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04 Aug 2020
BY Rowan Forster

Genetically modified mice and the patent bargain

South African patent law is derived from, and therefore quite similar to, British patent law. The recent judgment of the UK Supreme Court about the patenting of transgenic mice is therefore worth discussing. Not least because it reminds us just why it is we have a patent system.

The judgment is Regeneron Pharmaceuticals Inc v Kymab Ltd. This case involved patents for a new type of genetically modified mouse. The innovation here was a hybrid version of the gene that produces antibodies, combining a section of the mouse’s genetic material (the ‘constant region’) with a section of genetic material from a human (the ‘variable region’). The resulting mouse can produce antibodies which are suitable for medical treatment in humans, but are sufficiently similar to mouse antibodies that they do not cause immunological reactions in the mouse. 

The patentee, Regeneron, claimed that its patents had been infringed by Kymab and sued for patent infringement. Kymab responded by claiming that the patents were invalid because they were not detailed enough to enable scientifically skilled readers to make the invention themselves – a defence known as “lack of sufficiency”. The case started off in the High Court, progressed to the Court of Appeal, and finally ended up in the Supreme Court.

The High Court found in favour of Kymab. The judge said that “the skilled person would not have been able to perform the invention over the whole areas claimed without undue burden and without needing inventive skill”. The Court of Appeal, however, took a different approach. It held that the patents contained enough information to insert some of the human material into a mouse’s genes. It said that the patents were valid because they related to a “principle of general application” and did not require any teaching to make products commensurate with the scope of the claims. There was no need for the patents to explain how to make the full range of mice – put differently the patent didn’t need to do more than explain how to make mice having a very small section of the human variable region.

The Supreme Court was split. The majority view was that the patents did not enable a skilled person to make mice containing more than a very small section of the human variable region. Consequently there was insufficient disclosure - antibodies and mice of a more valuable type could not be made using Regeneron’s patents.

There was much emphasis in the majority judgment on the principle of sufficiency. This provision comes up in Article 83 of European Patent Convention, which reads: “The European patent application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art”. This proviso is mirrored in Section 14(3) of the UK Patents Act.

Both these pieces of legislation make it clear that there are consequences for failure to comply. Section 72(1)(c) of the UK Patents Act, for example, says that if “the specification of the patent does not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art,the patent can be revoked”.

The Supreme Court went on to make a number of points about the principle of sufficiency:

  • The requirement of sufficiency exists to ensure that the extent of the monopoly conferred by the patent corresponds with the extent of the contribution which it makes to the art.
  • In the case of a product claim, the contribution to the art is the ability of the skilled person to make the product itself.
  • Although patentees are at liberty to frame the range of products for which they claim protection as broadly as they choose, they must ensure that they make no broader claim than is enabled by their disclosure.
  • The disclosure required must, together with the general knowledge existing as at the priority date, be sufficient to enable the skilled person to make substantially all the types or embodiments of products within the scope of the claim.
  • A claim which seeks to protect products which cannot be made by the skilled person using the disclosure in the patent will exceed the contribution to the art made by the patent.

This judgment is a useful reminder of what is sometimes referred to as the “patent bargain”, something that is at the very heart of the patent system. The bargain goes something like this: patents exist as an inducement to inventors to invent; the inducement takes the form of a monopoly for any invention that is both new and inventive; the monopoly will be time-limited (usually 20 years); during this period the patentee will have the exclusive right to use the invention; this exclusivity gives the patentee the opportunity to both recoup the cost of the research and development and to make a meaningful profit; at the end of the 20-year period the exclusivity ends and the patent falls into the public domain, thus becoming available to everyone and benefiting society as a whole. It’s something worth remembering, given that there can be some scepticism about patents, most notably in the field of pharmaceuticals.


Rowan Forster

Executive | IP

+27 83 440 3170