Old drug could have new use as cancer stem cell killer

Date: Thursday May. 24, 2012 12:48 PM ET

An old drug once used routinely as a treatment for schizophrenia appears to be able to successfully kill human cancer stem cells while leaving healthy cells intact, Canadian researchers have discovered.

The discovery is an important one since traditional chemotherapy and radiationoften fail toeradicate cancer stem cells, which are cells that can lurk in the body and cause certain kinds ofcancer to return.

But a team of scientists at McMaster University has discovered that the antipsychotic medication thioridazine can destroy cancer stem cells by changing them into cells that are non-cancerous. And unlike chemotherapy and radiation, thioridazine appears to have no effect on normal stem cells, which could mean side effects like hair loss.

The team at McMaster's Stem Cell and Cancer Research Institute made their finding while testing hundreds of compounds using an automated robotic stem cell screening system. Thioridazine was one of abouta dozen already-known compounds that the robotic team found had good potential as cancer treatments.

Mick Bhatia, the principal investigator for the study and scientific director of the Institute, says what makes this drug so exciting is that it has already been approved for use in patients.

"I think it is fascinating because the drug has already been used already -- albeit for another purpose; here it is being repurposed for cancer. The fact that all that workup has been done already allows us to move this into the clinic quickly," he says.

The research is published in the science journal, Cell.

The next step is to test thioridazine in clinical trials on cancer patients. The first study will focus on 30 patients with acute myeloid leukemia, or AML, whose disease has relapsed after chemotherapy.

The team wants to find out if the drug can put their cancer into remission, and prevent it from returning, says co- investigator Terry Sachlos.

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Old drug could have new use as cancer stem cell killer