UK Court of Appeal Finds Eli Lilly’s Tadalafil Patent Obvious to Try

On November 1, in Actavis v ICOS, [2017] EWCA Civ 1671, the UK Court of Appeal held that Lilly’s EP (UK) 1,173,181 (the “Patent”) was invalid for obviousness. The Patent claims a dosage form comprising tadalafil (Lilly’s CIALIS®) at a maximum daily dose of 5 mg to inter alia, treat sexual dysfunction (ED).

All three Lord Justices commented on the issue of obvious-to-try, suggesting the need for clarification. The decision appears to suggest that an invention that would be arrived at by a line of routine and uninventive enquiry carried out by a skilled person in the art could be obvious, even though the success of this enquiry could not have been reasonably predicted in advance. That is, the requirement of a reasonable expectation of success (corresponding to Canada’s requirement that it be more or less self-evident that what is being tested ought to work) is directed to the line of enquiry, not to the specific outcome.

The difference between the claimed invention and the prior art is the low daily dose of 5 mg of tadalafil. In the decision below ([2016] EWHC 1955 (Pat)), Birss J found that the skilled team would have investigated lower doses, including the 5 mg dose, and would discover that this dose was efficacious and had reduced side effects, but prior to the actual testing, the team would have no reasonable expectation on the result (that is, surprising result). Birss J therefore found that the invention was not obvious to try. The Court of Appeal disagreed, noting the following:

“[172] It is true that the judge made a finding that the skilled team would be surprised by the result, namely efficacy at 5 mg/day. However it is a result which on his findings would be arrived at by the standard, routine enquiries into dose response which are required by Phase IIb clinical trials. The surprising result, once uncovered, does not make these routine enquiries inventive.”

Summary By: Junyi Chen