[An in vitro chemotherapy sensitivity test on leukemic colony-forming cells (L-CFU) and its clinical evaluation]

The sensitivity of leukemic progenitor cells (L-CFU) to cytosine arabinoside (Ara-C) and daunomycin (DM) in vitro was studied using PHA -LCM two step assay for L-CFU. Continuous exposure of leukemic and normal bone marrow cells to DM as well as Ara-C in vitro appeared to be more effective than pulse exposure because colony formation was suppressed by a dose dependent fashion. The relationship between in vitro sensitivity to DM and Ara-C and that of in vivo to chemotherapy was investigated in 17 untreated and 5 relapsed patients with acute nonlymphocytic leukemia. The sensitivity of L-CFU to the two chemotherapeutic agents varied from patient to patient. These studies indicated a clear-cut relationship between in vitro drug sensitivity and in vivo response to patients whose L-CFU were sensitive to both agents and entered complete remission, whereas patients whose L-CFU were insensitive to one or both drugs in vitro failed to enter remission. This assay system appears to be useful in predicting response of patients to chemotherapy and in selecting the most effective drugs for an individual patient use.