Introduction
Non-infringement (Apotex)
Obviousness (Apotex and Teva)
Utility (Apotex and Teva)
Overpromising in relation to Sub-section 27(3) of Patent Act (Apotex)
Anticipation (Apotex)
Double patenting (Apotex)
Comment
On September 22 2017 the Federal Court, in a pair of decisions, granted prohibition orders under the Patented Medicines (Notice of Compliance) Regulations preventing Apotex and Teva from marketing their generic o-desmethyl-venlafaxine (ODV) products (based on Pfizer's Pristiq) until the expiry of Canadian Patent 2,436,668 (the 668 Patent).(1) Both Apotex and Teva have appealed.
The claims at issue cover a specific polymorphic form (Form 1) of ODV succinate.(2) The court held that the following allegations presented by Apotex were not justified:
- non-infringement and invalidity on the basis of obviousness;
- inutility;
- anticipation;
- double patenting; and
- overpromising in relation to Sub-section 27(3) of the Patent Act.
The court also held that Teva's allegations of invalidity on the basis of obviousness and inutility were not justified.
The court rejected Apotex's argument of non-infringement of Claim 9 in view of its construction that the endotherm characterising Claim 9 was 131°C ± 2°C, rather than 131°C ± 1°C.
The court held that 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 a 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, a 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. Although salt screens, as well as crystallisation and polymorph screens, were known in the art, the court accepted the evidence of Pfizer's expert and concluded that a skilled person would face a 'research programme' (ie, "an extremely large number of studies and tests with no predictable result").(3) This evidence was confirmed by the lab that Pfizer's predecessor had engaged to perform crystal polymorph screening (which took five 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 court ruled that the existence of screening techniques and the mere possibility of identifying the specific salt and crystalline form does not establish that they are more or less self-evident, as "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 prodrug;
- salt screening;
- crystal polymorph screening; and
- considerable in vitro and in vivo testing.
The court held that the allegations of inutility were not justified. It adopted the recent two-step approach to utility set out in AstraZeneca v Apotex (2017 SCC 36), which consists of:
- identifying the subject matter of the invention claimed; and
- asking whether that subject matter is useful (ie, capable of a practical purpose).
The court 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". Further, it held that 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". The court held that stability had been demonstrated.
Overpromising in relation to Sub-section 27(3) of Patent Act (Apotex)
The court rejected Apotex's argument of overpromising (for further details please see "AstraZeneca and overpromising on grounds other than utility").
The court concluded that Apotex's anticipation evidence had failed to overcome the presumption of validity. Apotex's experts had not been instructed regarding the law of anticipation or the concepts of disclosure and enablement. Instead, Apotex had relied on evidence tendered by its experts in connection with obviousness. Absent instruction on the law, this evidence was found to be useless with regard to the anticipation inquiry. Further, 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".
The court rejected Apotex's allegation of double patenting over Claim 21 of Canadian Patent 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. According to the court, "[n]othing in Claim 21 pointed... specifically to Form I ODV succinate, nor indeed even to ODV succinate as a salt". In addition, the 540 Patent did not 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".
These decisions provide guidance on the validity of polymorphic form patents, including in relation to questions of utility and inventiveness.
For further information on this topic please contact Brandon Heard at Smart & Biggar/Fetherstonhaugh by telephone (+1 416 593 5514) or email ([email protected]). The Smart & Biggar/Fetherstonhaugh website can be accessed at www.smart-biggar.ca.
Endnotes
(1) Pfizer Canada Inc v Apotex Inc, 2017 FC 774; Pfizer Canada Inc v Teva Canada Limited, 2017 FC 777.
(2) Additional claims at issue concerned sustained release formulations and use to treat depression.
(3) On cross-examination, Teva's expert made several concessions regarding the inability to predict the existence and properties of crystalline forms.