Friday, June 18, 2021

A New Twist on the Patentability of Method of Medical Treatment

Hoffmann-La Roche Limited v Sandoz Canada Inc 2021 FC 38 Manson J

2,667,654 / 2,709,997 / pirfenidone / ESBRIET / NOC

Roche’s 654 and 997 patents at issue in this NOC proceeding relate to the use of pirfenidone in the treatment of idiopathic pulmonary fibrosis [IPF], a rare, chronic and incurable lung disease [7], [12]. Manson J held that Sandoz would induce infringement of the asserted claims of the 654 patent by making and selling its generic product, but the asserted claims of both patents were invalid for obviousness and as methods of medical treatment. The asserted claim of the 997 patent was also invalid for obviousness-type double patenting. Various other invalidity attacks failed. The obviousness analysis was legally straightforward and turned on the facts. This post will provide background and focus on the patentability of methods of medical treatment, where Manson J has introduced a novel twist into a confusing area of law. Another interesting issue relates to the construction of Swiss form claims, which I’ll deal with in a subsequent post.

It was common general knowledge at the relevant date that pirfenidone was under investigation as a treatment for IPF, and preliminary results were promising though inconclusive [70]. Consequently, the use of pirfenidone for the treatment of IPF could not be claimed. Instead, the 654 patent claimed a dose escalation regimen, intended to minimize side effects [8], [158]. The 997 patent claimed full dose treatment of a patient who had exhibited liver abnormality after initial treatment [10], [182]. The prior art indicated that treatment should be stopped if a patient developed liver function abnormalities with the use of pirfenidone, and the 997 patent disclosed that such patients could still receive the full dose, with suitable monitoring of liver function.

The 654 patent was held to be invalid on a straightforward obvious-to-try analysis, given that it was common general knowledge that a dose escalation regime was one way of minimizing side effects and that there was no particular difficulty in arriving at the claimed regime [166]–[181]. The 997 patent was obvious because management of drug-induced liver toxicity was part of the cgk and continuing treatment while doing so would be an obvious alternative to discontinuing treatment entirely if the benefits outweighed the risks [66(ii)], [190]. The 997 patent was also found to be invalid for obviousness-type double patenting over the 654 patent [148]–[153]. I’m a bit puzzled as to why this argument was run on a double-patenting basis, as the publication date of the 654 patent was June 26, 2008 and the claim date of the 997 patent was November 10, 2008 [9], [11], [153], so the 654 patent was prior art over the 997 patent and so, on Hospira 2020 FCA 30, would have been part of the state of the art against the 997 patent. Perhaps Sandoz felt it was safer to use double patenting rather than to rely on the Hospira doctrine—presumably the 654 patent was not part of the common general knowledge and would not have been discoverable in a reasonably diligent search.

Both patents had three distinct claim types [95]–[96]:

            1) “German-style” — Use of pirfenidone for treatment of IPF

2) “Swiss-style” — Use of pirfenidone in the manufacture of a medicament for treatment of IPF

3) “Product for use style” — pirfenidone for use in the treatment of IPF

Manson J construed all the claims as “use claims” including the Swiss-type claims [107], and consequently did not distinguish between them in assessing whether they claimed unpatentable methods of medical treatment. In this post, I’ll focus on the German-style claims of the 654 patent, which are use claims on their face, so as to avoid any of the tricky claim construction issues that arise with the Swiss-type claims.

Manson J stated that “Patent claims to methods of medical treatment are prohibited in Canada and are not patentable under section 2 of the Patent Act” [195]. This is perhaps now in doubt—see Cobalt 2015 FCA 116 [55]; Hospira 2020 FCA 30 [53]—but it’s well established at the Federal Court level and I won’t pursue the point here. The main battle ground is over what constitutes an unpatentable method of medical treatment: for background see here and here.

Claim 1 of the 654 patent was of the following form (the full claim is reproduced below):

1. Use of X for treatment of disorder Y at a [dosage regimen with fixed dose and schedule]

Manson J held this to be an unpatentable method of medical treatment, essentially for the following reason:

[195] Patent claims are invalid where they prevent or restrict physicians from applying their skill and judgment. . . . . [T]he crucial question remains of whether the 654 and 997 Asserted Claims encroach on the skill and judgment of physicians.

The claimed regimen specified fixed doses and a fixed schedule, and, as Manson J noted, such a regimen will not normally be held to be a method of medical treatment [197]. However, picking up on an obiter comment in AbbVie 2014 FC 1251 [114], Manson J held that a fixed dosage regime is patentable “unless there is evidence to contradict the claimed dosage” [197]. He held that such evidence exists in this case:

[204] [T]he evidence has established that there is a continued need for a physician’s exercise of skill and judgement, as the default dose escalation regimen is not appropriate for all patients taking pirfenidone for the treatment of IPF. There are several anticipated adverse effects and individualized patient characteristics that require the attention of the prescribing physician.

In particular, the specified dose escalation regimen would not be tolerable for all patients [205]; pirfenidone is associated with adverse effects that require individualized assessment [206]; deviations from the regimen might be warranted due to “dietary habits, experienced nausea, a patient’s assessment of the adverse events and frailty” [207].

The main take-away is that whether the claim is to a method of medical treatment doesn’t turn just on the claim itself, but requires a fact-based analysis as to how the treatment is likely to be administered in practice. The question isn’t whether the claim specifies a fixed dosage, but whether a fixed dosage will actually be administered in all cases. This is a novel holding. I wouldn’t say it is a departure from prior law. Rather, the prior cases have implicitly assumed that patentability is determined by the nature of the claimed subject-matter. That is, a claim to “the use of X to treat disorder Y” was considered to be patentable subject-matter, even if the use might be discontinued in practice. That assumption has now been disrupted.

A few observations:

1) This means that you can’t tell by reading the patent whether it claims patentable subject-matter. The question, on Manson J’s analysis, is whether it interferes with the physician’s skill and judgment in fact, not in principle. I find this odd for an attack that turns ultimately on whether the claimed subject-matter falls within a category specified in s 2. In Harvard Mouse 2002 SCC 76 [172], the SCC held higher life forms to be unpatentable in part because of concerns that “innocent bystanders” might inadvertently infringe through adventitious entry (see Harvard Mouse 2002 SCC 76 [172]. Under a fact-oriented approach, we might say that higher life forms are unpatentable if and only if the particular claimed form is likely to escape from the owner adventitiously. Of course, other validity attacks, such as obviousness or anticipation, turn on the facts, so it’s not objectionable in principle that validity should turn on the facts of the case, but it nonetheless seems strange to me for that to be true for subject-matter, though I can’t put my finger on exactly why.

2) The factual inquiry as to whether individualized assessment is necessary either radically disrupts established law or relies on an arbitrary distinction. For example, it is well established that “X for treatment of disorder Y” is patentable subject-matter: Wellcome / AZT 2002 SCC 77 [50]. From the little I know, in fact even AZT requires individualized assessment, eg if tolerance develops. More generally, I suspect that there are very few if any drugs that are well tolerated by 100% of the population and do not require any individualized assessment. If Manson J’s fact-based analysis is generally applicable, as suggested by his statements at [195], claims of the form “X for treatment of disorder Y” are unpatentable if it can be established on the facts that individualized assessment is necessary, or that some patients cannot tolerate the drug at all. If accepted, that would be a revolution in the law, resulting in the invalidation of many valuable patents. I can't imagine it would be very difficult to establish the factual basis for this kind of attack on a use claim, so I expect we will see it in due course. It will be interesting to see what happens.

An alternative would be to say that the fact-based inquiry applies only to claims to a fixed dosage or fixed dosage schedule: Manson J’s remarks at [195] were general, but his statement at [197] was more specific to those types of claims. In that case, the “rule” would be that “X for treatment of disorder Y” is patentable subject-matter regardless of whether individual deviations might be required, but “X for treatment of disorder Y at a fixed dosage” is patentable only if individual deviations are never required. Such a distinction strikes me as entirely unprincipled—though admittedly not more unprincipled than most of the distinctions in this area.

3) Manson J’s basic point was that the claim is unpatentable if it “prevent[s] or restrict[s] physicians from applying their skill and judgment.” This is the usual rationale for the restrictions on methods of medical treatment in the Federal Court caselaw. The difficulty with this rationale is that it isn’t consistent with the patentability of claims of the type “X for treatment of disorder Y.” As I noted in a previous post, the claim at issue in Wellcome / AZT was to a formulation comprising “an effective amount” of AZT ('277 claim 22). In the context of a use claim without any specific dosage regime, that effective amount must be determined by the physician in the exercise of their skill and judgment. Indeed, the SCC expressly held that the claims at issue were not unpatentable methods of medical treatment on the basis that the physician was left free to exercise her skill and judgment: “How and when, if at all, AZT is employed is left to the professional skill and judgment of the medical profession” [50]. If claims of the form “X for treatment of disorder Y” don’t restrict physicians from applying their skill and judgment, then I don’t see how claims of the form “X for the treatment of disorder Y according to fixed dosage regimen” are any different. Adding Manson J’s point that an individualized assessment may be required to decide whether the claimed use is appropriate doesn’t make it any easier to reconcile this holding with Wellcome / AZT. To paraphrase, “How and when, if at all, [the claimed fixed dosage regimen] is employed is left to the professional skill and judgment of the medical profession.” That is precisely the reason given by the SCC in Wellcome / AZT for holding the claimed use was not a method of medical treatment and I can’t see how the point is any different when a fixed regimen is claimed instead of a use.

In making these observations I mean no criticism of Manson J, who had the unenviable task of applying incoherent principles in an inconsistent area of law. As the Court of Appeal has recognized, and as Manson J recognizes in this decision [195], the law relating to what constitutes an unpatentable method of medical treatment is confused and inconsistent at best. Manson J’s basic point that a claim is unpatentable if it encroaches on the skill and judgment of physicians strikes me as unpersuasive, but it is certainly not new: see eg Janssen / galantamine 2010 FC 1123 [55]. Indeed, it is the main justification for the rule against patentability of methods of medical treatment. With that said, the fact-based analysis undertaken by Manson J adds a new twist to an already twisted area of the law. It will be interesting to see what happens if someone tries to run this kind argument in respect of a more standard claim to “X for the treatment of Y.” I doubt that argument would succeed, but given the state of the law, anything is possible.

More broadly, this decision illustrates how incoherent this area of the law is. It also shows that the issue isn’t going to go away on its own. We will be facing incoherent and inconsistent decisions on this issue until the Court of Appeal takes it up. In Hospira, the FCA articulated a willingness to do so in the appropriate case. I rather doubt that this will be the case, given the holding on obviousness, but this will be worth keeping an eye on if it goes to the FCA.

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