Cancer researchers snuff out misfit T-cells in stem cell therapies

Scientists have found a way to make T-cells used in some stem cell cancer therapies commit "suicide" if they go wild and become dangerous to the patient. The discovery could make the treatment safer and more successful in the long run.

Researchers at the Baylor College of Medicine in Houston made the crucial finding, which was first published in the New England Journal of Medicine and also covered by Bloomberg.

Patients treated by stem cells first have their own wiped out through chemotherapy or radiation. Doctors then infuse stem cells from a related donor to kill any cancer left over and also fight infection. The process is considered important to boost the chances of surviving and recovering from cancers such as leukemia or lymphoma. But those T-cells can grow uncontrollably and produce severe or lethal side effects such as graft-versus-host disease, which can disable or kill the patient.

Scientists address this by introducing a gene called iCasp9 into the T-cells, which produces something called "programmed cell death," by way of a protein that causes the cells to self-destruct. A drug called AP 1903 is given to patients in a single dose that activates the process, according to Bloomberg.

Investigators in the study treated five pediatric leukemia patients using donor cells that were a partial match, in order to boost the risk of side effects, Bloomberg noted, enhanced with the special gene. Four patients developed graft-versus-host disease and received the activating drug, which killed off most of the T-cells and made the disease go away within a day, Baylor said. The remaining T-cells did their proper job, expanding and fighting infections.

- here's the release
- see the Bloomberg story