Inventor’s Admission Proves to be a Pain in Pfizer’s Side

Published February 22nd, 2013

Pfizer Canada Inc. v Pharmascience Inc., 2013 FC 120 (Hughes)

Summary – A broad construction of the term “pain” to include all types of pain and an inventor’s admission that pregabalin (LyricaTM) does not block acute pain has led to the Federal Court siding with Pharmascience and determining Pfizer’s patent for the use of pregabalin for treating pain to be overly broad and lacking utility.

Analysis – The only claim in question, claim 3 of Canadian Patent No. 2,255,652, can be simplified as follows:

For use in treating pain, in a mammal, a therapeutically effective amount of pregabalin or its racemate [61].

Justice Hughes construed this claim and determined that the term “pain” encompasses both chronic and acute forms of pain.  Unfortunately for Pfizer, the inventor himself stated that pregabalin “doesn’t block acute pain” [92].  This was considered by Justice Hughes to be an admission of inutility and he found, therefore, that claim 3 was invalid for embracing forms of pain that cannot be treated [178].

Additionally, inclusion of the racemate in claim 3 was considered.  There was no mention of the racemate anywhere in the description, other than an agreed upon error, and no factual basis or line of reasoning provided that would lead a skilled person to predict that the racemate would have utility in treating pain [90], [183].  Accordingly, claim 3 was invalid for embracing the racemate, whose utility in treating pain could not be soundly predicted [184].

Interestingly, in 2005, the patentee had filed a request for re-issue of this patent, seeking to include 15 new claims in which pregabalin, but not the racemate, was claimed for the treatment of pain, with each claim being directed to a different specific form of pain.  The application for re-issue was allowed, however, for unknown reasons the request was subsequently withdrawn by the patentee.  Justice Hughes stated that his “decision may well have been different had the claims at issue been directed only to pregabalin and only to certain specific types of pain” [215].

Practice Point – Pregabalin, but not its racemate, is approved for use in Canada for the treatment of specific forms of chronic pain, such as neuropathic pain and pain associated with fibromyalgia or spinal cord injury.  A narrower, more specific claim to pregabalin for treating specific forms of chronic pain might very well have led to a different outcome in this case.  Since there are no claim fees in Canada and no limit to the number of independent or dependent claims that can be included, this decision serves as a reminder to Applicants to claim at least each preferred embodiment separately to help their commercial embodiments survive an invalidity attack.

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