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Federal Court rejects Apotex’s invalidity allegations on claims for use of abiraterone acetate in combination with prednisone

On October 29, 2019, the Federal Court issued its final decision under the pre-amended Patented Medicines (Notice of Compliance) Regulations: Janssen Inc v Apotex Inc, 2019 FC 1355. Justice Phelan granted Janssen’s application for an order prohibiting the Minister of Health from issuing a Notice of Compliance to Apotex for its generic version of Janssen’s ZYTIGA (abiraterone acetate).

Canadian Patent No. 2,661,422 generally claims the use of the combination of abiraterone acetate (AA) and prednisone (PN) for the treatment of prostate cancer. Apotex alleged that the patent was obvious, lacked utility, claimed unpatentable subject matter, and was improperly listed.

Patentable subject matter

Apotex alleged that the combination of AA and PN, two known anti-cancer drugs, was not patentable subject matter. The Court disagreed: neither drug was known as an effective monotherapy for prostate cancer and the skilled person would understand the patent claims a combination that overcomes resistance to other anti-cancer therapies, including the use of either compound alone.

Obviousness

The Court identified the inventive concept of the asserted claims as the use of AA and PN for prostate cancer. It identified several gaps between the state of the art and this inventive concept which required inventive ingenuity to bridge. Of particular importance, the drugs had not previously been combined to treat prostate cancer.

With respect to whether the invention was “obvious to try,” the Court found that although it was likely that the skilled person was motivated to test AA for prostate cancer and that the combination of AA and PN may have been “worth trying,” the combination was not self-evident.

Utility

The Court found that utility of the asserted claims had been demonstrated based on two small clinical studies. In the first, a single patient was treated with AA and dexamethasone, a different glucocorticoid. On its own, this study would have been insufficient to demonstrate utility. However, in the second study, 22 patients were treated with AA and PN, six of whom responded to the combination.

Listing eligibility

Apotex argued that the asserted claims lacked the relevance required for listing because while the patent claims the use of PN as an anti-cancer agent, ZYTIGA is indicated for the use of AA and PN where the role of PN is to mitigate the side effects of AA. The Court rejected this argument: while the approved role of PN is primarily to manage side effects, the ZYTIGA Product Monograph also discusses its anti-cancer effects.

Infringement

Apotex’s proposed product monograph includes an indication of use of AA and PN for the treatment of metastatic castrate resistant prostate cancer.  Based on similarities between the product monograph for Apotex’s abiraterone acetate product and the asserted claims, the Court concluded that “[t]his is a clear case where Apotex intends to use the same drugs in the same amounts and for the same overall purposes of the Patent.” Apotex’s allegation that it would not induce the infringement of the patent was therefore not justified.

Apotex has appealed.

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