A drug with a long list of heavy side effects, commonly used to treat sufferers of schizophrenia, also possesses some startlingly potent anti-cancer properties, according to research published Thursday in the medical journal Cell.
The drug, thioridazine, is usually dispensed as a last resort for schizophrenics whose symptoms did not respond to other treatments. Scientists said that after analyzing thousands of different drugs for possible anti-cancer effects, they discovered that thioridazine can be used to selectively target and eradicate cancerous stem cells present in leukemia, along with breast, blood, brain, prostate, ovarian, lung and gastrointestinal cancers, all without the worst side effects of today's most frequently used cancer therapies.
"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," Mick Bhatia, the study's principal researcher and scientific director of McMaster's Stem Cell and Cancer Research Institute in Canada, said in a media advisory.
Bhatia's team didn't find the drug all on their own, however. In order to siphon up large amounts of previously unknown data on already-available drugs, they actually created a robotic stem cell screening system that analyzed thousands of different chemical compounds for potential effects on leukemia and breast cancer.
"We discovered the drug by creating a new way of looking at different chemicals," he explained to MedicalXpress.com. "In order to do that, we have to put cancer stem cells in a dish, but also have normal stem cells to also test the compounds. We were able to do this with a robotic system, fully automated, that allowed us to go through 10 or 15 compounds [at first]. Now we can do this with thousands of compounds, eventually arriving at this drug that doesn't do anything to normal stem cells, but kills cancer stem cells."
The bad news: thioridazine is known to cause a wide variety of side effects in humans, including vomiting, constipation, swelling, slowed movements, the inability to produce facial expressions and sudden death from an irregular heartbeat -- meaning the drug won't get prescribed to cancer patients just yet.
However, scientists said that further study of how the drug interacts with cancer cells could broach a new frontier in cancer therapies, and noted that there are at least 12 other existing drugs that have "good potential for the same response." They are still testing the drug's effects on other types of cancers.
The McMaster advisory noted that Bhatia's team hopes to begin human trials soon, and plans to test the drug first on leukemia patients whose cancer has returned after remission. They reportedly hope to learn whether thioridazine can also help prevent cancers from returning.
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