AstraZeneca has been selling Nexium in Canada for 13 years. It is prescribed to treat ulcers, gastroesophageal reflux disease (GERD) and related diseases. The active ingredient in Nexium is esomeprazole, one of the enantiomers of omeprazole. Omeprazole is also prescribed to treat these same diseases.
Canadian patent no. 2,139,653 (the 653 patent) claims esomeprazole with a specified level of optical purity, and its use in the treatment of these diseases. After a 32-day trial (AstraZeneca Canada Inc. et al v. Apotex Inc. et al, 2014 FC 638), Justice Rennie found the claimed invention to be new and inventive. However, he held the 653 patent was invalid because it failed to meet the third basic requirement for patentability – utility. Specifically, the Court found that the inventors could not have soundly predicted one of the utilities promised in the patent at the time of filing the application.
Justice Rennie’s detailed and comprehensive Reasons for Judgment will be of interest to not only litigators engaged in the drug wars in Canada, but also to patent practitioners generally. What follows is a summary of three key issues in that case, but readers of the Court’s Reasons will note that Justice Rennie dealt in detail with several other issues.