Court Finds AstraZeneca Patent To Esomeprazole (NEXIUM) Invalid For Lack Of Sound Prediction And Obviousness

AstraZeneca Canada Inc. v. Apotex Inc., 2010 FC 714

This was an application brought by AstraZeneca under the provisions of the Patented Medicines (Notice of Compliance) Regulations for an order prohibiting the Minister of Health from issuing a notice of compliance to Apotex for 20 and 40 mg esomeprazole magnesium tablets until after the expiry of Canadian Patent No. 2,139,653 (the '653 patent). If successful on the application, this would have prevented Apotex from marketing a generic version of NEXIUM in Canada for treating conditions wherein a reduction of gastric acid secretion is required until May 27, 2014. Apotex, on the other hand, sought early market entry by arguing that the '653 patent was invalid for lack of sound prediction, anticipation (or lack of novelty), and obviousness.

The '653 patent relates to an improved process for preparing highly optically pure esomeprazole, one of the enantiomers of the racemate omeprazole, that is stable against racemisation (i.e. recombination). Claim 8 was the claim at issue and could be read as claiming a salt (e.g. magnesium) of esomeprazole having an optical purity of 99.8% or greater. There was no provision as to utility (or use of the invention) in claim 8. This was an important fact, as the Court noted that where the invention relates to a new compound, utility does not need to be included in the claim, so long as it is described in the description portion of the patent. On the other hand, when the patent relates to a new use for an old, known compound, that new use must be set out in the claims. In this case, claim 8 was not directed to a new compound; it was directed to a previously known compound having a particular purity.

Moreover, utility of the compound was simply described in the description of the patent as follows:

It is desirable to obtain compounds with improved pharmacokinetic and metabolic properties which will give an improved therapeutic profile such as a lower degree of interindividual variation. The present invention provides such compounds, which are novel salts of single enantiomers of omeprazole.

However, nowhere in the patent, whether in the Examples or otherwise, was any information given to the person skilled in the art as to whether, in fact, the highly pure esomeprazole salt does give an improved therapeutic profile such as a lower degree of interindividual variation. Moreover, there was no evidence from any witness to say that there was anything in the disclosure...