The drug thioridazine apparently kills cancer stem cells in humans while avoiding the toxic side-effects of conventional cancer treatments.
"The unusual aspect of our finding is the way this human-ready drug actually kills cancer stem cells by changing them into cells that are non-cancerous," said Mick Bhatia, scientific director of McMaster University's Stem Cell and Cancer Research Institute in the Michael G. DeGroote School of Medicine.
Unlike chemotherapy and radiation, thioridazine appears to have no effect on normal stem cells. The research team has identified another dozen drugs that have good potential for the same response.
For 15 years, some researchers have believed stem cells are the source of many cancers. In 1997, Canadian researchers first identified cancer stem cells in certain types of leukemia. Cancer stem cells have since been identified in blood, breast, brain, lung, gastrointestinal, prostate and ovarian cancer.
To test more than a dozen different compounds, McMaster researchers pioneered a fully automated robotic system to identify several drugs, including thioridazine.
"Now we can test thousands of compounds, eventually defining a candidate drug that has little effect on normal stem cells but kills the cells that start the tumor," said Bhatia.