Brevetabilité au Canada : la Cour d'appel fédérale se penche sur la question de la distinction entre le dosage fixe et la gamme posologique (article en anglais)

In Canada, claims to new uses based on the discovery of "hitherto unrecognized properties" constitute patentable subject matter.^[1] Use claims in the context of pharmaceutical inventions are also allowed; claims to the "use in the treatment or prophylaxis" of AIDS were unanimously held by the Supreme Court to be patentable subject matter and not an impermissible "method of medical treatment".^[2] Likewise, claims to the use of compound A at fixed dosage amount/dosing schedule B to treat disease C are patentable.^[3]

It has thus been to the great frustration of innovative companies that courts, and some examiners at the Patent Office, consider that use claims that contain a limitation pertaining to a dosage range or dosing schedule are unpatentable on the purported basis that they interfere with a physician's ability to practice and constitute a method of medical treatment.^[4] The recent Federal Court of Appeal ("FCA") decision in Hospira Healthcare v The Kennedy Trust [Remicade/Inflectra]^[5] considers the issue and candidly acknowledges some of the shortcomings with the current state of affairs.

Background

Methods of medical treatment are currently considered to constitute unpatentable subject-matter in Canada. The provenance of this restriction is the Supreme Court of Canada's decision in Tennessee Eastman v Commissioner of Patents.^[6] The Court in Tennessee Eastman founded the restriction on a now-repealed provision of the Patent Act (formerly section 41(1)). Given this, in 2016 the Federal Court of Appeal and academic commentary called for the Supreme Court to revisit this doctrine and whether it has any statutory basis.

More recent jurisprudence has drawn seemingly arbitrary distinctions between different types of use claims, with some being permitted and others objected to under the method of medical treatment prohibition. Since the repeal of section 41(1), Courts have distinguished between claims that ostensibly relate to professional skills and allegedly "fence in" an area of medical treatment/physician autonomy from those that relate to "vendible products", "commercial offerings", or "trade, industry or commerce".

Applying this distinction has led to the strange situation described in the introduction. Broader "use of compound X for the treatment of condition Y" claims are considered patentable subject-matter while claims that add a restriction in terms of a dosage range or a dosing schedule, and which are thus narrower in scope, are considered improper for "fencing in" an area pertaining to a physician's skills. Claims that are narrower still and that claim a use with the additional limitation of a strict dosage regime or dosage schedule are again considered to be patentable.

No appellate court has satisfactorily addressed this situation. Nonetheless, the Canadian Patent Office typically follows this rubric in assessing the patentability of use claims, denying protection to claims with dosage ranges or dosage schedules.

The Remicade/Inflectra Decision

Remicade/Inflectra raised a panoply of patentability issues, many of which will be discussed in other commentary. This piece is limited to the dicta concerning methods of medical treatment.

The Trial Judge in Remicade/Inflectra held that the patent at issue did not pertain to a method of medical treatment. The defendant asked the Trial Judge to ignore the "artificial" Swiss-type style of the at-issue claims as they purportedly restricted a rheumatologist's ability to practice and required a rheumatologist's skill and judgement to put into practice. In rejecting these arguments, the Trial Judge explicitly called out the "not entirely consistent" law on point, and found that the Swiss-type claims at issue relate to a vendible product and are patentable subject-matter. In summary, the Trial Judge stated that:

Taken to its logical end, Hospira's position would prevent an inventor from patenting any subsequent use for a known compound, as this would monopolize the "how and when" of using the compound for treatment - a proposition that is clearly at odds with the system and jurisprudence which allows such new use patents.^[7]

The defendants/appellants maintained their method of medical treatment argument on appeal. However, this argument was largely premised on the Swiss-style claims at issue being construed as use claims. Because the FCA rejected this construction argument, its discussion regarding methods of medical treatment is largely obiter.^[8]

Regardless, the FCA in Remicade/Inflectra acknowledged the distinction drawn in the jurisprudence between "dosage range" and "fixed dosage" claims, classifying this line as presenting "a tempting simplicity". Despite this, the FCA went on to state that:

However, it is not clear to me that the decisions of the Supreme Court of Canada that form the basis of the principle that methods of medical treatment are not patentable justify a distinction between a fixed dosage (or interval of administration) and a range of dosages (or intervals). It would seem that a medical professional will be constrained in their exercise of skill in either case. Also, a drug is arguably no less a vendible product simply because its dosage or interval of administration is not fixed.^[9]

The candid acknowledgement that there does not appear to be a basis for the principle differentiating fixed dosage claims and dosage range claims is welcome. The FCA went on to say that the issue "deserves deep analysis".

Indeed, one of the claims at issue in Remicade/Inflectra encompassed a dosage range (claim 33: "The pharmaceutical composition…as a dosage form containing from about 0.1 milligram to about 500 milligrams of infliximab"). While the parties' arguments did not focus on this claim, the Trial Judge's decision that it did not constitute a method of medical treatment was upheld by the FCA.^[10]

The FCA further held that other claims in issue which "are limited to fixed dosages and intervals of administration, or do not specify any dosage or interval of administration…concern a vendible product, and are not invalid as methods of medical treatment."^[11]

Brief Commentary

How did Canadian law on methods of medical treatment arrive at this juncture? It may be that a misguided concern over physician autonomy is at least in part to blame.

The Supreme Court in AZT recognized that the claims in issue, covering the use of a compound to treat a disease, related to attempts to market a product as a "commercial offering".^[12] Such claims do not seek to limit physician autonomy, nor are use claims asserted against physicians.^[13] This is made obvious by the facts upon which the litigations concerning these claims arise, with generic drug manufacturers seeking to come to market with a vendible, commercial product that falls within the scope of the patent claims. The Trial Judge in Remicade/Inflectra recognized this, stating that "clearly, the treatment of a medical condition can be a goal of both medications and of medical practitioners."^[14] However, use claims with dosage range and/or dosage schedule restrictions have sometimes been classified as being related to professional skills rather than vendible products, leading to this inconsistent jurisprudence.

The Remicade/Inflectra decision can be used to chart a path forward.

First, Swiss-type claims should be construed in a manner consistent with their plain language, as the Court did in Remicade/Inflectra. Except for the rare possible exception, claims to the use of a compound in the manufacture of a medicament do not pertain to a method of medical treatment.

Second, the distinction between use claims with fixed dosage amount limitations and use claims with dosage range/schedule limitations should be discarded. There is no basis to prevent innovators who discover new, useful and inventive dosage ranges and/or schedules from obtaining patent protection.

Third, following Professor Siebrasse's suggestion, and consistent with the Supreme Court's repeated guidance that patent law is entirely statutory (and the removal of the statutory underpinning for the method of medical treatment restriction in the first place), the doctrine should be done away with in favour of a defence to infringement that protects physician autonomy. This would remove the artificial barrier to patentability that has been applied while ensuring that physicians can practice without fear of infringement.