By Jahan Marcu
As a member of ASA’s Medical & Scientific Advisory Board, I’ve been actively engaged in pursuing further evidence of the medical efficacy of cannabis-based medicine. Some of this work occurred while I was working at the California Pacific Medical Center Research Institute (CPMCRI), and yesterday the findings of that work were published by the peer-reviewed journal Molecular Cancer Therapeutics. With this study, we have shown that cannabis compounds can work together to inhibit glioblastoma (GBM), one of the nastiest and most aggressive of all brain cancers. GBM is the type of brain cancer that caused the recent death of Senator Ted Kennedy.
Tetrahydrocannabinol (THC) is the most prevalent compound found in the cannabis (marijuana) plant. Many studies have focused on THC and its therapeutic qualities, however other compounds in the plant should not be overlooked from a medical and scientific standpoint. In fact, the recently published study illustrates how THC and other compounds (known as Cannabinoids) found in the cannabis plant work synergistically to kill cancer cells and reduce tumor size. The anti-cancer effect, which is mediated through the activation of cannabinoid receptors on cancer cells, has been shown through both in vitro and in vivo experimentation.
The other most abundant compound in the cannabis plant is Cannabidiol (CBD). One of the main findings of our research was how THC and CBD act synergistically to inhibit GBM brain cancer cell proliferation. The research team at CPMCRI, lead by Dr. Sean McAllister, discovered that a ratio of about 4:1 of THC to CBD resulted in a synergistic or enhanced killing effect. This THC and CBD combination was determined after assessing anti-cancer activity resulting from the interaction of THC with some of the more-than-70 cannabinoids found in the cannabis plant.
Interestingly, the individual doses of THC and CBD had little effect on the cancer cells or other proteins in the cells. However, when these two compounds were combined, the amount of cell death, or apoptosis, dramatically increased. And, as if this wasn’t enough, our research team discovered another potential breakthrough from the combined use of THC and CBD — a decrease in the protein known as ERK (extracellular signal-regulated kinase). The levels of ERK, often associated with cancer found in the body, were only affected by the combination of THC and CBD, suggesting that these compounds either converge on a shared pathway or together they activate a specific response in cancer cells.
Since these cannabinoids are relatively non-toxic and selectively kill cancer cells, large doses can be provided for in vivo studies. Hence, a direct injection to the site of the tumor or cancer, versus the more widely used methods of smoke or vapor inhalation, may be the most efficient for killing cancer cells. With more targeted applications, a much higher concentration of the active ingredients can be used without toxic side effects. We also speculate that other, non-cannabinoid components of the plant may also improve anti-cancer activity.
An improvement in the life expectancy of people with GBM has not occurred in 50 years, and because GBM is so aggressive and effective treatments have not yet been found, this study may represent a major breakthrough in the field. The next obvious step is further testing of how this combination of cannabinoids affects brain cancer and finding ways to put this important discovery to use.