The Canadian Patent Office recently released a new guidance document on “Examination Practice Respecting Medical Uses”. The guidance document, PN 2013-04, is directed to examiners, and relates to the consideration of claims directed to methods of medical use and, in particular, the patentability of claims containing a dosage regimen or dosage range.

While guidance documents are not binding on the courts, they may be used as evidence in proceedings. They are also highly indicative of the posi­tions that patent applicants can expect from the Canadian Patent Office.

The new guidance document reflects decisions of the courts on medical use claims, and purports to build on the more general guidance in section 17.02.03 of the Manual of Patent Office Practice and also an earlier guidance document (PN 2013-02). PN 2013-04 reiterates that:

  1. methods of medical treatment are not patentable subject matter; and
  2. medical use claims will generally be permitted as long as they do not equate to medical or surgical methods.

To determine whether medical use claims are patentable, the essential elements of each of the claims must first be identified based on a purposive construction of the patent. Thus, to determine which elements of the claim are “essential”, the examiners are instructed to look at the whole of a patent’s specification to identify both the problem the inventors set out to address and the solution disclosed.

Once the essential elements of the claims have been identified, the examiners must determine whether the subject matter of the claims is patentable in Canada. To constitute “patentable subject matter”, a claimed invention must fall within the categories of “invention” specified in section 2 of the Patent Act. Medical inventions such as methods of medical treatment have been interpreted to fall outside the scope of section 2. In contrast, medical use claims are generally permitted.

The guidance document provides some specific instructions to examiners on how to determine whether medical inventions are patentable.The question is whether the invention would prevent physicians from exercising their skill and judgment in using a known compound for an established purpose.

The primary rule of thumb is to consider whether the claim answers the questions of “how?”, or conversely, “what?”. Where an essential element only serves to instruct a medical professional as to “how” or “when” to treat a patient, the subject matter is most likely an unpatentable method of medical treatment, since the answer to such a question would likely place a limit on the professional skill or judgment of a physician. Examples of “how” include details of when or where a treatment is to be administered, or who is to receive a treatment.

On the other hand, if the essential element instructs the professional as to “what” to use to treat the patient, this will not amount to a method of medical treatment.

The guidance document also focuses on an issue that has proven to be particularly problematic in the assessment of patent claims: dosage regimens or dosage ranges recited in the claims. A claim is not unpatentable simply because it contains a dosage regimen or a dosage range. Rather, the question for the examiner is whether an essential element of the claim is a dosage regimen or a dosage range encompassing the use of a known compound in an established treatment. If it is, the claim covers a method of medical treatment, and according to the guidance document, is “non-compliant” with section 2 of the Patent Act.

Notably, the guidance document does not discuss the decision in the Finasteride case (Merck v. Pharmascience, 2010 FC 510), wherein Justice Hughes stated that there must be a distinction between:

“claims that rely upon the skill and judgment of a medical practitioner and those that deal with a vendible product, be it a scalpel, X-ray machine or 1 mg tablet that are to be used or prescribed for use by such practitioner. In the present case, we have a 1.0 mg tablet taken as a daily dose. No skill or judgment is brought to bear. It is a vendible product and not a method of medical treatment.”

In view of that decision, it may be possible to argue that a claim directed to a specific dose (as opposed to a range) and taken at a specific time (every two days) is a vendible product and not a method of medical treatment.

View the guidance document.