SLN.L Regulatory News (SLN)

25 Jun 2008 12:30

FDA approves Quark IND for DGFi, an siRNA therapeutic based on Silence Therapeutics' Unique Proprietary Chemistry

Quark Pharmaceuticals to develop drug candidate for prevention and treatment of

delayed graft function in kidney transplantation

London, UK, 25 June 2008 - Silence Therapeutics plc today announces that the U.S. Food and Drug Administration (FDA) has approved a Quark Pharmaceuticals Inc ("Quark") Investigational New Drug application (IND) for an siRNA therapeutic product based on Silence's unique proprietary chemistry. The product, DGFi, was discovered and is being developed by Quark for use in kidney transplantation. Rights to the AtuRNAi structure of DGFi were licensed to Quark by Silence Therapeutics.

DGFi is being investigated for the prevention and treatment of Delayed Graft Function ("DGF") associated with renal transplantation. DGF is a syndrome caused by ischemia and reperfusion injury, which frequently occurs in kidneys once they are removed from a donor and transplanted into the patient. In patients with DGF, the transplanted kidney does not function properly and requires intervention by dialysis. DGFi is designed to temporarily inhibit the activity of the p53 gene, which is associated with apoptosis, also known as programmed cell death, and is believed to be critical in the ischemia and reperfusion injury process. DGFi uses the same active AtuRNAi molecule as AKIi-5, which Quark is developing for treatment of Acute Kidney Injury.

Jeff Vick, Chief Executive Officer of Silence Therapeutics, said "We are very excited by this news, as it is the third IND approved for a product based upon our proprietary AtuRNAi chemistry and confirms our leading position in this revolutionary field of technology."

- ENDS -

Enquiries:

For further information, please contact the following:

Silence Therapeutics plc European Contacts: +44(0)20 7307 1620 Citigate Dewe Rogerson Jeff Vick, Chief Executive Officer +44(0)20 7638 9571 Melvyn Davies, Finance Director David Dible

Heather Keohane Nominated Advisers: U.S. Contacts:

Nomura Code Securities Limited LaVoie Group

+44(0)20 7776 1200 +1 978.745.4200 Chris Collins Bryan Murphy x 105 Gerard Harper Tim Allison x 102 Notes to Editors:

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

Silence Therapeutics plc (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 of 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.

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 field of RNAi therapeutics.

The Company'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 Quark compound 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.