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Fixed Dosage Regimen does not Limit a Physician’s Skill and Judgment

In Canada, methods of medical treatment are not patentable subject matter. In contrast, medical use claims, such as the use of metformin to treat type 2 diabetes, are considered to be patentable subject matter. To articulate its position on the fine line between a medical use claim and a method of medical treatment claim, in 2015, the Canadian Intellectual Property Office (“CIPO”) issued practice notice PN 2015-01 entitled Revised Examination Practice Respecting Medical Uses. This practice notice focuses its analysis on whether the essence of an invention is directed at “what” to use to treat a patient, which is patentable, versus “how” to use something to treat a patient, which may be unpatentable if it prevents, interferes with, or requires a physician’s skill and judgment.

Recent Decision No. 1409 of the Patent Appeal Board (“PAB”) and the Commissioner of Patents provides further clarity as to the CIPO’s interpretation of PN 2015-01. This decision confirms that claims restricted to a fixed dosage regimen are patentable if they do not prevent, interfere with, or require a physician’s skill and judgment. Decision No. 1409 is concerned with one substantive issue: whether patent application No. 2,504,868, titled “Multiple-Variable Dose Regimen for Treating TNF-alpha-Related Disorders” (the “‘868 application”) claims subject matter that is patentable.

Claim 1 of the ‘868 application recites:

Use of D2E7 [a TNF-alpha inhibitor sold commercially as HUMIRATM] in multiple doses for treating inflammatory bowel disease [such as Crohn’s disease] in a human subject, wherein the multiple doses comprise:

a first dose of 160mg of D2E7 for subcutaneous administration;

a second dose of 80mg of D2E7 for subcutaneous administration two weeks following administration of the first dose; and

a third dose of 40mg of D2E7 for subcutaneous administration two weeks following administration of the second dose.

During patent prosecution, the claims were rejected on the basis that they encroached upon the physician’s right to determine how to treat a particular patient, and therefore amounted to a method of medical treatment. However, in Decision No. 1409, the PAB recognized that the examination of method of medical treatment claims had evolved over time. The PAB noted that PN 2015-01 rescinded the earlier Practice Notice PN 2013-04 on Examination Practice Respecting Medical Uses, particularly with respect to the patentability of dosage regimens. In contrast with PN 2013-04, PN 2015-01 provides that where an essential element of a claim instructs a medical professional “how” to treat a patient, the claim is not necessarily directed to a method of medical treatment. Rather, a further inquiry must be undertaken to determine if the essential element prevents, interferes with or requires the professional skill of a physician. Essential elements that narrow treatment to a fixed dosage, a fixed dosage regimen, a patient sub-population, or a particular administration site are not considered to be a limitation on the physician’s professional skill or judgment, according to PN 2015-01.

Applying this analysis and having regard to the application as a whole, the PAB concluded that claim 1 of the ‘868 patent was not ambiguous and claimed a fixed dosage regimen in terms of the route of administration, the dose of D2E7, and the timing between the doses. As such, claim 1 went beyond claiming a composition of matter, and served to “instruct a medical professional ‘how’ to treat a patient” (see para. 59).

The PAB then applied PN 2015-01 to consider whether claim 1 of the ’868 application prevents, interferes with, or requires the professional skill of a physician. First, to administer D2E7 according to a fixed dosage regimen does not require the professional skill of a physician. Second, the PAB concluded that claim 1 does not prevent or interfere with a physician’s skill or judgment, and that a physician’s determination that an alternative dosage regimen is appropriate for a patient falls outside the scope of ‘868 claims. Claim 1 is restricted to a “specific” dosage regimen and does not encroach upon the physician’s right to exercise his/her professional skill and judgment when determining which dosage regimen a patient needs and when adjusting dosage regimens over time.

This decision is favourable for patent applicants and provides greater clarity on how the CIPO will interpret patent claims incorporating fixed drug dosage regimes. To help expedite patent prosecution, a patent applicant/drafter may consider clear claim language indicating a fixed dosage or a fixed dosage regimen and a well-crafted specification suggesting that a physician’s professional skill and judgment is not required in respect of that particular fixed dosage regimen.

One potential caveat to keep in mind, however, is that in Decision No. 1409, the claims were directed to preferred or most preferred embodiments that were supported by the specific examples contained in the application (see para. 10). In cases where it is less clear from the application as filed that there is in fact a preferred dosage regime, it may be more difficult for applicants to argue that professional skill and judgment is not required to determine an appropriate dosage regime for a particular patient.

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