Federal Court of Appeal upholds validity of two patents relating to ELIQUIS

On August 4, 2022, the Federal Court of Appeal (FCA) dismissed Pharmascience’s appeal of a Federal Court decision upholding the validity of Canadian Patent Nos. 2,461,202 (the 202 patent) and 2,791,171 (the 171 patent) relating to apixaban (Bristol-Myers Squibb’s ELIQUIS): Pharmascience Inc v Bristol-Myers Squibb Canada Co, 2022 FCA 142.

The 202 patent

The 202 patent claims apixaban, an anticoagulant, and the use of apixaban in the treatment of thromboembolic disorders. Several of the invalidity attacks in the issue on appeal were based on Canadian Patent No. 2,349,330 (the “genus patent”). The genus patent describes a broad class of inhibitors of the enzyme Factor Xa (FXa). The genus patent encompasses but does not identify apixaban.

Status as a selection patent

Pharmascience argued that the Federal Court erred, in part, by failing to recognize that (i) the 202 patent did not indicate a special advantage of apixaban over the compounds of the genus patent, and (ii) a selection patent must disclose the special advantage of the selection. 

The FCA rejected both arguments, finding that “there was evidence on which the Federal Court was entitled to, and did, rely to conclude that the 202 Patent does disclose a special advantage of apixaban over the genus of compounds described in the 330 Patent”:

[12]… The Federal Court cited testimony from Sandoz’ expert Dr. Gleason and BMS’s expert Dr. Weitz that a skilled person reading the 202 Patent, “would understand that apixaban was singled out from the genus of compounds [disclosed in the 330 Patent] because, while the genus had the potential to be useful in treating thromboembolic disorders, apixaban was selected in the 202 Patent because it was useful.” (Original emphasis.) The Federal Court also found at paragraph 79 of its reasons that “the skilled person reading the 330 Patent would understand that not all of the claimed compounds would be useful in treating and preventing thromboembolic disorders.”

Further, the Federal Court did not err in considering the claims (which focussed on apixaban) of the 202 patent in determining how a skilled person would understand the 202 patent as a whole or in finding that a special advantage was disclosed by inference. The FCA also held that the 202 patent need not explicitly compare apixaban to any other particular compound within the genus patent.

Anticipation, obviousness and double patenting

Anticipation, obviousness and double patenting were addressed together by the FCA. Pharmascience argued that the Federal Court erred in finding that the 202 patent discloses an invention (the special advantage of apixaban over the compounds of the genus patent) and by not identifying the inventive concept or the differences between the state of the art and the inventive concept.

The FCA rejected both arguments: there was no palpable and overriding error in the Federal Court’s conclusion that the 202 patent discloses a special advantage. Moreover, when read as a whole, the Federal Court’s reasons identified both the inventive concept (the selection of apixaban) and the differences between the inventive concept and the state of the art (an effective FXa inhibitor useful in treating thromboembolic disorders).

Insufficiency

Central to Pharmascience’s insufficiency attack on appeal was that claims focussing on apixaban were not part of the original or published application for the 202 patent. These claims were instead added shortly before the 202 patent was issued. Accordingly, Pharmascience argued that the 202 patent did not disclose an invention as of the filing or publication dates and that claims focussing on apixaban could not be reasonably inferred from the application as filed. Pharmascience also took issue with the Federal Court assessing sufficiency based on the claims of the 202 patent as issued and not the claims as filed or published.

In rejecting Pharmascience’s arguments, the FCA noted that there is nothing in the Patent Act or the passage from the Supreme Court cited by the parties¹ to suggest that a specification cannot be amended during prosecution to meet the sufficiency requirement. The FCA then drew a distinction between the date for determining sufficiency and the claims to be considered in doing so. In the FCA’s view, consideration of the specification (including the claims) as issued is consistent with both the Patent Act and the approaches used for anticipation, obviousness, utility and claim construction, all of which are based on the claims as issued.

The FCA framed the key question as to whether claims to apixaban introduced new matter that could not reasonably be inferred from the original application. This specific issue was not argued before the Federal Court. Nonetheless, the FCA stated that it would not be inclined to find that claims to apixaban were not reasonably inferable from the original application, noting that an example in the original application describes apixaban and how to make it.

The 171 patent

The claims in issue of the 171 patent relate to tablet formulations of apixaban. The claims contain thresholds for minimum dissolution rate and maximum particle size to ensure that the tablets provide consistent, solution-like exposures.

Obviousness

The FCA rejected Pharmascience’s argument that the Federal Court’s obviousness analysis was incomplete and conclusory and that the Federal Court should have found the invention of the claims in issue of the 171 patent obvious to try. It was open to the Federal Court to conclude that a skilled formulator would not have thought to reduce the particle size to improve absorption or to target the significantly lower dissolution rate of the claims in issue. Moreover, the Federal Court did not err in defining or applying the obvious to try test or in defining the inventive concept.

Ambiguity and overbreadth

The FCA also held that the Federal Court did not err in its analysis of ambiguity. It was open to the Federal Court to find that, if in doubt as to how to measure particle size, a skilled formulator would consult the 171 patent and employ the method described therein.

On overbreadth, the FCA rejected the argument that the dissolution rate threshold is a mere desired result not limited to what was invented and disclosed. The FCA viewed the desired result as solution-like behaviour in the body, which could be guaranteed by the claimed thresholds for particle size and dissolution rate. The 171 patent need not describe factors affecting dissolution rate other than particle size unless the skilled person would need that information to practise the invention. The FCA commented further that such a flaw (if present) seemed to relate to sufficiency rather than overbreadth.

Pharmascience would need leave from the Supreme Court of Canada to appeal this decision.

Should you have any questions, please do not hesitate to contact a member of the Pharmaceutical Litigation Group.

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