Silence Therapeutics plc announces the issuance of patent 4,705,370, titled “Further Novel Forms of Interfering RNA Molecules,” by the Japanese Patent Office. The issued patent covers aspects of Silence’s platform of novel, short interfering RNA (siRNA) molecules containing 2’-O-Methyl structures known as AtuRNAi. Silence’s AtuRNAi molecules offer important advantages over conventional siRNA molecules including increased stability and yield, lower manufacturing costs and the absence of toxic metabolites. Several therapeutics incorporating the company’s AtuRNAi technology are currently being studied in five ongoing clinical trials conducted by Silence and other industry leaders.

“The ability to expand our strong RNAi patent portfolio into a large pharmaceutical market such as Japan represents the latest success in our proactive ongoing intellectual property strategy. Not only does this milestone offer important protection for our RNAi technology in Japan, but it also provides another critical asset to support our efforts to establish valuable partnerships with leaders in the Japanese pharmaceutical industry,” stated Philip Haworth, PhD, chief executive officer of Silence Therapeutics. “We believe that this allowance by the Japanese Patent Office coupled with our broad, global protection offered by our core patents will highlight the value of our RNAi therapeutic technology to those Japanese companies with an interest in this exciting area of medicine.”

Silence Therapeutics is executing a proactive strategy to continue to build and strengthen a global, diverse and competitive intellectual property portfolio that provides the Company and its partners with a strong proprietary position in the RNAi therapeutics space. The Company believes that it will continue to make significant progress in these efforts as it expects additional RNAi patents to be issued during 2011. At present, Silence’s global patent portfolio contains issued patents and pending applications covering strategic areas of RNAi therapeutic development including 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.