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03 December 2012
The Supreme Court recently released its hotly anticipated decision in Teva Canada Limited v Pfizer Canada Inc.(1) In a unanimous decision written by Justice LeBel, the court found that the patent failed to satisfy the disclosure requirements of the Patent Act.
The '446 patent
The patent at issue, Canadian Patent 2,163,446 (''446'), discloses and claims a new use for a class of compounds – namely, the treatment of erectile dysfunction. In particular, the patent describes:
While the patent asserts that one especially preferred compound "induces penile erection in impotent males", the patent provides only a summary description of the study and does not identify the specific compound tested or present the data obtained.
The patent claims the new use for various classes of compounds and for the nine especially preferred compounds (as a group). The patent also claims the new use for two compounds individually, including sildenafil (Claim 7).
Key statutory provision
Section 27 of the Patent Act is the statutory provision governing disclosure of inventions. The key provision before the court was Section 27(3)(a), which provides that:
"(3) The specification of an invention must:
(a) correctly and fully describe the invention and its operation or use as contemplated by the inventor."
Teva (then Novopharm) alleged that the '446 patent was invalid, including for inutility and insufficiency of disclosure. In response, Pfizer commenced an application under the Patented Medicines (Notice of Compliance) Regulations. Pfizer succeeded at first instance and on appeal.
Teva's application was dismissed(2) by Justice Kelen, who addressed the inutility and insufficiency issues as follows:
While Kelen rejected the insufficiency allegation, he did so only grudgingly, expressing significant concerns in obiter about the patentee's failure to identify the tested compound:
"By withholding from the public the identity of the only compound tested and found to work, sildenafil, the patent did not fully describe the invention. Obviously Pfizer made a conscious choice not to disclose the identity of the only compound found to work, and left the skilled reader guessing. This is contrary to the statutory requirement to fully disclose the invention." (Emphasis added.)
Federal Court of Appeal
On appeal, the Federal Court of Appeal upheld Kelen's decision.(3) The Federal Court of Appeal agreed that the sufficiency of disclosure should be assessed through the prism of Claim 7. The patent was sufficient, since it answered the questions posed by the Supreme Court in Consolboard Inc v MacMillan Bloedel: "What is your invention?" and "How does it work?"(4) The court also upheld Kelen on the question of utility.
The focus of the decision was whether Pfizer had properly disclosed the invention of the '446 patent.(5) The court also commented on utility.
Insufficiency of disclosure
The court stated that "the first step is to define the nature of the invention" in the '446 patent. The lower courts had treated each claim as a separate invention and therefore considered the disclosure requirements with respect to each individual claim, not to the specification as a whole. The court rejected the claim-based approach, preferring to consider the specification as a whole. The court left open the possibility that different claims may disclose separate inventions, but this must be determined on a case-by-case basis.
Turning to the '446 patent, the court found only one inventive concept: the use of sildenafil and other compounds in the treatment of erectile dysfunction (ie, it did not accept that the use of sildenafil was a distinct invention). The court relied on the following factors:
As to whether the disclosure was sufficient, the court began with Pfizer's actual work (presumably to determine what Pfizer had actually invented), before turning to the specification to see whether Pfizer had disclosed that invention.
As Pfizer conducted only tests that demonstrated that sildenafil was effective and none of the other compounds had been shown to be effective, the court concluded that the invention was the use of sildenafil for the treatment of erectile dysfunction. As the court noted: "This had to be disclosed in order to meet the requirements set out in s. 27(3) of the Act."
In considering the invention disclosed by the specification, the court noted that "the specification does not indicate that sildenafil is the effective compound". Further, the disclosure would not enable the public to make the same successful use of the invention as the inventor since, even if a skilled reader could have narrowed the effective compound down to the two compounds that were individually claimed, further testing was necessary to determine which of the compounds actually worked.
In rejecting Pfizer's argument that Teva had been able to make use of the invention having only the specification because it had filed a submission for regulatory approval, the court stated:
"However, this does not change the fact that the specification required, at a minimum, 'a minor research project' in order to determine whether Claim 6 or Claim 7 contained the correct compound. The fact that Teva carried out this minor research project is irrelevant to Pfizer's obligation to fully disclose the invention. More importantly, what must be considered is whether a skilled reader having only the specification would have been able to put the invention into practice. The trial judge clearly found that the skilled reader would have had to undertake a minor research project to determine what the true invention was."
The court found that the courts below misread Consolboard when they stated that the only questions that must be answered were, "What is your invention?" and "How does it work?" The court indicated that these were not the only relevant questions, noting that the description must enable a skilled person to produce the invention using only the instructions contained in the disclosure: "Whether or not a specification is sufficient depends on what a skilled person would consider to be sufficient."
In concluding that the '446 patent was insufficient, the court commented on the practice of cascading claims (broad genus claims that progressively narrow). According to the court, such claims do not necessarily interfere with the public's right to disclosure, since the useful claim is usually the claim at the end for the individual compound. The problem in this case was that the "claims ended with two individually claimed compounds, thereby obscuring the true invention".
The court provides a stark warning to patentees on the need to make full disclosure:
"Pfizer gained a benefit from the Act — exclusive monopoly rights — while withholding disclosure in spite of its disclosure obligations under the Act. As a matter of policy and sound statutory interpretation, patentees cannot be allowed to 'game' the system in this way. This, in my view, is the key issue in this appeal. It must be resolved against Pfizer."
As a result of the failure to disclose the invention properly, the court ruled that the '446 patent was invalid and void. This appears to have been an oversight by the court, given that the proceeding arose under the Patented Medicines (Notice of Compliance) Regulations and the only issue was whether the allegation of invalidity was justified. Accordingly, the court would not appear to have jurisdiction on this appeal to void the patent.
Teva had argued that Claim 7 is invalid for insufficient disclosure of sound prediction. The court rejected this argument. As the patent stated that the claimed compound would be useful in treating erectile dysfunction and, at the time when the application was filed, sildenafil could assist in treating erectile dysfunction, the court found that this "is all that is required". The failure to identify the tested compound went to the issue of disclosure of the invention, not to disclosure of the invention's utility. The court expressly rejected the notion of a separate disclosure requirement for utility under Section 27(3).
On the issue of whether an enhanced disclosure requirement exists for sound prediction, as has been suggested in decisions of the Federal Court of Appeal, the court found that sound prediction was not in issue and declined to comment on the question.
While the court took some care to limit the decision to the facts of the case, this decision will almost certainly give rise to vigorous challenges by generic drug manufacturers on the basis of insufficiency of disclosure. Perhaps the most troubling aspect of the decision is the court's emphasis on looking to the disclosure, rather than the issued claims, to divine the nature of the invention.
For further information on this topic please contact J Sheldon Hamilton or Gunars A Gaikis at Smart & Biggar/Fetherstonhaugh's Toronto office by telephone (+1 416 593 5514), fax (+1 416 591 1690) or email (email@example.com or firstname.lastname@example.org). Alternatively, please contact Colin B Ingram at Smart & Biggar/Fetherstonhaugh's Ottawa office by telephone (+1 613 232 2486), fax (+1 613 232 8440) or email (email@example.com).
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