UK Court invalidates claims to an enantiomer of a known racemate

In Generics (UK) Limited v. Novartis AG, the UK Patents Court (Mr Justice Floyd), in a challenge by Mylan (Generics UK), invalidated claims to an enantiomer of a known racemate[1].

The action came to trial very quickly, as the initial action started on 3rd March 2011. Following an application for an interim injunction, an expedited trial of the action was ordered on 30th June 2011. The action was tried over three days from September 5th to 7th, just over six months from the issue of the claim. Expedition was justified because Mylan intended to launch a product prior to the expiry of the SPC, which will occur on 30th July 2012.

Rivastigmine is the modern name for the (-)-enantiomer (…). In around 1985 a team of scientists led by Marta Weinstock, working at the Hebrew University of Jerusalem, made and tested a compound named RA7, which is the unresolved racemic compound of which rivastigmine is the (-) enantiomer. RA7 was one of a number of compounds proposed by Weinstock for the treatment of AD, but her publications made no mention of resolving it into its individual enantiomers. The sole question which arises in this action is whether a relevantly skilled pharmaceutical development team, in ignorance of the patent in suit, would find it obvious in the light of the Weinstock publications to resolve the racemic mixture of RA7 into its individual enantiomers.

As framed by the Court, “the sole question … is whether a relevantly skilled pharmaceutical development team, in ignorance of the patent in suit, would find it obvious …to resolve the [prior art] racemic mixture … into its individual [claimed] enantiomer[ ].” (¶ 3)

The only ground of attack on the patent was lack of inventive step. The Court:

“I think the correct analysis is that a pharmaceutical composition for treatment of AD comprising rivastigmine was conceptually obvious in the light of Weinstock and would immediately occur to the skilled team. The team would consider that resolving RA7 would be a worthwhile step to take for good technical reasons. The team would find that the chemistry involved is trivial. Applying the principles outlined above I have no doubt that the inventive concept is obvious in the light of Weinstock.

I believe that conclusion to be consistent with the “problem and solution approach” employed by the Boards of Appeal. The objective technical effect demonstrated by the patent in comparison with the Weinstock prior art is simply that which one would expect from resolution of a chiral compound. The skilled person would know how to solve the problem of achieving those effects by an application of the common general knowledge about chiral compounds.

In the result all the claims relied on are invalid, and the SPC is accordingly invalid as well. It follows that the action succeeds and the counterclaim will be dismissed.”

[1] [2011] EWHC 2403 (Patents Court Sept. 30, 2011



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