Neurim Pharmaceuticals (1991) Ltd & Anor v Generics UK Ltd (t\a MYLAN)

For a second medical use patent, novelty requires an enabling disclosure of the claimed therapeutic effect, not merely disclosure of the medicament or another use. Obviousness is assessed against the inventive concept and the common general knowledge of the skilled person, considering separate items of prior art unless a proper mosaic is justified.

A claim directed to improving the restorative quality of sleep may be clear where the patent uses technical diagnostic concepts such as primary insomnia and non-restorative sleep. Those matters may be assessed subjectively through the patient’s report. Plausibility does not require conclusive proof: properly interpreted examples may suffice.

An exclusive patent licence must be construed as a whole. Although patent rights may be divided into exclusive fields, the licensee must retain the practical ability to vindicate the rights granted.

Neurim, the proprietor of a patent concerning prolonged-release melatonin for improving restorative sleep in patients aged 55 years or older suffering from primary insomnia characterised by non-restorative sleep, brought proceedings against Mylan. Mylan accepted infringement if the patent was valid, but challenged validity for lack of novelty, obviousness and insufficiency.

Flynn claimed standing as Neurim’s exclusive licensee. The court therefore also had to determine whether the licence satisfied the statutory definition of an exclusive licence and whether Flynn could bring infringement proceedings independently. The central issues were whether the claimed second medical use was disclosed or rendered obvious by the cited prior art, whether the patent was sufficiently clear and plausible, and whether Flynn had standing.

1. Validity. The challenges to validity failed. The patent was novel, inventive and sufficient.
2. Construction and skilled person. The skilled person was a UK sleep-medicine clinician with substantial expertise in primary insomnia and the relevant diagnostic guidelines. The expressions “primary insomnia”, “non-restorative sleep” and “restorative quality of sleep” had their technical meanings in context. Non-restorative sleep was a subjective phenomenon, ordinarily diagnosed and assessed from the patient’s account, supported where appropriate by history-taking or questionnaires.
3. Novelty. A second medical use claim requires disclosure and enablement of the claimed therapeutic effect. Haimov 1995 concerned melatonin-deficient elderly persons and the relationship between melatonin deficiency and sleep. It did not disclose the claimed treatment of primary insomnia characterised by non-restorative sleep and did not anticipate the patent.
4. Inventive step. The relevant inventive concept was the use of prolonged-release melatonin to improve restorative sleep in the specified patient group. Neither Haimov 1995, the Melatonex material nor Zisapel 1999 made that use obvious. The Melatonex Webpage was advertising material using “restful sleep” in a non-technical sense. Zisapel did not address the claimed sub-population or therapeutic effect.
5. Insufficiency. The claims were neither uncertain nor incapable of being worked. Examples 2 and 3 made the claimed effect plausible. Plausibility required more than bare assertion but did not require conclusive proof or the evidential standard applicable to a peer-reviewed scientific article or regulatory submission. The proposed anticipation/insufficiency squeeze failed because Haimov and the patent used materially different concepts.
6. Exclusive licence and standing. The licence could confer exclusivity over a defined slice of the patent monopoly. However, construed as a whole, the amended enforcement provisions left Flynn unable to bring infringement proceedings independently of Neurim. That deprived Flynn of the practical ability to vindicate the rights said to have been granted. Flynn was therefore not an exclusive licensee within sections 67(1) and 130(1) of the Patents Act 1977 and had no standing.

First-instance decision. The judgment records an earlier interim injunction decision, [2020] EWHC 1362 (Pat), which was affirmed by the Court of Appeal, [2020] EWCA Civ 793. Those decisions did not determine the present validity issues.