Astellas Pharma v Teva and Sandoz [2023] EWHC 2571 (Pat)
This was a claim for infringement of pharmaceutical Patent EP(UK) 2,345,410 for a modified release (“MR”) composition containing mirabegron. Mirabegron is used in the treatment of Overactive Bladder (OAB) syndrome. The Patent seeks to reduce the “food effect” which causes conventional formulations of mirabegron to show different pharmacokinetic effects in fed and fasted patients. The Defendants’ generics were alleged to infringe the Patent under a purposive construction. The trial followed an earlier action for revocation brought by Teva and Sandoz, whereby Astellas’ patent for the use of mirabegron in the treatment of OAB was found valid and infringed ([2022] EWHC 1316 (Pat), upheld on appeal).
Sandoz did not admit infringement. Teva admitted infringement of their Original Product, and the issue remains to be determined in relation to the New Teva Product. The Defendants counterclaimed for revocation of the Patent on the grounds of obviousness over three prior art citations, added matter and insufficiency (excessive claim breadth, including lack of plausibility, and uncertainty).
Following trial before Mr Justice Mellor, the Patent was found to be valid but not had not been proved to be infringed by Sandoz. The court also held that, if the Judge was wrong on the issue of construction, the Patent would be invalid for obviousness over two prior art citations relating to oral controlled absorption systems.
The case focused on the correct construction of the phrase “a pharmaceutical composition for modified release” in claim 1 and, in particular, on whether this integer required a reduction in food effect. The judgment included interesting comments on the extent to which construction of a patent claim should be influenced by findings on sufficiency and/or by the definitions of terms within such claim which are expressly provided in the Patent. The Judge regarded the voluntary inclusion of such definitions by the patentee as relevant and proceeded to construe the claim accordingly.
The judgment also includes a careful application of the relevant principles surrounding plausibility as a standard of sufficiency. Mellor J reinforced the test of “some reason for supposing” threshold for plausibility, as well as the distinction between structural and functional claim limitations and the three-step test laid down by the CA in FibroGen v Akebia. Further, the court emphasised the fact that arbitrary limitations in claims do not lead to insufficiency, provided the Patent promise is delivered up to that limit.
Anna Edwards-Stuart acted as junior counsel for the Claimant, instructed by Hogan Lovells Int. LLP.