Pfizer obtains orders of prohibition on polymorphic form patent

by Smart & Biggar
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On September 22, the Federal Court, in a pair of decisions, granted Orders of prohibition under the Patented Medicines (Notice of Compliance) Regulations preventing Apotex and Teva from marketing their generic o-desmethyl-venlafaxine (“ODV”) products (Pfizer’s PRISTIQ) until expiry of Patent No. 2,436,668 (the “668 Patent”): Pfizer Canada Inc v Apotex Inc, 2017 FC 774; Pfizer Canada Inc v Teva Canada Limited, 2017 FC 777. Both Apotex and Teva have appealed.

The claims at issue cover a specific polymorphic form, “Form 1”, of ODV succinate.1  Justice Brown held that Apotex’s allegations of non-infringement and invalidity on the basis of obviousness, inutility, anticipation, double patenting and “overpromising” in relation to subsection 27(3) of the Patent Act were not justified.  Justice Brown also held that Teva’s allegations of invalidity on the basis of obviousness and inutility were also not justified.

Non-infringement (Apotex)

The Court rejected Apotex’s argument of non-infringement of Claim 9 in view of its construction that the endotherm characterizing Claim 9 was 131°C ± 2°C, rather than 131°C ± 1°C.

Obviousness (Apotex and Teva)

The Court held the inventive concept of Claims 8 and 9 was the novel crystalline form, Form 1, of ODV succinate, rather than ODV succinate in any form as argued by Apotex and Teva.

The Court held that the skilled person could not know or predict whether “ODV succinate salt would form as a solid, whether that solid would form as a crystal, or what the properties of a hypothetical crystalline solid would be.”  Therefore, the skilled person “would not have come directly and without difficulty to the solution taught by the 668 Patent.” The prior art did not specifically teach the preparation of ODV succinate or its crystalline forms. Though salt screens as well as crystallization and polymorph screens were known in the art, the Court accepted the evidence of Pfizer’s expert and concluded that the skilled person would face a “research program”; i.e. “an extremely large number of studies and tests with no predictable result.”2 This evidence was confirmed by the lab engaged by Pfizer’s predecessor to perform crystal polymorph screening (which took 5 months).

The Court repeated and expanded on these difficulties in concluding that the invention was not “obvious to try”. Following Apotex Inc v Sanofi Synthelabo Inc, 2008 SCC 61, the existence of screening techniques, and the mere possibility of identifying the specific salt and crystalline form does not establish that they were more or less self-evident: “knowing a host or multiplicity of different facts and procedures does not necessarily lead to the conclusion that it was obvious to try to find everything that could be made based on those facts and procedures”.  In this case, the invention was not self-evident from the prior art and the common general knowledge. There was no motivation in the prior art pointing to any particular solid state form of ODV succinate, let alone the Form 1 monohydrate. Further, the actual course of conduct followed by Pfizer’s predecessor – which is partially redacted in the decisions – included work on other salts, a pro-drug, salt screening, crystal polymorph screening, and considerable in vitro and in vivo testing.  

Utility (Apotex and Teva)

The allegations of inutility were not justified. The Court adopted the recent two-step approach to utility set out in AstraZeneca v Apotex, 2017 SCC 36: (a) identify the subject matter of the invention claimed; and (b) ask whether that subject matter is useful, i.e. “capable of a practical purpose”. Justice Brown agreed with Pfizer that Form I ODV succinate was useful as a “stable, solid state form of ODV succinate” and that this use “is directly related to the subject matter of Claims 8 and 9”. Stability was a sufficient practical result “because it is the solid state stability of Form I that makes it possible to use Form I ODV succinate in formulation i.e., as a drug.” Stability had been demonstrated.

Overpromising in relation to subsection 27(3) of the Patent Act (Apotex)

The Court rejected Apotex’s argument of “overpromising” (see our article below). 

Anticipation (Apotex)

The Court concluded that Apotex’s anticipation evidence failed to overcome the presumption of validity. Apotex’s experts were not instructed regarding the law of anticipation or the concepts of disclosure and enablement. Instead, Apotex relied on evidence tendered by its experts in connection with obviousness. Absent instruction on the law, this evidence was found not useful to the anticipation inquiry. Moreover, basic fairness dictates that a party should not be “allowed to imbed critical evidence on one issue into material filed in relation to another and different issue, and then, after all the evidence including reply affidavits and cross-examinations is complete, rely on the imbedded evidence to attack the patent.”

Double patenting (Apotex)

The Court rejected Apotex’s allegation of double patenting over Claim 21 of Canadian Patent No. 1,248,540 (the “540 patent”).  Regarding “same invention” double patenting, Claim 21 of the 540 patent covers ODV or a pharmaceutically acceptable salt thereof, but does not identify specific salts or solid state forms.

Regarding obviousness double patenting, Claims 8 and 9 are patentably distinct from Claim 21 of the 540 patent. “Nothing in Claim 21 pointed... specifically to Form I ODV succinate, nor indeed even to ODV succinate as a salt”, nor did the 540 patent indicate “that the succinate salt of ODV could be formed, would be crystalline or would have any of the properties disclosed in the 668 Patent.”

Conclusion

These decisions provide guidance on the validity of polymorphic form patents, including in relation to questions of utility and inventiveness.

[1] Additional claims at issue related to sustained release formulations and use to treat depression.

[2] On cross-examination, Teva’s expert made several concessions regarding the inability to predict the existence and properties of crystalline forms. 

 

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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