First up we have the UK Supreme Court decision in Regeneron Pharmaceuticals Inc v Kymab Ltd ([2020] UKSC 27). The case concerned the ongoing dispute between the parties regarding Regeneron's European Patent (UK) No 1360287 and its divisional European Patent (UK) No 2264163, relating to transgenic mice which produce antibodies for use in the treatment of humans. The issue for the Supreme Court to decide was whether or not the patent specifications provided a "sufficient" disclosure of the invention. 

Under UK patent law, "sufficiency" refers to the requirement that a patent specification must disclose the invention being claimed sufficiently clearly and completely for a skilled person (in the case of a patented product) to be able to make the product using the teaching of the patent together with the common general knowledge available at the priority date of the patent, without undue experimental burden or inventive activity. If the patent claims a range of products, then the specification must be sufficient over that range. Insufficiency of disclosure is a ground of revocation of a patent, and thus a defence to infringement.

In this case, Regeneron brought an infringement claim against Kymab, who counterclaimed that the patents were invalid for insufficiency. At first instance, the patents were found to be invalid due to insufficiency, although it was also held that Kymab would have infringed if the patents had been valid. Regeneron appealed the finding of invalidity and Kymab cross-appealed the finding of infringement. The Court of Appeal overturned the original decision and found the patents to be both valid and infringed. Kymab was granted leave to appeal to the Supreme Court. 

The technology in question is complex, and a detailed discussion is beyond the scope of this post. In broad terms, the patents related to transgenic mice for the production of antibodies for use in the treatment of humans using a "chimeric" antibody gene structure - a mouse "constant region" combined with segments from a human "variable region". The use of a hybrid gene structure allowed human genes to be inserted into the mice without them becoming "immunologically sick". The patents claimed a range of mice: from those in which only one human variable segment had been introduced, to those in which all human variable segments had been introduced (125 of them).

It was accepted that at the priority date of the patents not all of the claimed mice could be made (in fact, only a small percentage could be made at that time, with others only being possible through future technical advances developed after the priority date). Kymab argued that this was important: the more human segments which could be introduced, the greater the range of antibodies which could be produced. Regeneron argued that this was not important: the benefit of the invention (mice which can produce antibodies without becoming "immunologically sick") is provided across the entire range being claimed, regardless of whether this was through the technology available at the priority date, or at a later date following future technical developments.

Lord Briggs gave the decision on behalf of the Supreme Court. He stated that the purpose of the invention was mice which produce a stream of antibodies with human variable regions for use in treating disease in humans, and that whilst the invention does reduce murine immunological sickness, this is not an end in itself (rather a means to an end): the chimeric gene sequence is not a "principle" which enables the products to be made, but is rather the result of successfully making the products.

The issue was not that the variable segments of the human genome hadn't been mapped, or that they couldn't be inserted into the mouse genome. The issue was that at the priority date there was no known way, even using the teaching of the patent, to combine more than a very small part of the human gene sequence with the mouse sequence in the same hybrid gene structure. It took several years, and further inventive steps, before it was possible to combine the whole of the human variable region gene sequence and the mouse constant gene sequence in the same hybrid gene structure.

Lord Briggs confirmed that for product claims the question to be asked is whether the specification, combined with the common general knowledge, allows a skilled person to make <u>all the products across the range being claimed at the priority date</u>. It is not a requirement that every embodiment falling with the scope of the claims must have actually have been made at that date: a general principle of application may be disclosed which means it is reasonably likely that that the whole range of products within the range is enabled. However, it is <u>not</u> enough to merely show that all the products within the range would deliver the same benefit if/when it might be possible to make them, if they can't actually be made at the priority date (without undue burden or inventive activity). Hence, the patents were found to be insufficient, and thus invalid.

So, what are the take-home messages from this decision? The Supreme Court confirmed that patents are not just about "ideas" or "general principles", but about actual products, and processes for making them (the "reduction to practice" of ideas). Here, Regeneron had the idea, but at the priority date could only reduce to practice a small fraction of the products being claimed. Thus, patent attorneys and inventors should carefully consider whether to file a patent application early with limited data, or wait for more data to become available to justify a broader "enabled" scope of protection. The decision also serves as a reminder to applicants and practitioners to draft patent applications with optional fall-back positions, allowing the the scope of the claims to be narrowed if necessary to a sub-range which is enabled.

We now move into the arena of Supplementary Protection Certificates ("SPCs", and the recent judgement of the CJEU in Santen (C-673/18).

The basic requirements for a valid SPC to be granted for a medicinal product are that the active ingredient is protected by a valid patent, and that it has been granted marketing authorisation to be placed on the market. According to the literal wording of Article 3(d) of Regulation (EC) No. 469/2009, the marketing authorisation must be the "<u>the first authorisation</u>to place the product [i.e. the active ingredient] on the market as a medicinal product". The meaning of this requirement has long been a matter of debate, not least following the decision in Neurim (C-130/11) (in which it was decided that SPCs for new applications of a previously authorised active ingredient are available). In Santen the Paris Court of Appeal referred questions to the CJEU relating to how to apply Article 3(d) of the SPC Regulation in light of specific aspects of the CJEU's earlier Neurim decision.

In Santen, the CJEU clarified that for the purposes of Article 3(d), a marketing authorisation <u>cannot&nbsp;</u>be considered to be the first marketing authorisation where it covers a new therapeutic application of an active ingredient, or of a combination of active ingredients, if that same active ingredient or combination has <u>already been the subject of a marketing authorisation for a different therapeutic application</u>. The term "active ingredient" is to be interpreted strictly, referring to the chemical substance per se, not its use.

So, it seems that SPCs are not available for for new therapeutic applications of previously approved active ingredients. Whilst this decision will no doubt be poorly received within the pharmaceutical industry, and arguably curtails the incentives for pharmaceutical research and development, it does at least seem to provide clarity on an issue which has been a matter of debate for years.

And finally (on a more general, non-life sciences note)...much to noone's surprise, the UK government has now withdrawn its ratification of the EU Unified Patent Court Agreement, thus confirming that the UK will not be taking part in the system. The UPC start date is of course still unknown, being dependent upon ratification by the German government, following the successful challenge in the German constitutional court to the legislation required to ratify the UPCA. The German government will need to propose new legislation to ratify the UPC, which will again be subject to possible further constitutional challenges.