High-Dose Chemo Patients to Get Stem Cells With the MDR-1 Gene

GAITHERSBURG, Md--Genetic Therapy, Inc. has begun phase I testingof a gene therapy protocol designed to protect patients' bloodfrom the destructive effects of high-dose chemotherapy. The trial,headed by Kenneth H. Cowan, MD, PhD, of the NCI, will includeapproximately 18 metastatic breast cancer patients being treatedat the NIH.

Patients who respond to chemotherapy and show no bone marrow involvementwill undergo both peripheral blood stem cell and bone marrow stemcell harvesting, 70% of which will be cryopreserved.

CD34+ cells, which include stem cells, will be separated fromthe remaining 30% and incubated with a retroviral vector containingthe human multiple drug resistance gene (MDR-1) in order to transferthe resistance trait to the cells. These cells along with thecryopreserved unmodified cells will be reintroduced followinghigh-dose chemotherapy.

It is hoped that the MDR-1 stem cells will contribute to the regenerationof the blood system and provide blood cells that have greaterresistance to subsequent chemotherapy.