British drug company GW Pharmaceuticals has announced that it has achieved positive results on a study using marijuana-derived chemicals to treat glioblastoma, a deadly form of brain cancer.
The study involved 21 patients with recurrent glioblastoma multiforme, or GBM, an aggressive form of brain tumour with a median survival rate of a little under 15 months. Study participants were given a combination of temozolomide, a medication commonly used to treat GBM, and GW’s own proprietary cannabinoid product which is composed of both tetrahydrocannabinol (or THC) and cannabidiol (CBD), the two prominently active chemicals in marijuana.
Researchers found that those in the study group who were given temozolomide plus GW’s THC:CBD drug had an 83 per cent one-year survival rate in comparison to those given just the temozolomide who had a 53 per cent one-year survival rate. Overall, the median survival rate for those on the THC:CBD drug was more than 550 days compared to 369 days for the placebo group.
The results show the promise of cannabis as a medical treatment for cancer, says Susan Short, Professor of Clinical Oncology and Neuro-Oncology at Leeds Institute of Cancer and Pathology at St James’s University Hospital and principal investigator of the study.
“The findings from this well-designed controlled study suggest that the addition of a combination of THC and CBD to patients on dose-intensive temozolomide produced relevant improvements in survival compared with placebo and this is a good signal of potential efficacy,” says Short. “These promising results are of particular interest as the pharmacology of the THC:CBD product appears to be distinct from existing oncology medications and may offer a unique and possibly synergistic option for future glioma treatment.”
Interest in the medicinal properties of marijuana is increasing. The Liberal government in Canada intends to hold good on its promise to legalize the possession and growing of marijuana for personal use, and last year, it launched its new Access to Cannabis for Medical Purposes Regulations in order to improve Canadians’ access to marijuana as a medicine.
The double-impact of THC and CBD seems to be the key to its effectiveness in treating brain cancer. A 2014 study from the University of London in the UK found that using THC and CBD together had a much greater ability to inhibit tumour growth related to GBM in mice in comparison to trials using either THC or CBD on their own, which turned out to have no positive effect.
“We think this is due to the different pathways that these cannabinoids hit,” said Dr. Wai Liu, study co-author from the University of London’s Department of Oncology, to Medical Daily. “Specifically, THC works via receptors, whilst CBD may not need them; consequently, using them together results in a ‘priming’ effect in tumour cells, making them more sensitive to the ‘cell killing’ effects of irradiation.”
For Canadians, glioblastoma came into public discussion this past year when Gord Downie, lead singer of the popular rock band, the Tragically Hip, announced that he had been diagnosed with GBM.