Cellular pharmacokinetics of daunorubicin: relationships with the response to treatment in patients with acute myeloid leukemia.

In an attempt to identify pharmacokinetic factors that determine the response of acute myeloid leukemia (AML) patients to induction chemotherapy, we determined the concentrations of daunorubicin (DNR) and the main metabolite daunorubicinol (DOL) in vivo and particularly evaluated the concentrations in blood and bone marrow nucleated cells. Cell measurements were obtained in 37 evaluable patients during their first remission induction treatment with DNR and cytarabine (ara-C) and directly compared with the plasma distribution kinetics of DNR. We show that (1) plasma DNR concentrations do not correlate with DNR concentrations in bone marrow nucleated cells; but (2) plasma area under the curve (AUC) values of DNR correlate inversely (P less than .01) with AUC values of DNR in WBCs; (3) concentrations of DNR in WBCs correlate positively (P less than .01) with DNR concentrations in bone marrow nucleated cells; and (4) the concentrations of DNR in WBCs show a negative correlation (P less than .01) with the numbers of peripheral blast cells at diagnosis. We then tested whether the pharmacokinetic parameters had predictive value for the clinical outcome of therapy, but none of the plasma levels or WBC and bone marrow concentrations of DNR predicted treatment outcome. The inverse correlation between the concentrations of DNR in WBC and the numbers of peripheral blast cells suggests that the effective DNR concentrations achieved intracellularly are mainly a function of the tumor load so that lesser amounts of DNR accumulate intracellularly when the AML cell numbers in blood are higher.