researchers may have found a way to save the skin of melanoma patients by using antibiotics to target and eliminate the power plants fuelling the evasive cancer cells.the study,
published in the journal of experimental medicine, successfully used bacteria-destroying medicine to exploit a vulnerability that arises in cancer cells as they try to survive cancer therapy in mice.“as the cancer evolves, some melanoma cells may escape the treatment and stop proliferating to ‘hide’ from the immune system,”
said eleonora leucci, a cancer researcher and rna biologist at ku leuven, belgium. “these are the cells that have the potential to form a new tumour mass at a later stage.”“in order to survive the cancer treatment, however, those inactive cells need to keep their ‘power plants’ — the mitochondria — switched on at all times. as mitochondria derive from bacteria that, over time, started living inside cells, they are very vulnerable to a specific class of antibiotics. this is what gave us the idea to use these antibiotics as anti-melanoma agents.”to test their theory, researchers implanted patient-derived tumours into mice and then treated the cancer in two different ways: with antibiotics alone or with antibiotics in tandem with an existing melanoma therapy. “the antibiotics quickly killed many cancer cells and could thus be used to buy the precious time needed for immunotherapy to kick in,” leucci said. “in tumours that were no longer responding to targeted therapies, the antibiotics extended the lifespan of — and in some cases even cured — the mice.”melanoma, the most serious form of skin cancer, is diagnosed in around 8,000 canadians every year,
according to the canadian cancer society. the disease, which originates in the skin’s melanocyte cells, can lead to cancerous tumours capable of destroying surrounding tissue and spreading to other parts of the body. roughly 1,300 canadians die from the disease every year, with the majority of diagnoses and deaths occurring in men, most likely because melanomas tend to develop on the extremities of women as opposed to the trunk, head or neck of men. in canada, the five-year net survival rate for melanoma skin cancer is 88 per cent.
while the class of antibiotics used in the study is rarely used to battle bacteria because of the rising risk of antibiotic resistance, leucci said this resistance has no effect on the effectiveness of their treatment. “the cancer cells show high sensitivity to these antibiotics, so we can now look to repurpose them to treat cancer instead of bacterial infections,” she said.leucci also warned that patients currently undergoing therapy for melanoma should not conduct their own experiments with any antibiotics they have on hand. “our findings are based on research in mice, so we don’t know how effective this treatment is in human beings,” she said. “our study mentions only one human case where a melanoma patient received antibiotics to treat a bacterial infection and this re-sensitized a resistant melanoma lesion to standard therapy.“this result is cause for optimism but we need more research and clinical studies to examine the use of antibiotics to treat cancer patients. together with oncologist oliver bechter (ku leuven/uz leuven), who is a co-author of this study, we are currently exploring our options.”
dave yasvinski is a writer with healthing.ca
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