Federal Court of Appeal addresses patentability of methods of medical treatment in Canada

Methods of medical treatment are considered to be an exception to patentable subject matter in Canada. However, it is acknowledged that the exception has no explicit statutory basis, and the supporting jurisprudence is both unclear and contradictory. The Court has recently characterized the jurisprudence on point as "inconsistent"^[1] and deserving of "deep analysis,"^[2] and 2015 the Federal Court of Appeal (FCA) called for "full consideration" of the status quo by it or the Supreme Court "in a case where the issue is squarely raised on the facts."^[3]

Over time, the exception as it relates to patents claiming the use of a dosage regimen in the treatment of a disease has evolved to distinguish claims covering fixed dosages and intervals (patentable subject matter) from claims covering a range of dosages and intervals (unpatentable subject matter). This distinction has come under scrutiny in recent years.^[4]

The recent FCA decision of Pharmascience v Janssen, 2024 FCA 23 [Janssen], addresses many aspects of the method of medical treatment exception to patentability, including: (i) the history of the exception and its statutory basis; (ii) the application of the exception to different claim types; and (iii) the fixed dosage versus range distinction. While Janssen provides a welcome analysis of the exception, significant uncertainty will remain for those seeking to secure and enforce patent rights in Canada.

The decision below and the patent at issue

Janssen is an appeal from a decision relating to a patent containing four claim sets, each with common elements relating to dosage regimens for the administration of the medicine paliperidone palmitate. The Court described the four claim sets as follows:

• Claims 1 to 16 relate to prefilled syringes adapted for administration according to the claimed dosing regimens;
• Claims 17 to 32 relate to a use of a "dosage form" according to the claimed dosing regimens;
• Claims 33 to 48 relate to use of paliperidone as paliperidone palmitate in the manufacture/preparation of a "medicament" adapted for administration according to the claimed dosing regimen; and
• Claims 49 to 63 relate to a "dosage form" adapted for administration according to the claimed dosage regimens.^[5]

The Trial Judge distinguished the "use" claims (17-32) from the remaining claims, which were characterized as "product" claims. The product claims were considered vendible products (and thus patentable subject matter) on their face and as such were not the focus of the Trial Judge's method of medical treatment analysis.^[6]

With respect to the use claims, the Trial Judge noted the distinction in the jurisprudence between claims restricted to particular dosages and specific administration schedules (patentable) versus claims to dosages or schedules with ranges (not patentable). The use claims were held to be patentable for two primary reasons: (i) the claims largely did not require choices to be made in respect of possible ranges for the dosage amounts, which were fixed; and (ii) any claim elements requiring choices to be made by a physician did not have clinical implications. As skill and judgment were not required to implement the claimed dosage regimens, they were held patentable.^[7]

The statutory basis for the exception and the history of the fixed vs. range distinction

The FCA's analysis of the history of the method of medical treatment exception begins with a discussion of the lack of an explicit prohibition in the Patent Act against claims for methods of medical treatment. It then considers the Supreme Court decisions of Tennessee Eastman, Shell Oil and AZT, each of which discuss (in varying detail) the method of medical treatment exception. The FCA concludes that these decisions support the exception on the basis that methods of medical treatment are not an "invention" as contemplated under section 2 of the Patent Act, reasoning that methods of medical treatment do not relate to trade, industry and commerce, but rather relate to non-economic professional skills and are unpatentable.^[8]  

Turning to the issue of fixed vs. variable dosage regimens, Janssen questions whether such a distinction is meaningful since it "would seem to make no difference to whether the drug in question is a vendible product." It does however allow for the distinction to be given weight "provided that the analysis remains tied to the ultimate question of whether professional skill is applied in using the invention." This statement is tempered by the Court, which acknowledges that it would "go too far to say that any drug regimen that requires a physician to monitor a patient is unpatentable," with the Court stating that this would encompass almost any drug.^[9]

Ultimately, the FCA holds that:

Whether or not a patent claim to a dosing regimen relates to a method of medical treatment cannot be based exclusively on whether its dosing and schedule is fixed or not. The proper inquiry remains whether use of the invention (i.e., how to use it, not whether to use it) requires the exercise of skill and judgment, and the burden remains on the party challenging the patent. It is difficult to provide more detailed guidance than this for parties involved in future litigation and courts faced with allegations of invalidity of patent claims due to unpatentable subject matter, namely methods of medical treatment. Such allegations will generally turn on the particulars of the case and the evidence on the record. [emphasis in original]

The reach of the method of medical treatment exception to different claim types

As mentioned, the Trial Judge's method of medical treatment analysis focused on the "use claims" (17 to 32), having concluded that the other claim sets were "product" claims and outside the reach of the exception. This point was appealed, with the appellant arguing that all four claim sets relate to a dosing regimen and should be subject to the method of medical treatment analysis. The appellant characterized the Trial Judge's finding of the three claim sets as being product claims as a form over substance analysis.^[10]

The FCA rejected this appeal. That all claims contained a dosage regimen as an essential element did not transform the product claims into use claims. Rather, the Court affirmed that the claims to pre-filled syringes, the use of paliperidone palmitate in the preparation of a medicament, and to dosage forms were all patentable claims to vendible products.^[11]

The use claims at issue were found not to constitute a method of medical treatment

The final issue considered in Janssen was whether the use claims constituted a method of medical treatment. The FCA affirmed the Trial Judge's decision that they did not.

In so doing, the Court also held that the Trial Judge properly focused on whether a physician would be required to use skill and judgement in deciding how to use the invention, not whether to do so [FCA's emphasis].  The FCA also recognized that "a fixed dosage and schedule may be a good indication" that skill and judgment is not required to use the claimed invention.^[12]

The FCA dismissed the appeal with the appellant not convincing the Court that any evidence existed to contradict the fixed nature of the dosing and schedule claimed in the patent at issue. This was despite the patent claims allowing, for example, for a "monthly ± 7 days dosing interval" and administration to different sites in the body, and despite the patent's disclosure allowing for the POSA to titrate a patient's dose up or down depending on their condition. Persuasive on these issues was that the choices left by the patent largely did not have clinical implications to the patient.^[13]

Conclusion

The FCA's attempt to reconcile and clarify this area of the law is commendable. The Court's confirmation that claim form is relevant to the analysis is welcome and should provide additional certainty to patentees. Also, the FCA's finding that elements in use claims which leave choices for a medical professional POSA do not automatically render such claims unpatentable is also a desirable development. The former practice of at times refusing or invalidating patents when inventive dosage regimens that involve some flexibility were discovered was arbitrary and without basis in the Patent Act.

However, it remains to be seen how the Court and patent office will interpret Janssen's guidance as to what constitutes a method of medical treatment. The suggestion that the inquiry should focus on whether the use of the invention requires the exercise of skill and judgment raises questions. Virtually all patent claims require the skill of the POSA to be applied in order to use the invention. For instance, claims to a chemical compound are often made and used by professional chemists, claims in computer-implemented inventions by professional engineers, and claims to the use of a compound to treat a disease by medical professionals.

By equating the method of medical treatment question with whether skill and judgment is required when "using" the invention, the analysis risks encroachment on the question of enablement of the specification under paragraph 27(3)(b) of the Patent Act. In this regard, it is trite that the POSA is permitted to apply their professional skill through trial and error experimentation in making and using an invention so long as inventive ingenuity is not required. Clearly, Janssen does not mean to alter or modify this established law. Further clarification of how Janssen will be applied may await a future decision:

It is difficult to provide more detailed guidance than this for parties involved in future litigation and courts faced with allegations of invalidity of patent claims due to unpatentable subject matter, namely methods of medical treatment. Such allegations will generally turn on the particulars of the case and the evidence on the record.^[14]

If you have any questions related to this article, contact one of the authors listed above.