New compounds that target leukemia stem cells are moving into the clinic this summer. But researchers have yet to pin down exactly how some of these compounds do their job.

Today at the International Society for Stem Cell Research's (ISSCR) annual meeting, Craig Jordan from the University of Rochester presented his group's recent work on a compound TDZD-8, which was originally developed to inhibit GSK-3, and potentially treat Alzheimer's disease.

Jordan's group reported last year that TDZD-8 is cytotoxic exclusively for malignant leukemia stem cells; the compound caused the death of leukemia and related disease stem cells within just 15 minutes of being applied to the cell samples. Further investigation showed that the cancer stem cells' membranes break down just before cell death.

Jordan's team has not come closer to understanding how the compound is able to achieve this dramatic effect. When an audience member asked just this question during Jordan's presentation this morning, Jordan answered that the membrane degradation leads his team to believe that the toxicity may stem from induced autophagy, rather than apoptosis.

Regardless of some of the missing links in the compound's mechanism of action, Jordan said that clinical trials on TDZD-8 for leukemia are scheduled to begin this summer. Along with other novel approaches, targeting leukemia's earliest progenitors may be stem cell science's answer to this intractable disease.