GAITHERSBURG, Md--Genetic Therapy, Inc. has begun phase I testing of a gene therapy protocol designed to protect patients' blood from the destructive effects of high-dose chemotherapy. The trial, headed by Kenneth H. Cowan, MD, PhD, of the NCI, will include approximately 18 metastatic breast cancer patients being treated at the NIH.
Patients who respond to chemotherapy and show no bone marrow involvement will undergo both peripheral blood stem cell and bone marrow stem cell harvesting, 70% of which will be cryopreserved.
CD34+ cells, which include stem cells, will be separated from the remaining 30% and incubated with a retroviral vector containing the human multiple drug resistance gene (MDR-1) in order to transfer the resistance trait to the cells. These cells along with the cryopreserved unmodified cells will be reintroduced following high-dose chemotherapy.
It is hoped that the MDR-1 stem cells will contribute to the regeneration of the blood system and provide blood cells that have greater resistance to subsequent chemotherapy.