel costs, allocated expenses and other expenses for outside professional services, including legal, audit, tax and accounting services, public relations and investor relations services. Personnel costs consist of salaries, bonuses, benefits, recruitment costs and share-based payment expenses for personnel in executive, finance, business development and other support functions. Other administrative expenses include office space-related costs not otherwise allocated to research and development costs, insurance expenses, and costs of our information systems and costs for compliance with the day-to-day requirements of being a listed public company in the United States. We anticipate that our administrative expenses will continue to increase in the future as we increase our headcount to support our continued research and development and potential commercialization of our product candidates. We also expect to continue incurring additional expenses as a public company in the United States, including expenses related to compliance with the rules and regulations of the SEC and Nasdaq, additional insurance expenses, expenses related to investor relations activities and other administrative and professional services.

Foreign Currency Gain/Loss, Net

Foreign exchange losses. Foreign exchange gains and losses relate to cash held in foreign currencies (primarily U.S. Dollars and Euros).

Other Income, net

Other income (expense) primarily relates to interest earned on our cash, cash equivalents, as well as accretion earned on our U.S. treasury bills.

Taxation and Benefit from R&D Tax Credit

We are subject to corporate taxation in the United Kingdom, United States and Germany. Due to the nature of our business, we have generated losses since inception. Our income tax credit recognized represents the sum of the

research and development, or R&D, tax credits recoverable in the United Kingdom. The U.K. R&D tax credit, as described below, is fully refundable to us. We have recorded the entire benefit from the U.K. R&D tax credit as a credit to “Benefit from R&D tax credit.”

As a company that carries out extensive research and development, or R&D, activities, we seek to benefit from the U.K. R&D tax credit regime. In respect of accounting periods in which we qualify as a Small and Medium-sized Enterprise, or SME, and in which our qualifying R&D expenditure represents 30% (for periods from April 1, 2024) or more of the total (meaning we also qualify as “R&D-intensive” during such accounting period), we may, under this regime, surrender the trading losses that arise from our R&D activities for a cash rebate of up to 26.97% of qualifying R&D expenditure. Accordingly, if we cease to qualify as an R&D-intensive SME, in future, we will either cease to be able to claim cash rebates in respect of our R&D activities, or only be able to receive cash payments or other tax relief (under other provisions of the U.K. R&D tax credit regime) at a significantly lower rate than at present. Further, the regime’s rules are complex, and if a tax authority were to challenge or seek to disallow our claims (in whole or in part), for example by asserting that we do not (or the relevant expenditure does not) meet the technical conditions to be granted tax credits (or cash rebates), then such challenge or disallowance, if successful, could have a material impact on our cash-flow and financial performance. In addition, future changes to the U.K. R&D tax credit regime may mean that we no longer qualify for it or have a material impact on the extent to which we can make claims (or benefit from them).

Unsurrendered U.K. tax losses may be carried forward indefinitely to be offset against future taxable profits, subject to numerous utilization criteria and restrictions. The amount that can be offset each year is limited to £5.0 million plus an incremental 50% of U.K. taxable profits. After accounting for tax credits receivable, we had accumulated tax losses for carry forward in the United Kingdom of $164.8 million as of December 31, 2024 ($165.1 million as of December 31, 2023). However, in the event of a change in ownership of a U.K. company, certain provisions may apply to restrict the utilization of carried forward tax losses in future periods. These provisions apply where there is a major change in the nature or conduct of a trade in connection with the change in ownership. For the avoidance of doubt, we do not recognize a deferred tax asset in respect of the accumulated tax losses. In addition to our accumulated tax losses in the United Kingdom, we also had $47.0 million of accumulated tax losses as of December 31, 2024 ($54.3 million as of December 31, 2023) related to our operations in Germany for corporate income taxes. We also had $45.6 million of accumulated losses related to trade taxes in our German entity ($52.7 million as of December 31, 2023). We had had a foreign tax expense in Germany of $0.6 million (2023: $0.5 million). Tax losses in the U.S. were negligible.

In the event we generate revenues in the future, we may benefit from the U.K. “patent box” regime that allows profits attributable to revenues from patents or patented products to be taxed at an effective rate of 10%.

Value Added Tax, or VAT, is charged on all qualifying goods and services by VAT-registered businesses. Where applicable, an amount of 20% of goods and services is added to all sales invoices and is payable to the U.K. tax authorities. Similarly, VAT paid on purchase invoices is reclaimable from the U.K. tax authorities.

Results of Operations

Comparison of the years ended December 31, 2024, 2023 and 2022

The following tables summarize the results of our operations for the years ended December 31, 2024, 2023 and 2022.

Year ended December 31,

Loss per share (basic and diluted) $ (0.33 ) $ (0.49 ) $ (0.52 )

Revenue

Revenue for the year ended December 31, 2024, was $43.3 million (2023: $31.6million). The increase was primarily due to revenue associated with the Hansoh Collaboration. We recognized $24.6 million in 2024 related to the Hansoh Collaboration resulting from a cumulative catch up as we have now completed all required obligations under the Hansoh Collaboration. This was partially offset by a decrease in revenue from the Mallinckrodt Collaboration as we have completed all required obligations under the Mallinckrodt Collaboration in 2024.

Revenue for the year ended December 31, 2023, was $31.6 million (2022: $21.7 million). The increase was primarily due to the advancement of targets in our AstraZeneca Collaboration and Hansoh Collaboration, resulting in $17.8 million payment to us in 2023, and $13.1 million from the Mallinckrodt Collaboration. In 2023, we acquired exclusive worldwide rights to two preclinical siRNA assets under the Mallinckrodt Collaboration which resulted in a contract modification.

Cost of Sales

Cost of sales consists of research and development expenditure that is directly related to work carried out on revenue generating contracts, which decreased to $11.8million for the year ended December 31, 2024 (2023: $12.9 million). The change was due to activity associated with our collaboration agreements, which fluctuates based on the timing of activities and project progression.

Cost of sales decreased to $12.9 million for the year ended December 31, 2023 (2022: $13.5 million). There were no costs associated with revenue recognized as a result of the Mallinckrodt Collaboration contract modification. The remaining change was due to activity associated with our collaboration agreements, which fluctuates based on the timing of activities and project progression.

Research and Development Expenses

The following table summarizes our research and development costs for the years ended December 31, 2024, 2023 and 2022.

Year ended December 31,

Research and development costs for the year ended December 31, 2024, were $67.9million as compared to $56.9million for the year ended December 31, 2023 and $43.6 million for the year ended December 31, 2022. Contract development costs in the current year increased by $7.9million from 2023 as a result of additional clinical trials and an increase in contract manufacturing activities for our proprietary programs. Other costs increased by $2.1million from 2023 associated with the increased shipping and license fees.

General and administrative Expenses

General and administrative expenses were $26.9 million for the year ended December 31, 2024, as compared to $26.2 million for the year ended December 31, 2023, and $25.7 million for the year ended December 31, 2022. The increase in the current year is mainly due to the cost of additional reporting and compliance requirements in connection with our transition to becoming a domestic issuer and large accelerated filer.

Foreign currency gain (loss), net

Net foreign exchange gains and losses result primarily from foreign currency (U.S. Dollar and EUR) denominated bank accounts.

Other income (expense), net

Other income primarily relates to accretion from U.S. Treasury Bills and interest on cash accounts.

Benefit from R&D credit

Benefit from R&D tax credit relates to U.K. research and development tax credits. The higher tax credit in current year due to an increase in R&D expenditure compared to previous year.

Taxation

Taxation expense relates to foreign taxation.

Liquidity and Capital Resources

Sources of Liquidity

Since our inception, we have incurred significant operating losses and negative cash flows. We anticipate that we will continue to incur losses for the foreseeable future. We expect that our research and development and administrative expenses will increase in connection with conducting clinical trials and seeking marketing approval for our product candidates, as well as costs associated with operating as a public company. As a result, we will need additional capital to fund our operations, which we may obtain from additional equity financings, debt financings, research funding, collaborations, contract and grant revenue or other sources.

As of December 31, 2024, we had cash, cash equivalents and short-term investments of $147.3 million.

To date, we have financed our operations primarily through the issuances of our equity securities and from upfront, milestone and research payments under collaboration agreements with third parties.

On October 15, 2021, we entered into an Open Market Sale Agreement, or the Sales Agreement, with Jefferies LLC, or Jefferies, pursuant to which we may offer and sell, from time to time, our ADSs through Jefferies. On October 15, 2021, we filed a registration statement, which became effective on October 22, 2021, for the issuance and sale of up to $100.0 million of ADSs. In 2024, we raised proceeds of $27.7 million before deducting $0.9 million in placement agent fees and other expenses, from sales of ADSs under the Sales Agreement. On October 22, 2024, we filed a new registration statement on Form F-3, which replaced the registration statement originally filed on October 15, 2021, for the issuance and sale, if any, of up to an additional $100 million of its shares represented by ADSs under the Sales Agreement. As of this filing, approximately $139.6 million of ADSs remained.

On February 2, 2024, we entered into a Securities Purchase Agreement, or the Purchase Agreement, with the purchasers named therein, or the Investors. Pursuant to the Purchase Agreement, we agreed to sell an aggregate of 5,714,286 of our ADSs to the Investors, at a purchase price equal to $21.00 per ADS, or the Private Placement. The Purchase Agreement contained customary representations and warranties from us and the investors and customary closing conditions. The closing of the Private Placement occurred on February 7, 2024, and we received aggregate gross proceeds from the Private Placement of approximately $120.0 million before deducting $7.7 million in placement agent fees and other expenses.

Pursuant to the Purchase Agreement, we filed a registration statement on Form F-3 (File No. 333-279185), which was declared effective by the SEC on May 14, 2024, covering the resale of the Registrable Securities (as such term is defined in the Purchase Agreement). We have agreed to use our commercially reasonable efforts to keep such registration statement effective until the earlier of (i) the date on which all Registrable Securities covered by such Registration Statement, as amended from time to time, have been sold, and (ii) the date on which there cease to be any Registrable Securities.

We have no ongoing material financing commitments, such as lines of credit or guarantees, that are expected to affect our liquidity over the next five years, other than operating leases.

Refer to Note 2 of our consolidated financial statements appearing elsewhere in this Annual Report on for additional discussion of liquidity and capital resources.

Operating and Capital Expenditure Requirements

We have not achieved profitability on an annual basis since our inception, and we expect to incur net losses in the future. We expect that our operating expenses will increase as we continue to invest to grow our product candidate pipeline, hire additional employees and increase research and development expenses.

Additionally, as a public company, we incur significant additional audit, legal and other expenses. We believe that our existing capital resources will be sufficient to fund our operations, including currently anticipated research and development activities and planned capital spending, at least for the next twelve months.

Our future funding requirements will depend on many factors, including but not limited to:

•

the scope, rate of progress and cost of our clinical trials, preclinical programs and other related activities;

•

the extent of success in our early preclinical and clinical-stage research programs, which will determine the amount of funding required to further the development of our product candidates;

•

the cost of manufacturing clinical supplies and establishing commercial supplies of our product candidates and any products that we may develop;

•

the costs involved in filing and prosecuting patent applications and enforcing and defending potential patent claims;

•

the outcome, timing and cost of regulatory approvals of our product candidates;

•

the cost and timing of establishing sales, marketing and distribution capabilities; and

•

the costs of hiring additional skilled employees to support our continued growth and the related costs of leasing additional office space.

Cash Flows

The following table summarizes the results of our cash flows for the years ended December 31, 2024, 2023 and 2022.

Year ended December 31,

Net cash (outflow)/income from investing activities (21,966 ) 19,294 (20,498 )

Increase/(decrease) in cash and cash equivalents $ 52,481 $ 1,769 $ (24,961 )

Operating activities

Net cash outflow from operating activities was $67.6 million for the year ended December 31, 2024, reflecting an increase from a net cash outflow of $49.5 million for the year ended December 31, 2023. This increase in cash outflow is largely due to increased spend in fiscal 2024 associated with additional spend on clinical trials and an increase in contract manufacturing activities for our proprietary programs.

Net cash outflow from operating activities was $49.5 million for the year ended December 31, 2023, from a net cash outflow of $57.0 million for the year ended December 31, 2022. This decrease in cash outflow was largely due to the 2021 R&D tax credit payment of $8.5 million paid in 2023. No related amount was received in 2022.

Investing activities

Net cash used in investing activities was $22.0 million for the year ended December 31, 2024, compared to an inflow of $19.3 million for the year ended December 31, 2023. This change was primarily due to the redemptions of U.S. Treasury Bills with maturities over three months of $117.4 million in 2024 partially offset by purchases of $139.2 million. For the year ended December 31, 2023, we had redemptions of $45.1 million partially offset by purchases of $25.8 million.

Net cash inflow from investing activities was $19.3 million for the year ended December 31, 2023, compared to an outflow of $20.5 million for the year ended December 31, 2022. This change was primarily due to the redemptions of U.S. Treasury Bills with maturities over three months of $45.1 million in 2023, partially offset by purchases of $25.8 million. For the year ended December 31, 2022, we had a purchase of £20.0 million with no redemptions.

Financing activities

The net cash inflow from financing activities was $142.1 million for the year ended December 31, 2024. In 2024, we raised additional proceeds of $27.7 million before deducting $0.9 million in placement agent fees and other expenses, from sales of ADSs under our Sales Agreement. We raised aggregate gross proceeds from the Private Placement (as defined below) of $120 million before deducting $7.7 million in placement agent fees and other expenses.

The net cash inflow from financing activities was $31.9 million for the year ended December 31, 2023, primarily due to the proceeds we received from the Sale agreement.

Contractual Obligations and Commitments

Research and Development and Manufacturing Agreements

We enter into agreements with certain vendors for the provision of goods and services, which includes manufacturing services with CDMOs and development and clinical trial services with CROs. These agreements may include certain provisions for purchase obligations and termination obligations that could require payments for the cancellation of committed purchase obligations or for early termination of the agreements. The amount of the cancellation or termination payments vary and are based on the timing of the cancellation or termination and the specific terms of the agreement. These obligations and commitments are not separately presented.

Collaboration Agreements

See “—Collaboration Agreements” included above for further details on our collaboration agreements. We have not included milestone or royalty payments or other contractual payment obligations under such collaboration agreements as the timing and amount of such obligations are unknown or uncertain and are contingent upon the initiation and successful completion of future activities.

Selected Financial Data – for the quarters ended 2024 under U.S. GAAP (unaudited)

The following table contains selected quarterly unaudited financial information for the year ended December 31, 2024 (in thousands, except per share data). The selected information for each of the quarters reflects our retrospective change due to the conversion from IFRS to U.S. GAAP and includes all normal and recurring adjustments necessary for the fair presentation of our results of operations.

Basic net (loss)/income per share $ (0.02 ) $ (0.14 ) $ (0.25 ) $ 0.09

Diluted (loss)/income per share $ (0.02 ) $ (0.14 ) $ (0.25 ) $ 0.09

As we had a net income for the three months ended December 31, 2024, we have added diluted net income (loss) per share. Diluted net income per share adjusts the basic net income per share and the weighted-average number of shares of common stock outstanding for the potentially dilutive impact of the Company’s stock awards, using the treasury stock method.

Critical Accounting Policies and Critical Accounting Estimates

Our financial statements are prepared in accordance with U.S. GAAP. The preparation of the financial statements and related disclosures requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that management believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Management evaluates estimates and assumptions on a periodic basis. Our actual results may differ from these estimates.

While our significant accounting policies are described in more detail in the notes to our consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K, we believe the following accounting policies to be most critical to the judgments and estimates used in the preparation of our consolidated financial statements.

Revenue Recognition under Collaboration Agreements

During the years ended December 31, 2024, 2023 and 2022, a significant portion of our revenue from collaboration agreements was derived from our agreements with Mallinckrodt, AstraZeneca, and Hansoh.

Mallinckrodt obtained an exclusive worldwide license for three RNAi programs, AstraZeneca obtained an exclusive worldwide license for up to ten RNAi targets and Hansoh obtained an exclusive option to license up to two targets in Greater China, Hong Kong, Macau and Taiwan and a third target worldwide.

We have out-licensed the rights to some of our intellectual property associated with our siRNA stabilization chemistry technology to AstraZeneca in the context of a Research Collaboration, Option and License Agreement dated March 24, 2020, under which we and AstraZeneca will collaborate to discover, develop and commercialize siRNA therapeutics for the treatment of cardiovascular, renal, metabolic and respiratory diseases. AstraZeneca made an upfront cash payment of $60 million, of which $20 million was paid in May 2020 and the remaining $40 million was paid in May 2021. The upfront payment has been allocated evenly between the ten targets on the basis of a benchmarking exercise that took into account the standalone selling price per target, of similar precedent transactions that had been publicly announced by comparable companies. Subsequent milestones are allocated to the target to which they are related. The upfront and milestone payments will be recognized as revenue as the services are provided. We anticipate initiating work on up to five targets in the early stages of the collaboration, with AstraZeneca having the option to extend the collaboration to a further five targets. Under the collaboration, utilizing our technology, we are responsible for designing siRNA molecules against gene targets selected by AstraZeneca, and for manufacturing of material to support GLP toxicology studies and phase 1 clinical trials. We and AstraZeneca will collaborate during the discovery phase, and AstraZeneca will lead clinical development and commercialization of molecules arising from the collaboration. For each target selected under the collaboration, we will be eligible to receive up to $140 million in milestone payments upon the achievement of milestones relating to initiation of specified clinical trials, the acceptance of specified regulatory filings and the first commercial sale in specified jurisdictions. AstraZeneca has the right to terminate the agreement in its entirety or on a target-by-target basis, for any reason upon specified prior written notice to us. We may terminate the agreement on a target-by-target basis in the event that AstraZeneca begins a legal or administrative proceeding challenging the patentability, validity, ownership or enforceability of our patents. Either party may terminate the agreement on a target-by-target basis upon a material breach by the other party that is not cured within a specified period after receiving written notice, or in its entirety upon giving written notice following the other party’s bankruptcy, insolvency or similar instance. The license of the intellectual property and the R&D services are not distinct, as AstraZeneca cannot benefit from the intellectual property absent the R&D services, as those R&D services are used to discover and develop a drug candidate and to enhance the value in the underlying intellectual property, which could not be performed by another party, indicating that the two are highly interrelated. On this basis, we have concluded that there is a single performance obligation covering both the R&D services and the license of the intellectual property in respect of each target (i.e., one for the initial target and one for each additional optioned complement-mediated disease target). We recognize revenue over the duration of the contract based on an input method based on percentage of cost incurred.

We granted an exclusive worldwide license to our C3 targeting program, SLN501, with options to license two additional complement-mediated disease targets, to Mallinckrodt in July 2019 to develop and commercialize RNAi drug targets designed to silence the complement cascade in complement-mediated disorders, with Mallinckrodt exercising the option for two additional targets from us in July 2020. The license of the intellectual property and the R&D services are not distinct, as Mallinckrodt cannot benefit from the intellectual property absent the R&D services, as those R&D services are used to discover and develop a drug candidate and to enhance the value in the underlying intellectual property, which could not be performed by another party, indicating that the two are highly interrelated. On this basis, we have concluded that there is a single performance obligation covering both the R&D services and the license of the intellectual property in respect of each target (i.e., one for the initial target and one for each additional optioned complement-mediated disease target). We recognize revenue over the duration of the contract based on an input method based on cost to cost.

The agreement with Mallinckrodt has four elements of consideration:

•

a fixed upfront payment, which we received in July 2019;

•

subsequent milestone payments, which are variable and depend upon our achievement of specified development, regulatory and commercial milestones;

•

payments in respect of certain research personnel costs on an FTE, basis, which costs are variable depending on activity under the collaboration; and

•

funding for phase 1 clinical development and certain preparatory activities, including GMP manufacturing, which costs are also variable.

The upfront payment has been allocated evenly between the initial target and the optioned complement-mediated disease targets, because the compounds are at a similar stage of development, on the basis of a benchmarking exercise that took into account the standalone selling price per target, of similar precedent transactions that had been publicly announced by comparable companies. Subsequent milestones are allocated to the target to which they are related. The upfront and milestone payments will be recognized as revenue as the services are provided.

In March 2023, we reacquired exclusive worldwide rights to two preclinical siRNA assets under its Mallinckrodt collaboration, which resulted in a modification of the agreement. No additional performance obligations were identified as a result of the modification as there were no additional goods or services to be provided by us and the modification resulted in the partially satisfied performance obligations relating to the two reacquired targets becoming fully satisfied as we were no longer obligated to develop these targets. SLN501, the C3 targeting program, remained under the original collaboration agreement through March 2024. We have accounted for the modification as if it were part of the existing contract as the remaining services to be delivered form part of a single performance obligation that is partially satisfied at the date of contract modification. The effect of the contract modification was the consideration originally received for the two preclinical siRNA assets was reallocated to SLN501. We have recognized the effect of the contract modification on the measure of progress towards complete satisfaction of the performance obligation and recognized an adjustment to revenue at the date of the contract modification on a cumulative catch-up basis. In relation to the reacquired targets, we will potentially pay future success-based milestones and low single digit royalties on net sales if the projects advance. We will recognize these variable success-based milestones as an intangible asset at cost when triggered. Any royalties will be expensed in cost of sales.

We granted an exclusive option to license two targets in Greater China, Hong Kong, Macau and Taiwan following the completion of phase 1 trials to Hansoh on October 15, 2021. We will retain exclusive rights for those two targets in all other territories. Silence will be responsible for all activities up to option exercise and will retain responsibility for development outside the China region post phase 1 trials. Hansoh will also have the exclusive option to license global rights to a third target at the point of IND filing. Hansoh will be responsible for all development activities post option exercise for the third target. Hansoh made a $16 million upfront payment to us in December 2021 which has been allocated between the three targets based on geography for each option, amount of reimbursable costs for activities provided by Silence for each target, as well as a benchmarking exercise that took into account the standalone selling price per target based on similar precedent transactions that had been publicly announced by comparable companies. Subsequent milestones are allocated to the target to which they are related. The upfront payment and subsequent milestone payments, which are variable and depend upon probability of achievement of specified development, regulatory and commercial milestones, will be recognized as revenue as the services are provided. The license of the intellectual property and the R&D services are not distinct, as Hansoh cannot benefit from the intellectual property absent the R&D services, as those R&D services are used to discover and develop a drug candidate and to enhance the value in the underlying intellectual property, which could not be performed by another party, indicating that the two are highly interrelated. On this basis, we have concluded that there is a single performance obligation covering both the R&D services and the license of the intellectual property in respect of each target (i.e., one for the initial target and one for each additional optioned complement-mediated disease target). We recognized revenue over the duration of the contract based on an input method based on cost to cost.

For all the collaboration agreements listed above, as there is only a single performance obligation per target, the revenue for each element of consideration will be recognized over the contract period based on a cost-to-cost method, which is considered to be the best available measure of our effort during the contract period. The total cost estimate for the contract includes costs expected to be incurred during the contract period. Other variable elements of consideration will only begin to be recognized when it is considered highly probable that a significant reversal of the amounts will not occur.

For the years ended December 31, 2024, 2023 and 2022, we determined actual costs and forecast costs for the remainder of the contract. We calculated total contract costs across the contract term, including costs that will be reimbursed to us, and costs incurred to date as a percentage of total contract costs. We multiplied this percentage by the consideration deemed highly probable of not having a significant reversal, calculating the cumulative revenue to be recognized. When variable consideration increases due to a further milestone becoming highly probable that a

significant reversal of revenue will not occur, a catch-up in revenue is recorded to reflect efforts already expended by us up to that point.

Recognition of Clinical Trial Expenses

As part of the process of preparing our consolidated financial statements, we may be required to estimate accrued expenses related to our preclinical studies and clinical trials. To obtain reasonable estimates, we review open contracts and purchase orders. In addition, we communicate with applicable personnel in order to identify services that have been performed, but for which we have not yet been invoiced. In most cases, our vendors provide us with monthly invoices in arrears for services performed. We confirm our estimates with these vendors and make adjustments as needed. Examples of our accrued expenses include fees paid to CROs for services performed on preclinical studies and clinical trials and fees paid for professional services.

Recently Issued and Adopted Accounting Pronouncements

We discuss the effect of recently issued and adopted pronouncements in Note 2.20 to the consolidated financial statements appearing elsewhere in this Annual Report.

Recent Accounting Pronouncements

See note 2.20 to our consolidated financial statements for the year ended December 31, 2024, appearing elsewhere in this Annual Report for a discussion of new standards and interpretations recently and not yet adopted by us.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Market risk arises from our exposure to fluctuation in interest rates and currency exchange rates. These risks are managed by maintaining an appropriate mix of cash deposits in the two main currencies we operate in, placed with a variety of financial institutions for varying periods according to expected liquidity requirements.

Credit and Liquidity Risk

Our cash, cash equivalents and U.S. Treasury Bills are on deposit with two financial institutions, one in the US and one in the UK, which management believes are of high credit quality. Such deposits may, at times, exceed federally insured limits. We invest our liquid resources based on the expected timing of expenditures to be made in the ordinary course of our activities. All financial liabilities are payable in the short term, meaning no more than three months, and we maintain adequate bank balances in either instant access or short-term deposits to meet those liabilities as they fall due. We do not believe we had any credit risk relating to our trade receivables as of December 31, 2024, 2023 and 2022, which consisted solely of amounts due from AstraZeneca, Mallinckrodt and Alnylam.

Currency Risk

The consolidated financial statements are presented in U.S. dollars. The individual financial statements of each Group entity are prepared in the currency of the primary economic environment in which the entity operates (its functional currency). Our transactions are commonly denominated in U.K pounds sterling; however, we receive payments under our collaboration agreements in U.S. dollars and we incur a portion of our expenses in other currencies, primarily Euros, and are exposed to the effects of these exchange rates. We seek to minimize this exposure by maintaining currency cash balances at levels appropriate to meet foreseeable short to mid-term expenses in these other currencies. Where significant foreign currency cash receipts are expected, we consider the use of forward exchange contracts to manage our exchange rate exposure.

Interest Rate Risk

As of December 31, 2024, we had cash and cash equivalents and short-term investments of $147.3 million. Our exposure to interest rate sensitivity is impacted primarily by changes in the underlying U.K. and U.S. bank interest rates. Our surplus cash and cash equivalents are invested in interest-bearing savings accounts and certificates of deposit

from time to time. During the years ended December 31, 2024, 2023 and 2022, we have not entered into investments for trading or speculative purposes. Due to the conservative nature of our investment portfolio, which is predicated on capital preservation of investments with short-term maturities, we do not expect our operating results or cash flows to be significantly affected by changes in market interest rates.

See Note 23 to our consolidated financial statements appearing elsewhere in this Annual Report for additional disclosures about market risk.

Item 8. Financial Statements and Supplementary Data

Our consolidated financial statements, together with the report of the independent registered public accounting firm required to be filed pursuant to this Item 8 are appended at the end of this Annual Report. An index of those financial statements is found in Item 15 of Part IV of this Annual Report.

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A. Controls and Procedures

Disclosure Controls and Procedures

We maintain “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, has evaluated the effectiveness of our disclosure controls and procedures (as defined in Rules 13a- 15(e) and 15d- 15(e) under the Exchange Act), as of the end of the period covered by this Annual Report. Based on such evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that as of December 31, 2024, our disclosure controls and procedures were effective.

Management’s Annual Report on Internal Control Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Exchange Act Rules 13a-15(f) and 15d-15(f) define this as a process designed by, or under the supervision of, our Chief Executive Officer and our Chief Financial Officer and effected by the Board of Directors, management and other personnel, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements in accordance with U.S. GAAP.

Due to its inherent limitations, internal control over financial reporting may not prevent or detect all misstatements. Furthermore, projections of any evaluation of the effectiveness of internal controls to future periods may prove invalid due to changes in our circumstances and the risk that compliance with policies, procedures and controls is not sustained.

Management has assessed the effectiveness of internal control over financial reporting as of December 31, 2024, based on the Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). Based on this assessment, management has concluded that our internal control over financial reporting as of December 31, 2024, was effective.

Report of Independent Registered Public Accounting Firm

Our independent registered public accounting firm, PricewaterhouseCoopers LLP, has audited the effectiveness of the Company’s internal control over financial reporting as of December 31, 2024, as stated in their report that appears on page F-2 of this Annual Report.

Changes in Internal Control over Financial Reporting

There was no change in our internal control over financial reporting that occurred during the period covered by this annual report, that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information

During the three months ended December 31, 2024, no director or officer of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

PART III

Item 10. Directors, Executive Officers and Corporate Governance

The information required by this item is incorporated by reference to our Proxy Statement for our 2025 Annual General Meeting of Shareholders to be filed with the SEC within 120 days after the end of the fiscal year ended December 31, 2024.

We have adopted a Code of Business Conduct and Ethics that is applicable to all our employees, executive officers, including our principal executive, principal financial and principal accounting officers, members of our board of directors, and consultants. If we make any amendment to the Code of Business Conduct and Ethics or grant any waivers, including any implicit waiver, to the principal executive officer, principal financial officer and principal accounting officer or controller or persons performing similar functions from a provision of the Code of Business Conduct and Ethics, we will disclose the nature of such amendment or waiver on our website to the extent required by the rules and regulations of the SEC. The Code of Business Conduct and Ethics is available on our website at https://silence-therapeutics.com/investors/governance/governance-documents. Information contained on, or that can be accessed through, our website does not constitute a part of this Annual Report and is not incorporated by reference herein.

We have adopted an Insider Trading Policy governing the purchase, sale and/or other dispositions of our securities by our directors, officers and employees. A copy of the Insider Trading Policy is filed as an exhibit to this Annual Report. In addition, it is our practice to comply with the applicable laws and regulations relating to insider trading.

Item 11. Executive Compensation

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Item 13. Certain Relationships and Related Transactions, and Director Independence

Item 14. Principal Accountant Fees and Services

PART IV

Item 15. Exhibits and Financial Statement Schedules

(a) Documents filed as part of Form 10-K.

(1) Financial Statements

Report of Independent Registered Public Accounting Firm

Consolidated Balance Sheets

Consolidated Statements of Income (Loss)

Consolidated Statements of Comprehensive Income (Loss)

Consolidated Statements of Changes in Equity

Consolidated Statements of Cashflows

Notes to the Consolidated Financial Statements

(2) Schedules

Schedules have been omitted as all required information has been disclosed in the financial statements and related footnotes.

(3) Exhibits

The following exhibits are filed as part of this Annual Report on Form 10-K or are incorporated herein by reference.

Incorporated by Reference to Filings Indicated

4.3 Description of Share Capital and Articles of Association X

19.1 Insider Trading Policy X

23.1 Consent of PricewaterhouseCoopers LLP X

101.SCH Inline XBRL Taxonomy Extension Schema with Embedded Linkbase Documents X

# Indicates management contract or compensatory plan.

† Portions of this exhibit (indicated by asterisks) have been omitted because the registrant has determined they are not material and would likely cause competitive harm to the registrant if publicly disclosed.

+ Certain schedules have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The registrant hereby undertakes to furnish supplementally a copy of any omitted exhibit or schedule upon request by the SEC.

* These certifications are being furnished solely to accompany this annual report pursuant to 18 U.S.C. Section 1350 and are not being filed for purposes of Section 18 of the Securities Exchange Act of 1934 and are not to be incorporated by reference into any filing of the registrant, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Item 16. Form 10-K Summary

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15 (d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

SILENCE THERAPEUTICS PLC

By: /s/ Craig Tooman

Craig Tooman

Chief Executive Officer

(Principal Executive Officer)

POWER OF ATTORNEY

Each of the undersigned officers and directors of Silence Therapeutics plc hereby constitutes and appoints Craig Tooman and Rhonda Hellums, and each of them, their true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for them and in their name, place and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K, with all exhibits thereto, and other related documents, and to cause the same to be filed with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing necessary and proper to be done in connection therewith, as fully to all intents and purposes as the undersigned could do if personally present, and each of the undersigned for himself or herself hereby ratifies and confirms that all said attorneys-in-fact and agents, or any of them, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature Title Date

/s/ Iain RossIain Ross Chairman of the Board of Directors February 27, 2025

/s/ Dave LemusDave Lemus Director February 27, 2025

/s/ Michael DavidsonMichael Davidson, MD, FACC, FNLA Director February 27, 2025

/s/ James Ede-GolightlyJames Ede-Golightly Director February 27, 2025

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting firm (PCAOB ID 876) F-2

Consolidated Balance Sheets F-3

Consolidated Statements of Income (Loss) F-4

Consolidated Statements of Comprehensive Income (Loss) F-5

Consolidated Statements of Changes in Shareholders' Equity F-6

Consolidated Statements of Cashflows F-7

Notes to the Consolidated Financial Statements F-8

F-1

Report of Independent Registered Public Accounting Firm

To theBoard of Directors and Shareholders ofSilence Therapeutics plc

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Silence Therapeutics plcand its subsidiaries(the “Company”) as of December 31, 2024and 2023,and the related consolidated statements of income (loss), of comprehensive income (loss), of changes in shareholders’ equity and of cash flows for each of the three years in the period ended December 31, 2024, including the related notes (collectively referred to as the “consolidated financial statements”).We also have audited the Company's internal control over financial reporting as of December 31, 2024, based on criteria established in Internal Control - Integrated Framework(2013)issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidatedfinancial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2024and 2023, and the results of itsoperations and itscash flows for each of the three years in the period ended December 31, 2024in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2024, based on criteria established in Internal Control - Integrated Framework(2013)issued by the COSO.

Basis for Opinions

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Annual Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidatedfinancial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidatedfinancial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidatedfinancial statements included performing procedures to assess the risks of material misstatement of the consolidatedfinancial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidatedfinancial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidatedfinancial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail,

F-2

accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Accuracy of Management's assessment of accruals and prepayments related to third party research and development contracts

As described in Notes 2.8, 12 and 14 to the consolidated financial statements, research and development expenditures included within prepayments and accruals and other payables as of 31 December 2024 was $11.0 million and $5.9 million, respectively. Management recognizes expenditure incurred in carrying out its research and development activities in line with their best estimation of the costs incurred to date for each separately contracted study or activity. This includes the calculation of research and development accruals and prepayments at each period to account for expenditure that has been incurred. This requires estimations of the full costs to complete each study or activity and also estimation of the current stage of completion.

The principal considerations for our determination that performing procedures relating to accuracy of Management's assessment of accruals and prepayments related to third party research and development contracts is a critical audit matter are (i) the significant judgment by management when estimating the stage of completion of these contacts; and (ii) a high degree of auditor judgment, subjectivity and effort in performing procedures and evaluating management’s significant assumptions related to the stage of completion.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to the accuracy of Management’s assessment of the accruals and prepayments related to third party research and development contracts. These procedures also included, among others (i) reading new significant research and development contracts; (ii) testing the completeness and accuracy of the underlying data including total contract costs and actual billed amounts for a sample of contracts; (iii) evaluating Management’s process for determining the stage of completion on a sample of contracts; (iv) evaluating the appropriateness of the methodology; and (v) evaluating the reasonableness of the significant assumptions used by management related to the stage of completion on a sample of contracts. Evaluating management’s assumptions related to the reasonableness of the stage of completion involved testing a sample of research and development activities and the associated incurred cost based on invoices, external confirmations or other information received from the suppliers.

/s/PricewaterhouseCoopers LLP

Reading, United Kingdom

February 27, 2025

We have served as the Company’s auditor since 2014.

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SILENCE THERAPEUTICS plc

Consolidated balance sheets

(in thousands)

Year ended December 31,

Current assets

Short-term investments 26,004 -

Operating lease right-of-use assets 15 157 370

Current liabilities

Operating lease liabilities, current 15 (117 ) (228 )

Operating lease liabilities, long-term 15 - (118 )

Commitments and contingencies (Note 20)

Shareholders’ equity

Total liabilities and shareholders' equity $ (202,635 ) $ (119,448 )

The accompanying notes form an integral part of these consolidated financial statements.

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SILENCE THERAPEUTICS plc

Consolidated Statements of income (loss)

(in thousands, except for loss per share)

Year ended December 31,

Loss per share (basic and diluted) 7 $ (0.33 ) $ (0.49 ) $ (0.52 )

The accompanying notes form an integral part of these consolidated financial statements.

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SILENCE THERAPEUTICS plc

Consolidated statements of comprehensive income (loss)

(in thousands)

Year ended December 31,

Other comprehensive income (loss):

Total other comprehensive (loss)/income for the year (1,055 ) 789 (86 )

The accompanying notes form an integral part of these consolidated financial statements.

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SILENCE THERAPEUTICS PLC

Consolidated statements of changes in SHAREHOLDERS' equity

(in thousands)

Ordinary Shares

Foreign currency translation adjustments (net of tax) - - - $ (86 ) - (86 )

Recognition of share-based payments - - 12,686 - - 12,686

Foreign currency translation adjustments (net of tax) - - - 789 - 789

Foreign currency translation adjustments (net of tax) - - - (1,055 ) - (1,055 )

The accompanying notes form an integral part of these consolidated financial statements.

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SILENCE THERAPEUTICS plc

Consolidated statements of cash flows

(in thousands)

Year ended December 31,

Cash flow from operating activities

Change in operating assets and liabilities:

(Increase)/decrease in trade receivables (904 ) 392 (723 )

(Increase)/decrease in other current assets (1,330 ) 1,955 (5,199 )

Increase in R&D benefit receivable (2,337 ) (3,403 ) (9,821 )

Decrease/(increase) in other long-term assets - (3,217 ) -

Increase/(decrease) in trade and other payables 499 (473 ) 2,024

Decrease in operating lease liabilities (165 ) (175 ) (235 )

Cash flow from investing activities

Purchase of property, plant and equipment (211 ) (56 ) (173 )

Purchase of intangible assets - - (372 )

Net cash (used in) provided by investing activities (21,966 ) 19,294 (20,498 )

Cash flow from financing activities

Increase/(decrease) in cash and cash equivalents 52,481 1,769 (24,961 )

Supplemental disclosures of cash flow information:

The accompanying notes form an integral part of these consolidated financial statements.

F-8

SILENCE THERAPEUTICS plc

Notes to the consolidated financial statements

1. General information

1.1. Nature of the business

Silence Therapeutics plc and its subsidiaries (together the "Group") are primarily involved in the discovery, delivery and development of RNA therapeutics. Silence Therapeutics plc, a public Company limited by shares registered in England and Wales, with company number 02992058, is the Group’s ultimate parent Company. The Company’s registered office is 27 Eastcastle Street, London, W1W 8DH and the principal place of business is 72 Hammersmith Road, London, W14 8TH.

2. Summary of significant accounting policies

2.1. Basis of preparation

The Group’s consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC"). Any reference in these notes to the applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). The consolidated financial statements include the accounts of the Group and its wholly owned subsidiaries, after elimination of intercompany accounts and transactions.

The Group previously prepared its consolidated financial statements in accordance with International Financial Reporting Standards ("IFRS") as issued by the International Accounting Standards Board (“IASB”) 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. The transition to U.S. GAAP was made retrospectively for all periods from the Group’s inception.

2.2. Functional and reporting currency

The reporting currency of the consolidated financial statements is the U.S. Dollars (“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, the Group as a domestic filer, changed its reporting currency of the consolidated financial statements from GBP to USD. The change in reporting currency was applied retrospectively. Consolidated financial statements for all periods have been recast into USD and presented to the nearest thousand dollars.

2.3. Principles of consolidation

The 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.

2.4. Use of estimates

The preparation of the 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 consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in the Group’s consolidated financial statements include, but are not limited to, the recognition of revenue and research and development expenses. The

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

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.

2.5. Going concern

The Group has incurred recurring losses since inception, including net losses of $45.3 million for the year ended December 31, 2024. As of December 31, 2024, the Group had accumulated losses of $474.0 million and cash outflows from operating activities for the year ended 31, December 2024 of $67.6 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 ADSs under its Sales Agreement. On February 5, 2024, the Group announced a private placement of 5,714,286 of the Group’s American Depositary Shares (“ADSs”), each representing three ordinary shares, at a price of $21.00 per ADS, with new and existing institutional and accredited investors (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 achieved another $2.0 million in milestone payments from the Hansoh collaboration. As of December 31, 2024, the Group had cash and cash equivalents and short-term investments of $147.3 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 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.

2.6. Segment reporting

The Group has determined that its chief executive officer is the chief operating decision maker (“CODM”). The CODM reviews financial information presented on a consolidated basis. Resource allocation decisions are made by the CODM based on consolidated results. There are no segment managers who are held accountable by the CODM for operations, operating results, and planning for levels or components below the consolidated unit level. As such, the Group has concluded that it operates as a single reportable segment (see Note 4).

2.7. Revenue recognition

The Group’s revenue for the year ended December 31, 2024, consists of royalty income and revenue from collaboration agreements. To determine revenue recognition for arrangements that the Group determines are within the scope of ASC 606: Revenue from Contracts with Customers, (“ASC 606”), it performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize

F-10

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

revenue when, or as, the Group satisfies the performance obligations. The Group only applies the five-step model to contracts when it is probable that the entity will collect substantially all the consideration it is entitled to in exchange for the goods or services it transfers to the customer. As part of the accounting for these arrangements, the Group must make significant judgments, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each performance obligation.

Royalty income

The Group’s royalty income is generated by a settlement and license agreement with Alnylam. Under this contract, Alnylam is obliged to pay royalties to the Group on the net sales of ONPATTROTM in the EU in a manner commensurate with the contractual terms. Invoices are raised in arrears on a quarterly basis based on sales information provided by Alnylam no later than 75 days after the quarter end.

Under ASC 606, royalty income is recognized at the later date of (i) when the subsequent sale of the commercial partner’s product occurs, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Revenue from collaboration agreements

The Group has considered the Mallinckrodt, AstraZeneca, and Hansoh contracts and assessed whether the research and development services and license of the IP in respect of each target are distinct.

For all contracts the Group has concluded the license of the intellectual property and the R&D services are not distinct, as Mallinckrodt, AstraZeneca, and Hansoh cannot benefit from the intellectual property absent the R&D services, as those R&D services are used to discover and develop a drug candidate and to enhance the value in the underlying intellectual property, and these services could not be performed by another party, indicating that the two are highly interrelated. On this basis, the Group has concluded that there is a single performance obligation covering both the R&D services and the license of the intellectual property in respect of each target. The Group recognizes revenue over the duration of the contract based on an input method based on cost to cost.

The contracts have multiple elements of consideration (some or all of the following), namely:

•

Upfront payments (fixed);

•

Subsequent milestone payments (variable);

•

FTE costs rechargeable (variable);

•

Recharges of direct costs for certain research activities (variable).

F-11

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

The Group’s effort under the contracts continues throughout their entire duration. On this basis revenue is recognized over the contract period based on costs to completion.

Revenue has been calculated on the following ongoing basis for the year ended December 31, 2024:

•

Total contract costs which includes actual FTE and direct costs incurred up to December 31, 2024 and forecast FTE and direct costs for the remainder of the contract

•

Actual costs incurred up until December 31, 2024 are calculated as a percentage of total contract costs (actual and forecast)

•

This percentage is then multiplied by the transaction price allocated to the performance obligation in question, thus calculating the cumulative revenue which is then used to calculate the revenue to be recognized in that period. In the case of the upfront and milestones, the consideration that is multiplied is in relation to the upfront and completed milestones only. Consideration in relation to milestones not yet been achieved is excluded from the calculation.

Forecast costs are monitored each period, with revenue recognized reflecting any changes in forecast or over/under spend in actuals.

Further details of the revenue amounts recognized in the year ended December 31, 2024 can be found in note 3.

2.8. Research and development

Research and development costs consist of salary and personnel related costs and third party costs for the Group's research and development activities. Personnel related costs include a share based compensation charge relating to its stock option plan. The largest component of third party costs is for clinical trials, as well as manufacturing for clinical supplies and associated development, and pre-clinical studies. Research and development costs are expensed as incurred.

The Group recognizes expenditure incurred in carrying out its research and development activities in line with management’s best estimation of the costs incurred to date for each separately contracted study or activity. This includes the calculation of research and development accruals and prepayments at each period to account for expenditure that has been incurred. This requires estimations of the full costs to complete each study or activity and also estimation of the current stage of completion. In all cases, the full cost of each study or activity is expensed by the time the final report or, where applicable, product, has been received. Further details on research and development can be found in note 2.15.

2.9. Taxation

Current tax payable is based on taxable profit for the year. Taxable profit differs from profit as reported in the income statement because it excludes items of income or expense that are taxable or deductible in other years and it further excludes items that are never taxable or deductible. Current tax liabilities are calculated using tax rates that have been enacted or substantively enacted by the balance sheet date.

As a company that carries out extensive research and development activities, the Group currently benefits from the U.K. research and development tax credit regime for small or medium-sized enterprises (“SMEs”). A benefit receivable arises from the U.K. legislation regarding the treatment of certain qualifying research and development costs, allowing for the surrender of tax losses attributable to such costs in return for a tax rebate. Research and development tax credits are recognized when the receipt is probable. Research and development costs which are not eligible for reimbursement under the U.K. Research and Development Tax Credit scheme, such as expenditure incurred on research projects for which the group receives income, may be reimbursed under the U.K. Research and Development Expenditure Credit (“RDEC”) scheme. Amounts receivable under either scheme are presented within the consolidated statements of income (loss) within Benefit from R&D credit. The U.K. R&D tax credit is fully refundable to the Group and is not dependent on current or future taxable income. As a result, the Company has recorded the entire benefit from the U.K. R&D tax credit as a benefit which is included in net loss before income tax and, accordingly, not reflected it as part of the income tax provision.

F-12

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial reporting basis and the respective tax basis of the Group’s assets and liabilities, and expected benefits of utilizing net operating loss, capital loss, and tax-credit carryforwards. The Group assesses the likelihood that its deferred tax assets will be realized and, to the extent management does not believe these assets are more likely than not to be realized, a valuation allowance is established. 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 or laws is recognized in consolidated statements of income (loss) in the period that includes the enactment date.

2.10. Foreign currency translation

Monetary assets and liabilities denominated in currencies other than the functional currency are remeasured into the functional currency at exchange rates prevailing at the balance sheet dates. Non-monetary assets and liabilities denominated in foreign currencies area remeasured into the functional currency at the exchange rates prevailing at the date of the transaction. Exchange gains or losses arising from foreign currency transactions are included in the consolidated statements of income (loss) and comprehensive income (loss) for each respective period.

For financial reporting purposes, the consolidated financial statements of the Group have been presented in USD, the reporting currency. The financial statements of the Group’s entities are translated from their functional currency into USD as follows: assets and liabilities are translated at the exchange rates at the balance sheet dates, revenues and expenses are translated at the average exchange rates for the periods presented, and shareholders’ equity is translated at the prevailing historical exchange rates. Translation adjustments are not included in determining net loss but are included as a foreign exchange adjustment to other comprehensive income, a component of shareholders’ equity.

2.11. Cash and cash equivalents

The Group considers cash and cash equivalents to comprise of cash on hand and demand deposits with original maturities of three months or less that are readily convertible to a known amount of cash and are subject to an insignificant risk of change in value.

2.12. Property, plant and equipment

The Group only holds equipment and furniture. These are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful life of the asset. The estimated useful life of furniture and equipment is 3 to 10 years. Estimated useful life and residual values are reviewed each year and amended if necessary.

Property, plant and equipment is assessed for impairment upon triggering events that indicate the carrying value of an asset group may not be recoverable. Recoverability is measured by a comparison of the carrying amount to future net undiscounted cash flows of the asset group expected to be generated from its use and eventual disposition. If the asset group’s carrying value is determined to not be recoverable, the impairment to be recognized is measured by which the carrying amount exceeds the fair value of the asset group. No impairment charges related to property and equipment were recorded in any of the periods presented.

2.13. Leases

The Group determines if an arrangement contains a lease at inception. The Group currently only has operating leases. The Group recognizes a right-of-use ("ROU") operating lease asset and associated short- and long-term operating lease liability in its consolidated balance sheets for operating leases greater than one year. Its right-of-use assets represent its right to use an underlying asset for the lease term and its lease liabilities represent its obligation to make lease payments arising from the lease arrangement. The Group recognizes its right-of-use operating lease assets and lease liabilities based on the present value of the future minimum lease payments it will pay over the lease term. The Group determines the lease term at the inception of each lease, and in certain cases its lease term could include renewal options if the Group concludes it is reasonably certain to exercise the renewal option. When the Group exercises a

F-13

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

lease option that was not previously included in the initial lease term, it reassesses its right-of-use asset and lease liabilities for the new lease term.

As its operating lease do not provide an interest rate implicit in the lease, the Group uses its incremental borrowing rate, based on the information available as of the lease inception date or at the lease option extension date in determining the present value of future payments. The Group recognizes lease expense for its minimum lease payments on a straight-line basis over the expected term of its lease. Its leases do not include material variable or contingent lease payments.

Leases with an initial term of 12 months or less are not recorded on the balance sheet. Instead, these lease payments are recognized on the consolidated statements of income (loss) on a straight-line basis over the lease term.

Similar to property, plant and equipment, ROU lease asset impairment is assessed upon triggering events that indicate the carrying amount may not be recovered by comparison to the future net undiscounted cash flows.

2.14. Goodwill

Goodwill is the excess of the purchase price over the estimated fair values of the underlying net assets of an acquired business. The Group assesses goodwill for impairment annually, or immediately if conditions indicate that such impairment could exist. Impairment testing for goodwill is performed at the reporting unit level. The Group first evaluates qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the qualitative assessment indicates potential impairment, or if the Group elects to bypass the qualitative assessment, a quantitative test is performed. The quantitative test calculates the excess of the reporting unit’s fair value over its carrying amount, including goodwill, utilizing a discounted cash flow method. The test for impairment of goodwill requires the Group to make several assumptions and estimates regarding market conditions and its future profitability to determine the fair value of the goodwill at the reporting unit. Significant assumptions used in the reporting unit fair value measurements include forecasted cash flows, including revenue and expense growth rates, discount rates, and revenue and earnings multiples. An impairment loss is recognized when the carrying amount of the reporting unit net assets exceeds the estimated fair value of the reporting unit. Impairment losses recognized for the reporting unit to which goodwill has been allocated are credited initially to the carrying amount of goodwill. Any remaining impairment loss is charged pro rata to the other assets in the reporting unit.

All goodwill for the Group is attributed to an acquisition that occurred in 2005 and the Group has determined that no impairment was recorded as of December 31, 2024 and 2023.

2.15. Other intangible assets

Other intangible assets that are acquired by the Group are stated at cost less accumulated amortization and less accumulated impairment losses. Amortization is charged to the consolidated statements of income (loss) on a straight-line basis over the estimated useful lives of intangible assets unless such lives are indefinite. Intangible assets with an indefinite useful life and goodwill are systematically tested for impairment at each balance sheet date. Other intangible assets are amortized from the date they are available for use. The estimated useful lives are as follows:

Licenses and software: 3 - 10 years.

Costs associated with research activities are treated as an expense in the period in which they are incurred.

Costs that are directly attributable to the development phase of software will only be recognized as intangible assets provided they meet the following requirements:

•

an asset is created that can be separately identified;

•

the technical feasibility exists to complete the intangible asset so that it will be available for sale or use and the Group has the intention and ability to do so;

•

it is probable that the asset created will generate future economic benefits either through internal use or sale;

F-14

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

•

sufficient technical, financial and other resources are available for completion of the asset; and

•

the expenditure attributable to the intangible asset during its development can be reliably measured.

Careful judgment by management is applied when deciding whether recognition requirements for software development costs have been met. This is necessary as the economic success of any product development is uncertain and may be subject to future technical problems at the time of recognition. Judgments are based on the information available at each balance sheet date.

2.16. Fair value measurements

The Group’s financial instruments include cash and cash equivalents, trade receivables, U.S. treasury bills, trade and other payables and accrued expenses. These are initially recorded at fair value and subsequently measured at cost, which is considered to approximate their fair value due to the short-term nature of such financial instruments.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The guidance prioritizes the inputs used in measuring fair value into the following hierarchy:

•

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 for similar assets and liabilities in active markets, 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 liability; or

•

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).

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

2.17. Share-based compensation expense

Historically the Group has issued equity settled share-based compensation to certain employees (see note 19). Equity settled share-based payments are measured at fair value (excluding the effect of non-market-based vesting conditions) at the date of grant. The fair value so determined is expensed on a straight-line basis over the vesting period, based on the number of stock that will eventually vest and adjusted for the effect of non-market-based vesting conditions.

The value of the charge is adjusted to reflect expected and actual levels of award vesting, except where failure to vest is as a result of not meeting a market condition.

Cancellations of equity instruments are treated as an acceleration of the vesting period and therefore any amount unrecognized that would otherwise have been recorded in future accounting periods is recognized immediately. The Group has elected to recognize the effect of forfeitures on share-based compensation when they occur. Any differences in compensation recognized at the time of forfeiture are recorded as a cumulative adjustment in the period in which the forfeiture occurs.

Fair value is measured using a Black Scholes model. The key assumptions used in the model have been adjusted, based on management’s best estimate, for the effects of non-transferability, exercise restrictions and behavioral considerations.

Any payment made to a counterparty on the cancellation or settlement of a grant of equity instruments (even if this occurs after the vesting date) should be accounted for as a repurchase of an equity interest (that is, as a deduction from equity). But, if the payment exceeds the fair value of the equity instruments repurchased (measured at the repurchase date), any such excess should be recognized as an expense.

F-15

SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

2.18. Equity

Ordinary shares is determined using the nominal value of shares issued.

The additional paid-in capital account includes any premiums received on the initial issuing of the ordinary shares. Any transaction costs associated with the issuing of shares are deducted from the additional paid-in capital account, net of any related income tax benefits.

Equity settled share-based payments are credited to a share-based payment reserve as a component of additional paid-in capital, until related options or warrants are exercised.

Foreign currency translation differences are included in the accumulated other comprehensive income.

Accumulated deficit includes all current and prior period results as disclosed in the consolidated statements of income (loss).

2.19. Loss per share

Basic income/(loss) per share is computed by dividing the net income/(loss) attributable to ordinary shareholders by the weighted-average number of ordinary shares outstanding for the reporting period without consideration for potentially dilutive securities. Net income/(loss) attributable to ordinary shareholders is computed as if all net income/(loss) for the period had been distributed.

The Group computes diluted income/(loss) per ordinary share after giving consideration to all potentially dilutive ordinary equivalents, except where the effect of such non-participating securities would be antidilutive. The Group been loss making for each fiscal year and therefore all potentially dilutive ordinary equivalents are considered to be antidilutive.

2.20. Recently Issued Accounting Pronouncements

Recently adopted accounting standards

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. This guidance expands public entities’ segment disclosures primarily by requiring disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss, an amount and description of its composition for other segment items, and interim disclosures of a reportable segment’s profit or loss and assets. The amendments are required to be applied retrospectively to all prior periods presented in an entity’s financial statements. The Group adopted the new accounting standard for fiscal year end 2024. See the Segment Reporting policy above and Note 4 below for further detail.

Accounting standards issued but not yet adopted

In December 2023, the 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 the adoption of this standard is not anticipated to have a material impact on the Group’s consolidated financial statements other than adding new disclosures, which the Group is currently evaluating.

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40). 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 reporting periods beginning after December 15, 2027, with early adoption permitted. The Group is currently evaluating the impact to its consolidated financial statements.

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SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

3. Revenue

Revenue from collaboration agreements for the years ended December 31, 2024, 2023 and 2022 predominately relates to the research collaboration agreements the Group entered into with Mallinckrodt in July 2019, AstraZeneca in March 2020, and Hansoh in October 2021.

Revenue comprised $0.1 million of royalty income (2023: $0.7 million; 2022: $0.7 million) and $43.1 million of Research collaboration income (2023: $30.9 million; 2022: $20.9 million). Disaggregation of revenue from contracts with customers is as follows:

Year ended December 31,

Revenue from Contracts with Customers

Under its collaboration agreement with Mallinckrodt, the Group received an upfront cash payment of $20 million in 2019 and are eligible to receive specified development, regulatory and commercial milestone payments. No milestone payments under this agreement were achieved (2023: nil; 2022: $3.0 million) during the year ended December 31, 2024. The Group recognizes the upfront payment, milestone payments, payments for personnel costs and other research funding payments over time, in accordance with ASC 606.

In March 2023, the Group reacquired exclusive worldwide rights to two preclinical siRNA assets under its Mallinckrodt collaboration, which resulted in a modification of the agreement. No additional performance obligations were identified as a result of the modification as there were no additional goods or services to be provided by the Group and the modification resulted in the partially satisfied performance obligations relating to the two reacquired targets becoming fully satisfied as the Group was no longer obligated to develop these targets. SLN501, the C3 targeting program, remained under the original collaboration agreement through March 2024. The Group accounted for the modification as if it were part of the existing contract as the remaining services to be delivered form part of a single performance obligation that is partially satisfied at the date of contract modification. The effect of the contract modification was that the consideration originally received for the two preclinical siRNA assets was reallocated to SLN501. The Group recognized the effect of the contract modification on the measure of progress towards complete satisfaction of the SLN501 performance obligation, and recognized an adjustment to revenue at the date of the contract modification on a cumulative catch-up basis. The Group recognized $10.0 million on the contract modification date. In relation to the reacquired targets, the two preclinical siRNA assets were recognized at fair value. The fair value of those assets has been determined to be nil. Under the modification, the Group agreed to pay future success-based milestones and low single digit royalties on net sales if the projects advance. The Group will recognize these variable success-based milestones as an intangible asset at cost when triggered. Any royalties payable will be expensed in cost of sales.

In March 2024, Mallinckrodt notified the Group that it will not pursue further development of the SLN501 program following the completion of the Phase 1 clinical trial. The completion of the Phase 1 clinical trial also represented the conclusion of all required development activities and commitments under the terms of the Mallinckrodt Collaboration. During the year ended December 31, 2024, the Group recognized a total of $0.6 million in revenue under this agreement (2023: $13.1 million; 2022: $14.4 million).

Under its collaboration agreement with AstraZeneca, the Group received an upfront cash payment of $20 million in 2020 with a further amount of $40 million received in May 2021. The Group is also eligible to receive specified development and commercial milestone payments as well as tiered royalties on net sales, if any. The Group recognizes the upfront payment and milestone payments over time, in accordance with ASC 606. During the year ended December

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SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

31, 2024, the Group achieved a milestone payment of $10.0 million (2023: $10 million; 2022: nil). During the year ended December 31, 2024, the Group recognized a total of $18.0 million in revenue under this agreement (2023: $17.1 million; 2022: $6.3 million).

The Group entered into a collaboration agreement with Hansoh on October 15, 2021. The Group received a $16 million ($14.4 million, net of taxes) upfront payment to us in December 2021. The Group is eligible to receive development, regulatory and commercial milestones as well as royalties on Hansoh net product sales. During the year ended December 31, 2024, the Group achieved milestone payments totaling $2.0 million (2023: $4.0 million; 2022: $1.5 million). The Group recognizes the upfront payment and milestone payments over time, in accordance with ASC 606.

In December 2024, Hansoh notified the Group that it will not pursue further development under the Hansoh Collaboration. This represented the conclusion of all required development activities and commitments under the terms of the Hansoh Collaboration. During the year ended December 31, 2024, the Group recognized a total of $24.6 million in revenue under this agreement (2023: $0.7 million; 2022: $0.2 million).

In December 2018, the Group entered into a settlement and license agreement with Alnylam Pharmaceuticals Inc. (“Alnylam”), pursuant to which the Group settled outstanding patent litigation with Alnylam related to its RNAi product ONPATTRO. As part of the settlement, the Group licenses specified patents to Alnylam, and Alnylam pays us a tiered royalty of up to one percent of net sales of ONPATTRO in the European Union. The Group was eligible to receive these royalties through December 2023. The Group invoices Alnylam quarterly in arrears based on sales data for that quarter as reported to us by Alnylam. Royalty revenue is recognized based on the level of sales when the related sales occur. During the year ended December 31, 2024, the Group recognized a total of $0.1 million in royalty income from Alnylam (2023: $0.7 million; 2022: $0.7 million).

4. Segment reporting

The CODM reviews Consolidated net loss for the year when assessing the Group’s performance, allocating resources and establishing management’s compensation. In addition to Consolidated net loss, the CODM receives discrete information for revenue by major customer and geographic location. Consolidated net loss is used to monitor budget versus actual results and is reviewed against the Group’s peers and competitors as benchmarking. The Group operates as one reportable segment in the specific technology field of RNA therapeutics.

The accounting policies of its operating segment are the same as those described in the Group’s summary of significant accounting policies.

The Group derives revenues from customers through royalty income and research collaboration agreements, each representing a major customer, specifically related to the development of RNAi-based medicines. Refer to Note 3 – Revenue for a further description of the types of products from which the Group derives its revenues.

The measure of segment assets is reported on the balance sheet as total consolidated assets.

The table below provides segment information about the Group:

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SILENCE THERAPEUTICS plc

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (Continued)

Year Ended December 31,

Less:

(a)

Contracted development costs primarily consist of costs incurred under agreements with CROs and investigative sites that conduct its preclinical studies and clinical trials; costs related to manufacturing active pharmaceutical ingredients and drug products for its preclinical studies and clinical trials; and costs for materials used for in-house research and development activities.

(b)

Personnel R&D costs primarily consist of salaries and personnel-related costs for personnel performing R&D activities or managing those activities that have been out-sourced; and consultants’ costs associated with target selection, preclinical and clinical research activities, and the progression of programs towards clinical trials.

(c)

Other R&D costs include associated facility costs, equipment and other overheads that are directly attributable to R&D and depreciation of capital assets used for research and development activities.

(d)

The other segment items include foreign currency gain (loss), net, benefit from R&D credit, and other income/ (expense), net inclusive of bank interest receivable and accretion on U.S. Treasury Bills.

An analysis of the group’s assets and revenues by location is shown below:

U.S.A. U.K. Germany Total

Non-current assets

SLN US Equity

SLN · 10-K · period ended 2024-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Item 13. Certain Relationships and Related Transactions, and Director Independence

Item 14. Principal Accountant Fees and Services

Item 15. Exhibits and Financial Statement Schedules

Item 16. Form 10-K Summary

SLN US Equity☆

SLN · 10-K · period ended 2024-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk.

Item 8. Financial Statements and Supplementary Data

Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

Item 9A. Controls and Procedures

Item 9B. Other Information

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Item 10. Directors, Executive Officers and Corporate Governance

Item 11. Executive Compensation

Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Item 13. Certain Relationships and Related Transactions, and Director Independence

Item 14. Principal Accountant Fees and Services

Item 15. Exhibits and Financial Statement Schedules

Item 16. Form 10-K Summary

SLN US Equity