“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  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  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 common non-aqueous solvent which had been used with corticosteroids was propylene glycol, but this did not work with the dual formulation. There were many other possibilities, but none worked except one called Arlamol E. This had been used for some years as a solvent in cosmetics. It had not been used for topical pharmaceuticals, although it had been proposed in a 1978 patent (called “Turi”) as a solvent for an anti-inflammatory steroid. Turi was the prior art relied on in this case.
The prior disclosure of Turi was of a mono-active product using Arlamol E. The Court of Appeal found that there was nothing disclosed or known about Arlamol E that made it stand out as a candidate for use with the dual active ointment, over and above any other non-aqueous solvent. There was nothing to suggest that just because a solvent was non-aqueous it would work. Arlamol E might have provided stability for the two actives, but so might many other non-aqueous solvents. Finding that it did provide stability was an invention.
This decision of the Court of Appeal reversed a judgment of the High Court ( EWHC 3096 (Pat) – Birss J, 6 October 2014), in which the judge had held that the patent was invalid for obviousness over Turi. The judge had in effect found that the idea of using Arlamol E as part of a research project amounted to obviousness. The Court of Appeal said that the “obvious to try” standard required a higher expectation of success than that.
The Court of Appeal could only get to the stage of making a decision on the issue of obviousness at all if there had been a point of principle on which the judge had erred. Once they had found that the judge’s approach to “obvious to try” was wrong – which they did – they could then revisit the whole question of obviousness based on the evidence given at the trial.
In doing this, it is striking how often the Court of Appeal referred to “reality” in the context of concepts such as a “real-world” formulator faced with the pH problem, not some notional person who is different from the real person. The decision refers to real organisations working in the field, and to real researchers with real prejudices facing real problems. It can sometimes seem that the classic, forensic approach to obviousness leads us into a parallel universe, a sort of SimCity in which androids in white coats grapple with hypotheticals. This decision grounds us firmly in reality.
One aspect of this approach is timing. The real world has a time frame. The need for a dual active ointment had been known since 1995, four years before the priority date. Yet nobody had found a way to put the two actives together in an ointment with any non-aqueous solvent (not just Arlamol A) until the invention was made. And when the dual active product came on to the market a few years later it was a great success and a significant advance in the treatment of patients with this distressing condition.
The Court of Appeal said this:
So we have here the classic sort of case where the courts have found invention over the years, a long-felt want, the desired solution and no explanation of why that solution was not done before when it could have been. The Judge’s failure to consider this seems to me to be another error of principle – he missed a relevant circumstance.
Or, as Sinatra sang: “Use your mentality, wake up to reality” (Cole Porter’s I’ve got you under my skin).