Obvious To Try – Waking Up To Reality

"Obvious to try" is a stratagem which can be used to try to knock out a patent on the ground of lack of inventive step, also known as obviousness. The argument goes something like this - the skilled person in possession of the cited piece of prior art would think of using it in a particular way, and would have some expectation of success when doing so. So, if success actually happens then there is no basis for a valid patent. One difficulty in applying the test is determining the extent of the expectation of success. Recent jurisprudence in the UK has urged caution in applying it; courts have emphasised that it is merely one of many considerations that can be looked at in determining whether there has been an inventive step. In Generics v Lundbeck [2007] RPC 32, Kitchen J stated that the considerations might include "the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them, and the expectation of success". The Court of Appeal decision in Teva v Leo Pharma [2015] EWCA Civ 779 on 28 July 2015 illustrates the current approach. The patent in suit claimed an ointment for treating psoriasis, an inflammatory disease of the skin. The claims were to a combination of two compounds, each of which was known as being efficacious for psoriasis, together with a specific type of non-aqueous solvent. The two active ingredients were calcipotriol, a vitamin D analogue, and betamethasone, a corticosteroid. As at the priority date, each of these was well-established for use as the sole active in a psoriasis ointment, but they could not be used at the same time. Indeed, patients were warned that they could not be applied together. The reason was that each was unstable save in a narrow range of pH. The right pH could only be achieved by buffering in an aqueous solvent. Calcipotriol is alkali; betamethasone is acid. The same solvent could not do the job for both. But clinicians wanted an ointment containing both ingredients. How to do this? An aqueous solvent would not work; it would have to be one that removed all water from the system. But nobody knew whether a non-aqueous solvent would produce a stable ointment. And if it was worth going down that research route, there was still the question of which solvent to investigate. The Court of Appeal looked at the "real world" evidence of what the skilled formulator would have done in 1999, the priority date. A...

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