2,371,684 – tadalafil dosage form – CIALIS
In Plavix 2013 FCA 186 the FCA held that utility will only be measured against the promise of the patent when an “explicit” promise is made and “it should not be taken to have assumed that every patent contains an explicit promise” -. As I noted in my post on that decision “The crucial question will be how explicit a promise must be in order to establish the standard for utility.” I predicted that direct statements of use such as ‘The compounds of this invention . . . are useful” for a particular purpose would be treated as promises. de Montigny J’s decision in Tadalafil Dosage Form confirms this prediction. (For a similar decision, see also 2014 FC 638, blogged here). Consequently, it seems that while Plavix may have restrained some of the more aggressive applications of the doctrine, the promise of the patent remains very much a central feature of Canadian patent law. The case also illustrates that the promise doctrine is unnecessary to deal with defects that are better addressed by the non-obviousness requirement.
It’s significant that de Montigny J began his discussion of utility with the following statement:
 The promise of a patent is fundamental to the utility analysis and must be ascertained at its outset. As stated by the Federal Court of Appeal in Sanofi-Aventis v Apotex, 2013 FCA 186, at para 47, “[t]he promise of the patent is the standard against which the utility of the invention described in the patent is measured”.
This would have been uncontroversial pre-Plavix, but it is difficult to square with the holding in Plavix that “it should not be taken to have assumed that every patent contains an explicit promise.” This reversion to this pre-Plavix premise suggests that Plavix’s impact may be quite limited.
The ‘684 patent was for tadalafil in a dosage form of less than 20mg. Lilly’s position was that the promise of the patent is that the claimed doses are efficacious and have a better side effects profile than sildenafil , while Mylan argued that the patent promised not just an improved side effects profile, but to reduce side effects to “clinically insignificant levels” . The particular side effects in question were flushing, vision abnormalities, and a potentially life-threatening reduction of blood pressure when tadalafil is co-administered with nitrates, which are used to treat heart conditions. The last was most important because it is potentially fatal .
Key language in the patent included the following statements -:
Most unexpectedly, the product also can be administered with clinically insignificant side effects associated with the combined effects of a PDE5 inhibitor and an organic nitrate. Thus, the contraindication once believed 20 necessary for a product containing a PDES inhibitor is unnecessary when Compound (I) is administered as a unit dose of about 1 to about 20 mg, as disclosed herein. (4)
The present invention is based on detailed 25 experiments and clinical trials, and the unexpected observations that side effects previously believed to be indicative of PDE5 inhibition can be reduced to clinically insignificant levels by the selection of a compound and unit dose. (10)
de Montigny J construed this and other similar language as promising a reduction of side effects to clinically insignificant levels. The promise was held not to be satisfied, in part because co-administration of tadalafil and nitrates is strictly contraindicated by both US and Canadian health regulatory authorities . Thus, the patent was construed as promising a regulatory standard of utility . Since it is well-established that regulatory approval is not the general standard for patentable utility, it is clear that the patent was construed as promising a much higher utility than the minimum which would be required to establish patentable utility in the absence of an explicit promise.
Consequently, the patent was held to be invalid for failing to meet this stringent standard for the promised utility . However, the heightened promise was not determinative, as de Montigny J held that even the promise proposed by Lilly, namely an improved side effects profile as compared with sildenafil, had not been established .
This decision shows that the promise doctrine continues to play a central role in the Canadian law of utility. I have been and continue to be critical of that doctrine: see Form and Function in the Law of Utility: A Reply to Gold & Shortt, (2015) 30(2) CIPR 109 (draft version available here). As I see it, even Lilly put the promise too high. The ‘684 patent is clearly useful, because the claimed invention is effective in treating ED.
With that said, the fact that tadalafil does not have an improved side effects profile as compared with sildenafil is certainly relevant to the validity of the '684 patent, but it goes to obviousness, not utility; and, as discussed yesterday, the patent was properly held to be invalid on that basis. Indeed, the question of whether the side effects are reduced to clinically insignificant levels is relevant to obviousness. This is not because obviousness is measured against statements made in the patent. Rather, as discussed in yesterday’s post, on the facts a reduced dosage is expected to result in reduced side effects, and therefore a reduced dosage form would only be inventive if the side effects were reduced to an unexpected degree. The assertion that the side effects were reduced to clinically insignificant levels was likely made to convince the examiner that the reduction in side effects was sufficiently unexpected to satisfy the inventive step requirement. This does not mean that the patentee should be held to such promises of utility, as some have suggested. On the contrary, it is will established that the standard for obviousness is objective; it is what a skilled person would find obvious, not what the inventor thought was obvious. (See eg Nichia Corporation v Argos Ltd,  EWCA Civ 741 .) The proper response is simpler. Regardless of what the patentee might have “promised” or not “promised” if the reduction in side effects are not in fact large enough to be unexpected to a person skilled in the art, then the patent will be invalid for obviousness. That is exactly what happened in this case.