Regeneron Pharmaceuticals v Kymab [2020] UKSC 27
In a landmark ruling on the law of sufficiency, the Supreme Court (Lord Briggs giving the leading judgment) overturned by a 4-1 majority the judgment of the Court of Appeal (Kitchin LJ, Arden LJ and Floyd LJ), thereby restoring the decision of the late Henry Carr J that Regeneron’s patents were invalid.
The case concerned transgenic mice intended to produce a variety of antibodies when challenged by antigens. The purpose is to identify effective antibodies which may become candidates for vaccines in humans. Immunoglobulin genes contain ‘variable’ and ‘constant’ segments. The recombination of the variable segments in B-cells is what produces variation in antibodies. The patents envisaged the replacement of the variable segments in the murine immunoglobin gene with human variable segments, leaving the murine constant segments in place. This was referred to as producing a ‘reverse chimeric locus’. By replacing only the variable segments, and leaving the mouse constant segments in place, the patents envisaged that the mice would be more productive, and lack the ‘immunological sickness’ which had affected mice in which the entire gene locus had been replaced. However, the replacement of only the variable segments was an extremely difficult process. Whilst the patents alleged that the method disclosed was capable of replacing all the murine variable segments with the corresponding human ones, it was not in fact able to do so.
The Court of Appeal held (reversing the trial Judge on the facts) that the skilled person could nonetheless have managed to insert a very small number of human variable segments using methods which were part of the common general knowledge at the time. They went on to hold that this was enough to justify the claims of the Patents even though those claims covered the whole range of mice with a reverse chimeric locus, including mice which had the entire human variable locus. They considered that the reverse chimeric locus was a ‘principle of general application’ from which all mice within the claim would ‘benefit’ as and when they could be made, and therefore the patentee was entitled to a monopoly over all such mice.
The Supreme Court rejected the idea that the disclosure of a beneficial principle of general application exempted a patentee from the well-established requirement that a claim must be enabled across substantially its whole scope. References to principles of general application in earlier authorities had been to principles which actually enabled the invention to be implemented. Similarly a patentee’s technical contribution for the purpose of the law of sufficiency was the ability to make the product which was the subject of the claims, not some other underlying inventive concept. Whilst it did not matter that the present claims were not limited so as to exclude irrelevant characteristics which the skilled person was not able to produce (such as very long tails), the number of human variable segments was an important characteristic which went to the very purpose of producing the mice, namely the creation of a multitude of different antibodies. Having not enabled the production of mice at the most desirable end of the range, Regeneron was not entitled to claim such mice. As a result the patents were invalid for lack of sufficiency.
The Supreme Court emphasised the importance of the patent ‘bargain’ between the inventor and the state which grants the monopoly, and in particular the fact that the enablement of the implementation of the invention must correlate with the scope of the monopoly. The Court of Appeal had tilted the balance of patent protection too far in favour of inventors by removing this correlation. The policy factors which had influenced the Court of Appeal, in particular the concern that inventors may be denied effective protection and reward for their work, did not justify watering down a principle which formed part of the ‘bedrock of the law, worked out over time both in the UK and by the EPO, which is essential to prevent patentees obtaining a monopoly which exceeds their contribution to the art.’
Iain Purvis QC represented the successful appellant, Kymab Limited, in the Supreme Court.