This article originally appeared in AIPLA’s Chemical Practice Chronicles, Spring 2015 edition. On 18 March 2015, the Canadian Intellectual Property Office (CIPO) issued revised examination guidelines on medical use claims, the complete text of which can be found on the Government of Canada website. The guidelines were revised following the recent Federal Court decision AbbVie Biotechnology Ltd. v. The Attorney General of Canada (AbbVie), 2014 FC 1251.  

By way of background, it is well-established that methods of medical treatment are not patentable in Canada. However, medical uses are generally patentable, as long as they do not contain limitations that would prevent physicians from exercising their skill and judgment – i.e. they are not methods of medical treatment “in disguise”.  

Although Canadian jurisprudence is very clear on the fact that methods of medical treatment are not patentable, it has been decidedly less clear at defining what is meant by a “method of medical treatment”.  

The difficulty ultimately stems from the Supreme Court of Canada decision in Apotex Inc. v. Wellcome Foundation Ltd (2002) 21 C.P.R. (4th) 499 (AZT). The AZT decision stands for the proposition that a new medical use of a known compound is patentable subject matter. It is the leading case in this area and was widely recognized as a major victory for pharmaceutical innovators.  

In the AZT decision, the Supreme Court of Canada stated (at paragraphs 48 to 50):

There is no serious challenge in this case to subject matter patentability. "[H]itherto unrecognized properties" can constitute a patentable new use for an old substance: Shell Oilsupra per Wilson J. at p. 549. In that case, it was disclosed in the patent that known chemical compounds revealed a previously unrecognized use as plant growth regulators.

At trial, the present appellants argued that the patent was invalid as seeking to monopolize a method of medical treatment contrary to Tennessee Eastman Co. v. Commissioner of Patents supra , but this was rightly rejected. Tennessee Eastman was concerned with the patentability of a surgical method for joining incisions or wounds by applying certain compounds. The decision was based on the former s. 41 of the Patent Act , R.S.C. 1970, c. P-4, now repealed. The Court concluded that the method (apart from the compounds) was not patentable. The policy rationale, as explained by Wilson J. in Shell Oil supra , at p. 554, was that the unpatentable claim was

essentially non-economic and unrelated to trade, industry or commerce. It was related rather to the area of professional skills.

The AZT patent does not seek to “fence in” an area of medical treatment. It seeks the exclusive right to provide AZT as a commercial offering. How and when, if at all, AZT is employed is left to the professional skill and judgment of the medical profession.

When the AZT decision was handed down, the patent profession expected it would support a broad range of medical use patents. However, the lower Courts have interpreted the abovementioned passage as meaning that: 1) patent protection is available for “vendible products” in the area of medical treatment such as a new substance to be used in the treatment of a disease, or an old substance where it has been discovered that it can unexpectedly treat another disease; but 2) patent protection is not available where the subject matter is directed to the skill of a professional, such as a surgical procedure or in some cases a dosage regimen.  

To use the terms employed by the Patent Office, it is possible to claim something that covers the “what” of treatment (i.e. a vendible product), but not the “how” of treatment (something requiring or encompassing professional skill).  

The difficulty arises in trying to distinguish between the “what” and the “how” of medical treatment, and in finding suitable wording to claim the former without encompassing the latter. As a result, the patentability of inventions relating to dosage regimens – where the compound X is known, its use for treating Y is known, and the invention lies in a new method of administering X to treat Y – has become a contentious issue in Canada, and a significant body of case law is developing in this area.  

The recent AbbVie decision belongs to this body of case law and represents an important victory for pharmaceutical innovators. In AbbVie, the appellant contested the Commissioner of Patents’ finding that certain claims of Canadian Patent Application No. 2,385,745 were not patentable under section 2 of the Patent Act because they were directed to methods of medical treatment. The claims in question were directed to a use of a known drug HUMIRA (anti-TNF alpha antibodies) at a specified fixed amount (40 mg) and fixed interval (bi-weekly) for treating an arthritic disease or inflammatory bowel disease. The Federal Court disagreed with the Commissioner and found the claims to be patentable. There was no evidence to suggest that any adjustments to the claimed dosage or its frequency would be needed, and therefore, the Court reasoned that the patent does not restrict methods of medical treatment or the skill and judgment of the physician, because no skill or judgment is needed to be exercised within the claim.  

Further, the Court concluded that the Commissioner of Patents had erred in interpreting that an earlier decision Janssen Inc v Mylan Pharmaceuticals ULC2010 FC 1123 (Janssen), which related to a “titration” regimen involving several variables, as a change in law that would establish a broad prohibition against any patenting of the “how and when” in the administration of a drug. As CIPO’s interpretation of Janssen is reflected in the previous guidelines on the examination of medical use claims (published June 10, 2013), these clearly required an overhaul in view of AbbVie. Consequently, CIPO published revised guidelines for examining medical use claims on March 18, 2015. In the revised guidelines, CIPO directs examiners to perform a purposive construction of the claims. This involves identifying the problem and solution addressed by the inventor, to assist with determining the essential elements that provide the solution to the problem. CIPO also provides guidance to distinguish between a claim directed to the “what” of treatment and the “how”, as follows:

For medical inventions, the problem faced by the inventor may relate to “what” to use for treatment. Generally the solution to such a problem will be provided by an element or set of elements in a claim that embody a treatment tool. This tool may include a compound, composition, formulation, or a dosage unit form. The importance of a purposive construction approach is highlighted when assessing the patentability of claims that recite a dosage regimen or dosage range since the mere recitation of either of these does not necessarily mean the claim is non-statutory. However, if it is determined after a purposive construction that a dosage range, or dosage regimen that includes a range, is an essential element of a claim encompassing the use of a known compound in an established treatment, then the claim may cover a method of medical treatment. Where an essential element only serves to instruct a medical professional "how" to treat a patient, rather than "what" to use to treat the patient, it must be determined whether the essential element prevents, interferes with or requires the professional skill of a physician. If the answer is "yes", this will lead to the conclusion that the claimed use encompasses a method of medical treatment that does not comply with section 2 of the Patent Act. Essential elements that point to a limitation of a physician's professional skill or judgment include those that provide details of a dosing schedule encompassing a range and those that represent a range of potential dosages that a patient may receive (as distinct from a range of dosage forms). In contrast, essential elements that narrow treatment to a fixed dosage, a fixed dosage regimen, a patient sub-population or to a particular administration site are not considered to point to a limitation of a physician's professional skill or judgment. (Emphasis added)

Therefore, AbbVie has made it easier to patent certain kinds of dosage regimens in Canada, namely those where the claims are limited to a fixed dosage and/or a fixed schedule. No doubt there will be some cases where this claim scope is enough, e.g. if the pharmaceutical product is sufficiently developed that these parameters have been established. But, for cases where the applicant would like to seek a broader scope of protection, such as a dosage range, it will apparently be necessary to convince the Patent office that the claims do not point to a limitation of a physician’s professional skill or judgment. Therefore while the revised guidelines provide practical guidance as to what CIPO will consider in assessing medical use claims for statutory subject matter, patentability will ultimately turn on the facts of each case.