Laboratory tests conducted in Newcastle have revealed that a modified form of medicinal cannabis can kill or inhibit cancer cells without impacting normal cells.
The outcome, which was determined at the University of Newcastle and Hunter Medical Research Institute (HMRI), followed three years of research by Dr Matt Dun in collaboration with biotech company Australian Natural Therapeutics Group (ANTG).
The group produces a cannabis variety containing less than 1% tetrahydrocannabinol (THC) – the chemical responsible for most of marijuana’s psychological effects.
“ANTG wanted me to test it against cancer, so we initially used leukaemia cells and were really surprised by how sensitive they were,” Dr Dun said.
“At the same time, the cannabis didn’t kill normal bone marrow cells, nor normal healthy neutrophils [white blood cells].
“We then realised there was a cancer-selective mechanism involved, and we’ve spent the past couple of years trying to find the answer.”
The Dun team has run comparisons between THC-containing cannabis and cannabis lacking THC, but with elevated levels of cannabidiol (CBD).
They found that, for both leukaemia and paediatric brainstem glioma, the CBD-enriched variety was more effective at killing cancer cells than THC varieties.
“There are trials around the world testing cannabis formulations containing THC as a cancer treatment but, if you’re on that therapy, your quality of life is impacted,” Dr Dun said.
“You can’t drive, for example, and clinicians are justifiably reluctant to prescribe a child something that could cause hallucinations or other side-effects.
“The CBD variety looks to have greater efficacy, low toxicity and fewer side-effects, which potentially makes it an ideal complementary therapy to combine with other anti-cancer compounds.”
The next phase for the study includes investigating what makes cancer cells sensitive and normal cells not, whether it is clinically relevant, and whether a variety of cancers respond to the treatment.
“We need to understand the mechanism so we can find ways to add other drugs that amplify the effect and, week-by-week, we’re getting more clues,” Dr Dun said.
“It’s really exciting and important if we want to move this into a therapeutic.”
However, he added that CBD-enriched cannabis isn’t yet ready for clinical use as an anti-cancer agent.
“Hopefully our work will help to lessen the stigma behind prescribing cannabis, particularly varieties that have minimal side-effects, especially if used in combination with current standard-of-care therapies and radiotherapy,” Dr Dun said.
“Until then, though, people should continue to seek advice from their usual medical practitioner.”
The study was funded by ANTG and HMRI through the Sandi Rose Foundation.
Visit HMRI’s website for more information or to donate.