Mylan Pharmaceuticals ULC v. Eli Lilly Canada Inc.2016 FCA 119

Patent owners applying for a new patent should be prepared to identify a degree of inventiveness from their previous patents, even those published within the last year, in order to avoid rejection on the grounds of obviousness-type double-patenting. In this case, the Federal Court of Appeal (“FCA”) dismissed the appeal, which alleged that Canadian Patent No. 2,226,784 (the “‘784 patent”) was invalid on the basis of obviousness-type double-patenting and for lack of utility due to no sound prediction. [1] As a result, the ‘784 patent was upheld.

Background of The ‘784 Patent

The ‘784 patent claims tadalafil and 3-methyl tadalafil for the treatment of erectile dysfunction (“ED”). [2] These compounds are PDE V inhibitors. As PDE V prevents erections, an inhibitor of PDE V will have the effect of stimulating erections. [4] Eli Lilly Canada Inc. (“Eli Lilly”) had previously acquired Canadian Patent No. 2,181,377 (the “’377 patent”) that claimed, among other compounds, tadalafil. These compounds were claimed as treatment for various disorders, but did not mention ED treatment specifically. [5]

After the priority date of the ‘377 patent, but before the priority date of the impugned ‘784 patent, Pfizer’s PCT patent application WO1994028902A1 (the “’902 patent application”) for sildenafil was published. [6] This application showed that a PDE inhibitor could treat ED. [6] However, there was evidence before the Federal Court (“FC”) judge that this was counterintuitive and initially met with skepticism. [6]

Eli Lilly had applied for an order under section 6 of the Patented Medicines (Notice of Compliance) Regulations (“PMNOC Regulations”) prohibiting Notice of Compliance being issued to Mylan Pharmaceuticals ULC (“Mylan”) for its generic version of tadalafil. [8] In response, Mylan filed a Notice of Allegation alleging that the ‘784 patent was invalid for lack of utility and obviousness-type double-patenting. [8] The FC rejected Mylan’s allegations. [10-13]

The Difference Between Prior Art and Common General Knowledge

Before delving into the analysis of this appeal, the FCA reviewed and restated a few relevant areas of patent law, the first being the difference between prior art and common general knowledge. Prior art is the publicly available collection of learning in the relevant field, regardless of it being obscure or not generally accepted. [23] In contrast, common general knowledge is what is generally known and accepted by persons skilled in the relevant art. [24]

The Difference Between Obviousness and Obviousness-Type Double-Patenting

The FCA noted that, although obviousness and obviousness-type double-patenting may seem like similar grounds for invalidity, each is aimed to achieve a different policy objective. Obviousness is directed at the question of whether an invention (in the legal sense) actually exists. Obviousness-type double-patenting, in contrast, is directed at preventing the evergreening of an existing patent, through what would otherwise be a valid patent, but is an extension of a patent that has already been granted. [28]

One major difference between these two tests is that any piece of prior art can be cited in an obviousness challenge, whereas only the earlier patent can be cited in an obviousness-type double-patenting challenge. [29] A second major difference is that in an obviousness challenge, subsection 28.3(a) of the Patent Act provides that any information disclosed by the patentee within a year prior to the filing cannot be cited as prior art that renders the patent obvious. [30] This section does not apply to double-patenting, where an earlier patent can be cited even if it was published within a year of the filing date of the impugned patent. [30]

The Test for Obviousness-Type Double-Patenting

In determining the proper test for obviousness-type double- patenting, the FCA concluded that the relevant question is whether there is an inventive step from the first patent to the second. [35] To execute this test, the claims of the second patent must be considered against the claims of the first patent. [37] In construing the claims, the FCA noted that the rules of patent construction preclude reference to the specification when the claims are clear and unambiguous. [39] The ‘377 patent’s claims are unambiguous, and as such, the FCA felt that the FC judge erred by referring to the specification in their analysis. However, it was of little consequence as the judge still came to the correct conclusion. [40, 43]

After settling the methodology of the obviousness-type double-patenting test, the FCA turned to the question of at which date the inquiry was to be conducted. [44] There were three potential dates which were reviewed: (1) the priority of the first patent (the ‘377 patent), (2) the priority date of the second patent (the ‘784 patent}, and (3) the publication date of the second patent. The third date was deemed to be inappropriate, as using a date after the claim date would mean that the court assessing an obviousness-type double-patenting claim would consider prior art beyond what section 28.3 allows the court to consider in a classical obviousness analysis. [49-50]

The FCA, however, opted not to determine whether the first or second date was correct, as both dates result in a finding of no double-patenting. [52] The primary difference between these two dates, as mentioned above, is that the ‘902 patent application was published after the first date, but prior to the second date. As mentioned above, the FC judge accepted evidence that the ‘902 patent application, which showed that a PDE V inhibitor could treat ED, was counterintuitive and met with skepticism. This meant that the ‘902 patent application would not be part of the common general knowledge, as a skilled person wouldn’t have unhesitatingly accepted its teachings. [53] This rendered the two remaining dates having the same outcome, and the FCA found that the FC judge did not commit a palpable and overriding error in concluding that the ‘784 patent was distinct from the ‘377 patent. [53]

Utility and Sound Prediction: A Reasonable Inference of Success Existed

Mylan alleged that while the oral administration of tadalafil to treat ED may have been soundly predicted, the oral administration of 3-methyl tadalafil was not. [54] The FCA stated that the FC judge erred in their finding that only one compound in a Markush claim has utility, since all of the compounds must have utility. This error ultimately had no consequence, though, as it was found that, on the evidence, there was both a factual basis and sound line of reasoning sufficient to ground a sound prediction. [57]