Idenix Pharmaceuticals v. Gilead Pharmasset

A look at a pharmaceutical patent case in which a patent owned by Idenix for the treatment of Hepatitis C was invalidated by the Federal Court

Norton Rose Fulbright Canada LLP and Belmore Neidrauer LLP successfully represented Gilead Sciences Inc., Gilead Sciences Canada Inc. and Gilead Pharmasset LLC (“Gilead”) in a Federal Court action against Idenix to invalidate a patent owned by Idenix for compounds that were claimed to be useful for the treatment of Hepatitis C. Idenix defended these allegations and filed a counterclaim to impeach a patent owned by Gilead and claim for infringement of the Idenix patent (bifurcated).

The trial judge found in favour of Gilead and found Idenix’s patent invalid, upholding the validity of Gilead’s patent. The appeal was argued before the Federal Court of Appeal in January 2017. In July 2017, the Federal Court of Appeal likewise ruled in favour of Gilead. This highly complex case was of importance in Canada and globally. 

Gilead initiated the underlying invalidity action against Idenix based on a belief that the manufacture, use or sale in Canada of sofosbuvir (marketed in Canada as SOVALDI®)  for treatment of Hepatitis C (HCV) would be impugned by Idenix as an infringement of the patent. Idenix counterclaimed, and claimed that Gilead’s sale of sofosbuvir in Canada constituted infringement of its patent. Idenix also sought to invalidate a Gilead owned patent on the basis that it was not novel in light of the Idenix patent at issue in the action.

Decision of the Federal Court

The Federal Court allowed Gilead’s claim, finding that each claim of the Idenix patent was invalid for: (i) for lack of sound prediction of utility; and (ii) failing to sufficiently disclose how to synthesize the compounds at issue. The Federal Court also dismissed Idenix’s counterclaim, finding that the Idenix patent did not enable (and therefore did not anticipate) the Gilead patent.

With respect to the allegations of lack of sufficiency, the Federal Court found that Idenix’s patent did not sufficiently disclose how to synthesize the compounds at issue, including sofosbuvir, a D-ribose-2’-methyl (up), 2’-fluorine (down) nucleoside. In particular, the 191 Patent did not teach: (1) how to make the intermediate compounds needed to synthesize these compounds; or (2) how to fluorinate the intermediate compounds needed to arrive at these compounds. The Federal Court compared Idenix’s Patent disclosure to Gilead’s Patent disclosure and noted that Gilead’s Patent set out six schemes for the synthesis for these compounds explicitly, while Idenix’s Patent did not.

With respect to the allegations of lack of utility, Idenix conceded that it had not tested any of the compounds in its Patent until March 2005 (after the filing date) and as such, utility had to be established based on sound prediction. Idenix argued that utility of the compounds could be predicted on the basis of testing of similar compounds (2’-methyl (up), 2’-hydroxy (down) nucleosides), which Idenix argued had demonstrated antiviral activity.

The Federal Court rejected this argument, noting that it would not have been possible to soundly predict the therapeutic advantages of substituting a fluorine for the hydroxyl group at the 2’ (down position). 

In obiter, the Federal Court found that the factual basis for sound prediction did not have to be disclosed because Idenix’s Patent related to a new composition. However, to the extent that a factual basis had to be disclosed, the Federal Court found that Idenix’s Patent did not disclose adequate testing on which to form a sound prediction.

In particular, the court found that Idenix’s patent disclosed testing of 2’-methyl (up), 2’-hydroxy (down) nucleosides in viruses other than the Hepatitis C virus, but did not disclose a factual basis to support that those tests would have been adequate surrogates for antiviral activity against the Hepatitis C virus specifically.

Findings of the Federal Court of Appeal

Idenix argued on appeal that the Federal Court made multiple errors in reaching its conclusions on insufficiency and lack of sound prediction. The Federal Court of Appeal dismissed Idenix’s appeal finding no error warranting the Court’s intervention.

In rejecting Idenix’s argument that the Federal Court applied an incorrect test for insufficient disclosure,  the Court of Appeal held that, read in context, the Federal Court correctly considered how the skilled person would have understood the patent when it concluded that the Idenix patent, together with the common general knowledge, did not sufficiently disclose how to synthesize the compounds at issue. The Idenix patent was invalid on this basis. Having reached this conclusion there was no need to determine other grounds on appeal.

Leave to appeal to the Supreme Court of Canada has been sought by Idenix.

Jordana Sanft, Amy Grenon and Jillian Hyslop of Norton Rose Fulbright Canada LLP were counsel for Gilead Sciences Inc.

Jason Markwell of Belmore Neidrauer LLP also acted for Gilead Sciences Inc.

Patrick Smith, Christopher Van Barr, Alex Gloor and Marc Crandall of Gowling WLG represented Idenix Pharmaceuticals Inc.