Second throw of the dice unsuccessful: Full Federal Court confirms Hepatitis C drug patent is invalid

The recent decision of the Full Court in Idenix Pharmaceuticals v Gilead Sciences [2017] FCAFC 196 illustrates the power of the grounds of lack of utility and lack of sufficiency under section 40 of the Patents Act when challenging the validity of a patent.

The decision concerned lack of utility and lack of sufficiency as those grounds existed prior to the introduction of the ‘Raising the Bar’ amendments to the Patents Act that were introduced in March 2013.  These amendments ‘raised the bar’ by:

  • replacing the requirement that an invention must be “useful” with a requirement that a specification disclose a “specific, substantial and credible” use for the claimed invention; and
  • requiring that the invention be disclosed in a manner that is clear and complete enough for the invention to be performed, rather than simply requiring that the invention be described.

Idenix’s HCV patent and the decision at first instance

The case concerned Idenix’s (a MSD subsidiary) patent relating to compounds used in the treatment of infections, including Hepatitis C. Gilead admitted that its product containing sofosbuvir would infringe Idenix’s patent, if the patent was valid.

At first instance, Justice Jagot found that the patent was invalid on the grounds that the specification did not properly describe the invention and provide the best method known to the applicant of performing the invention (sufficiency) and lacked utility on the basis that the claims encompassed compounds that the evidence indicated could not be made (lack of utility).

Lack of Sufficiency

On appeal, the Full Court found that Justice Jagot had properly applied the test for sufficiency set out by the High Court in Kimberley Clark v Arico Trading[1] – that is, whether the disclosure in the patent would enable the skilled addressee to produce something within each claim without new inventions or additions or prolonged study.  More specifically, the Full Court agreed with Justice Jagot’s finding that that there was no disclosure in the specification that would enable the skilled addressee to produce the claimed target compound without new invention or prolonged study.

Idenix argued that while the specification did not specifically describe a synthesis of the target compound, a method for doing so (involving the ‘DAST’ route of reacting a precursor compound with diethylaminosulfur trifluoride) was within the common general knowledge of the skilled addressee at the priority date.  The Full Court agreed with Justice Jagot that in order to form part of the common general knowledge, information must be generally accepted and assimilated by the bulk of those who are engaged in the particular art – it is not enough that information can be found in a journal or other publication, even if that publication is widely read.

In rejecting Idenix’s arguments, the Court was persuaded by the fact that it had been found at first instance that Idenix’s highly skilled scientists and expert consultants had not been able to synthesise a compound that fell within the relevant claim in a period of nearly three years, and only appeared to have been able to do so following the DAST synthesis described in a later Gilead patent.  The Court was also reluctant to overturn Justice Jagot’s findings that had been made in circumstances where it was necessary for the Court to put itself in the position of a hypothetical skilled person at the priority date and in doing so, weigh expert evidence that was before the Court.  The Full Court emphasised that an appellate Court should not interfere with findings made in such a setting unless they are erroneous in principle or plainly and obviously wrong, or where there is a clear difference of opinion.  It is not for parties to “put the dice into the box for another throw” on appeal.

Lack of utility

At first instance, Justice Jagot also found that the ‘promise’ of the patent was that certain compounds could be made in circumstances where the evidence suggested that they could not in fact be made. On appeal, Idenix sought to persuade the Court that Gilead had not proved by experiment that the compounds could not be made, instead relying on theoretical evidence. The Court rejected this, finding that a requirement that inutility be established by experiment would raise the evidentiary bar too high for parties attempting to revoke an inutile patent.

Implications of the decision

The decision is a useful illustration of the power of the s40 grounds of invalidity, particularly in circumstances where proceedings relating to invalidity on these grounds are usually much less costly and can be run much more quickly than proceedings where extensive expert evidence is required to support a claim that a patent is invalid for lack of novelty or lack of inventive step.

[1] (2001) 207 CLR 1