Patent Claims to dosage regimes fail to stand up to scrutiny
06 November 2017
In Actavis Group PTC EHF & Anor v Teva UK Ltd & Ors  EWCA Civ 1671 the Court of Appeal has found that various dosage regime claims were obvious and invalid, reversing the decision of the of the trial judge.
Tadalafil is sold under the brand name Cialis as a treatment for erectile dysfunction (ED). The patent had dosage regime claims to 5mg of tadalafil to treat ED. The claims were challenged on the basis that they were obvious over a piece of prior art which expressly disclosed tadalafil and indicated it may be efficacious across a dose range of 0.5 to 500mg. The evidence at trial was the skilled team would undertake dose-ranging studies to find the optimal dose, balancing efficacy with potential side effects. They would likely under several of those studies, which were straight forward and they would have a good expectation of success, based on what they knew about tadalafil and similar compounds. However, the trial judge said that it was not obvious that the team would settle on 5mg as the optimal dose – it may only go as far as 10mg, for example. Therefore the claims did involve an inventive step.
The Court of Appeal held that the purpose of the dose ranging studies was to identify they efficacious dose which balanced side effects. This work was entirely routine in this area and there was a reasonable expectation of success. The skilled team would be embark on a familiar and uninventive path and in so doing would inevitably come on the invention. Therefore, the trial judge should have held that the claims were obvious.
This decision will leave patentees who are relying solely on dosage regime claims a little nervous. The court has effectively said that conducting dose ranging studies is an uninventive and routine aspect of the drug discovery process and this may lead to challenges to dosage regime claims, particularly in circumstances where the main product patent has, or is about to expire and the only barrier in the path to market is the dosage patent. It remains to be seen whether this decision will be appealed, but given the commercial importance of Cialis to Lilly and the fact that the product SPC expires in November 2017, it is likely that Lilly will seek permission to appeal.
A link to the judgment is here: http://www.bailii.org/ew/cases/EWCA/Civ/2017/1671.html