On July 24, 2017, the Federal Court of Appeal released its Reasons for Judgement in Idenix’s appeal involving the drug sofobuvir, the active ingredient in Gilead’s SOLVALDI product. As previously reported here, Justice Annis had held that Idenix’s Canadian Patent No. 2,490,191 was invalid on a number of grounds, including lack of utility and lack of sufficiency.
The Court of Appeal, citing the Supreme Court of Canada in Teva sildenafil, concluded that subsection 27(3) requires that the specification disclose both the invention and how to make it. While Idenix did not dispute that it had not actually made sofosbuviur prior to filing the application for the 191 Patent, it argued that the Trial Judge had erred by not looking at the 191 Patent from the perspective of a skilled person. Specifically, Idenix argued that the Trial Judge erred in his sufficiency analysis by focusing on the “express written disclosure” rather than the disclosure as interpreted through the lens of the skilled person. The Court of Appeal agreed that having regard to the express disclosure would have been an error, but concluded that on a fair reading of the Reasons, the Trial Judge had properly considered the disclosure of the 191 Patent form the perspective of the skilled person:
 The judge concluded that Gilead had established that the 191 Patent, together with the common general knowledge, did not sufficiently disclose how to synthesize the Claimed Compound. While the judge’s choice of the term “express written disclosure” is not appropriate, it is apparent on a fair reading of the Reasons that he was concerned with how the skilled person would have understood the patent. For these reasons, Idenix’s allegations on this point fail.
Idenix argued that since the skilled person would know that there were three possible synthetic routes to make sofobuvir, the specific route need not be disclosed in the patent in order to comply with the disclosure requirement under subsection 27(3). In support of its sufficiency arguments, Idenix also relied on post-filing evidence that established that each of the three synthetic routes were viable. The Court of Appeal, citing its previous decision in Teva sildenafil, held that since the proper date for assessing sufficiency was the filing date, Idenix’s post-filing evidence could not be considered:
 Since the filing date, all three synthesis pathways (nucleoside, sugar ring and Gemcitabine) have been proven to work (Reasons at para. 512). According to Idenix, this fact supports the sufficiency of its disclosure because no matter which pathway the skilled person chose, they would arrive at the Claimed Compound. Though reversed on other points, this Court held in Novopharm Limited v. Pfizer Canada Inc., 2010 FCA 242 at paragraph 79,  2 F.C.R. 69, that courts must “determine whether the disclosure was sufficient as of the date of filing. As a result, anything which occurred subsequent thereto is of no relevance.” In my view, Idenix’s argument reflects the benefit of hindsight rather than the knowledge of the skilled person at the relevant date.
In the absence of a teaching as to how to make sofosbuvir, the Court held that the 191 Patent “necessitates the working out of a problem” and impermissibly imposes a burden that goes beyond the language of subsection 27(3). The Court of Appeal accordingly upheld the Trial Judge’s finding that the 191 Patent was invalid for insufficiency.
A copy of the Court of Appeal’s Reasons may be found here.