Charlotte May KC appeared on behalf of two sets of defendants (“Teva” and “Sandoz”) in patent infringement proceedings brought by the claimant (“Astellas”). Teva and Sandoz sought to revoke the patent on grounds of: (i) insufficiency; (ii) obviousness; and (iii) added matter.
The patent related to a modified release (“MR”) formulation for a drug, mirabegron, used to treat overactive bladder (OAB). It aimed to mitigate the ‘food effect’, whereby the rate and amount of a drug absorbed differs depending on whether it is taken with food. Requiring a drug to be taken before or after eating is known to reduce patient compliance.
Mellor J upheld the validity of the patent. On insufficiency, he found that the disclosure in the patent made it plausible that the food effect would be reduced when the formulation allowed for four hours or more drug absorption. This was the case across the breadth of the claim, which specified limits on how fast the formulation could dissolve.
Obviousness was considered in light of prior art ‘Fix’, and ‘Michel’ (intended to be read with or without another piece of prior art, ‘Chapple’). Both concerned ‘OCAS’, an MR formulation for another drug. The judge held the patent to be non-obvious over Fix: although some of the formulations disclosed in Fix would fall within the claim if adapted for mirabegron, the skilled person would only know this after in vivo testing (thereby involving hindsight). Similar reasoning applied to Michel.
One of the defendants’ added matter attacks fell away with a conditional amendment and the other was abandoned towards the end of trial, having served a tactical purpose in restricting Astellas construction of the claims.
However, the judge found that Astellas had failed to prove infringement because there was no evidence (either directly or by inference via expert evidence) that Sandoz Mirabegron reduced the food effect as required by the claim. Whilst Teva admitted that their original product infringed, the issue of infringement of their revised product was not ready for trial and remains to be determined.