Silence Therapeutics plc: Form 10-Q for the period ended Mar 31, 2025

You should read the following discussion and analysis of our financial condition and results of operations together with our condensed consolidated financial statements, the related notes thereto appearing elsewhere in this Quarterly Report. The following discussion is based on our financial information prepared in accordance with accounting principles generally accepted in the U.S., or U.S. GAAP, as found in the Accounting Standards Codification and Accounting Standards Update of the Financial Accounting Standards Board and the rules and regulations of the SEC. Some of the information contained in this discussion and analysis or set forth elsewhere in this Quarterly Report, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. Our actual results, performance or experience could differ materially from what is indicated by any forward-looking statement due to various important factors, risks and uncertainties, including, but not limited to, those set forth under “Risk Factors” included elsewhere in this

Quarterly Report on Form 10-Q.

Overview

We are 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 GOLD™ (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 GOLD 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 trial. 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. 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 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 dosed in the Phase 2 portion of the SANRECO clinical trial, which is currently underway. 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, which is 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 was shown to substantially lower Lp(a) levels in ASCVD patients with persisting effects following infrequent dosing and was observed to be well tolerated with no major safety concerns. During the fourth quarter of 2024, we received positive regulatory feedback from the FDA and European Medicines Agency, or EMA, on the Phase 3 cardiovascular, or CV, outcomes study design for zerlasiran in patients with high Lp(a). We are engaged in global partnership discussions to seek a third-party partner for potential Phase 3 development of zerlasiran as well as potential future commercialization activities.

In addition to our wholly owned clinical pipeline, we have a third siRNA product candidate from our mRNAi GOLD platform in Phase 1 development in an undisclosed indication through our collaboration with AstraZeneca. We believe the potential for our mRNAi 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 mRNAi GOLD platform by advancing a pipeline of both wholly owned and partnered programs.

First Quarter 2025 Business Developments

• In February 2025, we completed the Phase 1 portion of the SANRECO study of divesiran in PV patients. Additional Phase 1 results from the SANRECO study were accepted for oral presentation during the European Hematology Association, or EHA, 2025 Annual Congress being held in Milan, Italy from June 12 – 15, 2025.
• We advanced enrollment into the Phase 2 portion of the SANRECO study of divesiran in PV patients and remain on-track to complete enrollment by year-end 2025.
• We advanced core Phase 3 readiness activities for our zerlasiran program, including manufacturing and supply scale-up, which remain on-track to complete by mid-2025. Partnering discussions for potential Phase 3 development are ongoing.
• A Phase 1 study of SLN312 (licensed to AstraZeneca) is ongoing.

Collaborations

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 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 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.

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.

Hansoh

In October 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 GOLD™ platform. Under the terms of the agreement, Hansoh had the exclusive option to license rights to the first two targets in Greater China, Hong Kong, Macau and Taiwan following the completion of Phase 1 trials. We retained exclusive rights for those two targets in all other territories. We were responsible for all activities up to option exercise and will retain responsibility for development outside the China region post Phase 1 trials. Hansoh also had the exclusive option to license global rights to a third target at the point of Investigational New Drug filing. Hansoh was 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 of $2.0 million from the Hansoh collaboration. 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 and we will retain exclusive rights globally for all three targets.

Components of Results of Operations

Revenue

We do not have any commercially 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.

We recognized the upfront payment, milestone payments, payments for personnel costs and other research funding payments over time.

In March 2024, Mallinckrodt notified us that they 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 three months ended March 31, 2025, we did not recognize revenue under the Mallinckrodt Collaboration (three months ended March 31, 2024: $0.6 million).

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. We recognize the upfront payment and milestone payments over time. During the three months ended March 31, 2025, we recognized a total of $0.1 million in revenue under the AstraZeneca collaboration (three months ended March 31, 2024: $14.7 million).

Under the Hansoh Collaboration, we received an upfront cash payment of approximately $16.0 million (net of taxes based on the exchange rate at the payment date) in December 2021. 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 three months ended March 31, 2025, we did not recognize revenue under the Hansoh collaboration (three months ended March 31, 2024: $0.2 million).

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 three months ended March 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 contract research organizations, or 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:

• costs incurred under agreements with contract research organizations, or CROs, and investigative sites that conduct our preclinical studies and clinical trials;
• costs related to manufacturing active pharmaceutical ingredients and drug products for our preclinical studies and clinical trials; and
• costs for materials used for in-house research and development activities.

Our research and development personnel expense primarily consists of:

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

Other research and development costs primarily consists of:

• costs of related facilities, equipment and other overhead expenses that are considered directly attributable to research and development;
• costs associated with obtaining and maintaining patents for intellectual property; and
• 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:

• the scope, rate of progress, results and expenses of our ongoing and future clinical trials, preclinical studies and research and development activities;
• the potential need for additional clinical trials or preclinical studies requested by regulatory authorities;
• potential uncertainties in clinical trial enrollment rates or drop-out or discontinuation rates of patients;
• 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;
• the achievement of milestones requiring payments under in-licensing agreements, if any;
• any significant changes in government regulation;
• the terms and timing of any regulatory approvals;
• the expense of filing, prosecuting, defending and enforcing patent claims and other intellectual property rights; and
• 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 public company listed in the United States. We will continue to be prudent with administrative expenses required to support our continued research and development and potential commercialization of our product candidates. We also will continue to incur expenses related to being a public company, 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 gains and losses relate to cash held in foreign currencies (primarily USD 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 credit

We are subject to corporate taxation in the United Kingdom, the 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.

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 $6.5 million (£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 $187.7 million as of March 31, 2025 ($158.1 million as of March 31, 2024). 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 $48.7 million of accumulated tax losses as of March 31, 2025 ($52.3 million as of March 31, 2024), related to our operations in Germany for corporate income taxes. We also had $47.2 million of accumulated losses related to trade taxes in our German entity ($50.8 million as of March 31, 2024). We had a foreign tax expense in Germany of nil for the three months ended March 31, 2025 (three months ended March 31, 2024: $0.2 million). Tax losses in the United States 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.

Withholding tax is deductible from dividends, interest, lease of property, royalties, and other China-source passive income since we do not have an establishment or place of business in China.

Comparison of the three months ended March 31, 2025, and 2024

The following table summarizes the results of our operations for the three months ended March 31, 2025, and 2024 (in thousands).

Revenue

Revenue for the three-month period ended March 31, 2025, was $0.1 million, reflecting a decrease of $15.6 million from the same three-month period in 2024. This change was mainly due to revenue from our Collaboration with AstraZeneca which decreased by $14.5 million. This difference was mainly due to the fact that there were no similar milestones in 2025.

Cost of Sales

Cost of sales decreased $2.7 million for the three months ended March 31, 2025, as compared to the same period in 2024. The change was due to activity associated with our collaboration agreements, which fluctuates based on the timing of activities and project progression.

Research and development costs

The following table summarizes our research and development costs for the three months ended March 31, 2025, and 2024, based on their classification (in thousands).

Research and development costs increased by $9.0 million for the three months ended March 31, 2025, as compared to the same period in 2024. This was largely due to advancement of our clinical trials and an increase in contract manufacturing activities for our proprietary programs.

General and administrative expense

General and administrative expenses increased by $1.0 million for the three months ended March 31, 2025, as compared to the same period in 2024, which 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 (USD and EUR) denominated bank accounts.

Other Income (expenses), 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.

Taxation

Taxation expense relates to foreign taxation.

Liquidity and Capital Resources

Overview

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 in the future, which we may obtain from additional equity financings, debt financings, research funding, collaborations, contract and grant revenue or other sources.

As of March 31, 2025, we had cash, cash equivalents, and short-term investments of $136.5 million. We believe that our cash, cash equivalents, and treasury instruments will be sufficient to fund our anticipated operating and capital expenditure requirements into 2028, which includes receipt of anticipated milestones from collaboration agreements of $20 million in the next three years.

To date, we have financed our operations primarily through the issuances of our equity securities and from the receipt of 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. 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 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.

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.

Cash Flows

The following table summarizes the results of our cash flows for the three months ended March 31, 2025, and 2024.

Operating activities

Net cash outflow from operating activities increased by $3.2 million for the three months ended March 31, 2025, compared with the prior period, mainly due to an increase in expenditures related to contracted development costs.

Investing activities

Net cash outflow from investing activities relates to purchases of U.S. treasury bills offset by redemptions for the three months ended March 31, 2025. The same period in 2024 reflected only a purchase of a U.S. treasury bill.

Financing activities

In 2024, 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 remainder of the inflow was due to

proceeds from sales under our at-the-market facility. There was no related financing activities in 2025.

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.

Contractual Obligations and Commitments

The following table summarizes our contractual commitments and obligations as of March 31, 2025 and December 31, 2024.

The lease liability recognized on the balance sheet comprises our London office. There are two short-term leases in Berlin, Germany and a lease in New Jersey, United States, not included in the "lease liability" line of the table above. Both leases in Berlin are on a rolling contract basis with either party being able to end the lease with a cancellation notice period of 11.5 months, while the leases in the United States are on a rolling contract basis with a notice period of three months, thus allowing exemption using the practical expedient.

At March 31, 2025, we had a gross commitment on our office rental in Berlin, Germany and in the United States equal to an aggregate of $0.5 million in the next year. No amounts are payable after more than one year.

We have agreed to make payments to CROs and manufacturers under various CRO and manufacturing agreements that generally provide for our ability to terminate on short notice. We have not included any such contingent payment obligations in the table above as the amount, timing and likelihood of such payments are not fixed or determinable.

Critical Accounting Policies, Judgments and 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 condensed consolidated financial statements appearing elsewhere in this Quarterly Report on Form 10-Q, we believe the following accounting policies to be most critical to the judgments and estimates used in the preparation of our condensed consolidated financial statements.

Critical Accounting Estimates

Revenue Recognition under Collaboration Agreements

During the three months ended March 31, 2025, a significant portion of our revenue from collaboration agreements was derived from our agreement with AstraZeneca (three months ended March 31, 2024, revenue was from our collaborations 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.

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 three months ended March 31, 2025 and 2024, 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 condensed 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.

Recent Accounting Pronouncements

We discuss the effect of recently issued and adopted pronouncements in Note 2.20 “Summary of Significant Accounting Policies” to the condensed consolidated financial statements.

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 United States and one in the United Kingdom, 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.

Currency Risk

The condensed 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 March 31, 2025, we had cash and cash equivalents and short-term investments of $136.5 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. 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.

Disclosure Controls and Procedures

We maintain “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended, or 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 Exchange Act Rules 13a-15(e) and 15d-15(e)) as of March 31, 2025. Based on such evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that, as of March 31, 2025, our disclosure controls and procedures were effective.

Changes in Internal Control Over Financial Reporting

There have been no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) that occurred during the three months ended March 31, 2025, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Our business has significant risks. In addition to the other information set forth in this Quarterly Report on Form 10-Q, you should carefully consider the risks described in Part I, Item 1A. “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the Securities and Exchange

Commission, or SEC, on February 27, 2025. The risk factors set forth below are risk factors containing changes,

which may be material, from the risk factors previously disclosed in Item 1A of our Annual Report on Form 10-K

for the fiscal year ended December 31, 2024, as filed with the SEC. These are not the only risks facing our business. Other risks and uncertainties that we are not currently aware of or that we currently consider immaterial also may materially adversely affect our business, financial condition and future results. Risks we have identified but currently consider immaterial could still also materially adversely affect our business, financial condition and future results of operations if our assumptions about those risks are incorrect or if circumstances change.

We and the third parties with whom we work are subject to stringent and evolving U.S. and foreign data

privacy and security laws, regulations contractual obligations, industry standards, policies, and other obligations,

and our (or the third parties with whom we work) actual or perceived failure to comply with such obligations

could lead to regulatory investigations or actions; litigation (including class actions); fines and penalties;

disruptions of our business operations; reputational harm; loss of revenue or profits; and other adverse business

consequences.

In the ordinary course of business, we collect, receive, store, process, generate, use, transfer, disclose, make accessible, protect, secure, dispose of, transmit, and share (collectively, process) personal data and other sensitive information, including proprietary and confidential business data, trade secrets, intellectual property, sensitive third-party data, business plans, transactions, clinical trial data and financial information (collectively, sensitive data).

Our data processing activities subject us to privacy and data protection obligations, such as various laws, regulations, guidance, industry standards, external and internal privacy and security policies, contractual requirements, and other obligations relating to data privacy and security.

Outside the United States, an increasing number of laws, regulations, guidance and industry standards govern data privacy and security. For example, the European Union’s General Data Protection Regulation ("EU GDPR") and the United Kingdom’s GDPR ("U.K. GDPR") (collectively, “GDPR”) impose strict requirements for processing personal data (including health data). Under GDPR, companies may face temporary or definitive bans on data processing and other corrective actions; fines of up to 20 million Euros under the EU GDPR, 17.5 million pounds sterling under the UK GDPR or, in each case, 4% of annual global revenue, whichever is greater; or private litigation related to processing of personal data brought by classes of data subjects or consumer protection organizations authorized at law to represent their interests.

In the ordinary course of business, we may transfer personal data from Europe and other jurisdictions to the United States or other countries. Europe and other jurisdictions have enacted laws requiring data to be localized or limiting the transfer of personal data to other countries. In particular, the European Economic Area (EEA) and the United Kingdom have significantly restricted the transfer of personal data to third countries, including the United States, whose privacy laws it generally believes are inadequate. Other jurisdictions may adopt similarly stringent interpretations of their data localization and cross-border data transfer laws. Although there are currently various mechanisms that may be used to transfer personal data from the EEA and UK to the United States in compliance with law (e.g., the EEA Standard Contractual Clauses, the United Kingdom’s International Data Transfer Agreement / Addendum, and the EU-U.S. Data Privacy Framework and the United Kingdom’s extension thereto (which allows for transfers to relevant U.S.-based organizations who self-certify compliance and participate in the Framework)), these mechanisms are subject to legal challenges, and there is no assurance that we can satisfy or rely on these measures to lawfully transfer personal data to the United States. If there is no lawful manner for us to transfer personal data from the EEA, the UK or other jurisdictions to the United States, or if the requirements for a legally-compliant transfer are too onerous, we could face significant adverse consequences, including the interruption or degradation of our operations, the need to relocate part of or all of our business or data processing activities to other jurisdictions (such as Europe) at significant expense, increased exposure to regulatory actions, substantial fines and penalties, the inability to transfer data and work with partners, vendors and other third parties, and injunctions against our processing or transferring of personal data necessary to operate our business. Additionally, companies that transfer personal data out of the EEA and UK to other jurisdictions, particularly to the United States, are subject to increased scrutiny from regulators, individual litigants, and activist groups. Some European regulators have ordered certain companies to suspend or permanently cease certain transfers out of Europe for allegedly violating the GDPR’s cross-border data transfer limitations.

Additionally, the U.S. Department of Justice issued a rule entitled the Preventing Access to U.S. Sensitive Personal Data and Government-Related Data by Countries of Concern or Covered Persons, which places additional restriction on certain data transactions involving countries of concern (e.g., China, Russia, Iran) and covered individuals (i.e., individuals and entities located in or controlled by individuals or entities located in those jurisdictions) that may impact certain business activities such as vendor engagements, sale or sharing of data, employment of certain individuals, and investor agreements. Violations of the rule could lead to significant civil and criminal fines and penalties. The rule applies regardless of whether data is anonymized, key-coded, pseudonymized, de-identified or encrypted, which presents particular challenges for companies like ours and may impact [or has impacted] our ability to transfer data in connection with certain transactions or agreements.

In the United States, federal, state, and local governments have enacted numerous data privacy and security laws, including data breach notification laws, personal data privacy laws, consumer protection laws (e.g., Section 5 of the Federal Trade Commission Act), and other similar laws (e.g., wiretapping laws). For example, the California Consumer Privacy Act of 2018 (“CCPA”) requires covered companies to provide disclosures to California residents, including consumers, business representatives, and employees, and requires businesses to provide specific disclosures in privacy notices and honor requests of California residents to exercise certain privacy rights. The CCPA provides for statutory fines and allows private litigants affected by certain data breaches to recover significant statutory damages. Although there are limited exemptions for clinical trial data under the CCPA, the CCPA may impact (possibly significantly) our business activities, should we become subject to the CCPA in the future. Numerous other U.S. states have also enacted comprehensive privacy laws, and similar laws are being considered in several other states, as well as at the federal and local levels. While many of these state laws, like the CCPA, exempt some data processed in the context of clinical trials, these developments further complicate compliance efforts, and increase legal risk and compliance costs for us and the third parties with whom we work. Failure to comply with federal and state laws in the United States regarding privacy and security of personal data could further expose us to penalties under privacy and data protection laws. Even if we are not determined to have violated these laws, government investigations into these issues typically require the expenditure of significant resources and generate negative publicity, which could harm our business.

In addition, on occasion our employees and personnel use generative AI technologies to perform their work, and the disclosure and use of personal data in generative AI technologies is subject to various privacy laws and other privacy obligations. Governments have passed and are likely to pass additional laws regulating generative AI. Our use of this technology could result in additional compliance costs, regulatory investigations and actions, and lawsuits. If we are unable to use generative AI, it could make our business less efficient and result in competitive disadvantages.

We are bound by contractual obligations related to data privacy and security, and our efforts to comply with such obligations may not be successful. We also publish policies, marketing materials, and other statements concerning data privacy and security. Regulators are increasingly scrutinizing these statements, and if these policies, materials or statements are found to be deficient, lacking in transparency, deceptive, unfair, misleading, or misrepresentative of our practices, we may be subject to investigation, enforcement actions by regulators, or other adverse consequences.

Obligations related to data privacy and security (and individuals’ data privacy expectations) are quickly changing, becoming increasingly stringent, and creating uncertainty. Additionally, these obligations may be subject to differing applications and interpretations, which may be inconsistent or conflict among jurisdictions. Preparing for and complying with these obligations requires us to devote significant resources, which may necessitate changes to our services, information technologies, systems, and practices and to those of any third parties that process personal data on our behalf.

We may at times fail (or be perceived to have failed) in our efforts to comply with our data privacy and security obligations. Moreover, despite our efforts, our personnel or third parties with whom we work may fail to comply with such obligations, which could negatively impact our business operations and compliance posture. For example, any failure by a third party with whom we work to comply with applicable law, regulations, or contractual obligations could result in adverse effects, including inability to or interruption in our ability to operate our business and proceedings against us by governmental entities or others. If we or the third parties with whom we work fail, or are perceived to have failed, to address or comply with applicable data privacy and security obligations, we could face significant consequences, including but not limited to: government enforcement actions (e.g., investigations, fines, penalties, audits, inspections, and similar); litigation (including class-action claims); additional reporting requirements and/or oversight; bans or restrictions on processing personal data (including clinical trial data); orders to destroy or not use personal data; and imprisonment of company officials.

Any of these events could have a material adverse effect on our reputation, business, or financial condition, including but not limited to: loss of customers; interruptions or stoppages in our business operations (including, as relevant, clinical trials); inability to process personal data or to operate in certain jurisdictions; limited ability to develop or commercialize our products; expenditure of time and resources to defend any claim or inquiry; adverse publicity; or revision or restructuring of our operations.