Option exercise

Silence Therapeutics plc ("Silence" or the "Company")

Option Exercise

Silence Therapeutics plc announces that on 30 November 2012, an ex-employee informed the Company that he had on the same date exercised options over 216,667 ordinary shares of 0.1p each ("New Shares") at a price of 2.07p per Share.

Application has been made to the London Stock Exchange Plc for the admission of the 216,667 New Shares to trading on AIM. Dealings in the New Shares are expected to commence on 7 December 2012.

Following the issue of the New Shares there will be 1,871,552,737 ordinary shares in issue. The Company has no shares held in treasury and therefore the total number of voting rights in the Company is 1,871,552,737 Shares.

The above figure may be used by shareholders as the denominator for the calculations by which they will determine if they are required to notify their interest in, or a change to their interest in, the Company, under the FSA's Disclosure and Transparency Rules

Notes for editors

About Silence Therapeutics plc (www.silence-therapeutics.com)

Silence Therapeutics plc (AIM: SLN) is a leading biotechnology company dedicated to the discovery, development and delivery of targeted, systemic RNA interference (RNAi) therapeutics for the treatment of serious diseases. Silence offers one of the most comprehensive short interfering RNA (siRNA) therapeutic platforms available today based on a strong intellectual property portfolio and large clinical safety database. Silence's clinical siRNA product pipeline is one of the broadest in the industry. The Company possesses multiple proprietary siRNA delivery technology platforms including AtuPLEX™, DACC and DBTC. AtuPLEX enables the broad functional delivery of siRNA molecules to targeted diseased tissues and cells, while increasing their bioavailability and intracellular uptake. The DACC delivery system allows functional delivery of siRNA molecules selectively to the lung endothelium with a long duration of target mRNA and protein knock-down. The DBTC delivery system enables functional delivery of siRNA molecules selectively to liver cells including hepatocytes. Additionally, the Company has a platform of novel siRNA molecules based around its AtuRNAi chemical modification technology, which provides a number of advantages over conventional siRNA molecules. Silence's unique RNAi assets also include structural features for RNAi molecules and specific design rules for increased potency and reduced off-target effects of siRNA sequences.

The Company's lead internal drug candidate is Atu027, a liposomal formulation in clinical development for systemic cancer indications and one of the most clinically advanced RNAi therapeutic candidates in the area of oncology. Atu027 incorporates two of the Company's technologies, AtuRNAi and AtuPLEX™.

The Company's RNAi therapeutic platform has received key validation through multiple partnerships with pharmaceutical companies including AstraZeneca, Dainippon Sumitomo, Pfizer/Quark, and Novartis/Quark. Silence is actively pursuing the establishment of additional partnerships. Silence Therapeutics has operations in both Berlin and London.