Quarterly Case Summaries - April 1 to June 30, 2009

Andrew Shaughnessy, Andrew Bernstein, Vincent de Grandpré and Sandra Perri for the Applicants, Pfizer Canada Inc., Pfizer Inc., Pfizer Ireland Pharmaceuticals, and Pfizer Research and Development Company N.V./S.A. (“Pfizer”)
David Aitken and Marcus Klee for the Respondent, Novopharm Limited
John H. Sims, Q.C. for the Respondent, The Minister of Health

Pfizer brought an application for an order under the PM(NOC) Regulations prohibiting the Minister from issuing an NOC to Novopharm for a generic version of Viagra until Pfizer’s Canadian Patent No. 2,163,446 (“‘446 Patent”) expires in 2014. The ‘446 Patent claims the use of sildenafil citrate in a treatment of impotence, including erectile dysfunction (ED). Novopharm alleged that Pfizer’s patent for Viagra was invalid for obviousness, lack of utility, and insufficiency of disclosure. Three main issues were considered on the application: 1) whether the use of sildenafil for the treatment of ED was obvious at the time of the priority date; 2) whether the ‘446 Patent meets the utility requirements by demonstrating or soundly predicting the utility of sildenafil by the Canadian filing date; 3) whether the disclosure in the ‘446 Patent met the statutory requirements for disclosure set out in Section 27(3) of the Patent Act as of the publication date.

Prior Litigation Regarding Pfizer’s Sildenafil Patents

The Court noted the Viagra patent was found to be invalid for obviousness in England by the decision of Mr. Justice Laddie, which was confirmed on appeal by the UK Court of Appeal in 2002.

In 2006, Apotex sought an NOC which dealt with the ‘748 Patent. In that case, Justice O’Reilly held that Pfizer had failed to establish the compounds of the ‘748 Patent, or sildenafil in particular, had been shown or soundly predicted to be potent and selected cGMP PDE inhibitors by the priority date of the patent. He held that the language of the patent was vague, and the patent did not enable a skilled reader to appreciate the properties in the compounds. He dismissed Pfizer’s application to prohibit the issuance of an NOC.

In 2007, Apotex sought to market sildenafil Citrate tablets for all administration in strength equal to Viagra for the treatment of ED in men. While the ‘748 Patent considered by Justice O’Reilly claimed the use of a number of cGMP PDE inhibitors in the treatment of a number of a heart conditions, the ‘446 Patent claims the use of cGMP PDE inhibitors, including sildenafil, in the treatment of ED. Apotex alleged that the ‘446 patent was invalid for obviousness, anticipation, and failure to meet the requirements of the legislation. Mr. Justice Richard Mosley found that the ‘446 Patent was not invalid for obviousness. The most that could be said at the priority date is that sildenafil would be “worth a try” as a treatment for impotence. Justice Mosley also found that the patent was not invalid for anticipation, over breadth, or invalid disclaimer. Unlike the case of bar, Apotex did not allege the ‘446 Patent was invalid for insufficient disclosure or lack of utility.

Issue 1 - Obviousness

Pfizer raised an initial point of abuse of process given the decision of Justice Mosley which found that the allegations against the validity of the ‘446 Patent for obviousness were unjustified. Justice Kelen determined that since Novopharm has raised specific arguments in relation to obviousness attempting to distinguish the case of bar from that before Justice Mosley, that this was not an abuse of process and that he would decide the arguments on the merits with reference to Justice Mosley’s decision where appropriate. Justice Kelen reviewed the law on obviousness, taking into account the decision in Apotex v. Sanofi-Synthelabo in 2008. Justice Kelen determined that the Federal Court of Appeal held in January of 2009 that the test for obviousness in England, which Mr. Justice Laddie applied to the Pfizer patent for Viagra, is a different test than the Canadian test for obviousness set out by the Supreme Court of Canada in Sanofi-Synthelabo. Justice Kelen stated that “in Canada it is only obvious if the skilled person has good reason to pursue “predictable” solutions that provide a “fair expectation of success”.

The Court was persuaded on a balance of probabilities that the person skilled in the art in 1994, when the patent application was filed, was surprised that Pfizer was claiming the effective oral treatment for ED and that none of the experts in field were considering sildenafil as a compound for treating ED. Justice Kelen agreed with and adopted Justice Mosley’s conclusions on obviousness. Accordingly, the Court determined that the allegations by Novopharm as to the invalidity on the basis of obviousness were unjustified.

Issue 2 - Whether the 446 Patent meet the utility requirements by demonstrating or soundly predicting the utility of sildenafil by the Canadian filing date.

There was no dispute as to the actual utility of sildenafil. Novopharm submitted that utility must be demonstrated in the patent itself, and the patent must explain what the invention is in order to have utility. Novopharm argued that because the ‘446 Patent does not demonstrate utility, it is a patent based on sound prediction. Novopharm further submitted that the ‘446 Patent does not meet the sound prediction test because sildenafil is not named as the active pharmaceutical ingredient and because the results of a study were not disclosed in the patent. Additionally, Novopharm alleged that study 350 itself does not demonstrate the utility of sildenafil, in order to soundly predict the utility of sildenafil, in the treatment of ED, because it is a flawed study. Finally, Novopharm submitted that the ‘446 Patent lacks utility because it includes inoperative species, that is, thousands of compounds which are inoperative in treating ED.

The Court determined that there was no requirement in patent law that evidence of the demonstrated utility of the patent must be included in the patent. It is sufficient that the patent states the invention has been demonstrated to be useful, as the ‘446 Patent does in making reference to the clinical testing of the compound. The Court found that study 350 established that sildenafil, when tested in humans suffering from ED, induced erections that were deemed to be sufficient for intercourse. While the study may not have met the standards for regulatory approval, the court was satisfied that it is sufficient for the purposes of establishing the demonstrated utility of invention. Accordingly, the patent’s utility need not be established on the basis of sound prediction.

Novopharm attempted to argue that in determining utility, the patent as a whole must be considered rather than claim 7 alone, and that where a material portion of the invention is useless, the patent is void. The Court found that Section 58 of the Patent Act provides that the invalidity of the claims to the inoperative compounds does not affect the validity of a claim to a compound which works as promised.

Issue 3 - Whether disclosure in the ‘446 Patent met the statutory requirement for disclosure set out in Section 27(3) of the Patent Act.

Novopharm alleged that the patent was invalid because it did not provide sufficient information about the invention as required under subsection 27(3) of the Patent Act.

The court relied heavily on the Federal Court of Appeal’s decision in Pfizer Canada v. Raubaxy Laboratories Ltd. The Court of Appeal held that the patent must answer only two questions to meet the sufficiency requirement for the purpose of Subsection 27(3); (1) what is the invention?; and 2) how does it work? The Court stated that while an allegation of insufficiency normally does not operate to defeat a patent for meritorious invention, an insufficiency attack will succeed where a person skilled in the art could not put the invention into practice.

The Court further stated that from the jurisprudence, the language in the patent cannot obfuscate, obscure or bewilder the skilled reader of the patent. The description in the patent must be “free from avoidable obscurity or ambiguity and be as simple and distinct as the difficulty of the description permits”. The description must not be misleading or calculated to deceive or render it difficult for the skilled reader, without trial and experimentation, to comprehend what the invention is. The description must give all the necessary information for the successful use of the invention without leaving such result to the chance of successful experiment. The inventor must provide all of the information in good faith.

The Court found that at no point in the patent is sildenafil identified as the compound which is the actual embodiment of the invention on which Pfizer relied exclusively for this invention. At page 10 of the disclosure it states that “moreover, patient studies conducted thus far have confirmed that one of the especially preferred compounds induces penile erections in impotent males”. The disclosure does not state that this compound is sildenafil. However, claim 7 is for a formula which is sildenafil.

Patent 446 does not disclose that claim 7 and sildenafil is the only claimed compound that Pfizer found in its patient studies to induce penile erection in impotent males and is the only active compound in the invention sold commercially under the trade name Viagra. Patent 446 does not disclose that the many of other claims and compounds in the patent are “red hearings”, that is, they are proclaimed compounds which have been found not to work for treating erectile dysfunction.

Ultimately, Justice Kelen found that he could not disregard the jurisprudence which has condoned the claiming of classes of compounds and single compounds within that class as separate monopolies, and construes only the claim for the single compound which contains relevant commercial product. Justice Kelen further found that the importance and value of the patent should not be invalidated by such an objection 13 years after the patent was laid open for public inspection because it was allegedly not clear to the notional skilled reader that sildenafil was the active compound which made the invention work.

Prohibition Order granted.

By: Peter W. Choe, Gowling Lafleur Henderson LLP