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UK Supreme Court judgment: Regeneron v Kymab

 On 24 June 2020, the UK Supreme Court handed down its landmark judgment in Regeneron Pharmaceuticals Inc v Kymab Ltd [2020] UKSC 27 in a dispute that has been rumbling on for seven years. It was good news for Kymab and bad news for Regeneron, which saw two of its patents invalidated. For the rest of us, it’s an important case which includes key rulings on insufficiency.




This case relates to two of Regeneron’s patents: EP2264163 (the 163 patent) and EP1360287 (the 287 patent), both of which have a priority date of 16 February 2001. The patents claim the inventions behind Regereron’s VelocImmune humanized mice, which are genetically modified to produce human antibodies.Unlike the genetically modified mice that came before them, which were linked with suppressed  immune responses,  humanized mice can produce antibodies more efficiently.

Kymab Ltd later developed its Kymouse technology, which also uses genetically modified mice to produce human antibodies. In 2013, Regeneron commenced proceedings for infringement of its 163 and 287 patents against Kymab; Kymab counterclaimed for invalidity of both patents on the basis that they were insufficient.

(Those of you who are not very familiar with biopharmaceuticals might be wondering why anyone wants to make a genetically modified mouse in the first place, let alone fight over one in the courts for seven years. Put simply, these mice provide so-called “platforms” for the development of human antibodies for use in the prevention and treatment of human diseases, and antibody therapeutics have become some of the best-selling drugs in the pharmaceutical market.)

In February 2016, the High Court found that both the 163 patent and the 287 patent were insufficient as, at the priority date, the skilled person would not have been able to perform the invention across the full scope of the claim without undue burden and without needing inventive skill, and that only developments in technology since the priority date allowed the claimed invention to be worked. (This means effectively that the judge considered that the 163 patent and the 287 patent sought to protect more than Regeneron had actually invented.) Indeed, the trial judge (the late Henry Carr J) concluded that the patents did not enable any mouse within the scope of the relevant claims to be made, never mind their full range of variants. The judge also concluded that the 163 patent and the 287 patent were novel and inventive and that, if the patents were valid, they would be infringed by all strains of Kymouse. 1-0 to Kymab. Sort of.

Both Regeneron and Kymab appealed the High Court decision. Regeneron appealed the decision that both the 163 patent and the 287 patent were invalid, while Kymab cross-appealed the decision that its various strains of Kymouse would infringe the patents 163 patent and the 287 patent had they not been found invalid. 

The Court of Appeal decision handed down in March 2018 stated that the trial judge had erred in his interpretation of claim 1 of the 287 patent and that the sufficiency of the disclosure of the patents had not been properly assessed. It was found that the 163 patent and the 287 patent did indeed disclose the claimed inventions clearly enough and completely enough for some, but not all, of the mice within the scope of the relevant claims to be made by a person skilled in the art. It was held that the patents were sufficient, and that even though they did not enable all mouse variants to be made, they conferred fair protection on Regeneron because the relevant claims related to an inventive general principle. The High Court’s assessment of infringement was upheld by the Court of Appeal, and Kymab’s appeal was dismissed. Regeneron 1-1 Kymab

However, as we’ve come to expect with these sorts of cases, things did not end there, and Kymab appealed the decision to the UK Supreme Court.

UK Supreme Court Decision

The question for the Supreme Court to answer was whether a product patent passes the sufficiency test if it only enables the skilled person to make some of the products within the scope of the claim, even if the invention would contribute to the utility of all the products covered by the scope of the claim, if and when they could be made.

In its judgment on 24 June 2020, the Supreme Court took us back to the High Court’s decision of 2016, reversing that of the Court of Appeal in 2018. The consequence of this is that a patent will be found invalid if a claim covering a broad range of variants does not enable all those variants to be made. In its reasoning, the Supreme Court stated that, for a product claim, the contribution to the art (and the rightful monopoly) is the product enabled by the disclosure in the patent, and that it does not extend to other products within the scope of a claim. The judgment states that “[t]he essence of the bargain between the patentee and the public is that the patentee dedicates the invention to the public by making full disclosure of it, in return for a time-limited monopoly of its use.” The analysis in the judgment goes on to state that while patentees are free to choose how widely to frame the range of products for which they claim protection, they need to ensure that what they claim is enabled by their disclosure.

The Supreme Court stated that the disclosure in a patent should enable substantially all products within a claim’s scope to be made by the skilled person at the priority date; to make the assessment at any other date would be to protect products which could only be made at some point in the future. Patentees do not need to show that every embodiment within the scope of claim has been enabled, but if it is later found that a general principle of application does not enable the full scope of the claim, the claim will be found to be insufficient.

The Supreme Court allowed Kymab’s appeal, with the consequence that the 163 patent and the 287 patent were found to be insufficient at the priority date, and therefore invalid. Regeneron 1-Kymab 2. And Kymab gets to keep its mice.

While broad claims might sound appealing to patentees, we think that it’s quite clear from this case that they can become rather a risky business if they are too broad. Sufficiency may not be examined in detail during prosecution so a patentee may find that they are granted a patent with a broad main claim which might be novel and inventive, but which is not necessarily sufficient. In order to not find themselves in the same position as Regeneron, patentees should ensure that the claims are sufficient across their breadth; they must ensure, at the very least, what they believe they have contributed to the art is disclosed in the application in a way that would allow a person skilled in the art to work the invention and the range of alternatives that they wish to protect at the priority date.  A broad claim can be narrowed down to ensure that it is sufficient across its breadth during prosecution, but only to the extent that the information being relied upon to narrow the claim has been disclosed in the application as filed.

In addition, if there are aspects or embodiments in a later application that rely upon developments that have taken place since the filing date of an earlier application from which the later application claims priority, it may make sense to separate those aspects into different claims so that they can be dealt with separately as of the filing date. These types of considerations will be particularly relevant to highly-complex areas of technology such as biotechnology.  

(It’s worth noting that the EPO Technical Board of Appeal upheld the validity of the 287 patent, while the Opposition Division upheld the validity of the 163 patent, although proceedings before the EPO’s Technical Board of Appeal on the 163 patent are still ongoing.)


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