Silence Therapeutics Highlights Recent Company Progress and Reports Third Quarter 2023 Financial Results

SLN124 phase 1/2 study in polycythemia vera progressing well – data expected in mid-2024

Zerlasiran multiple dose study in patients with high Lp(a) and stable ASCVD showed significant and durable reductions in Lp(a) of up to 99%

Fully enrolled zerlasiran phase 2 study in patients with high Lp(a) at high risk of ASCVD events on-track for 36-week topline data readout in 1Q 2024

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 third quarter ended September 30, 2023 and reviewed recent business highlights.

“This has been a year of strong execution across Silence,” said Craig Tooman, President and CEO at Silence. “We continue to see great results emerge from our mRNAi GOLD™ platform, including the very rapid enrollment of our zerlasiran phase 2 trial for high Lp(a) in just four months, the initiation and good progression of our PV trial, and the important milestones achieved in our AstraZeneca and Hansoh research collaborations. We remain well positioned with important additional data milestones in the short term.”

Third Quarter 2023 and Recent Business Highlights

mRNAi GOLD™ Proprietary Program Updates

Zerlasiran (cardiovascular disease)

• Announced positive topline data in the multiple dose portion of the APOLLO phase 1 study in subjects with high lipoprotein(a) (“Lp(a)”) and stable atherosclerotic cardiovascular disease (“ASCVD”). Data highlights included:
  • Showed significant and durable reductions in Lp(a) of up to 99%
  • Lp(a) levels remained around 90% lower than baseline at study endpoint
  • Well tolerated; no clinically important safety concerns were identified
• Continued to advance the fully enrolled ALPACAR-360 phase 2 study in subjects with high Lp(a) at high risk of ASCVD events.

SLN124 (hematological disorders)

• Advanced enrollment into the phase 1 portion of the SANRECO phase 1/2 study in polycythemia vera (“PV”) patients and provided guidance for data in mid-2024.
• Completed the multiple dose portion of the GEMINI II phase 1 study in non-transfusion dependent thalassemia patients. SLN124 was well tolerated at all doses with no safety issues identified. While proof of mechanism has been established in healthy volunteers, the effects on indicators of iron metabolism were variable in this study population of heterogeneous thalassemia subjects. Silence is prioritizing R&D efforts on the ongoing PV program and does not have plans to advance development in thalassemia at this time.

Anticipated Milestones

• Zerlasiran phase 2 topline 36-week data in the first quarter of 2024 and topline 48-week data in the second quarter of 2024.
• SLN124 data from the phase 1 portion of the SANRECO PV study expected in mid-2024.

Third Quarter 2023 Financial Results

For the three-month period ending September 30, 2023, the net loss after tax was £8.3 million, or weighted average loss per share of 7.4 pence, compared to £7.1 million, or weighted average loss per share of 7.2 pence, for the same period in 2022. The increase in net loss was primarily related to a decrease in finance and other income as a result of fluctuations in foreign exchange rates.

For the nine-month period ending September 30, 2023, the net loss after tax was £28.9 million, or weighted average loss per share of 26.4 pence, compared to £26.7 million, or weighted average loss per share of 28.8 pence, for the same period in 2022. The increase in net loss for the nine-month period was primarily related to an increase in research and development expense as we advance our pipeline partially offset by an increase in gross profit from our collaboration agreements.

Revenue

Revenue recognized for the quarter ending September 30, 2023 was £2.8 million, compared to £3.4 million for the quarter ending September 30, 2022. For the nine-month period ending September 30, 2023, revenue recognized was £23.3 million, compared to £12.7 million for same period in 2022. The Company records revenue from collaborations based on percentage of contract completion. The increase in 2023 was primarily a result of our Mallinckrodt collaboration, in which we reacquired exclusive worldwide rights to two preclinical siRNA assets resulting in a modification of the agreement and the achievement of a $14 million in milestones from our existing collaboration agreements.

Cost of sales

The cost of sales decreased for the three months ending September 30, 2023 to £1.6 million from £2.4 million in the three-month period ending September 30, 2022. The cost of sales increased for the nine-month period ending September 30, 2023 to £9.0 million from £7.0 million for the same period in 2022. Cost of sales includes research and development expenditure that is directly related to work carried out on revenue-generating contracts. The increase for the nine-month period was largely due to the further advancement of collaboration programs.

Research and Development

During the three-month period ending September 30, 2023, research and development expenditures were £8.9 million compared to £8.8 million for the same three-month period in 2022. Research and development expenditures increased for the nine-month period ending September 30, 2023 to £34.1 million from £27.2 million for the same period in 2022. This was largely due to an increase in contracted research and development expenses as we continue to advance the SLN124 and SLN360 studies.

General and Administrative

General and administrative expenses decreased by £0.9 million to £5.0 million for the three-month period ending September 30, 2023 from £5.8 million for the corresponding period in 2022. For the nine-month period ending September 30, 2023, general and administrative expenses increased to £16.5 million compared to £16.1 million for the same period in 2022. This increase was predominantly related to the increase in equity-based compensation.

Liquidity, cash and cash equivalents

As of September 30, 2023, the Company had £58.8 million of cash and cash equivalents and U.S. Treasury Bills, or approximately $71.7 million. During the three months ended September 30, 2023, we raised net proceeds of approximately $15.2 million. We believe that our current cash, cash equivalents and U.S. Treasury Bills will extend the ability to fund operations into the first quarter of 2025.

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 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 March 15, 2023. 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.

Condensed consolidated income statement (unaudited)

Condensed consolidated balance sheet (unaudited)

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