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USPTO Upholds Silence's 'Zamore Design Rules' Patents


Silence Therapeutics has scored a victory in its efforts to defend its intellectual property estate, announcing this week that the US Patent and Trademark Office has upheld the validity of four patents related to the design of RNAi molecules.

The USPTO had undertaken re-examinations of four patents — Nos. 7,459,547; 7,732,593; 7,772,203; and 7,750,144 — at the request of undisclosed parties who argued that they were invalid in light of prior art. The patents cover the so-called Zamore design rules, which broadly relate to methods of enhancing the ability of an antisense strand to act as a guide strand; RNAi agents with enhancing silencing activity; and compositions for siRNAs, as well as pre-microRNAs, shRNAs, and vectors that perform gene silencing.

Named after inventor and University of Massachusetts Medical School researcher Phillip Zamore, the IP is exclusively licensed to Silence and has long been a cornerstone of the company's IP portfolio. Last year, Silence's then-CEO stated that the patents are expected to drive partnerships and licensing deals since other firms are likely incorporating technology covered by the IP into their own RNAi drug candidates (GSN 7/15/2010).

Though it is not clear who sought the re-examination, three companies — Alnylam Pharmaceuticals, Novartis, and Alcon — have taken steps to invalidate certain Zamore IP in Europe (GSN 7/28/2011).

“We are very pleased that the USPTO has reissued these four patents,” Silence CEO Thomas Christely said in a statement. “This outcome sends a clear message regarding the strength of Silence’s intellectual property. We believe that there is significant value in the Zamore technology as a fundamental tool for the development and
commercialization of RNAi therapeutics with enhanced efficacy.”

“The unequivocal affirmation of the intellectual basis of these discoveries by the US Patent Office clears up any misapprehension about the origins of these discoveries, and we are excited that laboratories and research organizations around the world have had the benefit of using this science to work toward therapeutics to treat human disease,” Zamore added in a statement.

The USPTO's decision on the Zamore patents come less than a week after Silence announced that the European Patent Office upheld an amended form of a patent covering protein kinase N beta, which is the target of its phase I cancer drug Atu027 (GSN 12/8/2011).