Dosage Regimens Affirmed in Canada Again

June 2, 2021
By Melanie Szweras, Andrea Uetrecht and Madelaine Lynch

The Commissioner’s Decision Re Genentech, Inc. (2021 CACP 8) is the most recent case to consider medical use claims following the clarification of patentable subject matter in the CIPO guidance document (PN2020-04). The Patent Appeal Board allowed medical use claims reciting a mg/kg dosage regimen in Genentech’s Canadian Patent Application 2,382,100 (the ‘100 application).

In Canada, methods of medical treatment are not patentable subject-matter, but medical use claims can be considered patentable. PN2020-04 notes that, in determining patentability it is necessary to consider whether professional skill and judgment is part of the actual invention. Examples of situations in which the exercise of skill and judgment would be required include those in which a medical professional would be expected to monitor or adjust treatment, or where not all doses from a claimed range will work for all subjects. In such instances, the necessity of professional skill and judgment would be considered a method of medical treatment and thus not patentable subject-matter.

Earlier this year, in the Commissioner’s Decision Re Amgen Research (Munich) GmbH (2021 CACP 2), the Patent Appeal Board permitted medical use claims for dosage based on body surface area. The finding that calculation of body surface area does not involve professional skill or judgment was a welcome step forward for pharmaceutical patentees (read our article here). This finding expanded on PN2020-04 published following Yves Choueifaty v Attorney General of Canada,1 which clarified that where a claim contains a dosage, regardless of whether it is fixed or covers a range, this in itself is not indicative that the claim is directed to a method of medical treatment, and thus the question of patentability is still a live issue. 

The claims at issue in the ‘100 application are directed to an antibody for treatment in breast cancer, wherein the antibody is administered at an initial dose of 8 mg/kg and a plurality of subsequent doses of 6 mg/kg, wherein the doses are separated by three weeks. In the Final Action, the Examiner asserted that the exercise of a physician’s skill and judgment is required to (1) determine the appropriate dose; (2) determine how many subsequent doses to administer; and (3) calculate the dose to be administered and therefore refused the claims on the basis that they encompass unpatentable subject matter.

The description of the ‘100 application contains the type of broad, generic statements discussing a physician’s discretion in selecting an appropriate dosage based on patient-specific factors that are commonly found in applications relating to medical or therapeutic uses. The Board reiterated that medical use claims must be read in the context of the specification as a whole, and in the case of fixed dosage claims it is necessary to consider whether there is evidence indicating that the skill and judgment of the physician would be called on to select an appropriate dose or make any adjustments to the dosage. The Applicant successfully argued to the Board that the broad, generic statements in the description did not pertain to the actual invention as claimed.

Second, the Patent Appeal Board agreed with the Applicant that it cannot be the case that claims of the type “the use of X for treating Y” necessarily encompass a medical professional’s decision to start or stop treatment. To be patentable, the decision to prescribe, which could require the exercise of skill and judgment, must be outside the scope of the claim. Once the decision to prescribe has been made, the fixed dose as claimed cannot call on or restrict the exercise of skill or judgment. Similarly, the Board accepted the Applicant’s argument that the decision to stop treatment (the number of subsequent doses) is analogous to the decision to start treatment, and agreed that in this case the decision to stop treatment was also outside the scope of the claim.

Finally, the Board agreed with the Applicant that the weighing of a patient and calculation of dose (i.e. number of mg/kg) does not require professional judgment. The Board noted that there was no evidence that monitoring of a patient’s weight would be required, and thus the doses are fixed and the mere calculation to convert from mg/kg to a patient-specific dose would not require the skill and judgment of a medical professional.

The allowance of a fixed body weight-dependent dosage regimen is a win for patentees in the pharmaceutical industry, and reaffirms that dosage regimens can be allowable subject matter, so long as no physician skill or judgment is required to exercise the full scope of the claims. While methods of medical treatment remain unpatentable subject matter in Canada, this decision further clarifies the potential scope of protectable medical use claims involving dosage regimens.

1 Yves Choueifaty v Attorney General of Canada, 2020 FC 837.

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