Effects of in vitro treatment with 4-hydroperoxycyclophosphamide and hyperthermia on leukemic progenitor cells

A key point of autologous bone marrow transplantation for leukemic patients is how to remove leukemic cells from their own bone marrow grafts. In this study a leukemic progenitor cell assay was used to evaluate the antileukemic efficacy of marrow-purging protocols that employed hyperthermia or 4-hydroperoxycyclophosphamide (4HC) against leukemic blasts obtained from patients. After the treatment of 2 x 10(7) nucleated bone marrow cells/ml with 100 micrograms/ml of 4HC in the presence of 7% suspension of packed autologous erythrocytes, leukemic colonies were eradicated in 10 of 13 cases and reduced to less than 0.3% as compared with the colony count in untreated cultures in two cases. More than 10% of leukemic progenitor cells survived after hyperthermia treatment (42 degrees C 60 min) in 7 of 9 cases. It is suggested that treatment of leukemic cells and 7% autologous erythrocytes with 100 micrograms/ml of 4HC is effective to eliminate leukemic progenitor cells. Treatment with hyperthermia may not be effective enough to eliminate leukemic progenitor cells from autologous bone marrow.