UK Supreme Court upholds Kymab's appeal imposing a stricter interpretation of sufficiency of disclosure for patents

This decision will have a profound effect on the validity of many patents, particularly in the life sciences area, especially in biotech. The decision flows from the requirement under the European Patent Convention (of which the UK is a contracting state) that a patent provide sufficient disclosure of the invention it claims. This means that the patent must contain enough information for its invention to be reproduced by others without due burden. This basic principle has proved difficult to apply to patents with claims that may cover a range of products. Should a patent's monopoly be restricted to the specific information it provides or can the monopoly be broader if the patent discloses enough to make some of the product types in the range? Earlier English decisions, influenced by the European Patent Office case law, had allowed broader claims in circumstances where the products may all be produced using a principle that is of general application even if the patent does not disclose specifically how to make each type. 

By its decision today the Supreme Court has firmly confirmed sufficient disclosure as a basic ingredient of the 'patent bargain' which is understood to be the justification for patent monopolies. The monopoly is granted for a limited time in exchange for the patent holder providing (in the patent) sufficient information to allow the subject of the monopoly to be used by the public – once the monopoly expires.

As explained below, Regeneron's patents covering transgenic mice were said by Kymab to be over-broad, covering transgenic mice beyond those made possible by the teaching in the patents. Regeneron's case was that the patents disclosed a principle of general application for how to produce improved transgenic mice and this principle justified broader monopolies. For further details of the arguments put forward during the hearing in February, see our earlier report here.

The patents covered transgenic mice that were better for producing anti-bodies than previous transgenic mice, and methods for producing such mice. Transgenic mice for producing human antibodies had been produced previously by introducing into the mice's DNA the complete human gene sequence for the desired antibody. The antibodies thereby produced by the mice would be less likely to cause adverse immunological reactions in humans than antibodies produced from mixed human and mouse (murine) DNA. These were particular reactions known as 'HAMA' responses – human anti-mouse antibody responses. However, transgenic mice with full human antibody DNA sequences became "immunologically sick", meaning that they produced less effective antibodies compared with unmodified 'wild type' mice. Regeneron's researchers apparently solved these problems by producing transgenic mice with mixed human-murine DNA sequences for the antibodies and later modifying the antibodies produced by the mice in order to replace the murine portions with human portions, avoiding the HAMA response. These mice had what was termed a "reverse chimeric locus" in their DNA, whereby part of the human antibody DNA referred to as the 'human variable sequence' was replaced with a mouse variable sequence. The mice did not suffer significant immunological sickness and the HAMA response was avoided as well.

Kymab's case stemmed from the level of detail provided in the patents about how to introduce the reverse chimeric locus into the murine DNA. This had to be done in a precise, targeted way which Kymab argued left too much to the reader of the patents to do for themselves. Specifically, the patents' claims covered a wide range of sequence lengths and Kymab argued the skilled reader of the patents could not achieve the introduction of the reverse chimeric locus into the murine DNA across the whole range of what was covered at the relevant date.

In the end, the outcome here depended on the Supreme Court's analysis of what the monopoly was and what was required to enable it. The Court considered the monopoly was a range of product types (mice with different length reverse chimeric loci). In part this was because "murine immunological health is not an end in itself. It is a means to a different end" (paragraph 22), the "different end" being the effective production of antibodies from transgenic mice not suffering from immunological sickness.

What had to be enabled, therefore, was the making of mice with reverse chimeric loci across substantially the whole range – from short loci to long loci. The Court of Appeal had been in error on focussing on the benefit that the reverse chimeric loci gave (reduced immunological sickness) because this was not the subject of the monopoly.

Thus while it was correct that the reverse chimeric loci was a generally applicable principle for achieving reduced immunological sickness in transgenic mice, that did not enable the production of mice across the scope of the monopoly. What was required was disclosure of how to make such mice, i.e. how to introduce the reverse chimeric locus into the mouse DNA for the whole range of loci lengths. 

The evidence showed that at the priority date it would only have been possible, using the information in the patent and the common general knowledge, to introduce reverse chimeric loci at the shorter end of the range into the mouse DNA. Achieving this with longer loci only came later.

The Supreme Court was perhaps influenced by the evidence that longer reverse chimeric loci were preferable for producing the most reduced immunological sickness. Thus although the reasoning of the majority sought to focus on the actual monopoly claimed, the benefit achieved by the invention covered by the monopoly still featured strongly in their analysis. In setting out general principles for future cases, however, the Court was clear to differentiate between disclosure required to make products across the range and whether products from across the range, once made, will possess the benefits of the invention. Showing the latter is not enough to establish that the patent is sufficiently disclosed.

The Court's statement of the general principles of sufficient disclosure for future cases are found in paragraph 56 of the judgment.  Of particular interest are sub-paragraphs (ii), (iv) and (viii). These make clear that for a product claim, the contribution of the patent is to be equated with the ability to make the product, that the disclosure must be sufficient to enable substantially all the types of the product covered to be made at the priority date and that it is not good enough to show instead that all the products in the claimed range have a benefit generated by the invention.

Lord Briggs' judgment did not show any lack of awareness as to the possible consequences of this judgment for innovation. He said that it may well be that "the consequences … [will be to] give the patentee scant and short-lived reward for their efforts and ingenuity, viewed in particular with the benefit of hindsight" (paragraph 60). However, the Court regarded this as a consequence of the law as they saw it, settled by earlier authorities and clarified here.

A dissenting judgment was delivered by Lady Black. In essence, she disagreed with the majority's focus on the making of products across the scope of the monopoly and focused herself more on the contribution made by the invention – i.e. the benefit provided by the reverse chimeric locus. This was possessed by transgenic mice across the range of the invention. Regeneron had claimed a monopoly which "coincides with the technical contribution of the patents which was to solve the problem of immunological sickness" (paragraph 86). Lady Black's analysis echoes that of the Court of Appeal which whom she expressly agreed.

This decision will have important consequences for patent holders and applicants in the UK (and potentially across Europe) particularly in the life sciences field where a range of product types may be covered by a patent's claims. An important ingredient in the Court's decision is recognition that Regeneron's monopoly was one that covered a range of product types rather than a single product, thereby requiring disclosure that would enable production of each type of product. A further important ingredient was the recognition that the although one benefit of Regeneron's invention was achieved across the full range claimed, that benefit was not the subject of the monopoly. The monopoly related to making transgenic mice and the relevant range for considering sufficiency was the range of transgenic mice that could be successfully made using the patent's teaching at the time. Although later it was discovered how to make mice across the full range and those mice had the same benefit, that did not justify the claimed monopoly.

By re-enforcing the importance of the requirement for sufficient disclosure, the Supreme Court makes clear that a patent's monopoly and teaching must correspond. Specifically, the correspondence be between providing the information needed for others to make products across the monopoly, not to a monopoly believed to correspond to the range of products that will possess the same benefit but which cannot yet be made. 

A point of interest on this decision is that the Court of Appeal's decision, which the Supreme Court overturned was given by Lord Kitchin who was appointed to the Supreme Court in October 2018 a few months after this decision. Lord Kitchin is the career patent specialist to be appointed to the Supreme Court yet was unable to participate in this decision because of his presence on the previous role in deciding the case. The other Supreme Court justices have not shied from disagreeing with their new colleague's interpretation of the law, which had itself overturned the decision of the first-instance judge, Henry Carr J.