In the Patents Court of England & Wales, Mr Justice Carr has recently decided on the infringement and validity of two patents that relate to transgenic mice used as platforms for therapeutic antibody discovery. The case is Regeneron Pharmaceuticals Inc v Kymab Limited & Novo Nordisk A/S [2016] EWHC87 (Pat) and the patents in dispute were Regeneron's Patent (UK) No 1,360,287 ("the 287 Patent") and its divisional European Patent (UK) No 2,264,163 ("the 163 Patent"). In his decision of 1 February 2016, the judge dismissed Regeneron's claim for infringement of the patents and allowed Kymab's and Novo's counterclaim for revocation.

The technology protected by the patents was the replacement of mouse variable (VDJ/VJ) gene with human variable genes to produce immunoglobulin loci that will undergo the natural process of rearrangement during B cell development to produce hybrid antibodies. A locus comprising a combination of human variable gene segments and endogenous mouse constant gene segments is known as a "reverse chimeric locus". Subsequently, fully human antibodies can be made by replacing the mouse constant regions with the desired human counterparts.

The activity of Kymab that was alleged to infringe, was the offering of various strains of transgenic mice to the pharmaceutical industry, which were either per se or through the process of their production covered by certain claims of the patents. Carr J found that all strains of Kymab's mice were or would be generated from a product within the scope of claims 5 and 6 of the 287 Patent and mice strains having both modified IgH and IgK loci are within the scope of claim 1 of the 163 Patent. He nonetheless dismissed the infringement case because all of the claims of the 287 and 163 Patents were, the judge held, invalid for insufficiency.

In order to be sufficient a patent does not need to set out every detail necessary for performance of the invention, because the skilled person is entitled to use their common general knowledge to fill in certain technical gaps. However, there is a balance to be struck between ordinary steps of trial and error on the one hand, and prolonged research, enquiry or experiment on the other. In this case, the judge held the patents were insufficient because, at the priority date of the patent, the skilled person would not have been able to perform the invention over the whole area claimed without undue burden and without needing inventive skill. In particular, claim 1 of the 287 Patent was not capable of being performed at the priority date. The problem lay in the amounts of genetic sequence of which it contemplated the deletion and insertion. On the evidence, none of the methods of the 287 Patent for achieving this would have worked; the task contemplated was unprecedented and could not have been achieved, if at all, without a great deal of creative thinking at the priority date. Claims 5 and 6 of the 287 Patent and claim 1 of the 163 Patent were also held invalid for insufficiency. These were considerably wider in scope than claim 1 of the 287 Patent and so even if the judge had concluded that claim 1 of the 287 Patent was sufficient and therefore valid, he would still have concluded that these wider claims were insufficient.

The decision

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