PREDICTION OF RESPONSE OF ACUTE NONLYMPHOCYTIC LEUKEMIA TO THERAPY WITH HIGH-DOSE CYTOSINE-ARABINOSIDE

The Leukemia Intergroup Study has treated 110 patients with acute nonlymphocytic leukemia with high dose cytosine arabinoside remission induction therapy and studied the factors which were related to the outcome of therapy. With respect to death during remissionm induction therapy, only the patient age was of prognostic significance. Treatment failure due to resistant leukemia was associated with a high pretherapy leukemia cell mass, the presence of a few cells in S phase and insensitivity of DNA synthesis to cytosine arabinoside. If, after 6 days of therapy, > 40% of the marrow cells were leukemic, the patient almost invariably failed to enter complete remission because of persistent leukemia. Simultaneous consideration of the pretherapy labeling index and the per cent abnormal cells in the day 6 marrow permitted a distinction to be made between almost all patients who would enter remission or fail therapy because of presistent leukemia.