Cannabis has a long history as a medicinal plant, dating back at least to the 19th century. A renewed interest in the therapeutic uses of cannabis emanates from the substantial changes that have taken place in both social attitude and the legal landscape surrounding its use in recent years. The proposed legalization of recreational cannabis in Canada has resulted in a significant growth in the potential economic market associated with cannabis. Since Justin Trudeau became prime minister, after campaigning on a promise to legalize recreational cannabis, the number of medical marijuana users has quadrupled.
Important differences exist in the way that recreational cannabis and medicinal cannabis are developed, tested and marketed to consumers. In this context, recreational cannabis tends to have high levels of psychoactive cannabinoids like Δ9-tetrahydrocannabinolic acid (THC). THC has received much attention for being the main psychoactive component of cannabis. The psychoactive effects of THC are due to its ability to activate type-1 cannabinoid (CB1) receptors that are located mainly in the central nervous system.
In contrast, it is generally desirable for medicinal cannabis to have a minimal level of psychoactive cannabinoids, but to contain high levels of other useful cannabinoids like cannabidiol (CBD). CBD does not appear to have any intoxicating effects such as those caused by THC, but may have effects on anxiety and act as an anti-psychotic. In addition to cannabinoids, cannabis also contains a number of different potentially beneficial compounds, including terpenoids, flavonoids and nitrogenous compounds.
To date, more than 100 different cannabinoids have been identified in cannabis. Some cannabinoids have been used to relieve chronic pain, chemotherapy-induced nausea and vomiting, and anorexia and weight loss associated with HIV/AIDS. However, the full therapeutic potential of these cannabinoids remains to be explored and commercial embodiments of these therapeutic properties can potentially receive patent protection.
This article briefly reviews some potential hurdles to patenting medicinal cannabis-related inventions in Canada, and provides examples of some recently granted patents in this field.
Patentable Subject Matter
A first potential hurdle in seeking patent protection for new applications of medicinal cannabis in Canada is the patentability of methods of medical treatment. In Canada, judicial interpretation of what constitutes an “invention” under section 2 of the Patent Act (RSC 1985, c P-4) has imposed potential hurdles on the ability of applicants to obtain patent protection for medical uses of cannabis.
The Supreme Court of Canada (SCC) held that a method of medical treatment lies outside the definition of “invention”: Tennessee Eastman Co v Canada (Commissioner of Patents),  SCR 111. That decision was fundamentally underpinned by a now-repealed section of the Patent Act that prohibited claims to a medical substance itself, apart from its method of manufacture. However, this decision remains the governing law in Canada today.
Notwithstanding this position, the use of a substance for a medicinal purpose can be claimed as an invention in Canada, so long as the claims do not require the skill and judgment of a medical practitioner to determine how the substance should be administered. Accordingly, with careful drafting, patent protection may be available for novel therapeutic uses of cannabis and its components in Canada.
A further complication to securing patent protection for new applications of medicinal cannabis in Canada relates to relatively strict requirements for establishing the utility of an invention. Canadian law requires that an invention be useful as of the filing date of the application. Fanciful, speculative or inoperable inventions are not patent-eligible. A claimed invention is useful if it is capable of a practical purpose, i.e. an actual result: AstraZeneca Canada Inc v Apotex Inc, 2017 SCC 36.
Utility can be demonstrated, for example, via working examples, or based on a sound prediction. Whether a prediction is sound is a fact-specific inquiry and depends on the following three factors:
(1) there must be a factual basis for the prediction;
(2) the inventor must have at the date of the patent application an articulable and “sound” line of reasoning from which the desired result can be inferred from the factual basis; and
(3) there must be proper disclosure.
Cannabis research faces a unique set of challenges owing at least in part to the illegal status of cannabis presently in Canada and in many other parts of the world. Certain regulations and policies exist to restrict access to the plant and its derivatives. Additionally, physicians may feel reluctant to refer patients to clinical trials. These challenges complicate an applicant’s ability to gather sufficient experimental data to establish utility.
Because utility is a fact specific inquiry and depends on the scope of the patent claims, diligent consideration of existing experimental data and careful patent drafting are important to secure patent protection for new therapeutic uses of cannabis.
Some Recently Issued Patents Relating to Therapeutic Properties of Cannabinoids
Canadian patent No. 2582289 to Whittle et al. (“Whittle”) discloses that CBD has the ability to modulate the motility of human glioma cells and thereby inhibit brain tumour cell migration. This therapeutic property of CBD was demonstrated by an in vitro cell migration assay.
Another recently issued patent, Canadian patent No. 2636634 to Guy et al (“Guy”), discloses the use of cannabinoid-containing plant extracts of Cannabis sativa in the prevention or treatment of neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, Huntington’s disease, frontotemporal dementia, prion disease, Lewy body dementia, progressive supranuclear palsy, vascular dementia, normal pressure hydrocephalus, traumatic spinal cord injury, HIV dementia, alcohol induced neurotoxicity, Down’s syndrome and epilepsy.
Guy discloses that cannabinoid-containing plant extracts containing a cannabinoid-containing fraction and a non-cannabinoid containing fraction are more efficacious than essentially pure cannabinoids in the prevention of neural degeneration. The cannabinoid-containing fraction has one or more of THC, CBD, cannabigerol (CBG), cannabichromene (CBC), tetrahydrocannabidivarin (THCV), tetrahydrocannabinolic acid (THCA), cannabidivarin (CBDV) and cannabidiolic acid (CBDA). The non-cannabinoid containing fraction has one or more of terpenes, sterols, triglycerides, alkanes, squalene, tocopherol, carotenoids, chlorophyll, flavonoid glycosides and alkaloids.
The claims in Guy are supported by experimental data demonstrating the effects of cannabinoid-containing plant extracts on the concentration of intracellular calcium ions in hippocampal neurones prepared from Lister-Hooded rat pups. The ability to decrease the concentration of intracellular calcium ions in rat hippocampal neurones is expected to have predictive value for promising neuroprotective agents for humans.
The identification and verification of new therapeutic properties of cannabinoids will likely require significant financial investment. Patent protection can ensure a return on such financial investment when the resulting products are eventually commercialized. Companies should consider filing patent applications to secure protection for potentially valuable commercial embodiments of these therapeutic properties before there is any public disclosure thereof.