4-Demethoxydaunonibicin (Idarubicin) in Combination with 1-β-D-Arabinofuranosylcytosine in the Treatment of Relapsed or Refractory Acute Leukemia

We conducted a Phase I—II trial of 4-demethoxydaunorubicin (idarub-icin, IDR) in combination with 1 -β-D-arabinofuranosy lcytosine (ara-C) in 51 patients with relapsed or refractory acute nonlymphocytic leukemia, acute lymphocytic leukemia, or chronic myelogenous leukemia in blast crisis. Only 1 of 12 patients treated at the first dose level (idarubicin, 10 mg/m2/day for 3 days and ara-C, 25 mg/m2 i.v. bolus followed by 200 mg/m2 continuous infusion daily for 5 days) achieved aplasia and complete remission. The dose of idarubicin was subsequently increased to 10 mg/ m2/day for 4 days with the ara-C dose held constant. Complete remission incidence for this dose schedule was: 7 of 31 patients with acute nonlym-phocytic leukemia, 0 of 5 patients with acute lymphocytic leukemia, 0 of 1 patient with chronic myelogenous leukemia in blast crisis, and 1 of 2 patients with biphenotypic leukemia. Nonhematological toxicity included nausea, vomiting, mucositis, and abnormal liver function tests. Detailed pharmacological studies were performed to determine whether ara-C altered IDR metabolism or that of its main metabolite, 13-hydroxyida-rubicinol or IDR clearance. A high degree of variability among patients was apparent and no consistent effect could be demonstrated. In summary, 9 of 37 patients (24%) with relapsed or refractory ANLL, including 1 patient with biphenotypic leukemia, achieved remission. We conclude that idarubicin in combination with ara-C is an active combination in patients with relapsed or refractory leukemia.