Sound Prediction and False Promise in Pfizer / sildenafil

Teva Canada Ltd v Pfizer Canada Inc, 2012 SCC 60 LeBel J for a unanimous court,* rev’g 2010 FCA 242 Nadon JA: Blais CJ, Trudel JA rev’g 2009 FC 638 Kelen J

            2,163,446 VIAGRA

While the SCC decided Pfizer / sildenafil on the basis that disclosure of the invention was insufficient under s 27(3), the issue of whether the factual basis for sound prediction must be disclosed in the specification was also raised. The SCC declined to decide this question, but what it did say on the point is nonetheless of some interest.

The current state of the law is summed up in this statement from Lilly / atomoxetine 2010 FC 915, [116-17] (original emphasis) aff’d 2011 FCA 220:

It seems to me that it is beyond debate in Canada that where a patentee asserts that the utility of its invention has been demonstrated, it need not assert its supporting evidence in the patent.

In a case involving a claimed sound prediction of utility, it is equally beyond debate that an additional disclosure obligation arises [which] is met by disclosing in the patent both the factual data on which the prediction is based and the line of reasoning followed to enable the prediction to be made.

Teva argued that in this case the utility of sildenafil was based on sound prediction, so a disclosure of the factual basis was required, and this requirement had not been met [Appellant’s Factum 48-67, esp 62]. The SCC declined to address this argument on the basis that the main issue was whether the patent meets the disclosure requirements of the Act, and “[t]his is not a case about sound prediction” [27-28, 36]. “Since sound prediction is not an issue, the question whether there is an “enhanced” or “heightened” disclosure requirement with respect to sound predictions does not arise in this case and need not be addressed” [43].

This is a very important question in pharmaceutical patent law, and it is one which the SCC will likely have to address at some point. In some ways, it would have been appealing for it to have taken this opportunity to do so. But on the whole, I am happy with the SCC’s decision not to address the issue. For many years now the SCC has apparently tended to see a patent case as an opportunity to deal with an entire area of patent law. The result has often been confusion rather than clarity, as the Court has made new law, sometimes without even realizing it was doing so, in areas that were not fully argued. In this case, it is true, the point was fully argued. But nonetheless, if this signals a return to a more tightly focused approach, in which the Court will confine itself to the central issues, I think it is a move in the right direction.

With that said, the fact that the SCC did not consider the issue is in itself significant, because it shows that the Court considers that the law is not settled. So, the Court stated that “The lack of certainty that comes from predicting rather than demonstrating an invention’s utility has led some courts to conclude that there is a ‘heightened’ or ‘enhanced’ disclosure requirement in cases in which a claim of utility is based on sound prediction” [37], citing Lilly / raloxifene 2009 FCA 97, which is the leading FCA decision holding that such disclosure is required. This is very far from an endorsement of the Lilly / raloxifene position.

Moreover, the SCC also appeared to affirm that when utility is based on demonstrated utility, the factual basis need not be disclosed in the specification: “Patent ’446 states that the claimed compounds, including sildenafil, will be useful in treating ED. At the time the application was filed, sildenafil could assist in treating ED. This is all that is required. The fact that Pfizer did not disclose that the tested compound was sildenafil goes to the issue of disclosure of the invention, not to that of disclosure of the invention’s utility” [38]. This is significant, because one objection to the raloxifene doctrine, as I argue in my paper on the subject, is that there is only one requirement for “utility” under the Act; sound prediction, like demonstrated utility, is simply a means of establishing the single requirement for utility, so there cannot be more onerous disclosure requirements for sound prediction than for demonstrated utility. However, this point was strictly obiter, both because the main holding was that the issue need not be addressed at all, and also because the Court went on to say that “In any event, Pfizer disclosed the utility of sildenafil by disclosing that tests had been conducted” [41].

Another important issue in pharmaceutical patent law is the promise of the patent doctrine. On this point the SCC remarked that “As the courts below noted, all that is required to meet the utility requirement in s. 2 is that the invention described in the patent do what the patent says it will do, that is, that the promise of the invention be fulfilled” [38]. This could be taken as an endorsement of the promise of the patent doctrine. However, I do not see this as significant. First, the entire discussion was obiter. This statement was made in the context of the Court explaining why it was not going to deal with the issue of sound prediction. Secondly, the problem with the promise of the patent doctrine is that it imports a higher standard of utility than the minimum that would otherwise be required under the Act. In this statement, the SCC is explaining why the utility requirement is less onerous than Teva was arguing: “all that is required...” This statement is no more significant than the similar statement in Consolboard, which, as I argue in my False Promise paper at p24-28, was also in the context of holding that the threshold for utility is relatively low. Finally, this is a case in which defining the utility by the promise of the patent is innocuous. Sildenafil is an old compound, and it is only the use in treating ED which is new and inventive. That use must be disclosed in the specification as a matter of the disclosure requirement, and indeed it is specifically claimed. In a case in which the use is the inventive concept and so must be disclosed, then the minimum utility necessary to support a patent – namely the use for treating ED, rather than some prior known use, such as treating a heart condition – is the same as the utility disclosed in the patent and claimed. Thus, even if utility need not be measured by the promise of the patent as a general matter, in this case it would still be true that sildenafil would have to be useful for the purpose disclosed in order for the patent to be valid. (The promise of the patent may be an important issue in use claims, for example where the claimed use is treatment of a condition, and the description is interpreted as promising chronic treatment – see Pfizer v Apotex / latanoprost 2011 FCA 236, blogged here – but that is not the case here.)