Issue of Equity

5 Dec 2008 12:05

Silence Therapeutics plc

Issue of 29,856 shares pursuant to exercise of options

London 5 December 2008 - Silence Therapeutics plc (the "Company") announces that it has issued 29,856 new ordinary shares of 1p (the "New Ordinary Shares") pursuant to the exercise of options by staff at a price of 12.75p per share.

The issue of the New Ordinary Shares is subject to the New Ordinary Shares being admitted to trading on AIM (the "Admission"), application for which has been made. The Admission is expected to take place on 11 December 2008.

Following the issue of the New Ordinary Shares, the Company will have an issued share capital of 119,913,392 ordinary shares of 1p each.

- Ends -

Enquiries:

For further information, please contact the following:

Silence Therapeutics plc Powerscourt +44(0)20 7307 1620 +44(0)20 7250 1446 Iain Ross, Chairman & CEO Paul Durman Melvyn Davies, Finance Director Kay Larsen Nominated Advisers Nomura Code Securities Limited +44(0)20 7776 1200 Richard Potts Notes to Editors:

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

Silence Therapeutics plc (AIM: SLN) is a leading European RNAi focused biotechnology company.

RNA interference (RNAi) is a Nobel Prize winning technology and one of the most exciting areas of drug discovery today. It represents a completely new approach to selectively 'silence' or inactivate disease relevant genes and as such it has the potential to create a new class of therapeutic products. RNAi could therefore offer a therapeutic approach to a broad range of diseases (cancer, infectious diseases, inherited diseases), many of which have been regarded as incurable and are not addressed by current therapeutics, therefore providing a large market opportunity.

Silence Therapeutics has developed a platform of novel short interfering RNA ('siRNA') molecules, AtuRNAi, which provide a number of advantages over conventional siRNA molecules, including increased stability against nuclease degradation. In addition, the Company has developed a proprietary systemic delivery platform, AtuPLEX. This platform enables the functional delivery of siRNA molecules to targeted diseased tissues and cells, while increasing their bioavailability and intracellular uptake.

Following the granting of its patents in Europe, Australia and the USA, Silence Therapeutics is one of only two companies worldwide with a proprietary position on composition of matter for siRNA therapeutics.

Silence's lead internal product, Atu027, is a proprietary AtuRNAi molecule in preclinical development for systemic cancer indications. Atu027 has successfully completed single and repeat dose toxicology and geno-toxicology studies, as well as a 28-day toxicology study using multiple dosing regimens. Silence plans a regulatory filing in 2008 to commence clinical trials for Atu027.

In March 2008 Silence Therapeutics announced a collaboration with AstraZeneca focused on the development of a range of novel delivery approaches for siRNA molecules. Under the terms of the agreement both Silence Therapeutics and AstraZeneca will be allowed to commercialize the truly novel delivery systems that the two partners develop together.

Silence Therapeutics has granted a licence to AstraZeneca to develop novel AtuRNAi therapeutics against five specific targets, including those in respiratory indications. This collaboration was the first industry validation of the potential application of Silence Therapeutics' proprietary AtuRNAi molecules and solidified the Company's leadership position in field of RNAi therapeutics.

The Company's AtuRNAi technology also has been sublicensed to Pfizer via Quark's license to them of the compound RTP-801i-14 for the treatment of age-related macular degeneration (AMD) and a number of other indications. This compound entered a phase II clinical study in July 2008. Silence Therapeutics also has licensed to Quark rights to the AtuRNAi structure for Quark's proprietary compound, AKIi-5, which is in a Phase I human clinical study for treatment of acute kidney injury.

Silence Therapeutics is based in London, UK, and Berlin, Germany, and is listed on AIM.

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.