On July 24, 2013, the Federal Court of Appeal overturned the 2011 trial decision that had invalidated sanofi’s patent for the blockbuster drug Plavix® (clopidogrel bisulfate) (sanofi-aventis v. Apotex Inc., 2013 FCA 186). In concurring sets of reasons, both Justice Pelletier (concurred in by Justice Noël) and Justice Gauthier held that the trial judge erred in finding the patent to be invalid on the grounds of inutility and obviousness. The focus of both sets of Reasons was on the issue of utility, which is currently a topic of great interest in Canadian patent law.

The Plavix® patent is a selection patent, meaning that it identified an inventive selection over a prior art patent.   In this case, the prior art patent (the “genus patent”) covered a large genus of compounds having platelet aggregation inhibiting activity. The compounds of the genus patent were racemates, meaning that they are each comprised of 50:50 mixtures of two structurally different compounds, called enantiomers. The inventors of the Plavix® patent had separated one of these racemates into its two enantiomers and found that they had distinct properties. One of the enantiomers, clopidogrel, had all the platelet aggregation inhibiting activity of the racemate and was less toxic and better tolerated than the racemate and the other enantiomer. 

The Plavix® patent was first litigated in Canada under the Patented Medicines (Notice of Compliance) Regulations. Apotex Inc. had alleged that the patent was invalid on the grounds of anticipation, double patenting and obviousness. Sanofi was successful in defending the patent on each of these grounds before every level of court in Canada, including the Supreme Court (Apotex Inc. v. Sanofi-Synthelabo Canada Inc., 2008 SCC 61, [2008] 3 SCR 265).

Following the Supreme Court’s decision, Apotex Inc. began an action in the Federal Court to impeach the Plavix® patent. Sanofi then commenced an action for infringement of the patent, based on Apotex’s importation into Canada and exportation out of Canada of clopidogrel. These two actions were consolidated and heard by the trial judge in 2011, who found the patent to be invalid. Although the trial judge also found that Apotex had infringed the patent, that finding was overtaken by his conclusion that the patent was invalid.

In addition to the same grounds of invalidity it had argued before the Supreme Court, Apotex raised the ground of inutility for the first time. The trial judge’s finding of inutility turned on his construction of the “promise of the patent” as being that clopidogrel could be used in humans. While this was found to be soundly predicted, the trial judge held that the inventors had not disclosed enough of their factual basis and line of reasoning to satisfy the doctrine of sound prediction.

The doctrine of the “promise of the patent” is unique to Canadian patent law. Simply put, the promise doctrine holds that if a patent promises a particular utility, the patentee will have had to demonstrate or soundly predict that utility by the Canadian filing date. In recent years, several patents have been invalidated by the Federal Courts on the basis that the patentee had failed to fulfill the promise of the patent by the relevant date.

Both Justice Pelletier and Justice Gauthier brought some welcome clarification to the relationship between the requirement that an invention be useful and the promise doctrine.  First, the Court cautioned that, since not every patent has a promise, judges should not try to read a promise into a patent where none exists. A patentee should only be required to satisfy the promise doctrine where the patent makes an explicit promise of a specific result.

The Court of Appeal held that it was in his construction of the promise that the trial judge erred in his utility analysis. The trial judge had wrongly based his construction of the promise on “inferences” that clopidogrel could be used in humans, rather than on explicit language in the specification. In contrast, the patent had made clear and unambiguous statements with respect to clopidogrel’s advantages over the genus patent, which the trial judge held had been demonstrated by the filing date. Thus, the Court of Appeal held that the patent was not invalid for lack of utility.

In coming to the conclusion that the patent did not promise that clopidogrel would be useful in humans, both Justices Pelletier and Gauthier introduced some welcome practicality into the construction of the promise. Justice Pelletier noted that while the ultimate goal of those in the pharmaceutical industry would have been to use clopidogrel in humans to treat disorders related to platelet aggregation, this goal or hope should not be equated to a promise.  

Justice Gauthier also identified the danger of equating statements in the patent referring to potential applications of an invention to an explicit promise of a specific result. She explained that Canadian patents are often based on European priority applications, which (unlike the requirements under Canadian patent law) are required to state in their disclosures how their inventions are capable of industrial application. Thus, the Court should take care to distinguish between statements made in the patent’s disclosure and statements of utility made in the claims.

The approach by the Court of Appeal to the issue of the promise doctrine provides helpful guidance for both litigants and the Courts. Most importantly, one should not strain to find a promise where there is no explicit language of a promise in the specification. As stated by Justice Pelletier, “… Courts should not strive to find ways to defeat otherwise valid patents.” 

The Court also overturned the trial judge’s obviousness finding on the basis that the trial judge incorrectly focused on whether the method of separating the enantiomers was obvious, as opposed to whether the beneficial properties of clopidogrel over the racemate and the other enantiomer would have been obvious. Further, the trial judge had not addressed why the person skilled in the art would have started with the racemate in the first place, given the hundreds of thousands of compounds disclosed in the genus patent.

Finally, the Court rejected Apotex’ defences that would have limited sanofi’s recovery for Apotex’ importation and exportation of clopidogrel. As the issues of  liability and quantification of damages were bifurcated, the latter issue has been remanded to the trial judge.