SLN.L Regulatory News (SLN)

19 Nov 2007 13:00

Silence Therapeutics plc

Silence Therapeutics plc announces that a 2nd siRNA therapeutic based upon its unique proprietary chemistry has moved into clinical development.

London, UK, 19 November 2007 - Silence Therapeutics plc today announces that a second siRNA therapeutic based on the company's unique, proprietary AtuRNAi chemistry has moved into clinical trials. The product, AKIi-5, was discovered and developed by Quark Pharmaceuticals Inc for the treatment of Acute Kidney Injury (AKI), known also as Acute Renal Failure or ARF. Rights to the AtuRNAi structure of AKIi-5 were licensed to Quark by Silence Therapeutics.

AKIi-5 is Quark's lead product candidate for the prevention of Acute Kidney Injury in high-risk patients undergoing major cardiovascular surgery. The aim of the product is to reduce the frequency of post-surgery AKI requiring dialysis as well as AKI associated mortality. AKI is a very serious disease with a high mortality rate in patients developing it either in the intensive care unit or following major cardiovascular surgery.

Jeff Vick, Chief Executive Officer of Silence Therapeutics, stated "Following the announcement we made in March that this product had been granted an IND by the FDA we are pleased to announce that Quark has confirmed clinical testing has commenced. This means that through the relationship with Quark, which we expanded in July to include 3 additional specific targets, there are two products based upon our proprietary AtuRNAi chemistry (RTP801i for age-related macular degeneration and AKIi-5 for acute kidney injury) in phase I clinical trials."

- Ends - Enquiries:

For further information, please contact the following:

Silence Therapeutics plc Investor Relations +44(0)20 7307 1620 Citigate Dewe Rogerson Jeff Vick, Chief Executive Officer +44(0)20 7638 9571 Melvyn Davies, Finance Director David Dible Yvonne Alexander Nominated Adviser Grant Thornton Corporate Finance +44 (0) 20 7383 5100 Gerry Beaney Colin Aaronson Notes to Editors

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

Silence Therapeutics plc is a leading RNAi company. RNA interference (RNAi) can selectively "silence" genes linked to the onset of disease.

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

In July 2007, Silence Therapeutics formed a research and development collaboration with AstraZeneca to develop AtuRNAi against five specific targets including those in respiratory indications. The Group's AtuRNAi technology also has been sublicensed to Pfizer through Quark's license to Pfizer 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 its proprietary compound AKIi-5. This compound is in a Phase I human clinical study for treatment of acute kidney injury. In addition, Silence Therapeutics expects to begin the clinical development of its own proprietary AtuRNAi therapeutic molecules for systemic cancer indications in 2008.

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

About RNAi

RNA interference (RNAi), a Nobel Prize winning technology, is 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.