The recently issued judgement from Mr Justice Arnold in the matter of Idenix Pharmaceutical, Inc v Gilead Sciences, Inc & Ors, found Idenix’s patent (EP 1523489), relating to particular compounds and their use in the treatment of hosts infected with a Flaviviridae virus, to be infringed by Gilead’s sofosbuvir product but also to be invalid.

Whilst infringement was decided upon relatively quickly by Mr Justice Arnold, the validity assessment involved greater consideration and concerned investigations into novelty, inventive step, sufficiency and added matter.

An intermediate prior art document (Gilead’s International Patent Application PCT/US2004/012472, originally filed by Pharmasset who were subsequently acquired by Gilead) was cited for novelty.  This patent application had a priority date earlier than the filing date of the Idenix patent but had a filing date after that of Idenix’s patent and was published after Idenix’s patent application had been filed.  PCT/US2004/012472 was therefore citable for novelty only, but only if the relevant subject matter was entitled to priority.  (Priority of Idenix’s patent was not asserted). 

The priority entitlement of PCT/US2004/012472 was therefore assessed.  The priority application was filed in the name of the inventor, Mr Clark, who was employed by Pharmasset Georgia, together with another inventor, who was subsequently removed.  However, the PCT application was filed in the name of Pharmasset Barbados.  Gilead asserted that Pharmasset Barbados were the successors in title to Mr Clark by virtue of an employment contract and an agreement between Pharmasset Georgia and Barbados and thus were entitled to claim priority from the earlier application.  

The priority entitlement of PCT/US2004/012472 was upheld by Mr Justice Arnold and the claims of Idenix’s patent were found to lack novelty. 

Additionally, the claims were found to lack an inventive step as compounds were encompassed which would not have the necessary antiviral activity.  Thus, the claims were found to be too broad. 

In line with this objection, the claims were also found to lack sufficiency in view of their breadth.

A lack of sufficiency finding was also raised indicating that the specification did not enable the invention to be performed at all, since there was no disclosure of how to make the compounds (an element of which would be difficult to make).

Added matter was also assessed.  An amendment made to claim 1, to define a subclass, was held not to add matter.  However, an amendment made to claim 4, to select 8 bases, was found to add matter. 

The patent was therefore revoked.