Canada: Federal Court Of Appeal Limits Scope Of Prohibition Against Patenting Methods Of Medical Treatment

On February 1, 2024, the Federal Court of Appeal dismissed an appeal from a decision of the Federal Court, finding the claims of a patent to be valid and infringed. On appeal, the only issue before the Court was whether the patent claims in question were invalid because they impermissibly claimed "methods of medical treatment". The Court of Appeal reviewed the history and scope of the prohibition against patenting methods of medical treatment and concluded that the Janssen patent in issue did not fall within that prohibition¹.

What you need to know

• The prohibition against patenting methods of medical treatment as being unpatentable subject matter under section 2 of the Patent Act has existed for decades but has always been unclear.
• Prior to this decision, the case law seemed to suggest that claims to fixed doses were permitted; however, claims to dose ranges were often held to be invalid as claiming methods of medical treatment.
• The Federal Court of Appeal has now confirmed that this is not the controlling question. Rather, a patent claim will only constitute a prohibited method of medical treatment if it usurps the exercise of skill and judgment of a treating physician—if it goes to how to treat a patient as opposed to whether to treat a patient.
• This decision gives pharmaceutical and biotech companies more leeway in drafting their patents.

Facts

Janssen holds a patent relating to the medicine INVEGA SUSTENNA, which constitutes a suspension of paliperidone palmitate for the treatment of schizophrenia and related disorders. The patent teaches a dosing regimen aimed at achieving an optimum plasma concentration/time profile, comprising a first loading dose, a second loading dose, and monthly maintenance doses thereafter. The patent was the subject of an action under the PMNOC Regulations against Pharmascience, in which Pharmascience asserted that the patent claims were invalid for claiming unpatentable subject matter; namely, methods of medical treatment.

The trial judge commented that there are inconsistencies in Canadian law on what constitutes a prohibited method of medical treatment. Canadian courts tend to consider claims involving dose ranges to fall within the prohibition, whereas pure product claims or claims to specific doses are generally held to be acceptable as claiming "vendible products". However, the trial judge noted that this dichotomy had a "questionable underpinning". The trial judge concluded that Janssen's patent was valid, because although the claims included dose ranges, they did not require professional skill and judgment to apply or, if choices were required, did not require choices that had clinical implications.

Pharmascience appealed the decision. The Court of Appeal reviewed the prohibition on patenting methods of medical treatment and its development through the jurisprudence, including the leading Supreme Court of Canada cases (Tennessee Eastman, Shell Oil, and AZT). It traced the history of this prohibition back to the rules for patentable subject-matter, noting that "vendible products" cannot be prohibited methods of medical treatment, since they have the type of economic value that the patent system seeks to protect.

The Court of Appeal rejected the notion that one can identify a method of medical treatment claim simply by distinguishing between fixed and variable doses and schedules. Rather than undertaking this line-drawing exercise, the Court of Appeal reiterated that it was important to distinguish between claims that require skill and judgment to decide whether to use the claimed intervention (which are not methods of medical treatment) and claims that require skill and judgment in order to determine how to use them (which are). It ultimately settled on an approach where each case will turn on its own particular facts:

To summarize, 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 [the] use of the invention (i.e., how to use it, not whether to use it) requires the exercise of skill and judgment ... 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 ...

Against this backdrop, the Federal Court of Appeal held that the Federal Court was right to (a) characterize many of the claims in question as product claims (i.e., vendible products, such as the pre-filled syringes) and (b) find the others (even claims with different dosage implications) to be patentable. The Court held that the exercise of discretion used in deploying the treatment regimen was a question of "whether" not "how" the drug should be dosed.

Analysis and implications

This decision relaxed what appeared to be an illogical rule that distinguished between claims for fixed doses (allowed) and claims for dosage ranges (not allowed). Rather, each case is to be decided on the evidence, and the specific claims, before the court. While we interpret the decision as largely patentee-friendly, the previous approach had the advantage of predictability. As the Court stated:

Though a fixed dosage and schedule may be a good indication that no [medical] skill and judgment would be required, evidence may indicate otherwise.

As a result, patentees should not expect to see a reduction in allegations that patent claims to dosage ranges (and even to dosages) do not contravene the prohibition against claiming methods of medical treatment. However, this decision provides guidance on the type of evidence that may be important to rebut such an allegation.

What's next

While most patent cases do not go beyond the Federal Court of Appeal, this case may be an exception. The same judge who wrote Janssen also wrote in a different case that:

This state of the jurisprudence has a tempting simplicity. 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.

There is still a chance that the Supreme Court of Canada will wish to revisit this issue. Pharmascience has 60 days until April 1, 2024 to file an application with the Supreme Court of Canada to seek leave to appeal this decision.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.