Directors’ share purchases

3 Oct 2011 07:00

FOR IMMEDIATE RELEASE

Directors' share purchases

London, UK, October 3, 2011 -Silence Therapeutics plc (AIM: SLN) ("Silence"), a leading RNA interference ( RNAi) therapeutics company, today announces that on 28 September 2011, its executive directors and a senior manager acquired ordinary shares of 1p each ("Ordinary Shares") in the Company as follows:

Interest after purchase Director/Senior Price per Number of Number of % ofmanager Ordinary Ordinary Shares Ordinary total Share acquired on 29 Shares (GBp) September 2011 issued share capital Thomas Christ©ly, 1.8 1,662,162 2,162,162 0.36CEO Max Herrmann, CFO 1.8 1,114,864 1,614,864 0.28 Tony Sedgwick 1.8 1,108,108 1,108,108 0.18

Thomas Christ©ly, Chief Executive Officer of Silence Therapeutics, said: "As Silence's new and strengthened management team continues to execute on its strategy, we expect the sharper commercial focus to build significant shareholder value. The share purchases announced today demonstrate our confidence in the prospects of the Company and help to ensure that our interests are aligned with shareholders in the Group."

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For further information, please contact:

Silence Therapeutics Singer Capital Markets Thomas Christ©ly/Max Herrmann Shaun Dobson/Claes Sp¥ng +49 30 9489 2800/+44 20 7491 6520 +44 20 32057500 t.christely@silence-therapeutics.com shaun.dobson@singercm.com m.herrmann@silence-therapeutics.com claes.spang@singercm.com M:Communications (Europe) Vida Communication (US) Peter Laing / Emma Thompson Tim Brons (media)/Stephanie Diaz (investors) +44 20 7920 2345 / +44 20 7920 2342 +1 (415) 675-7400 healthcare@mcomgroup.com tbrons@vidacommunication.com sdiaz@vidacommunication.com 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 AtuPLEXâ„¢ and DACC. 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. 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 AtuPLEXâ„¢. Silence is currently conducting an open-label, single-centre, dose-escalation Phase I study with Atu027 in patients with advanced solid tumors involving single, as well as repeated, intravenous administration. Encouraging interim data were presented at the American Society of Clinical Oncology Annual Meeting in June 2011. The study is expected to be completed in the first half of 2012.

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.

Forward-Looking Statements

This press release includes forward-looking statements that are subject to risks, uncertainties and other factors. These risks and uncertainties could cause actual results to differ materially from those referred to in the forward-looking statements. All forward-looking statements are based on information currently available to Silence Therapeutics and Silence Therapeutics assumes no obligation to update any such forward-looking statements.

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