29 June 2020
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On 24 June 2020, the UK Supreme Court (UKSC) confirmed the UK courts’ strict approach to sufficient disclosure in Regeneron Pharmaceuticals Inc (Respondent), vs Kymab Ltd (Appellant) [2020] UKSC 27.

In their decision, the UKSC overturned the findings of the Court of Appeal and invalidated both of the EP(UK) patents at issue for insufficient disclosure. In particular, the UKSC emphasised that a claim to a product claim lacks sufficient disclosure if it is not possible at the priority date to make substantially all the products that fall within the scope of the claim.

The issue

The technology of the patents at issue concerns transgenic mice. Mice that are genetically engineered to produce human antibodies display reduced immune responses and are immunologically sick. The inventors found that this immunological sickness can be prevented by replacing mouse antibody variable regions with human antibody variable regions, so that, instead of human antibodies, the mice express hybrid antibodies containing human variable regions and mouse constant domains. The increases the usefulness of the transgenic mice in therapeutic antibody drug discovery.

Importantly, although the claims of the patents at issue did not explicitly recite a range, the UK courts interpreted them to cover a range of types of transgenic mouse, from those in which just one of the many antibody variable regions in the mouse is replaced to those in which all of the antibody variable regions in the mouse are replaced.

It was not technically possible at the priority date to replace large numbers of mouse antibody variable regions with human variable regions in a single mouse, so sufficient disclosure was a key issue in the case

History of the case

At first instance, the judge found that it was not possible at the priority date to make any mice that fell within the scope of the claims, so the claims were not enabled and the both EP(UK) patents at issue were invalidated for lack of sufficient disclosure.

In contrast, the UK Court of Appeal (CoA) found that it was possible to make some types of mouse that fell within the range of the claims at the priority date, even though it was not possible to make all types of mouse across the whole range. The CoA ruled that the requirement for a sufficient disclosure was fulfilled in these circumstances because all the mice that fell within the range of the claims would display the benefit of the invention in avoiding immunological sickness, whereas this benefit would not be displayed by mice falling outside the range of the claims.

The factual findings of the CoA were not challenged in the appeal to the UKSC, so the sole issue for consideration by the UKSC was whether or not the sufficient disclosure requirement in the UK is fulfilled if a patent enables the skilled person to make some (but not all) of the products that fall within the scope of the claim, in circumstances when the benefit of the invention would apply to all of the products that fall within scope of the claim, if and when they could be made.

The findings

In giving the majority opinion, Lord Briggs observed that European and UK legal authorities concur that the principle of sufficient disclosure ensures that the extent of the monopoly conferred by the patent corresponds with the extent of the contribution which it makes to the art. This is sometimes referred to as the patent bargain.

In identifying the “contribution to the art” made by the patents at issue, the UKSC took the rather unusual and dogmatic view that the “contribution to the art” of a product claim is the ability to make the product and is not concerned with whatever the actual invention might be. From this starting point, if a claim covers products that cannot be made at the priority date, then it is inevitably broader than the “contribution to the art” made by the patent and is therefore invalid for lack of sufficient disclosure.

Focussing the “contribution to the art” on the ability to make the product meant that the UKSC was able to dismiss the patentee’s arguments that the “contribution to the art” related to the prevention of immunological sickness and this contribution was commensurate with scope of protection because all mice within the claims would display the preventative benefit.

Since the claims at issue were directed to a product (“a mouse”) and it had already been established that it was not possible to make all types of mouse across the whole range of the claims, this focus on the ability to make the product meant that the UKSC were able to swiftly invalidate the claims as exceeding the “contribution to the art” made by the patent and lacking sufficient disclosure.

In a dissent, Lady Black criticised the majority view for focussing on the range of mice and the quantum of genetic material replaced, rather than the reverse chimeric locus as a general principle for preventing immunological sickness.

Summary

This UKSC decision illustrates the increasingly strict approach now taken by the UK courts to sufficient disclosure. In particular, UK courts may seek to divide broad claims into different notional portions and assess each portion individually as to whether it can be performed by a skilled person. If any individual portion can be identified that is not enabled for any reason, this is likely to mean the downfall of the whole claim. This is likely to make it harder to assert patents and may cause innovative businesses to review the value of broad patent claims and patent applications that are filed in advance of supporting data.

Nick is a Partner, Patent Attorney and Litigator at Mewburn Ellis. He works across the full range of patent activity in the life sciences sector, from pre-drafting advice and drafting of applications to worldwide portfolio management, prosecution and appeal. Nick is also experienced in defensive and offensive European oppositions and due diligence work.
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