SLN.L Regulatory News (SLN)

20 Dec 2011 07:00

FOR IMMEDIATE RELEASE

Additional Listing

London, December 20, 2011 - Silence Therapeutics plc (AIM: SLN) ("Silence" or the "Company") a leading global RNA interference (RNAi) therapeutics company, today announces that application has been sought for 530,000 new ordinary shares of 1 pence each ("Ordinary Shares") to be admitted to trading on AIM. The new Ordinary Shares are being issued in accordance with a contractual agreement with Dr. Philip Haworth, former Chief Executive Officer of Silence.

It is expected that dealings in the new Ordinary Shares, which will rank pari passu in all respects with the existing issued share capital of the Company, will commence on 21 December 2011.

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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 3205 7500 t.christely@silence-therapeutics.com shaun.dobson@singercm.com m.herrmann@silence-therapeutics.com claes.spang@singercm.com M:Communications (Europe) Peter Laing / Emma Thompson / Claire Dickinson +44 20 7920 2345 / +44 20 7920 2342 healthcare@mcomgroup.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„¢, 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 endo-thelium 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 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 safety and pharmacokinetic 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.

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