In Scinopharm Taiwan Ltd v Eli Lilly & Company [2009] EWHC 631 (Pat), the English High Court rejected an attack on the validity of a process patent brought on grounds of obviousness, based on reading two prior art publications in combination. The Court held that it was only permissible to read two documents together if it was obvious to do so. An attack on grounds of insufficiency also failed.


Eli Lilly’s patent relates to a process for making a drug, gemcitabine, used in the treatment of cancer and follows on from an earlier patent on gemcitabine that expired in 2009.


The patented process involved a reaction proceeding via the SN2 mechanism whereas the prior art disclosed this reaction proceeding via the SN1 mechanism. The question of obviousness hinged on whether it was obvious, as Scinopharm alleged, to try and induce the reaction disclosed in the prior art to proceed via the SN2 mechanism. On that basis, Kitchin J identified this as an “obvious to try” case and, as such, a case in which there was a fair expectation of success (Conor v Angiotech [2008] UKHL 49).

Scinopharm’s case depended, in part, upon reading two items of prior art together. Scinopharm contended that it was permissible to do this if they were in the same technical field. The judge disagreed, stating that it was only permissible to read two documents together if it was obvious to do so.

Kitchin J stated that although he had no doubt that the skilled person would have read the prior art with interest with the aim of finding a better way to make gemcitabine, he did not accept that the skilled person would have approached the documents with a predisposition to look for a way of persuading the reaction to proceed by the SN2 process.

In particular, the skilled person would have known from his common general knowledge that SN2 reactions are rare for the type of compound at issue and general knowledge did not provide any signposts as to what would be successful. Moreover, the skilled person would also have appreciated that there are many steps involved in the synthesis of gemcitabine and these provided lots of scope for optimisation and improvement. So, looking at the synthesis as a whole, there were many areas worthy of study apart from the synthesis step at issue in this case.

In light of the evidence, Kitchin J held that the process for producing a high yield of gemcitadine as described in the patent was not obvious and Scinopharm’s allegation of obviousness therefore failed.