Another Application of the Duty to Disclose the Invention

Pfizer Canada Inc v Apotex Inc / celecoxib (NOC) 2014 FC 314 Harrington J
            2,177,576 / celecoxib / CELEBREX

I blogged yesterday about the promise of the patent in Apotex / celecoxib. This post concerns the second main issue, which is the duty to disclose the invention. There are several points of interest, though none represent major legal developments.

Apotex made three submissions regarding sufficiency of disclosure [43]:

(1) that one individually claimed compounds (Claim 5) was toxic and therefore useless;

(2) Claim 16, to the compounds for use in the prevention of colorectal cancer is unfounded; and

(3) Pfizer failed to disclose that the true invention was celecoxib, (Claim 4) with respect to which Pfizer had already formed the intention to seek regulatory approval.

Taking the second point first, Pfizer effectively conceded, for the purposes of this application, that the compounds were not useful for treating colorectal cancer [46]. But Pfizer has only to establish that one valid claim is infringed in order to obtain an order of prohibition [45], and so Pfizer accordingly argued that the validity of Claim 16 was not determinative of the application, because s 58 provides that claims stand or fall independently. Apotex responded by arguing that the utility of the invention, which is found in the disclosure, is inherent in every claim, and if Claim 16 is invalid, the entire patent falls. Apotex’ argument is set out only summarily by Harrington J, but it is presumably based on on the SCC Teva / Sildenafil 2012 SCC 60, in which a claim to a useful compound was struck down because other claimed compounds lacked utility. I can’t speculate on how exactly Apotex felt that Sildenafil applied to the facts at hand, but in my article The Duty to Disclose “The Invention”: The Wrong Tool for the Job, (2013) 25 IPJ 269, I did argue that the Sildenafil decision eviscerates s 58. Harrington J rejected Apotex’ allegation on this point, holding simply that the submission “is not in accord with s. 58 of the Patent Act and the decision of the Supreme Court in Teva (Sildenafil/Viagra)” [47]. While Harrington J did not elaborate further on the relationship between Sildenafil and s 58, it is clear that he views the two as consistent. While this is contrary to the argument I made in my article, I am nonetheless very pleased by this holding, because I felt that the SCC was wrong to undermine s 58. I said in my article that “I hope that I have misunderstood the court’s holding; I have certainly not found it easy to interpret.” Harrington J’s holding on this point, while not fully reasoned, is a welcome indication that I was indeed wrong in my interpretation of Sildenafil.

The first point, regarding the utility of Claim 5, similarly appears to be relevant only because of its effect on Claim 4, and would also be susceptible to being answered by s 58. But Harrington J addressed the point more directly, holding that

[44] The fact that tests had revealed high doses of the compound in Claim 5 were toxic in rats does not detract from the fact that Claim 5 works as an anti-inflammatory. There was no promise it would receive regulatory approval.

There is a certain tension here with the SCC statement in Tennessee Eastman [1974] SCR 111 that

There is no doubt that when a new substance is claimed as an invention of a "medicine", it has to be shown that it is active and nontoxic in therepeutic doses. Otherwise the patent fails for lack of utility and this is so if a class of substances is claimed some of which are useful as a "medicine", some of which are not.

We might distinguish this on the basis that Tennessee Eastman refers to “therepeutic” [sic] doses, while in this case the toxicity was revealed at “high” doses. However, I think it is more realistic to say that Harrington J’s holding relfected the point made that in Cameron ed Canadian Patent Law Benchbook at §4.8.1.2 that “some care must be exercised in the application of [the Tennessee Eastman] principle].” Apotex Inc / celecoxib should be added to the several cases cited therein as illustrating the conservative interpretation the courts have given to that principle.

I would note also that the view that the claimed compound must be nontoxic in therepeutic doses was obiter in Tennessee Eastman, and it was also obiter in Ciba v Commissioner of Patents [1959] SCR 378, which was relied on in Tennessee Eastman. Ciba in turn cited the decision of Jekins J in Re May & Baker Ltd (1948) 65 RPC 255 (Ch). In May & Baker there was no evidence at all of any utility for the substantial majority of the compounds of the claimed class (p287), which is quite different from a situation, as in this case, where the compounds clearly have a therapeutic effect, and the question is whether side effects would make them not clinically useful in practice. With that said, Jenkins J’s opinion does have statements which might suggest that therapeutic utility in humans, including lack of toxicity, is necessary to support a patent (see esp p 284); but such a suggestion is inconsistent with the holding in Wellcome / AZT 2002 SCC 77 [3] that regulatory approval is not the measure of patentable utility. I note also that the invention at issue in May & Baker was effectively a type of selection invention (p 282-83), so that the claimed compounds had to exhibit some advantage or lack of disadvantage as compared with the prior art compound, which was therapeutically useful, and this may justify the requirement for therapeutic utility on the particular facts.

The third point gets to the heart of the Teva / sildenafil duty to disclose the invention. Apotex argued that Pfizer failed to disclose that the true invention was celecoxib, with respect to which it had already formed the intention to seek regulatory approval [43]. Harrington J readily distinguished Teva / sildenafil from the facts at hand; in the SCC case, the utility of the individually claimed compounds, other than sildenafil itself, had not been established, whereas in this case the utility of all three of the individually claimed compounds was established [59]. Consequently, “[t]he true invention was the class of compounds” [59]. This distinction is, in my view, entirely sound. It is quite similar to, and consistent with, Snider J’s holding in Teva / imatinib 2013 FC 141 (blog). A more difficult question would have arisen had Harrington J come to the opposite conclusion with respect to the compound of Claim 5, so that it could not be said that the true invention was the whole class. In my view, that scenario is where there is a tension between s 58 and Teva / sildenafil. But given Harrington J’s holding that Claim 5 was valid, that tension will have to be resolved on another day.

One point of general importance is that “[t]here was no obligation upon Searle at the time the patent was filed to disclose therein its hope to commercialize Claim 4" [60]. This implies that “the invention” is determined by patentability criteria, and not by business intent. In my view, this holding is entirely consistent with both the Act and Teva / sildenafil.

Finally, Harrington J [50]-[52] also applied the FCA’s direction in Pfizer v. Novopharm / sildenafil (NOC) 2010 FCA 242 [72], to hold that the best mode requirement applies only to machines, notwithstanding Thorson P in Minerals Separation [1947] Ex CR 306, 12 CPR 102, that “the inventor must act uberrima fide and give all information known to him that will enable the invention to be carried out to its best effect as contemplated by him.” While Harrington J was bound to apply the law as set out by the FCA, in a recent article, Best Mode Disclosure in Canadian Patents 25 IPJ 303 (2013), Professor Vaver has argued that on the contrary, the express inclusion of a best mode duty for machines does not impliedly exclude the same duty for all inventions.