Canada’s Intellectual Property Law Firm

Patent protection for a new use of a known compound

After considerable amounts of work have gone into the latest project, you finally have a well-deserved eureka moment: your lab results demonstrate that compound X normally used for treating migraines is also efficient for treating breast cancer. Such a discovery may represent a unique opportunity to expand the available commercial offerings in the oncology field and as such, obtaining patent protection should make business sense. However, given that compound X is already known, and patent protection is not available for a known compound, what can be protected in this case?

What can be protected? Provided that your discovery is novel and non-obvious, one way of protecting it would be by filing a patent application in the markets of interest, including claims worded along the following general lines: "A method of treating breast cancer in a patient, comprising administration of a therapeutically effective amount of compound X to the patient."

As discussed in the May/June 2012 edition of IP connections, while the above claim language is in a format that is generally acceptable in the U.S., it would not be acceptable in other jurisdictions, such as Canada and Europe.

Indeed, while there is no explicit prohibition in the Canadian Patent Act or Patent Rules against patents in this area, methods of medical treatment are not patentable in Canada. This arises largely from a 1972 Supreme Court decision, Tennessee Eastman Co et al v Commissioner of Patents. In that decision, the Court rejected a claim relating to a surgical procedure, holding that methods of medical treatment neither produce a result in relation to trade, commerce or industry nor a result that is essentially economic.

Europe differs from Canada in that this prohibition is specifically provided in the European Patent Convention per se, which explicitly excludes methods of medical treatment from patent protection on the basis that public health in the member states would be at risk if patent rights could be used to impede medical doctors in the normal course of practicing medicine.

When a product having therapeutic properties is newly discovered, it can be claimed as a product and for its particular use. When a product having therapeutic properties is old, the exclusion of methods of medical treatment assumes particular significance, because normally the claim would be for the product for use in a particular therapeutic method — i.e. a claim to a method of medical treatment. This prohibition therefore has a significant impact in the medicine, health care and pharmaceutical fields.

Are there any exceptions in Canada to this prohibition? Despite the continuing prohibition on patents related to methods of medical treatment, there are exceptions to this prohibition. Indeed, in Canada, any method that does not aim at curing, alleviating, or preventing a disease, restoring health or producing a therapeutic benefit is generally not considered a medical treatment method.

For example, claims relating to a method of preventing pregnancy, to a method of diagnostics, to a cosmetic method or to a method of ameliorating the adverse effects of aging are generally considered patentable subject matter, since none involve treatment of a disease or produce a therapeutic benefit.

How should methods of medical treatment be protected in Canada and Europe? While methods of medical treatment are excluded from patentability in jurisdictions such as Canada and Europe, in certain cases it may be possible to redraft a method claim into a "use" claim. While at first glance this may seem a matter of semantics, generally a "method" has been construed by Canadian courts as a step or a series of steps used to arrive at a desired result while a "use" may not require any step or series of steps to be followed. Such redrafting thus provides patent protection where none would otherwise be available.

Thus in Canada, while a claim that reads "A method of treating cancer by administering compound X" is not patentable, a claim that reads "Use of compound X in the treatment of cancer" may be patentable. Indeed, the compound thus claimed would be used in circumstances and ways that were unknown and not contemplated before the invention. Another example would be the discovery that Aspirin, developed and patented as a pain medication, was useful in the prevention of heart disease.

In Canada, in order to protect the above discovery, claims along the following general lines could be presented:

"Compound X for use in treatment of breast cancer."
"Use of compound X for treatment of breast cancer."
"Use of compound X in the manufacture of a medicament for treatment of breast cancer."

In Europe, "Compound X for use in treatment of breast cancer" and "Use of compound X for treatment of breast cancer" are also generally an acceptable format, whereas "Use of compound X in the manufacture of a medicament for treatment of breast cancer" is no longer an acceptable format as of January 2011.

Another way of protecting the above discovery would be via claims directed to a medical device, for instance a drug delivery device, such as a transdermal patch. In other words, while patent protection may not be obtained for a known compound, it may still be possible to patent a medical device that delivers the compound. Also, such devices are often used as part of a medical treatment such that while the method of medical treatment per se may not be patentable in Canada, the device for implementing the method may be.

Conclusion. In summary, patent applications for innovations in medicine, health care and pharmaceuticals should be carefully drafted, considering local and foreign patent law practice, to maximize the potential scope of intellectual property rights. This is particularly relevant in the life science sector where many years of research and development are typically required before a company develops a commercial product.


The preceding is intended as a timely update on Canadian intellectual property and technology law. The content is informational only and does not constitute legal or professional advice. To obtain such advice, please communicate with our offices directly.