Home: Maucher Jenkins

Intellectual Property


Patents | Trade Marks | Designs

News & Commentary

UK Court of Appeal provides welcome guidance on what constitutes a sufficient disclosure

Date: 14 May 2018


Please see an update to this case as per the Supreme Court's decision of June 2020: Supreme Court reverses Court of Appeal Decision in Regeneron v Kymab


In the Decision of Regeneron v Kymab & Novo Nordisk, the Court of Appeal has clarified what is considered sufficient disclosure of a claim to a generalised concept even if certain specific parts of the scope of the claim cannot actually be put into practice at a patents filing date.


The patents in question (European Patent (UK) No 1360287 and its divisional European Patent (UK) No 2264163) claim a new way of producing human antibodies using transgenic mice as well as the transgenic mice themselves.


Antibodies comprise variable regions, which can be tailored to specific targets, and constant regions, which form the remainder of the antibodies structure.


Previously, transgenic mice were used to produce fully human antibodies with both human variable regions and constant regions. The endogenous mouse genes were “knocked out” of the mice and the genes replaced with the corresponding human counterparts. However, it was found that mice producing fully human antibodies have a reduced immune response. In order to overcome this problem, the patents described in situ replacement of mouse variable region gene segments with human variable region gene segments, while maintaining the mouse constant regions. This creates a “reverse chimeric locus”.


Kymab argued that the patents lacked sufficiency of disclosure because the claims covered an embodiment of the invention, set out in Example 3 of the specification, which could not be carried out at the priority date. Example 3 described the deletion and replacement of a large segment of DNA and it was generally agreed that the skilled person at the priority date would not have been able to carry out the invention exactly as contemplated in the example. Regeneron, on the other hand, argued that the skilled person would be able to use his or her common general knowledge to adapt the technique to supplement the teaching of the patent and arrive at the invention, e.g. through creating a “minigene” and inserting this rather than the entire gene.


The Court of Appeal sided with Regeneron and was of the opinion that the skilled team, equipped with the common general knowledge, could have produced without undue effort a transgenic mouse falling within the scope of the claim.


It is well-established that the skilled person is not bound to carry out the invention precisely as described and can use the common general knowledge to perform the invention and make any obvious changes that may be necessary, provided of course that any work involved is not undue.


The skilled person would have regarded the implementation of Example 3 as extremely challenging and in these circumstances the obvious thing to have done would have been to shorten the inserts. The team would also have understood that there was no need to carry out deletions in the same step as insertions, and that any necessary deletions could be effected without undue difficulty in a later and separate step.


The law does not require a patentee to enable each and every embodiment of a claimed invention . . . were protection to be limited to only those embodiments which could have been made at the priority date without undue effort, the protection provided by the patent would have rapidly become ineffectual.




In practical terms, there has been no change in the law regarding sufficiency of disclosure. There has however been a welcome clarification that the patentee can rightfully expect to be safe-guarded against unfair limitations on the scope of an invention where it applies to a general principle which could be adapted in the future in ways not possible at the priority date of a patent.