On 14 November 2018 the Supreme Court handed down its decision that Warner-Lambert's EP(UK) patent relating to the second medical use of pregabalin for the treatment of pain is invalid. This decision came in the case of Warner-Lambert vs Generics (UK) Ltd  UKSC 56 where the relevant claims were also held to have not been infringed even if they were valid. However, the Justices of the Supreme Court came to this conclusion for different reasons.
Pregabalin is marketed in the UK for the treatment of epilepsy by Warner Lambert under the brand name Lyrica. An EP(UK) patent covering pregabalin expired in 2013 however, Warner-Lambert are also the proprietors of "second medical use" patent covering the use of pregabalin for the treatment of pain (EP(UK) 0934061), which is the subject of this dispute.
Patent protection can be granted in Europe and in the UK for a known drug where it is for a new indication. However, from the patent it must be at least plausible that the drug treats the new indication in order for the patent to be sufficient. In this way, a hurdle is in place to prevent purely speculative applications directed to known drugs for new indications.
In this case, claims 1 and 3 of the patent in suit are directed to the treatment of pain (in general) and neuropathic pain (whether peripheral or central), respectively. Three of the five Supreme Court Justices found that the disclosure in the specification supports the claims in relation to inflammatory pain, but not neuropathic pain, whether peripheral or central. The Supreme Court found that claims 1 and 3 therefore fail for insufficiency. Their view requires the patentee to demonstrate that the specification discloses some scientific reason why the implied assertion of efficacy in the patent claim may well be true. More than a bare assertion or mere possibility of therapeutic efficiency is required. Further, Warner-Lambert were not allowed to narrow their claim to cover the indications which they considered plausible, as such amendment was thought to be an abuse of the procedure.
Some will see this as a higher hurdle than previously applied by the UK courts, but is roughly in line with the increasing high standard that the EPO are applying to the plausibility of second medical use inventions.
The Supreme Court also considered the infringement of these claims had they been valid. Actavis markets a generic pregabalin product under the brand name "Lecaent", launched in 2015. It was not...