Pharma in brief - Canada: Federal Court of Appeal upholds prohibition order: No “promise” of acceptable toxicity or superiority over prior art compounds

April 2012 Author: Adam Haller

Contacts

Case: Mylan Pharmaceuticals ULC v. Pfizer Canada Inc. et al.

Drug: ARICEPT® (Donepezil)

Nature of case: Appeal from a prohibition order pursuant to section 6 of the PM(NOC) Regulations

Successful party: Pfizer Canada Inc. et al.

Date of decision: March 29, 2012

Summary

On March 29, 2012, the Federal Court of Appeal upheld a decision of Mr. Justice Hughes (2011 FC 547) to issue a prohibition order preventing the Minister of Health from issuing a Notice of Compliance to Mylan Pharmaceuticals ULC (“Mylan”) for its generic version of ARICEPT® until the expiry of Canadian Patent No. 1,338,808 (the “’808 Patent”). The Federal Court of Appeal held that Justice Hughes did not err in refusing to decide whether the ‘808 Patent fully and accurately set out the work done by the inventors, or in his construction of the promised utility.  

Background

Claims 6 and 18 of the ‘808 Patent claimed respectively (i) donepezil; and (ii) a composition comprising donepezil and a therapeutically acceptable carrier for treating senile dementia. At the hearing, Mylan advanced two grounds of invalidity.

First, Mylan argued that some of the testing and resulting data reported in the ‘808 Patent were inaccurate. Justice Hughes held that this allegation was not raised in the Notice of Allegation and did not need to be addressed.

Mylan’s second argument was that the ‘808 Patent promised, inter alia, that donepezil had an acceptable toxicity profile and was safer and longer acting than prior art compounds, properties that were not demonstrated or soundly predicted at the relevant date.  

Justice Hughes held that the patent promised compounds that were effective for the treatment of Alzheimer’s disease without reference to toxicity or advantages over prior art compounds. He found that this promise had been soundly predicted at the relevant date based on animal testing showing AChE inhibition and an understanding in the field linking AChE inhibition with the treatment of Alzheimer’s disease.

Mylan appealed on the grounds that:

(i) Justice Hughes erred in finding that he could not consider Mylan’s assertion that wrong or misleading data were included in the ‘808 Patent; and

(ii) Justice Hughes erred in failing to find that the ‘808 Patent promised that donepezil would have acceptable toxicity and be safer and longer acting than prior art compounds.

Decision of the Federal Court of Appeal

1. Wrong or misleading data  

The Court of Appeal held that Justice Hughes’ reading of the Notice of Allegation was not based on a palpable and overriding error. The Court went on to find that even if the issue had been considered, it would not have altered the outcome of the proceeding. Consequently, the Court dismissed this ground of appeal.

2. The “promise” of the patent  

The Court agreed with Justice Hughes that the promise of the ‘808 Patent did not include reference to toxicity or advantages over prior art compounds. The Court adopted a claims-based approach to the promise of the patent and distinguished its earlier decision in Xalatan (2011 FCA 236) on the basis that in the “unique circumstance of that case”, the claim at issue specifically mentioned the avoidance of side effects. In contrast, claim 18 of the ‘808 Patent did not make a specific promise relating to the avoidance of side effects or toxicity.

The Court noted that while the ‘808 Patent made some reference to toxicity and advantages over prior art compounds, Justice Hughes was correct in not including those as part of the promise. The Court referred to Justice Hughes’ statement that the use of the specification of a patent in order to construe its promise “is not to serve as an invitation to a zealous lawyer to read a patent specification in such a way as to persuade a Court, one way or the other, as to what the promise is” and an earlier Federal Court decision in which the Court noted that “the jurisprudence does not permit an unescorted and unchaperoned romp through the disclosure”.

Having concluded that Justice Hughes committed no error in construing the promise of the patent, the Court declined to consider Pfizer’s alternative argument that the promise of claim 6 (the compound claim) could be construed differently than that of claim 18 (the composition for treatment claim). While Justice Hughes noted in obiter that different claims in the same patent could have different promises, this concept remains unsettled in Canadian patent law.

Link to decision:

Mylan Pharmaceuticals ULC v. Pfizer Canada Inc et al., 2012 FCA 103

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