In Canada, methods of medical treatment are not considered to be patentable due to a long-standing, court-created exclusion established under an old compulsory licensing regime (Tennessee Eastman Co. et al. v Commissioner of Patents, (1972), 8 C.P.R. (2d) 202 (S.C.C.)). The exclusion has persisted in Canadian law, despite the regime no longer being in force. Separately, the Supreme Court has considered and upheld medical 'use' claims (Apotex Inc. v. Wellcome Foundation Ltd., (2002), 21 C.P.R. (4th) 499 (S.C.C.)). The tension between these two precedents can be a significant source of confusion for applicants and foreign practitioners with applications in Canada.
More recently, decisions of the Federal Court have expanded the exclusion, striking down 'use' claims in instances when the claimed invention was deemed to inhibit or require the professional skill or judgement of a physician (e.g., Axcan Pharma Inc. v Pharmascience Inc. et al., 2006 FC 527; Janssen Inc. v. Mylan Pharmaceutical ULC et al., 2010 FC 1123; Bayer Inc. v. Cobalt Pharmaceutical et al., 2013 FC 1061). Claims limited by dosage range, for example, have been invalidated on this basis when the Court found that a physician's skill would be required to select an appropriate dose from within the range.
Prospective patentees accordingly face a somewhat paradoxical situation in Canada: broad 'use' claims are generally permissible from the perspective of statutory subject matter, while narrower claims limited in particular ways can be problematic.
Against this backdrop, the Canadian Patent Office issued a Practice Notice to its examiners in 2014 with guidelines on the examination of medical 'use' claims. Under these guidelines, claims limited by 'what' to use were generally permissible, while those limited by features perceived to require 'how' or 'when' determinations were generally impermissible.
The Practice Notice and its attendant examples were revised in March 2015. The reason for the update is a 2014 decision of the Federal Court, which criticized an earlier decision of the Commissioner of Patents for over-reliance on policy considerations (AbbVie Biotechnology Ltd. v. The Attorney General of Canada, 2014 FC 1251 at -). The most notable changes in the new Practice Notice are a softening of its language, and stark reversal of two previous policies concerning new sites of administration and patient populations.
Whereas the previous Notice indicated that a 'use' claim limited by a 'how' element "will lead to the conclusion that the claimed 'use' encompasses a method of medical treatment", the revised Practice Notice inserts a passage before this to indicate that "it must be determined whether the essential element prevents, interferes with or requires the professional skill of a physician" (emphasis added in both instances). The intention, it seems, is greater deference to an Examiner's determination based on the facts at hand.
Pertinent examples from the revised Practice Notice are summarized below.
Uses of new compounds and new uses of known compounds
Claims to 'uses' of both new and known compounds remain statutory under the revised Notice when the invention rests in the new compound or the new 'use', respectively. Dosage range features do not make claims non-statutory in these circumstances if they are deemed "unnecessary limitations to the scope of the monopoly" (it is unclear, however, how such "unnecessary limitations" would be subsequently interpreted in the courts).
New fixed dosage form of a known drug for a known use
'Use' claims reciting fixed dosage units are judged to be directed to specific products, and remain statutory.
New dosage range of a known drug for a known use
'Use' claims reciting dosage ranges remain non-statutory, when the invention resides in the dosage range. The example indicates that "the dosage range... requires the skill and judgment of a physician to make a determination as to the dose the patient receives". Features such as "13 to 15 mg/kg/day" and "14 mg/kg/day" are considered to be equally problematic, because the physician has to make a determination in each case.
New dosage regimen of a known drug for a known use
'Use' claims including dosage regimens with fixed time points and fixed amounts remain statutory, though a new cautionary note indicates that such claims would not be statutory if "it is determined that the schedule claimed is a titration", which "always requires monitoring by a professional". Likewise, a new example involving a time range of "3-5 weeks" is deemed to be non-statutory due to the requirement for a physician's judgement.
New physical formulation of a known drug for a known use (new area of administration)
The revised Practice Notice reverses previous examination policy on use claims for inventions involving sites of administration. The two examples involve an orally administrable pharmaceutical composition (the same drug was used previously to treat the same condition), and a 'use' of an existing patch on a new site on the body (the upper leg instead of on the arm). Both are considered to be patentable subject matter.
Known compound, for a specific group of patients
The Practice Notice also reverses earlier examination practice for 'uses' of known compounds in a specific group of patients: a key area for personalized medicine. Application of a known drug to either an entirely new patient group or a patient sub-population (e.g. bearing a specific mutation) is deemed to be statutory. However, a new cautionary note indicates that the latter would be considered anticipated, and would also not qualify as a selection.
While the deference to the determination of an examiner afforded by the revised Practice Notice is a positive development, the foray into anticipation in the example concerning patient subpopulations is a puzzling development. No precedent is referenced to support the example, and the resolution of a previously homogenous patient group into new sub-groups (with attendant inventive advantages) is conceptually similar to the resolution of an existing drug based on racemic mixture. Claims to purified enantiomers with special advantages have been upheld as a selection on more than one occasion by the courts (e.g., Sanofi-Synthelabo v. Apotex, 2008 SCC 61; Sanofi-Aventis v. Apotex, 2013 FCA 186), and this may provide a basis for applicants to argue against application of the revised Practice Notice where 'use' claims involving personalized medicine are concerned.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.