The Supreme Court addresses sufficiency
Regeneron v Kymab [2020] UKSC 27

Yesterday, the Supreme Court made up of Justices Lord Reed, Lord Hodge, Lady Black, Lord Briggs and Lord Sales handed down the eagerly awaited judgment in Regeneron v Kymab, allowing Kymab’s appeal by a majority of four to one (Lady Black dissenting).  The judgment addresses the law on sufficiency in relation to product claims that cover a range of embodiments, and the extent to which a patentee may seek to rely on principles of general application.  Reversing the Court of Appeal’s decision on sufficiency, the Supreme Court found the Regeneron patents insufficient because the patents in question only enabled the skilled person to make products across what it assessed to be a small part of the deemed relevant range within the scope of the claims.

The facts

The decision concerns two Regeneron patents: EP 1 360 287 (EP’287) and divisional EP 2 264 163 (EP’163), which relate to transgenic mice that contain hybrid genes (the so-called “Reverse Chimeric Locus”) allowing them to produce antibodies with both a human variable region and a mouse constant region. Broadly speaking, EP’287 claims methods of producing mice which possess human immunoglobulin variable gene sequences, while EP’163 claims the product – the mouse itself.   The mice in question are capable of a stronger immune response and produce better quality antibodies than “immunologically sick” transgenic mice in which both the variable and constant regions are replaced with human genes and which generally do not produce good quality antibodies.  It was common ground before the court that the validity of all the product claims in question turned on the validity of claim 1 of EP’163, which claimed a range of genetically engineered mice, all of which would produce hybrid antibodies and contained a Reverse Chimeric Locus in their genome.

Supreme Court

The question before the Supreme Court was whether EP ‘287 and EP 163 were insufficient because, Kymab argued, they did not enable the ordinary skilled person to work the claimed invention across the breadth of the claims. A brief summary of the Patents Court and Court of Appeal decisions can be found towards the end of this article.

Before the Supreme Court, Regeneron argued that the existence of a range of mice covered by claim 1 was irrelevant to the question of sufficiency, because the unique advantage conferred by the use of the Reverse Chimeric Locus, namely the reduced immunological sickness of the claimed transgenic mouse, worked across the whole range, regardless of the amount of human variable region DNA that had been inserted into the mouse genome.  By contrast, Kymab argued that a mouse that had only a small number of segments from the human variable region would have only a limited potential to produce useful antibodies.  The Supreme Court found there to be truth in both these submissions but concluded that the improved immunological health of the claimed mice was a means to an end, namely the production of antibodies for eventual use in treating human disease.  The number of human variable gene segments within the mouse was therefore a “relevant range” for the purpose of determining sufficiency.

In describing the essential patent bargain in relation to a claim for a range of products, the court used the analogy of a patent that claimed five types of product (A to E), with separate claims in relation to each type of product.  If the disclosure of the patent enabled product types A and B, but not C, D and E, then claims to A and B would be valid and the remainder invalid.  If, instead, all five products were covered by the wording of a single claim, then using a general claim in this way should not enable the patentee to obtain a monopoly for the making of products C, D and E.  The Supreme Court held that the Court of Appeal had departed from this basic position, justifying its decision on the basis that where the invention consists of a new generally applicable principle, such a principle may contribute to the art in products that could be made at the priority date, but equally in products which will only be capable of being made in the future.

The Supreme Court considered the authorities from the EPO’s Technical Boards of Appeal (the “Board”) and from the UK courts, finding that the case bore “obvious similarity” to the issues in Exxon/Fuel Oils (T 409/91).  In Exxon, Exxon had claimed fuel oils containing suspended wax crystals with a range from 1 nm to 3,999 nm,   with smaller crystals less likely to clog filters in diesel engines.  However, the teaching of the patent did not enable fuel oil to be made with a wax crystal size smaller than 1,000 nm.  The Board defined the sufficiency requirement, stating that “the disclosure of the claimed invention is only sufficient if it enables the skilled person to obtain substantially all embodiments falling within the ambit of the claims.”  Even if the invention did disclose a general principle, this made no difference. The invention was not enabled by the disclosure in the patent at the more beneficial end of the range.

The Court also considered Unilever/Detergents (T 435/91), in which the Board had stated that in order to qualify as a general principle, the specification in the patent must disclose “a technical concept fit for generalisation which makes available to the skilled person the host of variants encompassed by the respective “functional” definition of the … claim.” The Court distinguished the facts of the present case from a line of EPO cases stemming from the decision in Genentech I/Polypeptide expression (T 292/85) where the patents were found to disclose a sufficient general principle.  In Genentech, the principle allowed the skilled person to work the relevant invention across the range of known input substances without further inventive step, and alternative input substances that were not yet known in the art at the priority date could be slotted in to make products within the scope of the claims.

By contrast, the disclosure in the Regeneron patents did not enable the skilled team to make mice with the Reverse Chimeric Locus across the whole range of human variable regions.  This was not because any of the human variable region gene locus had not yet been discovered and mapped.  The whole human variable region had already been inserted into mice, but only in conjunction with the human constant region – producing immunologically sick mice.  The limitation of the claim lay in the impossibility at the priority date of creating a mouse with a Reverse Chimeric Locus which contained more than a small part of the human variable region in combination with the mouse constant region.

Reflecting on its review of the case law, the Supreme Court set out what it considered to be the principles of the law of sufficiency [56], which can be summarised as follows:

  1. The extent of the monopoly conferred by the patent should correspond with the extent of the contribution the patent makes to the art.
  2. In the case of a product claim, the contribution to the art is the ability of the skilled team to make the product itself, rather than the invention, where these differ.
  3. Patentees are free to choose how widely they frame their claims, but need to ensure that the claim is no broader than is enabled by their disclosure in the patent.
  4. The disclosure in the patent, coupled with the common general knowledge (“CGK”) at the priority date, should enable the skilled team to make substantially all the embodiments within the scope of the claim.
  5. A claim which seeks to protect products which cannot be made by the skilled team at the priority date using the disclosure in the patent will exceed the contribution to the art made by the patent.
  6. This does not mean that the patentee must demonstrate that every embodiment within the scope of the claim has been proved to have been enabled – they may rely upon a principle of general application, if it would appear reasonably likely to enable to whole range of products within the claim scope to be made, but this bears risks.
  7. The requirement to show enablement across the whole scope of the claim applies only across a relevant range, which will be denominated by reference to a variable which significantly affects the value or utility of the product.
  8. Merely showing that all products within the range will deliver the same general benefit intended to be delivered by the invention is not enough to establish enablement across the scope of a product claim.

Applying these principles to the facts of the case, the Supreme Court held that Regeneron’s patents, when coupled with the CGK, did not enable the uninventive skilled team to make mice containing more than a small section of the human variable region.  Regeneron was claiming a monopoly wider than its contribution to the art and claim 1 therefore failed for insufficiency.

The Supreme Court concluded that the Court of Appeal’s analysis had not been a legitimate development of the law.  In particular, its view was that the Court of Appeal had been reluctant to confine a patentee with a ground-breaking invention to protection over only the range of products which were enabled at the priority date.  It further went on to say that, in so deciding, the Court of Appeal stretched its interpretation of the patent bargain and had tipped the balance in favour of the patentee and against the public and so, it illegitimately exceeded the scope for the development of the law by judicial decision making.  The Supreme Court concluded by confirming that it is settled law that “the contribution in the art is to be measured by the products which can thereby be made at the priority date, not by the contribution which the invention may make to the value and utility of products, the ability to make which, if at all, lies in the future.”

The decisions below

Patents Court [2016] EWHC 87 (Pat)

Regeneron first brought infringement proceedings against Kymab in 2013 for infringement of EP’ 287 and EP ‘163.  Kymab counterclaimed for invalidity of both patents, on the grounds that the patents were insufficient, and lacked novelty and inventive step.  In the Patents Court, the late Mr Justice Carr rejected the novelty and inventive step attacks, but revoked the patents on the basis of a lack of sufficiency.  Carr J concluded that the expert evidence showed that Example 3 of the specification, which described the insertion of human variable sequences into and the removal of murine variable sequences from the mouse genome, could not have been put into effect without undue burden by the skilled team at the priority date in February 2001.  He held that the teaching in the patent did not enable any mouse within the claimed range to be made and that therefore the invention was insufficiently disclosed.  However, he held that were the product claims valid, then Kymab would have infringed them.

Court of Appeal [2018] EWCA Civ 671

Justices Lady Arden, Lord Kitchin and Lord Floyd overturned Carr J’s decision on sufficiency, concluding that Carr J had made a series of errors of principle which undermined his decision.  The Court of Appeal held that the patents were not insufficient, but dismissed Kymab’s cross-appeal against Carr J’s finding of infringement, holding the patents both valid and infringed.

The Court held that while the method set out in Example 3 would have required the skilled team to make “unprecedented” insertions into and deletions from the mouse genome, it would have been obvious to the skilled person that they could use methods known in the CGK, alongside the teaching of the specification, to work the invention without undue effort.  The teaching of the patent allowed the skilled team to make some types of mouse within the range, but not all types across the whole range.  Specifically, the skilled person would have been able to make a hybrid gene structure with a small subset of the human segments within the variable region, but not for the whole human variable region. The Court of Appeal found that the character of the invention was such that any mouse falling within the scope of the claim and producing hybrid antibodies with human variable regions and murine constant regions would benefit from the technical contribution that EP’163 has made to the art.  The Court of Appeal relied on case law from the EPO’s Technical Boards of Appeal to hold that “a claim may embrace variants which may be provided or invented in the future and which achieve the same effect in a manner which could not have been envisaged without the invention” [231]. The Court found that the invention was a principle of general application and therefore the claims could be in correspondingly general terms [232].

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