Introduction
Test for sufficiency of disclosure
Skilled person and witness evidence
Analysis of sufficiency and post-filing date evidence
Other issues
The Federal Court of Appeal recently affirmed a trial decision relating to two competing patents over Gilead's SOVALDI (sofosbuvir). In the trial decision, the court had declared Idenix's Patent 2,490,191 invalid on the basis of insufficiency of disclosure and inutility, while upholding the validity of Gilead's Patent 2,527,657.
Idenix's appeal on both patents was dismissed unanimously by the court ([2017] FCA 161). In its decision, the court noted that the case did not raise new issues of law; its primary focus was whether reviewable errors had been made by the trial judge. Nevertheless, some points arose which may have broader applicability to future cases.
Test for sufficiency of disclosure
On the matter of the disclosure, the court reiterated that patents are not directed to lawyers or judges but to a person skilled in the art; as such, it would be incorrect to apply the test of whether there is 'express written disclosure'. Instead, common general knowledge must be considered in interpretation.
Skilled person and witness evidence
Idenix argued that the trial judge erred by using one of the fact witnesses, a chemist employed by Idenix and involved in chemical synthesis at the relevant time, as a proxy for the skilled person. While this argument was rejected, the court cautioned that courts must be "careful not to lose sight" of the identity of the person of ordinary skill in the art, who is a "mythical creature"– not a real person. Therefore, courts must be informed by evidence as to the knowledge of the skilled person and what they would have been able to do with that knowledge.
Analysis of sufficiency and post-filing date evidence
One of the main issues in this case was whether a skilled person would have been able to synthesise the compound, given that the disclosure of Idenix's patent did not explicitly teach a required fluorination step. Idenix argued that there were three potential approaches to the particular synthesis, which the skilled person would have tried successfully, as proven by post-filing date evidence. However, the court considered this to be of little relevance as it reflected the benefit of hindsight rather than the skilled person's knowledge as of the filing date.
Drawing an analogy to Teva v Pfizer (Sildenafil) ([2012] SCC 60), the court held that the specification required a skilled person to work out a problem: determining which pathway, reagents and reaction conditions would successfully lead to the claimed compound, rather than leading the skilled person step by step through the synthesis. This constituted "a burden beyond that borne by the text of paragraph 27(3)(b) of the Patent Act" and therefore rendered the patent insufficient.
The court did not address sound prediction of utility as it agreed with the trial judge's finding of invalidity on the basis of insufficient disclosure. The court also upheld the trial judge's finding that Gilead's patent was valid.
For further information on this topic please contact Kevin Siu at Smart & Biggar/Fetherstonhaugh by telephone (+1 416 593 5514) or email ([email protected]). The Smart & Biggar/Fetherstonhaugh website can be accessed at www.smart-biggar.ca.