GW Pharmaceuticals’ cannabinoid combination has achieved positive results in a phase 2 trial as a treatment for glioblastoma multiforme. 

The company’s treatment is a combination of both tetrahydrocannabinol (THC) and cannabidiol (CBD) – both active ingredients from the cannabis plant.

The phase 2 trial investigated GW’s treatment as an add-on therapy with temozolomide in 21 patients with recurrent glioblastoma multiforme (GBM).

The combination had previously been given Orphan Drug Designation from both the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

Both designations were based on GBM’s extremely low survival rates. One-year survival currently stands at 28.4% whilst five-year survival is even lower at 3.4%.

Results from the study showed that those patients treated with the THC:CBD and temozolomide combination had an 83% one-year survival rate, compared to a 53% one-year survival rate in those patients given a placebo.

Median survival was also better in the THC:CBD cohort at 550 days, compared to 369 days in the placebo group.

In addition, THC:CBD was well tolerated by almost all patients – only two discontinued treatment due to adverse effects. The most common side effects from the treatment were vomiting (75%), dizziness (67%), nausea (58%), headache (33%), and constipation (33%).

“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,” said Professor Susan Short, principal investigator of the study. “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.”

Prior to testing its THC:CBD combination in GBM, GW had produced 15 publications investigating several cannabinoids in a range of different cancers. Research has shown that cannabinoids can promote autophagy (cell self-degradation) in cancer cells by affecting a commonly overactivated cell signalling pathway called the AKT/mTOR pathway.

Pre-clinical studies also showed both THC and CBD to have synergistic effects, producing a greater anti-cancer effect in laboratory cancer cell cultures when combined than when used separately.

“We believe that the signals of efficacy demonstrated in this study further reinforce the potential role of cannabinoids in the field of oncology and provide GW with the prospect of a new and distinct cannabinoid product candidate in the treatment of glioma,” stated Justin Gover, GW’s chief executive officer.