Combining the two most common cannabinoid compounds in Cannabis may boost the effectiveness of treatments to inhibit the growth of brain cancer cells and increase the number of brain cancer cells that die off.
Researchers at the California Pacific Medical Center Research Institute (CPMCRI) combined the non-psychoactive Cannabis compound, cannabidiol (CBD), with ?9-tetrahyrdocannabinol (?9-THC), the primary psychoactive active ingredient in Cannabis. They found the combination boosts the inhibitory effects of ?9-THC on glioblastoma, the most common and aggressive form of brain tumor and the cancer that claimed the life of Sen. Ted Kennedy last year.
Image: 3D representation of tetrahydrocannabinol, more commonly known as THC. It is the main psychoactive chemical in cannabis.
“Our study not only suggests that combining these two compounds creates a synergistic effect,” says lead author of the study Sean McAllistery. “But it also helps identify molecular mechanisms at work here, and that may lead to more effective treatments for glioblastoma and potentially other aggressive cancers.”
Previous studies had shown that ?9-THC was effective in inhibiting brain cancer growth in cell cultures and in animal models and prompted a small clinical trial in Spain. There is also evidence that other compounds in Cannabis might prove effective against tumors, but limited scientific evidence is available. The CPMCRI researchers screened a number of different cannabis-based compounds before settling on CBD as the most active one.
“Compared to using ?9-THC alone against glioblastoma cell lines, the combination therapy of ?9-THC and CBD showed a significant improvement in activity, both in slowing down the growth of those cells and also, and perhaps more importantly, in doubling the number of cancer cells which underwent apoptosis or programmed cell death,” says Dr. McAllister.
The next step in the research is to carry out similar studies in animal models of aggressive brain cancer. Even if the synergistic effect is not evident in those studies, the combination treatments may allow for stronger doses to be given to patients due to non-overlapping toxicities and decrease development of resistance to the activity of ?9-THC or CBD alone.
Despite the promising findings of the study the researchers point out that they are not a recommendation for people with brain cancer to smoke marijuana. They say it is highly unlikely that effective concentrations of either ?9-THC or CBD could be reached by smoking cannabis.
References:
1. Sean D. McAllister, Cannabidiol Enhances the Inhibitory Effects of ?9-Tetrahydrocannabinol on Human Glioblastoma Cell Proliferation and Survival. Molecular Cancer Therapeutics, January 2010; doi: 10.1158/1535-7163.MCT-09-0407
