The Patents Court has upheld the validity of Ono’s EP (UK) 1 537 878 entitled “Immunopotentiating Compositions” relating to the use of anti-PD-1 antibodies for the treatment of cancer in the face of a wide-ranging attack by Merck on the basis of added matter, priority/insufficiency/lack of technical contribution, novelty and inventive step. The Court also found infringement by Merck’s product, Merck having accepted that its product infringed if the patent was valid. Both Ono’s anti-PD-1 antibody nivolumab (brand name Opdivo) and Merck's pembrolizumab (brand name Keytruda) have obtained clinical approval for the treatment of some cancers and are in clinical trials in relation to many others. Given the life-saving nature of the therapy, Ono confirmed that it would not seek an injunction provided an appropriate royalty was agreed or awarded by the Court.
There are a couple of interesting aspects in the decision. First, one of the major issues between the parties concerned knowledge of contradictory reports relating to the inhibitory nature of the PD-1 pathway. Birss J stressed that common general knowledge of a skilled person was capable of including contradictory ideas on a subject. Ono argued that the field of cancer immunotherapy had, until the mid-2000s, been controversial; whilst there were those in the field who were more optimistic, Birss J concluded that a "history of pessimism and failure remained part" of the skilled person's thinking at the priority date.
A further key issue was that unamended claims 1 and 3 (a Swiss form claim and purpose limited product claim respectively) related to the treatment of any and all cancers in general, which had implications for the arguments of sufficiency of disclosure, priority and plausibility. Birss J noted that evidence post-dating the patent showed that anti-PD-1 therapies plainly worked or were worth investigating in a very wide range of cancers, albeit they were not promising treatments for e.g. most colorectal cancers and prostate cancer. He concluded that it was plausible that the invention would work for cancer in general: “the skilled person would not predict 100% success across the board". He further concluded that the generalisation was fair at the time, and supported by the disclosure, and indeed remained a fair generalisation today. Accordingly, the fact that anti-PD-1 monotherapy did not treat prostate and most colorectal cancers did not demonstrate a lack of technical contribution or undue burden: as Birss J succinctly put it, "the law does not require perfection".