SLN.L Regulatory News (SLN)

Business Update

23 June 2020

LONDON, Silence Therapeutics plc (LON: SLN) ("Silence" or "the Company"), a leader in the discovery, development and delivery of novel RNA therapeutics for the treatment of serious diseases, today provides a mid-year business update. The Company has today separately announced that it has confidentially submitted a registration statement to the U.S. Securities and Exchange Commission (the "SEC") in connection with a proposed listing of American Depositary Shares ("ADSs") representing the Company's ordinary shares on the Nasdaq Capital Market ("Nasdaq").

The Company confirms the progress on the clinical development of its lead assets and a further strengthening of its senior leadership team and Scientific Advisory Board as follows:

Pipeline and clinical development remain on track

SLN360

Preparations to submit to the FDA an investigational new drug (IND) package for the prioritised and wholly-owned asset, SLN360, are on schedule for later this year.

SLN124

· SLN124, in late stage pre-clinical development, has received Rare Paediatric Disease Designation (RPDD) for beta-thalassaemia and Orphan Drug Designation for myelodysplastic syndrome (MDS) from the FDA. Patient recruitment will recommence under two new protocols, SLN124-002 and SLN124-003, with clinical trial applications (CTAs) to be filed in H2 2020 for both protocols.

· SLN124-002 will be a global, randomized, single-blind, placebo-controlled Phase Ib single-ascending dose and multiple dose study in up to 112 adults with non-transfusion dependent thalassemia and very low- and low-risk MDS. The study is designed to investigate the safety, tolerability, pharmacokinetic and pharmacodynamic response to SLN124.

· SLN124-003 will be a randomised, double-blind placebo-controlled Phase I single-ascending dose study in healthy volunteers to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of SLN124. Up to 24 healthy volunteers are expected to be treated.

Strengthened team

· Eric Floyd has been appointed as SVP, Head of Global Regulatory Affairs, as from July, following an effective consultancy role with the Company during which time he played a pivotal role in securing the RPDD and Orphan Drug Designation granted for SLN124 by the FDA. Eric will be based in our US Office.

· Dr. John Whittaker has joined the Scientific Advisory Board. John is currently a VP in Human Genetics at GSK, where his main role is working on the identification of the causal genes and mechanisms underlying genetic association signals. Prior to GSK, John was Professor of Genetic Epidemiology and Statistics at the London School of Hygiene and Tropical Medicine.

Strong cash position

· As of 29 May 2020, the Company had cash, cash equivalents and short-term deposits of £52.0 million, reflecting the proceeds from the issuance of ordinary shares to AstraZeneca in March 2020 and a $20 million upfront payment from AstraZeneca received in May 2020. The Company is unconditionally entitled to receive a further $40.0 million from AstraZeneca no later than the first half of 2021.

Iain Ross, Executive Chairman of Silence Therapeutics, said: "2020 to date has seen Silence continue to make exceptional progress in securing additional high value partnerships, advancing our proprietary pipeline and further augmenting our senior team. The Board is continuing its search for a new CEO as we move on to the next exciting phase of expansion for the Company with our intention to issue ADSs on Nasdaq. We continue to monitor the evolving COVID-19 pandemic but are pleased to note that we have not experienced any significant disruption to our operations. Our significantly strengthened balance sheet ensures that we are in a robust position to weather any uncertainty whilst equipping us with the capital to further accelerate our important RNAi programmes and platform."

For more information, please contact:

About Silence Therapeutics plc

Silence Therapeutics is developing a new generation of medicines by harnessing the body's natural mechanism of RNA interference, or RNAi, within its cells. Its proprietary technology can selectively inhibit any gene in the genome, specifically silencing the production of disease-associated proteins. Silence's proprietary RNA chemistries and delivery systems are designed to improve the stability of molecules and enhance effective delivery to target cells, providing a powerful modular technology well suited to tackle life-threatening diseases. The Company has secured high value research and collaboration agreements with AstraZeneca, Mallinckrodt Pharmaceuticals and Takeda. For more information, please visit: https://www.silence-therapeutics.com/

Forward Looking Statements

Certain statements made in this announcement are forward-looking statements including with respect to the proposed listing of ADSs representing the Company's ordinary shares on Nasdaq and the timing and design of any planned clinical trials of the Company's product candidates. These forward-looking statements are not historical facts but rather are based on the Company's current expectations, estimates, and projections about its industry; its beliefs; and assumptions. Words such as 'anticipates,' 'expects,' 'intends,' 'plans,' 'believes,' 'seeks,' 'estimates,' 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 if the Company's registration statement is not declared effective by the SEC or if Nasdaq fails to approve the Company's ADS listing application, or if applicable regulatory authorities fail to approve the Company's applications to undertake clinical trials in the manner requested by the Company. The Company cautions securityholders and prospective securityholders 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.