Lack of relationship between in vitro cell measurements and response to busulfan in chronic myelocytic leukemia.

Twenty-three patients with chronic-phase CML have been treated with intermittent courses of busulfan to determine if the duration of unmaintained remission becomes progressively shorter with successive courses of therapy and to determine whether there was a relationship between cluster and colony formation, suicide index of CFUc, labeling index, percentage of cells in S-phase (as determined by cytofluorographic DNA histogram analysis), in vitro sensitivity of the CFUc to busulfan, and response to busulfan therapy. Serial studies in individual patients and the group as a whole revealed no relationship between changes in the cellular parameters described above and response to busulfan. The white blood cell (WBC) doubling time with serial courses of busulfan in individual patients did not always progressively decrease as has been previously reported. In vitro studies of CFUc in chronic-phase CML appear to be of no value in predicting response to busulfan.