Sequential intermediate‐dose cytosine arabinoside and mitoxantrone for patients with relapsed and refractory acute myelocytic leukemia

Based on in vitro evidence of time‐dependent synergistic kill of HL‐60 leukemia cells exposed to Ara‐C and mitoxantrone, 44 patients with relapsed or refractory AML and 3 with blastic CML were treated with a timed sequence of both drugs. There were 25 females and 22 males, with a median age of 53 (range 21–75). Of 31 patients with relapsed AML, 24 had one prior remission, 6 had two and 1 had three. Of these, 15 had failed a second reinduction attempt. Thirteen patients were primarily refractory to induction with Ara‐C plus daunorubicin. Each dose of Ara‐C, 500 mg/m2, was followed after 6 hr by mitoxantrone, 5 mg/m2, and the sequence was repeated four to six times (44–68 hr) in different cohorts of patients. All but two patients (one with blastic CML and one in relapse and refractory) are evaluable for response and toxicity. Of 16 patients in relapse without prior reinduction 7 achieved CR and 3 PR (62% response rate); there were 3 CR in the 14 patients who were in relapse and refractory (21% response rate) and 4 CR and 1 PR (35% response rate) in the 14 patients with primary anthracycline resistance. Five of seven patients previously exposed to mitoxantrone achieved CR. Response lasted from 2 to 42 months, with two patients alive and in continuing remission at 34 and 42 months. Average marrow recovery was seen after 25 days and time to remission was 30 days. Six patients died in induction (four from sepsis and two from the tumor lysis syndrome) and 21 had progessive disease. Chemotherapy was well tolerated with minor nausea and vomiting in 13 patients, moderate in 20, and severe in 2. Most patients did not have evidence of drug‐induced mucositis: it was minor in 9 and moderate in 2. Renal dysfunction was attributable to the use of nephrotoxic antibiotics. Hepatic dysfunction was reversible and was minor in 10 patients, moderate in 13, and severe in 3. Sequential, timed administration of intermediate‐dose Ara‐C and mitoxantrone is an active and well‐tolerated antileukemic regimen.