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. That’s the finding of a new study published in the latest issue of the journal Molecular Cancer Therapeutics.
Researchers at the California Pacific Medical Center Research Institute (CPMCRI) combined the non-psychoactive Cannabis compound, cannabidiol (CBD), with Δ9-tetrahyrdocannabinol (Δ9-THC), the primary psychoactive active ingredient in Cannabis. They found the combination boosts the inhibitory effects of Δ9-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.
“Our study not only suggests that combining these two compounds creates a synergistic effect,” says Sean McAllister, Ph.D., a scientist at CPMCRI and the lead author of the study. “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 Δ9-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 Δ9-THC alone against glioblastoma cell lines, the combination therapy of Δ9-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 Δ9-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 Δ9-THC or CBD could be reached by smoking cannabis.
The study was funded by the National Institute of Health and the SETH group.
January 10, 2010