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Hospira UK Limited v Cubist Pharmaceuticals LLC, Court of Appeal, London, UK, 18 January 2018, [2018] EWCA Civ 12

This is a judgment from an appeal by Cubist Pharmaceuticals LLC (“Cubist”) in which a two-judge panel (Lewison LJ and Kitchin LJ) upheld Henry Carr J’s first instance decision, that Cubist’s patent EP (UK) 2,264,047 (“the patent”) for a method of purification of the antibiotic daptomycin, is obvious over the cited prior art. At first instance Henry Carr J had found that three patents owned by Cubist were invalid. However, Cubist only pursued an appeal in respect of one. A headnote covering the first instance decision can be found here.

Daptomycin is a surfactant, meaning that it tends to lower the surface tension between two liquids or a liquid and a solid. When such surfactant molecules are present in a solution at a sufficient concentration (the critical micelle concentration or “CMC”) they form structures called micelles. The patent teaches a method of purification of daptomycin whereby the pH of a solution containing daptomycin is lowered, changing the CMC so that the monomeric molecules group together to form micelles, at which point contaminant particles smaller than the micelles are filtered out. The pH is then increased, changing the CMC and returning the daptomycin to its monomeric state, at which point contaminants larger than the monomers are filtered out.

This process had been disclosed in the prior art (“Lin and Jiang”), save that the surfactant used was surfactin not daptomycin and that the CMC was adjusted by adding methanol, rather than changing the pH.

On appeal the parties did not dispute that the applicable legal principles were those set out in MedImmune v Novartis Pharmaceuticals [2012] EWCA Civ 1234 and Hospira v Genentech [2016] EWCA Civ 780. However, Cubist contended that Henry Carr J had been wrong to find: (i) that the skilled team would have considered daptomycin to be a micelle-forming surfactant; and (ii) that the CMC could be adjusted by changing the pH.

After reviewing the evidence before Henry Carr J, Kitchin LJ, giving the leading judgment, found that the first instance judge had been entitled to find that skilled team would confirm, using routine and straightforward techniques, that daptomycin is a surfactant. He also held that they would have considered varying the pH of the solution to be an obvious, attractive and straightforward way of implementing Lin & Jiang (it had been accepted by Cubist that this would have been a known method of changing the surfactant properties of a lipopeptide biosurfactant (such as daptomycin)). Further, there would have been a strong motivation to move away from using methanol, and changing the pH would have been seen as a “good” alternative.

He further noted that as the patent was not limited in scope to an industrial scale, it did not matter that the Lin & Jiang prior art disclosure may only be effective on a laboratory or pilot scale. It would be obvious to the skilled person reading Lin & Jiang to try the patented process on a small scale, and this would fall within the scope of the claims.

In assessing the actions of the skilled team, Kitchin LJ noted that whether something is “obvious to try with a fair expectation of success” will be entirely dependent upon the circumstances of the case.

A copy of the judgment can be found here.

Headnote: Ben Millson, Bristows LLP