Silence strengthens RNAi IP portfolio with issuance of key patent in structural modification technology

Silence Therapeutics plc (AIM: SLN) ("Silence" or the "Company") announces the issuance of United States patent 7,750,144, titled Methods and Compositions for Enhancing Efficacy and Specificity of RNA Silencing, by the United States Patent and Trademark Office (USPTO).  The issued patent generally claims methods of producing double stranded (RNAi) agents having decreased off-target silencing activity through certain structural modifications.  The ability to minimize the off-target effects of RNAi therapeutics is critical for controlling unwanted cellular activity and/or potential safety concerns.  The issued claims not only cover minimizing off-target gene expression silencing using short interfering RNA (siRNA) but also include specific claims directed to micro RNA (miRNA).  

This latest issued patent is based on the seminal research of Phillip D. Zamore, Ph.D., Howard Hughes Medical Institute Investigator, the Gretchen Stone Cook Chair of Biomedical Sciences, and Professor of Biochemistry & Molecular Pharmacology at University of Massachusetts Medical School.  Silence owns exclusive licenses in the human healthcare fields to three Zamore patent families from the University of Massachusetts Medical School, where Zamore is the co-director of the RNA Therapeutics Institute.  These patent families disclose various efficacy-enhancing methods and structural elements for RNAi therapeutics, informally known as the Zamore "Design Rules" and based on Dr. Zamore's work at UMass Medical School.  This is the third patent to issue among the Zamore design rule patents licensed by UMass Medical School to Silence.  The Company expects additional U.S. and European patent issuances related to the Zamore portfolio in the coming months.

"This latest in a series of related patent issuances continues to highlight the significant value of the groundbreaking Zamore patent families.  For the second time in the past month, we have strengthened our rapidly expanding RNAi IP position with a key patent issuance in the area of structural modification technology," stated Philip Haworth, Ph.D., chief executive officer of Silence Therapeutics.  "Whereas our last patent provided key guidance in enhancing the desired silencing activity of RNAi agents, this latest patent covers the equally valuable ability to minimize the undesired off-target silence activity of RNAi agents."

Silence Therapeutics is executing a proactive strategy to continue to build and strengthen a 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 throughout 2010 as it expects a number of additional valuable RNAi patents to be issued in both the United States and Europe during the year.  This consistent and meaningful IP portfolio growth reinforces Silence's belief that the company can sustain its position as a preferred partner in RNAi therapeutics. 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.