In a blow for Regeneron Pharmaceuticals, the UK Supreme Court this summer reversed a Court of Appeal decision by ruling that its patents relating to transgenic mice are invalid due to lack of “sufficiency”.

In 2001, Regeneron Pharmaceuticals filed patents for transgenic mice, which are used to produce antibodies for the treatment of humans. Thirteen years later the company sued Kymab when it produced its own genetically modified mice, for an infringement of its patents.

Kymab contested the validity of the patents, on the grounds of “insufficiency”. It is a requirement of UK patent law and of the European Patent Convention (EPC) that a patent application has to disclose an invention in a manner which is sufficiently clear and complete for it to be carried out by a person skilled in the art (article 83 of the EPC and section 14[3] of the Patents Act 1977).

It argued that in the years since the original patents had been filed, it had become possible to create more advanced and medically useful transgenic mice, which were not covered by Regeneron’s patents.

The High Court and the Court of Appeal upheld the patents, however, saying there was no need for the patents to explain how to make a full range of transgenic mice because Regeneron’s idea was a “principle of general application”.

The courts ruled the idea contributed to the art by its use not only in products that could be made at the priority date, but also relating to products that were capable of being made only in the future. Ultimately, the Court of Appeal thought it was unfair to restrict

Regeneron’s monopoly to types of hybrid mice which could be made only when the patent was filed. Kymab appealed this decision in the Supreme Court.

Sufficiency principles

Following a detailed review of UK case law and the EPC in relation to sufficiency, the majority of the Supreme Court found on June 24 that it could not agree with the Court of Appeal’s analysis. The Supreme Court outlined eight principles in relation to sufficiency, including that the disclosure required in the patent must be sufficient to enable the notional skilled person to make substantially all the types or embodiments of products within the scope of the claim.

In addition, the court held that sufficiency cannot be established merely by showing that all products within the range will, if and when they can be made, deliver the same general benefit intended to be generated by the invention.

The Supreme Court considered that, when these principles were applied in this case, it clearly failed. Although the Supreme Court considered that the Court of Appeal’s analysis had an internal logic, it held that it did not follow the established case law and was not a legitimate development of the law.

The Supreme Court ruled that the patent did not disclose sufficient information so that a full range of transgenic mice could be produced and agreed with Kymab that the most valuable transgenic mice could not be made using Regeneron’s patents.

The Supreme Court’s finding confirms that the law in relation to sufficiency remains unchanged. The bargain for obtaining a monopoly requires the disclosure of information sufficient to enable the reproduction of the invention across the entire range of claimed products.

The judgment does, however, leave applicants with inventions featuring a principle of general application in a potentially difficult position. Applicants can include a range of products within a claim, but if the disclosure in the patent is not enough to enable the skilled person to create products across the whole range, by the priority date, they will risk a finding that the claim is invalid due to insufficiency.

However, if they restrict their claim to those products within a range that are clearly enabled by the patent specification, they run the risk that others may be able to circumvent their patent claims. This may be done if rivals produce products that use the principle of general application disclosed in the patent but fall outside the types of product claimed for.

In addition, unless the applicant is the first person to work out how additional types of product using the general principle can be made, it leaves room for others to register patents for products.

They may use the general principle, if they overcome the hurdle of “inventive step”, which may include variants that are more effective than the original products, leaving the original invention with limited commercial value.

David Fyfield is an associate in the IP team at Charles Russell Speechlys. He can be contacted at david.fyfield@crsblaw.com

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