In a judgment handed down on 28 July ([2015] EWCA Civ 779), the Court of Appeal overturned Birss J’s finding of obviousness in respect of two patents.  In doing so the Court of Appeal has reaffirmed the principle that an invention is not obvious merely by way of being obvious to try; rather, there must also be a reasonable expectation of success.

Leo Pharma A/S is the proprietor of two European patents relating to an ointment comprising two active ingredients, calcipotriol (a vitamin D analogue) and betamethasone (a corticosteroid), together with a commercially available non-aqueous solvent called Arlamol E (a polyoxypropylene 15 stearyl ether).  Each active ingredient was known for use in the treatment of psoriasis by topical application in an aqueous ointment or cream.  However, it had not been possible to make a formulation containing both actives, because calcipotriol and betamethasone are each only stable within certain, non-overlapping, pH ranges.  It was desirable to find a way to co-administer the two actives.  Leo solved this problem by using a nonaqueous solvent.

Teva asserted that Leo’s patents were obvious over the common general knowledge and a US prior art document, “Turi” (US patent 4,083,974), which disclosed a topical cosmetic preparation comprising the solvent polyoxypropylene 15 stearyl ether and a corticosteroid.

At first instance (reported here), Birss J held that it would be a matter of common general knowledge to aim for a non-aqueous formulation comprising both active ingredients.  The skilled formulator would carry out compatibility tests on a number of non-aqueous solvents.  Turi disclosed the relevant non-aqueous solvent as an emollient in cosmetic products.  While acknowledging that the skilled formulator may never have heard of the particular solvent disclosed in Turi, that there was no evidence of the solvent’s utility with calcipotriol, and that the solvent did not have a well established track record in pharmaceutical formulations, this “would not be sufficient to put the formulator off including it in the test”.  He concluded that “based on what the skilled formulator knew about it at the time there was a sufficient prospect of a positive result in the tests with this compound to make it worth testing” and that the patents were obvious.

On appeal, Sir Robin Jacob disagreed.  He noted that it was “far from established that any non-aqueous non-toxic solvent would produce a stable ointment”: there was no guarantee that an arbitrarily chosen non-aqueous solvent would be expected to work.   In his opinion, “having the property of being non-aqueous was a necessary, but well short of sufficient, condition.  Finding [a solvent which would work] was a research project.  And that was because there was no sufficient expectation of success.  Yes, a particular candidate might work, but it was far from certain that it would.”

Sir Robin also noted that Birss J’s opinion that the skilled formulator would find it obvious to try the Turi solvent, despite its unfamiliarity, was “rather odd” as this amounted to “saying that the notional person skilled in the art would be different from the real person skilled in the art”, which was contrary to established legal principles.

In Sir Robin’s opinion, the judgment at first instance effectively said that “the idea of including [Arlamol E] as part of a research project amounted to obviousness”.  However, the “obvious to try” standard requires a higher expectation of success: as noted in the St Gobain v Fusion Provida case, “Mere possible inclusion of something within a research programme on the basis you will find out more and something might turn up is not enough.  If it were otherwise there would be few inventions which were patentable.” There was no “reasonably optimistic expectation” from Turi that Arlamol E would produce a stable formulation; finding that it really did “was an invention and an advance in human knowledge”.  Upon reconsideration of the question of obviousness Sir Robin thus reversed the finding of obviousness in respect of both patents.

The Court of Appeal’s decision thus reaffirms the principle that a finding of obviousness cannot rest solely upon an invention being “obvious to try”, but rather that there should be “a fair expectation of success”.  As noted in Conor v Angiotech[2008] UKHL 49, the level of expectation needed to establish a finding of obviousness will depend upon the particular facts of any given case.