[2009] EWHC 996 (Pat)

In his judgment of 15 May 2009 Mr Justice Floyd considered novelty and obviousness attacks on Leo Pharma’s European Patent (UK) 0,679,154 directed to the monohydrate pseudopolymorph of the vitamin D analogue calcipotriol, which is used in the topical treatment of psoriasis. The Hague District Court had previously found the equivalent EP valid but in Germany it had been found invalid – the judge remarked that were there to be a supra-national European Patents Court then conflicting results of this kind would be avoided. Sandoz had conceded infringement even though their product contained de minimis amounts of the monohydrate, an interim injunction having been granted earlier in the UK proceedings.

The attack on novelty relied on the disclosure of a prior published PCT application which in its Example 4 described an emulsion containing calcipotriol anhydrate for the treatment of acne. Sandoz relied on three arguments (i) that the disclosure described a milling process which if followed by the skilled man would be a wet milling process, giving the monohydrate (ii) that an experimental repetition of Example 4 by Sandoz gave the monohydrate and (iii) that the expert evidence on what, on the balance of probabilities, a skilled man would obtain from following Example 4 was sufficient to establish “experiment-free” anticipation. All three attacks failed because (i) although wet milling was an obvious variant it was not actually disclosed (ii) the materials used in the Sandoz experiments were seeded with monohydrate and (iii) the evidence on the physicochemical environment in Example 4 did not enable one to predict, on the balance of probabilities, that monohydrate would be the inevitable result.

On the issue of obviousness the judge’s conclusions on the evidence went quite some way to acceptance of the submissions made by Sandoz, specifically he accepted that (i) it would be obvious for the skilled team for regulatory reasons to investigate the formation of hydrates in the Example 4 formulation (ii) in doing so the skilled team would look at a wide range of solvents and (iii) wet milling was an obvious step to take with Example 4. Nevertheless the judge was not satisfied that such steps would guarantee the production of calcipotriol monohydrate.