LONDON, July 17 /PRNewswire/ --

Silence Therapeutics plc (London AIM: SLN), a leading European RNAi focused biotechnology company, announces that for personal reasons, Jeffery Vick has resigned as Group CEO and left the Company.

The Board of Directors has appointed Iain Ross, currently Non-Executive Chairman, full time Chairman and Group CEO with immediate effect. Jeremy Curnock Cook, a Non-Executive Director of the Company has been appointed Senior Independent Non-Executive Director.

LONDON, July 17 /PRNewswire/ --

On behalf of the Board of Silence Therapeutics plc, Jeremy Curnock Cook said:

"Iain Ross was responsible for the financial and operational turnaround of the Company from July 2004 until July 2007, and the Silence Board of Directors is confident that under his executive leadership, significant shareholder value can be generated. Iain is an experienced business negotiator and we believe he can bring to fruition a number of deals and collaborations currently under discussion."

LONDON, July 17 /PRNewswire/ --

Iain Ross, Chairman & CEO added:

"I believe that by employing a more focused and aggressive approach, and with the continued support of a first class management team, we can achieve meaningful technical and commercial milestones over the next 12 months.

We have a unique proprietary position in the RNAi space and I am confident that this will be further strengthened in the coming months and will be the basis upon which investors and pharmaceutical partners alike will take an increasing interest in this Company.

Through current licensing agreements, products based upon the Company's AtuRNAi technology are in the clinic and we plan to submit a regulatory filing before the end of 2008 to commence clinical trials for our lead internal development compound Atu027. I intend to commence partnering discussions, following the interest that has been expressed by a number of third parties in this development program."

Notes to Editors:

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

Silence Therapeutics plc (London AIM: SLN) is a leading European RNAi focused biotechnology company. RNAi can selectively 'silence' genes linked to the onset of disease. RNAi is a Nobel Prize winning technology and one of the most promising areas of drug discovery and development today.

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 system, AtuPLEX. This system enables the functional delivery of siRNA molecules to targeted diseased tissues and cells, while increasing their bioavailability and intracellular uptake.

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 (LSE: AZN) 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.

In July 2007, Silence Therapeutics formed its first research and development collaboration with 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 the 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 the clinic in early 2007. 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.

About RNAi

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.

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.

Web site: http://www.silence-therapeutics.com

Iain Ross, Executive Chairman, or Melvyn Davies, Finance Director & Company Secretary, both of Silence Therapeutics plc, +44-(0)20-7307-1620; or European Contacts: David Dible or Heather Keohane, both of Citigate Dewe Rogerson, +44-(0)20-7638-9571; or Nominated Advisers: Chris Collins of Nomura Code Securities Limited, +44-(0)20-7776-1200; or U.S. Contacts: Lisa Rivero, +1-978-745-4200, ext. 106, or Tim Allison, +1-978-745-4200, ext. 102, both of LaVoie Group for Silence Therapeutics plc