Company to host fourth quarter conference call and webcast today at 8 a.m. EDT / 12 p.m. GMT

Silence Therapeutics plc, Nasdaq: SLN (“Silence” or “the Company”), an experienced and innovative biotechnology company committed to transforming people’s lives by silencing diseases through precision engineered medicines, today reported its financial results for the fourth quarter and full year ended December 31, 2022 and reviewed recent business highlights.

“With a strong finish to 2022 and a great start to 2023, Silence is well positioned for an impactful year highlighted by our advancing clinical pipeline,” said Craig Tooman, President and CEO of Silence. “We remain very focused on executing against the zerlasiran (SLN360) and SLN124 clinical programs while continuing to buildout our broader pipeline both internally and through our partnerships. Along with our clinical advancements, our technology is increasingly being acknowledged as a platform.”

“We are committed to responsibly investing in initiatives that will advance our pipeline and expanding our platform into new targets,” said Rhonda Hellums, Chief Financial Officer of Silence. “We believe we are well positioned to advance our clinical pipeline and will continue to evaluate collaborations that could provide additional non-dilutive funding opportunities.”

Fourth Quarter 2022 and Recent Business Highlights

Wholly Owned Programs

Zerlasiran (SLN360) - cardiovascular disease

• In November 2022, we presented a further analysis from the APOLLO phase 1 program in healthy adults with high Lp(a) in a moderated poster session at the American Heart Association Annual Meeting. The analysis showed median time-averaged reductions during 150 days of follow up exceeded 80% in 300 mg and 600 mg treatment groups.
• In December 2022, SLN360's INN (international nonproprietary name) was approved – zerlasiran.
• In January 2023, we started dosing subjects in the ALPACAR-360 phase 2 clinical trial evaluating zerlasiran in patients with high Lp(a) ≥ 125 nmol/L at high-risk of atherosclerotic cardiovascular disease (ASCVD) events.
• In February 2023, we started dosing the last subject in the multiple dose portion of the APOLLO phase 1 study of zerlasiran in people with high Lp(a) ≥ 150 nmol/L and stable ASCVD. We remain on-track to report topline data in the fourth quarter of 2023.

SLN124 - hematological conditions

• In January 2023, we opened sites for enrollment in the SANRECO phase 1/2 clinical program of SLN124 in polycythemia vera patients.
• In March 2023, we completed dosing in the multiple dose portion of the GEMINI II phase 1 study of SLN124 in thalassemia patients. We remain on track to report topline data in the fourth quarter of 2023.

Partnered Programs

Hansoh Collaboration

• In December 2022, we initiated work on the second target under our Hansoh collaboration. We retain global rights to this target outside the China Region.

Fourth Quarter and Full Year 2022 Financial Results

For the twelve-month period ending December 31, 2022, the net loss after tax was £40.5 million, or weighted average loss per share 41.9 pence compared to the same period in 2021 of £39.4 million, or weighted average loss per share 44.3 pence. The increase in net loss was primarily related to an increase in R&D expenditures as the Company continues to further advance and expand its pipeline of innovative medicines.

Revenue

Revenue recognized for the year ending December 31, 2022 increased to £17.5 million, compared to £12.4 million for the year ending December 31, 2021. The Company records revenue from collaborations based on percentage of contract completion and the increase was driven by the advancement of current collaboration programs. As the Company’s current collaboration programs progress and additional programs are initiated revenues are also expected to increase over time.

Cost of sales

The cost of sales increased for the twelve months ending December 31, 2022 to £10.9 million from £7.5 million in the period ending December 31, 2021. Cost of sales includes research and development expenditure that is directly related to work carried out on revenue generating contracts.

Research and Development

During the year ending December 31, 2022, research and development expenditures were £35.6 million, compared to £30.8 million for the year ending December 31, 2021. The increase is a result of additional clinical studies and an increase in contract manufacturing activities for Silence’s proprietary programs, as well as an increase in personnel costs to expand internal capabilities and expertise to further advance the Company’s siRNA platform.

General and Administrative

General and administrative expenses decreased by £0.4 million to £19.6 million for the year ending December 31, 2022 from £20.0 million for the same corresponding period in 2021. The decrease was mainly due to a reduction in consulting and recruiting costs as well as the monitoring of administrative expenses.

Liquidity, cash and cash equivalents

As of December 31, 2022, we had cash, cash equivalents and U.S. Treasury Bills of £71.1 million ($86.0 million), which reflects the registered direct offering of 5,950,000 ADSs in August 2022. Our aggregate gross proceeds from this offering were $56.5 million (approximately £46.4 million) before deducting $4.1 million (approximately £3.3 million) in underwriting discounts, commissions and estimated offering expenses. We believe that our current cash, cash equivalents and U.S. Treasury Bills will be sufficient to fund our operating expenses and capital expenditure requirements through the first quarter of 2024. We may also achieve further milestones from our current collaboration partners which will further extend our cash runway.

Conference Call & Webcast

Company management will host a conference call and webcast today, Wednesday, March 15, 2023, at 8 a.m. EDT / 12:00 p.m. GMT to discuss fourth quarter and full year 2022 results.

Webcast link: https://edge.media-server.com/mmc/p/7vduw4ku

Conference call registration link: https://register.vevent.com/register/BIbe6ada25ddb74c528acb36048aec7227

The conference call and webcast will also be archived on the Company’s website at www.silence-therapeutics.com.

About Silence Therapeutics

Silence Therapeutics is developing a new generation of medicines by harnessing the body's natural mechanism of RNA interference, or RNAi, to inhibit the expression of specific target genes thought to play a role in the pathology of diseases with significant unmet need. Silence's proprietary mRNAi GOLD™ platform can be used to create siRNAs (short interfering RNAs) that precisely target and silence disease-associated genes in the liver, which represents a substantial opportunity. Silence's wholly owned product candidates include zerlasiran (SLN360) designed to address the high and prevalent unmet medical need in reducing cardiovascular risk in people born with high levels of lipoprotein(a) and SLN124 designed to address hematological diseases. Silence also maintains ongoing research and development collaborations with AstraZeneca, Mallinckrodt Pharmaceuticals, and Hansoh Pharma, among others. For more information, please visit https://www.silence-therapeutics.com/.

Forward-Looking Statements

Certain statements made in this announcement are forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995 and other securities laws, including with respect to the Company’s cash runway and forecast operating cash flow, the Company’s clinical and commercial prospects, regulatory approvals of the Company’s product candidates, potential partnerships or collaborations or payments under new and existing collaborations, the initiation or completion of the Company’s clinical trials and the anticipated timing or outcomes of data reports from the Company’s clinical trials. These forward-looking statements are not historical facts but rather are based on the Company's current assumptions, beliefs, expectations, estimates and projections about its industry. Words such as “anticipate,” “expect,” “intend,” “plan,” “believe,” “seek,” “estimate,” and similar expressions are intended to identify forward-looking statements. These statements are not guarantees of future performance and are subject to known and unknown risks, uncertainties, and other factors, some of which are beyond the Company's control, are difficult to predict, and could cause actual results to differ materially from those expressed or forecasted in the forward-looking statements, including those risks identified in the Company’s most recent Admission Document and its Annual Report on Form 20-F filed with the U.S. Securities and Exchange Commission on the date hereof. The Company cautions security holders and prospective security holders not to place undue reliance on these forward-looking statements, which reflect the view of the Company only as of the date of this announcement. The forward-looking statements made in this announcement relate only to events as of the date on which the statements are made. The Company will not undertake any obligation to release publicly any revisions or updates to these forward-looking statements to reflect events, circumstances, or unanticipated events occurring after the date of this announcement except as required by law or by any appropriate regulatory authority.

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