By Doug Macron
Alnylam Pharmaceuticals has opposed a European patent recently issued to Silence Therapeutics, claiming in a document filed with the European Patent Office that the intellectual property is neither new nor inventive, and that the patent does not describe the invention sufficiently clearly.
Notably, the patent in dispute is part of the so-called Zamore IP family. Alnylam's top official earlier this year publicly dismissed a related US patent from the Zamore family as "not worth anything."
Published by the EPO in October, the patent — EP1633890 — is entitled "Methods and Compositions for Enhancing Efficacy and Specificity of RNAi," and claims rules for designing RNAi molecules with improved potency and fewer off-target effects. It is based on the work of University of Massachusetts researcher and Alnylam co-founder Phillip Zamore.
According to Silence, specific claims in the patent include 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.
The patent, along with related patents already granted by the US Patent and Trademark Office, form the cornerstone of Silence's IP estate, which the company maintains will help drive licensing deals and partnerships in the RNAi space.
In July, Silence CEO Philip Haworth told Gene Silencing News that these patents are "going to prove to be a very significant IP asset, not just for Silence but for the space, in general" (GSN 7/15/2010).
"I think [the Zamore design] criteria have been deployed quite widely" by a number of companies developing RNAi drugs, which will mean that these firms will ultimately need a license to Silence's IP, he said at the time.
Meanwhile, "as the big pharma guys start to bring more into the clinic, there will be a recognition that this technology is something that is useful to them, and they're going to start talking to us about it," he added.
A month later, officials from Alnylam, which has long touted the importance of its own IP estate, downplayed one of the US patents in the IP Zamore family, No. 7,750,144, which is entitled "Methods and Compositions for Enhancing the Efficacy and Specificity of RNA Silencing" (GSN 8/12/2010).
During a conference call held to discuss Alnylam's second-quarter financial results, Alnylam CEO John Maraganore noted that since Zamore is a company co-founder, "we were obviously aware of [the US patent] years ago."
Alnylam "chose not to license it … because it wasn't worth anything from our perspective," he added.
But apparently the company views at least certain of the Zamore patents as worthy enough to formally oppose.
According to documents on file with the EPO, Alnylam has opposed the '890 patent, claiming that it "lacks novelty and/or [an] inventive step, and cannot be carried out by a person skilled in the art."
In its opposition, the company also cites as examples of prior art a number of peer-reviewed publications, among them a paper published in 2003 by another Alnylam co-founder, Thomas Tuschl; another by Zamore and colleagues published in 2001; and a 2002 paper co-authored by University of California, San Francisco, researcher Michael McManus, who worked in the Massachusetts Institute of Technology lab of Alnylam co-founder Phillip Sharp.
The company also points to a 2004 patent application, on file with the World Intellectual Property Organization as WO/2004/080406 and entitled "Therapeutic Compositions," as prior art.
Invented by Muthiah Manoharan, Alnylam's senior vice president of drug discovery, and David Bumcrot, director of research at the firm, this IP claims RNAi agents with particular chemical structures and modifications.
Officials from Alnylam and Silence were not available for comment.
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