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Merck Sharp and Dohme Limited v Shionogi & Co. Limited, High Court of England and Wales (Arnold J), 25 November 2015, Neutral Citation Number [2016] EWHC 2989 (Pat)

The claimant, Merck, sought revocation of Shionogi’s EP(UK) 1 422 218. The defendant, Shionogi, counterclaimed for infringement by Merck’s integrase inhibitor raltegravir, marketed as Isentress. Shionogi made an unconditional application to amend the patent, so that the claims conformed to the claims that had been upheld by the EPO in parallel opposition proceedings, and also made two conditional amendment applications.

Merck argued that the patent was invalid for lack of inventive step, insufficiency and added matter. In particular, Merck contended that the claims, both as granted and as proposed to be amended, made no technical contribution to the art, along the lines of the EPO Technical Board of Appeal decision in T 939/92 AgrEvo/Triazoles [1996] EPOR 171.

The formula found in Claim 1 of the amended claims in particular was said by Merck’s expert witness, Professor Neamati, to cover some 10^39 possible compounds. Merck argued that this figure should be borne in mind when assessing plausibility. The judge considered that, in the light of all the evidence, it was at best only plausible that a tiny fraction of the possible compounds would have the desired effect (integrase inhibition). The fact that claim 1 also included a functional limitation did not detract from the proposition that the question of plausibility had to be assessed having regard to the number of compounds which fulfilled the structural requirements. The scope of the monopoly claimed was not justified by the extent of the technical contribution to the art. Claim 1 (as unconditionally proposed to be amended) was therefore invalid for lack of inventive step. The court further held that the proposed conditional amendments would not have affected this conclusion.

On Insufficiency, Merck made two distinct arguments. The first was that the specification did not enable the claimed inventions to be performed over the whole scope of the claim without undue burden; specifically, the disclosure of the patent did not make it plausible that the invention would work across the scope of the claims. The court held, first that the specification of the patent did not make it plausible that substantially all of the claimed compounds would possess integrase inhibitory activity; still less that they would be useful for preventing or treating a viral disease. On the contrary, the formula of claim 1 covered large groups of compounds that were unlikely to have these characteristics.

Furthermore, the patent presented the skilled team with a “vast research project with a high likelihood of failure” but claimed any product that turned out to work, even if that success was not attributable to the teaching of the patent. It was therefore held not to be possible to perform the invention across the scope of the claims, which were accordingly held to be invalid for insufficiency.
The added matter objection failed. Consequently, the Patent was found invalid on the bases of lack of inventive step and insufficiency, but not added matter.

Finally, it is worth noting that the judge considered that counsel on both sides were guilty of being overly critical in their cross-examination of the expert witnesses, particularly with regard to what counsel sought to portray as material omissions from the experts’ reports. The judge considered, citing his own earlier comments in Medimmune v Novartis [2011] EWHC 1169 (Pat) that, as the court is rarely aware of the full scope of the instructions given to an expert witness it, opposing counsel should hesitate to criticise a witness for an omission “… unless it is clear that the fault lies with the expert rather than those instructing him.” The judge went on to comment that “… generally, in my experience too much time is spent by cross-examiners in patent cases on ad hominem attacks that are unfair to the witness, unhelpful to the court and waste expensive time.”

A copy of the judgment can be read here.

Peter Lyons and Graham Burnett-Hall, Marks & Clerk Solicitors LLP