In a May 12, 2021 decision (Hoffmann-La Roche Limited v Sandoz Canada Inc) from Justice Manson of the Federal Court, the asserted claims of two patents were found to be invalid as methods of medical treatment, which are not patentable in Canada. The asserted claims of both patents were also found invalid on the basis of obviousness, and one patent's asserted claim was additionally invalid for obviousness-type double patenting. No direct infringement was found for either patent, but induced infringement of certain claims of one patent was also found.

The two patents at issue, Canadian Patent Nos. 2,667,654 (the 654 Patent) and 2,709,997 (the 997 Patent), claim dosing regimens of pirfenidone (marketed in Canada by Hoffmann-La Roche Limited as ESBRIET) in the treatment of idiopathic pulmonary fibrosis (IPF), a rare, chronic and incurable lung disease.

The asserted claims of the 654 Patent claim the use of pirfenidone in a dose escalation regimen. The sole claim of the 997 Patent that was asserted claims the use of a full dose of pirfenidone in a patient who had experienced certain abnormal liver function following previous treatment with pirfenidone.

Patent claims to methods of medical treatment are prohibited in Canada and are not patentable under section 2 of the Patent Act. Justice Manson noted that there are inconsistencies in the applicable case law, but the crucial question with respect to patentability is whether the asserted claims encroach on the skill and judgment of physicians – if they do, the claims are not valid (see Hospira Healthcare Corporation v Kennedy Trust for Rheumatology Research; AbbVie Biotechnology Ltd v Canada (Attorney General)).

The asserted claims of both patents relate to fixed dosages and fixed intervals – the claimed dosing escalation regimen in the 654 Patent specified daily dosages (801 mg for seven days, followed by 1602 mg for seven days, then 2403 mg), while the 997 Patent also claimed one daily dosage (2400 or 2403 mg, in separate claims from which the asserted claim depends).

Generally, claims for fixed dosages and fixed intervals of administration suggest a vendible product, which is patentable (see Hospira Healthcare Corporation v Kennedy Trust for Rheumatology Research). Further, a fixed dosage or a fixed dosage schedule does not restrict, interfere with, or engage professional skill or judgment, unless there is evidence to contradict the claimed dosage (see AbbVie Biotechnology Ltd v Canada (Attorney General)), as Justice Manson found in this case.

Justice Manson noted that, "[a]lthough the line between fixed dosages and a range of dosages may not provide clear guidance when determining patentability, a range of dosages has been more readily found to constitute a method of medical treatment...[but] the presence of fixed dosages is not the end of the inquiry."

After distinguishing a line of cases where claims were not found to cover methods of medical treatment, Justice Manson found the current case to more closely approximate Janssen Inc v Mylan Pharmaceuticals ULC. That case set out that a claim to the administration of a drug whereby the physician, while relying upon the dosage advice of the patentee, would still be expected to be alert and responsive to a patient's profile and to the patient's reaction to the compound, is an unpatentable method of medical treatment.

With respect to both patents, Justice Manson found that there is a continued need for a physician's exercise of skill and judgment, as the claimed dosage regimens are not appropriate for all patients taking pirfenidone for the treatment of IPF and require an assessment of the individual patient's circumstances. The claimed dosages in both patents were found not to be vendible products, but rather to improperly interfere with a physician's skill and judgment and thus not to constitute patentable subject matter in Canada.

This decision is a reminder that an assessment of the patentability of claims to dosing of drugs is not limited to the form of the claims (i.e., fixed dosages good, dosage ranges bad), but rather to the substance of the claims and whether a physician's skill is required to treat patients using the claimed dosages.

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