Michael Tappin KC, Tom Moody-Stuart KC and James Whyte successfully represented the Claimants (“Gilead”) in a claim for the revocation of the UK designation of two European patents (the “Patents”) belonging to the Defendant (“NuCana”). The claims of the Patents, which are of the same family, were product claims defined by a Markush formula that cover certain modified nucleoside analogues. NuCana had counterclaimed for infringement of its Patents by the use of the compound sofosbuvir in Gilead’s anti-viral products. The issue at trial was validity.
Meade J held that that the Patents were invalid for the following reasons: 1) Added matter: the unconditional and conditional amendments to the Patents that deleted various substituent groups were not mere reductions leaving the same generic class differing only in size, but disclosed a new class of compounds that were not disclosed in the original applications. 2) Lack of Industrial Applicability and Plausibility: it was not plausible that substantially all the compounds within the claims would have anticancer activity. Moreover, for a significant number of compounds within each of the claims in issue, there is no meaningful anticancer activity. 3) Undue Burden Insufficiency: taking primary and secondary evidence into account, there was undue burden involved in making compounds that were precursors for making some of the compounds of the claims.