Gilead commenced proceedings against Idenix seeking revocation of Idenix's Australian patent no 2003247084 (Patent). The Patent was filed on 27 June 2003 and discloses and claims sofosbuvir amongst many possible (trillions of) compounds. Idenix cross-claimed for infringement, which Gilead conceded. Thus the case turned on the validity of the Patent.

Gilead raised six grounds of invalidity, including novelty, lack of fair basis, insufficiency, inutility, lack of manner of manufacture and false suggestion. Gilead was ultimately successful on the grounds of insufficiency and inutility, which we explore further below.


Gilead argued that the Patent specification failed to describe the invention fully, including the best known method of performing the invention. One of the claims in suit described a certain compound, which included a particular type of chemical substitution (for the chemists out there – fluorine substitution at the 2' down position of a nucleoside). Gilead submitted that the specification did not adequately describe how to synthesise such a compound, and that such chemistry was not routine at the priority date of the Patent.

Conversely, Idenix argued that the synthesis of a compound within the relevant claim was common general knowledge to the skilled person at the priority date of the Patent, and could be done using a known synthetic approach called "DAST" (to which Gilead described as Idenix's "Just DAST it" approach). Idenix adduced a significant volume of supporting evidence by experts.

However, three matters were against Idenix.

  1. During the proceedings, documents had been produced that recorded Idenix's own attempts to make a compound within the relevant claim of the Patent. The documents demonstrated that, over a period of around three years from before the priority date to some years after, Idenix attempted to synthesise the compound in question but had failed to do so. This led Jagot J to the conclusion that armed with the Patent, and with the benefit of the common general knowledge (and even knowledge that exceeded the common general knowledge), a skilled team of scientists working with the aim to make such a compound had failed in all attempts to make it.
  2. A later patent disclosed the synthetic pathway required to manufacture the compound, and this synthesis was considered a novel piece of chemistry at the time that was worthy of publication in a prestigious peer-reviewed journal.
  3. The Patent did not provide any direction or motivation for the skilled addressee to attempt to obtain this nucleoside.

Accordingly, Jagot J found that the claim was invalid for insufficiency.


Gilead argued that the relevant claim of the Patent encompassed compounds that either could not be made, and/or did not meet the promise that the compounds could be used to treat Flaviviridae infections including HCV (or are toxic or both).

Jagot J agreed with Gilead in relation to its first argument. Her Honour agreed that a promise of the Patent is that such compounds in the claim can be made. Although none of the experts had ever tried to make compounds with the relevant substitution (again, for the chemists, where a Y3 group is bromine or iodine), two experts gave evidence that they considered it most likely that such compounds could not be made. Therefore, her Honour found that this is a case where the claim encompasses compounds which, on the evidence, at least two of the experts expect cannot be made and so the claim fails for lack of utility.

In relation to Gilead's second inutility argument, Jagot J found that no skilled addressee expected that every compound claimed in the relevant claim would be useful in treating Flaviviridae infections – they all expected that testing would be required to identify such a compound. Therefore, Jagot J found that the claim made no such promise and thus there could be no inutility in relation to that promise.


This case is one of a number of recent cases where the section 40 grounds of invalidity have succeeded (for another example, see our recent post on Servier v Apotex concerning the best method ground of invalidity). These recent cases show that section 40 grounds are proving fruitful for revokers. Such cases have a time and cost advantage, as running an invalidity case on s 40 grounds is generally less expensive and faster compared to the traditional stalwarts of novelty and inventive step.