Wednesday, September 7, 2016

VIREAD Patent Valid on the Facts

Gilead Sciences v Apotex Inc 2016 FC 857 Brown J
            2,261,619 / tenofovir disoproxil / VIREAD / NOC

In this NOC decision. Apotex’s validity attacks on the ‘619 patent, based on anticipation / invalid selection, obviousness and lack of utility, all failed on the facts. The main point of legal interest is Brown J’s agnostic approach to the question of “blinding the witness.”

Tenofovir, or PMPA, is a nucleotide reverse transcriptase inhibitor which was known to be effective against retroviral infections such as HIV. However, its oral bioavailability was poor and it was only effective when administered intravenously [32]. The claim of the ‘619 patent at issue, Claim 32, claims tenofovir disoproxil (TD) and its salts, tautomers and solvates [6], [70]. TD is an oral prodrug of tenofovir, which allows effective oral admininstration of tenofovir [31].

Blinding Experts
There is an evolving debate over the practice of “blinding” the expert witnesses. In this case the parties took different approaches:

[55] While counsel for Gilead provided the legal framework to its experts early, including legal tests for anticipation, obviousness, and utility, Apotex states it did not do so before the experts had drawn their own conclusions on issues such as the promise of the patent, claim construction, and the prior art.

Citing Gleason J in Cialis 2015 FC 875 [166] and Locke J in Adderall XR 2016 FC 382 [42]-[48] (discussed here) [58], Brown J held that “In my view the blinding of a witness is a factor, one of perhaps several, that goes to weight, but it is not a matter that goes to admissibility” [56], and “the blinding issue is a question of relevance, reliability and weight, and is not a doctrinal matter” [59]. Brown J is no doubt right to say that there is no firm rule that evidence should be excluded if the witness is not blinded appropriately (whatever that might mean), and it also seems reasonable that the effect of blinding a witness will depend on the circumstances of the case. However, Brown J provided no guidance as to how and when blinding might affect the weight given to expert evidence. My impression is that this is because in this case it made no difference at all. He made no specific reference to blinding in his discussion of the evidence, and the reasons he did give for preferring one expert over another turned on their relative expertise. So, while I get the sense that Brown J will not  generally be heavily influenced by whether the expert was blinded, this decision leaves the door open to the possibility that it might make a real difference in a case in which the opinions were otherwise more evenly balanced.

Anticipation requires enabling disclosure, but in this case enablement was conceded [73], and the only question was whether TD was disclosed by the prior art European Patent Application 0,481,214 [49]. The EP 214 application at p 5 identified a class of preferred compounds [75], and the main dispute between the parties was as to whether the R4/R5 combination substituent disclosed in the EP 214 application should be understood as including carbonates [79]. Gilead argued that it did not, and consequently EP 214 did not “disclose” TD [77]. In the end Brown J concluded on the evidence that “the EP 214 application does not disclose the carbonate group” [84].

I must say that I find this whole argument quite difficult to follow. There is no suggestion in the decision that TD itself is specifically identified in the EP 214 application; the debate seems to be over whether it is encompassed in the class of compounds defining the preferred embodiment [88]. But if TD is not specifically disclosed, then EP 214 does not anticipate, even if the disclosed class did encompass TD. That is, the genus does not anticipate the species: Sanofi 2008 SCC 61 [19]. Otherwise, selection patents could not exist. As the SCC said in Free World 2000 SCC 66, quoting with approval the leading Canadian decision on anticipation, Beloit (1986), 8 CPR(3d) 289 (FCA), “the prior publication must contain so clear a direction that a skilled person reading and following it would in every case and without possibility of error be led to the claimed invention” [26, my emphasis]. The possibility that one might arrive at the invention is not enough.

Perhaps I’ve misunderstood the nature of the debate in this case. Or perhaps I’ve misunderstood the law. I had thought it was quite clear, but the argument that the genus anticipates the species continues to be regularly raised, even since Sanofi, and sometimes successfully (see here and here).

Selection Patents
Apotex also argued that the 619 Patent is an invalid selection patent from the genus disclosed in the EP 214 application [87]. In light of Brown J’s conclusion that his conclusion that EP 214 did not encompass TD at all, then the question of whether it was a valid selection did not arise [88]. Brown J nonetheless went on to hold that even if TD was encompassed by EP 214, he would have held it to be a valid selection patent on the basis of its superior bioavailability [90]. This conclusion turned on the facts.

Brown J’s conclusion that TD was neither obvious nor obvious to try [112] also turned on the facts, which were quite compelling. One minor point is that he noted the strong motivation to find a prodrug such as TD, and he remarked that “the presence of such strong motivation to invent a drug with the properties now known to TDF does not itself render the invention obvious or obvious to try under the Sanofi test” [111]. I would point out that a strong motivation actually reinforces the conclusion that the invention was not obvious. Given the strong motivation, if TD had been obvious, then it would have been invented sooner.

The utility attack raised the usual debate over the promise of the patent: did it promise improved oral bioavailability over the parent drug, or effective treatement of HIV [119]-[120]? Brown J held that the former was the promise, and the latter was merely a goal [122], and he held that improved oral bioavailability was demonstrated [132]. He emphasized that he was entitled to, and did, look outside the patent itself for evidence of demonstrated utility [135]. One minor point of interest is that Brown J somewhat ran together the “scintilla” and promise branches of the utility requirement. After determining the promise of the patent [125], he quoted Celebrex 2014 FCA 250 [64] to the effect that all that is required is a scintilla of utility [126]. Then, after reviewing the facts, he held that “I find these facts demonstrate the utility of the 619 Patent in terms of its promise, i.e., it has more than a ‘scintilla of utility’” [133]. So, Brown J seems to have understood that the utility requirement was satisfied if the invention had a scintilla of utility for the promised purpose. While that is a logical enough position, the promise of the patent and the scintilla standard are generally considered to be two different branches of the utility standard: see Celebrex [65] saying “The promise doctrine represents an exception to the above minimum statutory requirements,” (ie the scintilla of utility). I don’t see this point as making any difference to his conclusion.

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