In vitro sensitivity of clonogenic cells in resisting and relapsing patients with acute myelogenous leukaemia.

The evolution of in vitro bone marrow clonogenic leukaemic cells (CFU-L) drug sensitivity was studied in 23 patients with acute myeloid leukaemia treated with anthracycline and cytosine arbinoside (ara-C). In 12 patients tested before and after first induction treatment failure (interval: 6 +/- 4 weeks), the sensitivity remained stable for daunorubicin and showed little variation for ara-C. Among eleven patients tested before treatment and at first relapse (interval: 13 +/- 7 months), in vitro CFU-L sensitivity revealed no correlation between the two measurements, and a trend in decreased sensitivity to daunorubicin and ara-C. These findings suggest that induction failures could be related to factors other than simple selection of a resistant CFU-L subclone.