Apotex Successfully Invalidates Patent on Nexium

Apotex Successfully Invalidates Patent on Nexium

AstraZeneca has been selling Nexium in Canada for 13 years.  It is prescribed to treat ulcers, gastroesophageal reflux disease (GERD) and related diseases. The active ingredient in Nexium is esomeprazole, one of the enantiomers of omeprazole.  Omeprazole is also prescribed to treat these same diseases.

Canadian patent no. 2,139,653 (the 653 patent) claims esomeprazole with a specified level of optical purity, and its use in the treatment of these diseases.  After a 32-day trial (AstraZeneca Canada Inc. et al v. Apotex Inc. et al, 2014 FC 638), Justice Rennie found the claimed invention to be new and inventive.  However, he held the 653 patent was invalid because it failed to meet the third basic requirement for patentability – utility.  Specifically, the Court found that the inventors could not have soundly predicted one of the utilities promised in the patent at the time of filing the application.

Justice Rennie’s detailed and comprehensive Reasons for Judgment will be of interest to not only litigators engaged in the drug wars in Canada, but also to patent practitioners generally.  What follows is a summary of three key issues in that case, but readers of the Court’s Reasons will note that Justice Rennie dealt in detail with several other issues.

Ascertaining the “Promise” of the Patent

The Court began its utility analysis by noting that utility is a requirement for an “invention” under section 2 of the Patent Act.  A patent will satisfy the requirement of utility if, from the perspective of the skilled person as of the filing date of the application for the patent, its utility was demonstrated, or in the alternative, its utility was soundly predicted. Prior to engaging in this utility analysis, it is necessary to first ask: “useful for what?”  That is, a preliminary inquiry is to ascertain the “promise of the patent”, or in other words, determine what the patent says is the utility of the invention.

Justice Rennie recognized that a patent does not need to promise any particular level of utility, in which case the patent will be valid as long as there is a scintilla of utility (citing Eli Lilly Canada Inc v Novopharm Limited, 2010 FCA 197). However, where a patent promises a specific result, utility will be measured against that promise so that the question becomes whether the invention does what the patent promises it will do.  Identifying the promise of the patent requires a consideration of the patent as a whole construed through the eyes of the skilled person in relation to the science and information available at the time of filing.

Justice Rennie dealt with a number of issues regarding the promised utility of the 653 patent, however, two specific issues are of note: (1) is a property of a compound a promise of utility? and (2) what is the distinction between a promise of utility on the one hand and a goal or advantage on the other hand?  With regard to the first issue, the Court found that esomeprazole’s stability against racemization (the single enantiomer does not convert back to the racemate) is a property of the compound – it is not related to the patent’s utility.  Specifically, the Court held that the “patent in this case is not useful for possessing the chemical property of being stable against racemization; it is useful as a pharmaceutical drug in therapy. Stability against racemization merely enables that use and is not a use in itself” (at paragraph 97).  Thus, stability against racemization is a property of esomeprazole that may lead to the ultimate utility of use in treating certain diseases.

As for the distinction between a promise and a goal/advantage, some recent cases (notably Apotex Inc v Sanofi-Aventis, 2013 FCA 186) have held that not all statements of goals or advantages set out in a patent rise to the level of a promise of utility.  In particular, a “goal” is not necessarily a “promise”, thus it is necessary in some cases to distinguish between the two.  In Justice Rennie’s view, “goals” describe “a hoped-for advantage of the invention” and “merely relate to potential uses for the patent”, whereas “promises are explicit and define guaranteed or anticipated results from the patent” (at paragraph 117, emphasis in original).  In the context of the 653 patent, the Court held that the patent’s language (“will give an improved therapeutic profile such as a lower degree of interindividual variation”) clearly refers to a promise of utility. The use of the word “will”, although prospective, nevertheless conveys “a high threshold of probable or certain outcomes that will occur” (at paragraph 120, emphasis in original). Had the patent used language such as “may” or “could” then there would have been a more compelling argument that the statements referred to goals as opposed to promises.

Two final notes of importance about the promised utility of the 653 patent.  First, the Court found that the patent made three promises of utility (there has been some debate as to whether a patent can only make one promise), and second, the Court found that the three promises of utility applied to all the claims of the 653 patent (the claims included both compound claims and use claims).

The Disclosure Requirement in Sound Prediction Cases

Having ascertained the promised utility of the 653 patent, Justice Rennie then turned to the question of whether the inventors had demonstrated the promised utility prior to the filing of the patent application, and if not, whether the promised utility was soundly predicted as of that date.

Determining whether the promised utility was demonstrated is generally straightforward.  The question is whether, as of the filing date, there was “evidence that establishes that the embodiment at issue does in fact work in a manner that gives rise to the advantages stated in the patent” (at paragraph 137, citing Eurocopter v Bell Helicopter Textron Canada Ltée, 2013 FCA 219).  In the case of the 653 patent, the promised utility had not been demonstrated. Thus, the issue became whether the promised utility could have been soundly predicted.

It was established by the Supreme Court in the so-called “AZT” case (Apotex Inc v Wellcome Foundation Ltd, 2002 SCC 77, [2002] 4 SCR 153) that a three-part test must be satisfied for a patent to be valid based on sound prediction: (1) there must be a factual basis for the prediction, (2) the inventor must have at the date of the patent application an articulable and sound line of reasoning from which the desired result can be inferred from the factual basis, and (3) there must be proper disclosure.

The application of the AZT case has led to a significant debate in Canada as to whether the third step (“proper disclosure”) means that a patent based on sound prediction must satisfy a heightened disclosure requirement in order to be valid.  That is, did the Supreme Court require that the patent must disclose both the factual basis and the sound line of reasoning that underlie the prediction of utility?  Although the Supreme Court did not have to answer this question in the AZT case, Justice Rennie was not as fortunate.  In formulating his answer, he reviewed the law on this point and held that only in the case of a new use patent must the patentee satisfy this heightened disclosure requirement; in the case of all other types of patents, no such requirement exists.  His reasoning is as follows.

First, Justice Rennie noted that the AZT case dealt with a new use patent – the drug AZT was a known drug at the time and the inventors discovered and claimed its use in the treatment of HIV (a new use).  Second, certain specific language used in the AZT case suggests that the disclosure requirement applies only to new use patents.  Third, obiter dicta in the Supreme Court’s recent decision in Teva Canada Ltd v Pfizer Canada Inc, 2012 SCC 60 (the Viagra case) rejected the requirement for heightened disclosure and this obiter had the effect of overturning prior Federal Court of Appeal decisions where heightened disclosure was required.

Having decided that the factual basis and line of reasoning did not have to be disclosed in the 653 patent, Justice Rennie proceeded to look at all evidence adduced by AstraZeneca relating to the making of the invention, whether disclosed in the patent or not.  The Court found, based on the evidence, that two of the three promised utilities had been demonstrated or soundly predicted as of the filing date.  However, despite referring to information not disclosed in the 653 patent, Justice Rennie found that the third promised utility was not soundly predictable.  As a result, the patent was invalid for failing the utility requirement.  Thus, where a patent, properly construed, promises more than one utility, the inventors must have demonstrated and/or soundly predicted each of the promised utilities, failing which the patent is invalid.

One last point on utility.  Justice Rennie began his analysis of the disclosure requirement by saying that the “law on proper disclosure with respect to utility is unsettled” (at paragraph 141).  As a result of his decision, the law may now be more “unsettled” than it was previously.  Is he correct in his interpretation of the AZT case and of the importance of the obiter statements in the Viagra case, or do the holdings in the prior Federal Court of Appeal decisions still apply?  As well, how are Examiners in the Patent Office to determine whether the claimed invention was soundly predicted if the factual basis and sound line of reasoning need not be disclosed in the specification?

Ascertaining the Inventive Concept

A further construction issue faced by Justice Rennie was determining the “inventive concept”.  As practitioners are well aware, the Supreme Court in Apotex Inc v Sanofi-Synthelabo Canada Inc, 2008 SCC 61, [2008] 3 SCR 265 has mandated a four-part test for assessing obviousness.  The second step in the analysis is to “[i]dentify the inventive concept of the claim in question or, if that cannot readily be done, construe it.”

The issue faced by Justice Rennie was how to identify the inventive concept of the 653 patent.  He began by noting that the Supreme Court expressly stated that it is the “inventive concept of the claims” that must be identified.  Thus, according to Justice Rennie the analysis “begins with the claims, and only looks to the disclosure when necessary” (at paragraph 267).  One of the examples given by the Supreme Court as to when the disclosure may be relied on to determine the inventive concept is in the case of a claim to a bare chemical formula.

Tying the inventive concept to the claims is significant because patentees will generally want to advocate for an inventive concept that includes as many features as possible (thus making it more difficult for a court to find the invention obvious).  In some cases, patentees have been successful in convincing the Court that features disclosed in the patent, but not claimed, form part of the inventive concept (see, for example, Allergan Inc. v. Canada (Health), 2014 FC 566 at 25 where a claim to a formulation was characterized as a “bare list of ingredients”).  That was precisely what AstraZeneca tried to argue with regard to the 653 patent.  Justice Rennie, however, rejected this argument because the claims in issue related to esomeprazole having a specific degree of optical purity.  Because of this claimed property, he held there was no need to look to the disclosure, and in particular, no need to import into the inventive concept properties of esomeprazole that were disclosed but not claimed.

Justice Rennie’s conclusion on when to venture outside the claims to ascertain the inventive concept is consistent with the provisions of section 28.3 of the Patent Act, which provides that “[t]he subject-matter defined by a claim in an application for a patent in Canada must be subject-matter that would not have been obvious on the claim date …” (emphasis added)).

Dino Clarizio is a partner at the Toronto office of Goodmans LLP, and also a registered patent and trade-mark agent.  His work includes all types of intellectual property litigation and, in particular, patent litigation in the chemical and pharmaceutical area. Mr. Clarizio received an LLB from Osgoode Hall Law School (’89) and a Bachelors of Engineering from McGill University (’86).