Cristina Sanchez, a young biologist
at Complutense University in Madrid, was studying cell metabolism when
she noticed something peculiar. She had been screening brain cancer cells because they grow faster than normal cell lines and thus are useful for research purposes. But the cancer cells died each time they were exposed to tetrahydrocannabinol (THC), the principal psychoactive ingredient of marijuana. In 1998, she reported
in a European biochemistry journal that THC “induces apoptosis [cell
death] in C6 glioma cells,” an aggressive form of brain cancer.
A team of Spanish scientists led by Manuel Guzman conducted the first clinical trial assessing the antitumoral action of THC on human beings. Guzman administered pure THC via a catheter into the tumors of nine hospitalized patients with glioblastoma, who had failed to respond to standard brain-cancer therapies. The results were published in 2006 in the British Journal of Pharmacology: THC treatment was associated with significantly reduced tumor cell proliferation in every test subject.
Around the same time, Harvard University scientists reported
that THC slows tumor growth in common lung cancer and “significantly
reduces the ability of the cancer to spread.” What’s more, like a
heat-seeking missile, THC selectively targets and destroys tumor cells
while leaving healthy cells unscathed. Conventional chemotherapy drugs,
by contrast, are highly toxic; they indiscriminately damage the brain
and body.
Dr. Sean McAllister, a scientist at
the Pacific Medical Center in San Francisco, has been studying
cannabinoid compounds for 10 years in a quest to develop new therapeutic
interventions for various cancers. Backed by grants from the National
Institute of Health (and with a license from the DEA), McAllister discovered
that cannabidiol (CBD), a nonpsychoactive component of the marijuana
plant, is a potent inhibitor of breast cancer cell proliferation,
metastasis, and tumor growth.
In 2007, McAllister published a detailed account
of how cannabidiol kills breast cancer cells and destroys malignant
tumors by switching off expression of the ID-1 gene, a protein that
appears to play a major role as a cancer cell conductor.
“Cannabidiol
offers hope of a non-toxic therapy that could treat aggressive forms of
cancer without any of the painful side effects of chemotherapy,” says
McAllister, who is seeking support to conduct clinical trials with the marijuana compound on breast cancer patients.
