The in vitro effects of vincristine on peripheral blood leukocyte progenitor cells (CFU-C) in patients in blast crisis of chronic granulocytic leukemia: Correlation with clinical response

The in vitro sensitivity of circulating progenitor cells (CFU-C) of 20 patients in blast crisis of chronic granulocytic leukemia (CGL) to vincristine was correlated with the clinical response to vincristine in vivo. Eleven patients who achieved either a good or partial clinical response displayed a reduction in the number of colonies or clusters formed by their peripheral blood leukocytes in a double layer agar culture assay following incubation with vincristine. The CFU-C of five of six patients who failed to respond clinically to vincristine and prednisone were not suppressed following incubation with up to 12 microM vincristine. Three additional patients were not evaluable due to early post-treatment deaths. In vitro assay of the effects of vincristine on CFU-C appears to have predictive value for in vivo response in blast crisis of CGL.