Silence Therapeutics a leading global RNA interference (RNAi) therapeutics company, announces that the United States Patent and Trademark Office (USPTO) has issued the company a notice of allowance on a patent application directed to the fundamental technology involved in AtuPLEX, one of Silence’s proprietary small interfering RNA (siRNA) delivery systems.

The allowable subject matter is directed to AtuFect, the specific proprietary lipid that serves as the basis for the AtuPLEX delivery system, and provides proprietary protection for one of the RNAi industry’s most clinically advanced and promising delivery technologies. These claims will cover the delivery system incorporated in Silence’s lead clinical compound, Atu027, as well as a number of the company’s other RNAi therapeutic candidates.

“This is a highly valuable patent. Not only does it provide direct protection for AtuPLEX, one of the most advanced and exciting solutions addressing the challenge of delivering siRNAs, but also adds  key layers of protection for our pipeline of RNAi therapeutics, including our lead RNAi therapeutic candidate, Atu027,” said Max Herrmann, chief financial officer of Silence Therapeutics. “This notice of allowance follows the recent presentation of data from our ongoing clinical study of Atu027 at the 2011  American Society of Clinical Oncology conference which showed that the treatment, and therefore the AtuPLEX delivery technology, is safe and well-tolerated in all patients.”

At the 2011 American Society of Clinical Oncology annual meeting, Silence presented interim phase I clinical study results that  showed promising anti-tumour activity associated with Atu027, as well as demonstrating that the treatment is well tolerated with no observed dose-limiting toxicities or evidence of cytokine activation. Favourable pharmacokinetic data showed dose-dependent increases in both siRNA and lipid levels, suggesting no evidence of drug accumulation during repeat treatment. Additionally, the maximum tolerated dose for Atu027 has yet to be reached, further supporting the tolerability of the treatment. These findings provide broad support for AtuPLEX as a safe and effective siRNA delivery technology with the potential to overcome the well-known delivery challenges associated with RNAi therapeutics.

AtuPLEX is the delivery technology incorporated in a number of Silence’s partnered and internal RNAi therapeutic candidates. In addition, Silence’s non-exclusively partnered DACC delivery system also incorporates the proprietary AtuFect lipid that is  the subject of this notice of allowance.

“The AtuPLEX and DACC delivery systems are key assets for Silence and for our current and future partners,” stated Herrmann. “This latest intellectual property protection for our growing portfolio strengthens our ongoing business development activities that are focused on partnering Atu027 and also our world class delivery systems for individual genes or specific disease areas.”

Silence Therapeutics is proactively building and strengthening its global,  diverse and competitive intellectual property portfolio. This provides the Company and its partners with a strong proprietary position in the RNAi therapeutics space. The Company expects to make significant further  progress in reinforcing its patent portfolio during 2011. At present, Silence’s global patent portfolio contains issued patents and pending applications covering strategic areas of RNAi therapeutic development. These include multiple proprietary siRNA delivery technologies, potent siRNA sequences specific for high-value disease targets and key RNAi sequence and chemical modifications.

Silence Therapeutics plc 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.