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
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.