Michael Conway acted on the counsel team for Astellas, one of the appellants in this appeal against the judgment of Lord Justice Arnold in [2020] EWHC 866 (Pat) concerning six patents in two families (referred to as Family A and Family B).
The Patents claimed the use of compounds with broadly defined structural features that inhibited an enzyme, HIF-PH, for use increasing endogenous EPO in the treatment of anaemia. In the first instance decision Arnold LJ, sitting in the High Court, had held all of the patents invalid for insufficiency, finding that they were not plausible across the scope of the claim (and were Agrevo obvious for the same reason), and that the invention could not be worked across the scope of the claims without undue burden. He further found the claims of the Family B patents were obvious over the Family A application, that the claims of Family A would be infringed by Akebia’s product (“vadadustat”) on a normal construction if those claims were valid, and that there was no current threat to infringe the Family B patents even if they were valid.
In this appeal FibroGen and Astellas challenged the conclusions on insufficiency and Agrevo obviousness in relation to both patent families, and challenged the conclusion that Family B is obvious over the cited prior art.
Lord Justice Birss gave the principal judgment of the court, with which Sir Christopher Floyd and Lord Justice Phillips agreed. Birss LJ disagreed with the judge’s conclusion on reasonable prediction/plausibility and allowed the appeal on the sufficiency of the Family A patents both in relation to breadth of claim and uncertainty, at least in relation to one of the patents in that family, with the result that that patent is valid and would be infringed by vadadustat to treat chronic kidney disease anaemia. The appeals on obviousness of the Family B patents and on the finding that vadadustat was within the relevant chemical definition for Family A were dismissed.
Sir Christopher Floyd noted in his judgment that the test for undue burden is not the cumulative burden of identifying and testing for efficacy all the compounds covered by the structural formula, or even by the functional requirements of the claim; had the judge approached the question of undue burden correctly then he would have found that the patents met the test for sufficiency.