Cobalt served a NOA with respect to repaglinide, the S enantiomer of a previously disclosed racemic compound (the “388 compound”), alleging invalidity of the '851 patent on grounds of anticipation, obviousness and s. 53(1). The Court dismissed the application of Novo Nordisk, finding the allegation of invalidity for obviousness was justified.

The '851 patent disclosed that the S enantiomer had suprising pharmacokinetic properties over the R enantiomer and the racemic compound. Cobalt argued that the suprising allegedly advantageous properties constituted an express promise and should be read into the claims covering the S enantiomer compound. The Court disagreed that these advantageous properties should be read into the compound claims, but did note that as these properties are inherent to the compound, they will be taken into account when considering anticipation and obviousness.

For anticipation, the Court found that there was no enabling disclosure in either the ’398 patent or the ’331 patent application that defines in clear terms the nature of the pharmacokinetic advantages allegedly possessed by repaglinide. The mere disclosure of the 388 compound and that enantiomers could be separated in the prior art was not an enabling disclosure of the invention.

For obviousness, the court applied the Sanofi test and found the allegation of obviousness justified. In particular, she found that it was known as of the relevant date that the 388 compound had hypoglycemic activity, and that such activity likely resided primarily in one of the enantiomers. Further, it was known at the relevant time that the person skilled in the art would know how to prepare substantially pure enantiomers of racemic compounds such as the 388 compound. While this notional person would not be able to predict what the pharmacokinetic properties of any given enantiomer would be, it was known that the pharmacokinetic properties of enantiomers could differ significantly from the racemate and from each other, and that it was therefore important to test them.

Thus, while one could not predict the surprising pharmacokinetic properties identified as advantageous with respect to replaglinide, the court considered that it would be “obvious to try” to a person skilled in the art, by June 1991, it was more or less self-evident that repaglinide’s pharmacokinetic properties could well be very different from those of the (R) enantiomer or the 388 compound. Given that the extent, nature and amount of effort required to make repaglinide in the first place was neither prolonged nor arduous, and the methods used and processes followed to test its pharmacokinetic properties were admittedly routine and that there was motivation to investigate, there existed more than the mere possibility that testing the enantiomers of the 388 compound for their pharmacokinetic properties was something that might be worth trying.

The Court addressed the s. 53(1) argument due to its potential impact on costs. The Court rejected Cobalt's allegation under s. 53(1), inter alia, on the basis that the alleged omissions were inadvertent and as Cobalt had not squarely put its allegations of omissions to the inventors whom they cross-examined. Further, with respect to criticisms raised with the study in the patent, the court held that the standard for patents should not be equated with regulatory standards.

For more information, please see the following link: