Predictive value of the CFU-C assay in acute nonlymphocytic leukemia.

A double-layer agar culture assay for granulopoietic progenitor cell (CFU-C) was employed to study the in vitro growth pattern of bone marrow or peripheral blood cells from 37 patients at diagnosis of acute nonlymphocytic leukemia. The patients were classified as having type A growth if there were greater than 50 colonies (A1), or greater than one colony and greater than 50 clusters was observed after 14 days in culture (A2). Type B growth was defined as no growth (B1), less than 50 colonies and less than 50 clusters (B2) or cluster growth only (B3). Agar cultures containing marrow cells from 10 patients were stained in situ, and the colonies and clusters revealed abnormal cellular maturation. Treatment with cytosine arabinoside and an anthracycline resulted in a complete remission of leukemia in one of 15 patients with type A growth and 17 of 22 patients with type B growth. The subtype of growth pattern did not correlate with the mechanism (i.e., drug resistance versus kinetic resistance) for the failure to achieve a complete remission. The subtype of type B growth (B1, B2 or B#) did not correlate with the duration of complete remission. Nonetheless, the growth patterns observed in cultures of cells obtained from patients with acute nonlymphocytic leukemia appear to be excellent predictors of the success of achieving complete remission with induction therapy.