Year-end Update

FOR IMMEDIATE RELEASE

Silence Therapeutics Provides Year-end Update

~ Milestone Payment from Quark Pharmaceuticals of up to $1.5 Million for QPI-1002 & Future Milestone Payments to Reach up to $80 Million ~

London, December 21, 2010 - Silence Therapeutics Plc (AIM:SLN) ("Silence" or the "Company"), a leading global biotechnology company dedicated to the discovery, development and delivery of targeted, systemic RNA interference (RNAi) therapeutics for the treatment of serious diseases, today provides a year-end update on trading and the offer-period.

Phil Haworth, CEO of Silence Therapeutics, comments: "2010 has been an exciting year for Silence Therapeutics. The Company is delighted with the clinical progress it has made with Atu027 and our Phase I trial continues on track. In addition, our partner, Quark Pharmaceuticals, has made significant progress with QPI-1002, both in advancing the product into Phase II trials and in partnering it with Novartis. We are pleased to be announcing a milestone payment from Quark today."

Offer Period

Further to the announcement dated 6th September 2010, Silence confirms that it remains in an offer period. The Company continues to explore a variety of strategic opportunities.

Atu027 Phase I trial

During the course of 2010, excellent progress has been made with the Company's flagship Phase I trial of Atu027 in patients with solid tumours. This trial remains on track and, to date, 18 patients have been treated. Trial completion is expected in the second half of 2011.

Milestone from Quark

Silence is pleased to announce today that it has reached agreement with Quark Pharmaceuticals Inc. ("Quark") whereby Silence is due to receive milestone payments of up to $1.5 million in relation to the option agreement signed between Quark and Novartis for QPI-1002. Silence anticipates that its share of future milestone payments relating to Quark's license agreement with Novartis could reach $80 million. 

·; Based on Silence's AtuRNAi technology, Quark is developing its QPI-1002 for the prevention of acute kidney injury (AKI) in patients undergoing major cardiovascular surgery, and for the prophylaxis of delayed graft function (DGF) in patients receiving deceased donor kidney transplants. Phase I studies in these patient populations have been completed.

·; In September 2010, Quark initiated a Phase II trial of QPI-1002 for the prophylaxis of delayed graft function (DGF) in patients receiving deceased donor kidney transplants. Quark plans to initiate dosing in a Phase II trial in acute kidney injury (AKI) in 2011.

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Notes for editors

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

Silence Therapeutics plc (AIM: SLN) is a leading global biotechnology company dedicated to the discovery, development and delivery of targeted, systemic RNA interference (RNAi) therapeutics for the treatment of serious diseases. The company possesses multiple proprietary short interfering RNA (siRNA) delivery technology platforms including AtuPLEX™, a system that enables the functional delivery of siRNA molecules to targeted diseased tissues and cells, while increasing their bioavailability and intracellular uptake. A second, complementary delivery technology known as PolyTran™ uses a library of novel peptide-based biodegradable polycationic polymers for systemic siRNA administration. Additionally, the company has a platform of novel siRNA molecules, AtuRNAi, which provide a number of advantages over conventional siRNA molecules, including increased stability against nuclease degradation. Silence's unique RNAi assets also include structural features for a next generation of RNAi molecules and additional proprietary siRNA sequences against more than 50 highly valued oncology and other disease targets.

The company's strong and diverse intellectual property portfolio includes exclusive licenses from the University of Massachusetts Medical School on three patent families associated with the "Zamore Design Rules," which cover broad structural features of siRNA design for more potent next generation siRNA sequences.

Silence Therapeutics is headquartered in London, UK, with research and development activities in Berlin and operations in Redwood City, CA.

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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