[Successful treatment of relapsed and refractory acute promyelocytic leukemia with arsenic trioxide (As2O3)].

It has been shown that arsenic trioxide (As2O3) may induce hematologic remissions in patients with acute promyelocytic leukemia (APL) refractory to all-trans retinoic acid (ATRA). We reported on a patient with ATRA and drug-resistant APL that was successfully treated with As2O3. The patient had been given a diagnosis of typical APL and was treated with ATRA and chemotherapy for 12 months. He achieved complete remission (CR), but leukemia relapsed with 43% APL cells in the bone marrow in the 16th month of treatment. ATRA and cytarabine plus daunorubicin were administered; however, the APL cells in the bone marrow increased to 97.2%. As2O3 was initiated intravenously, and bone marrow showed a decrease of APL cells (6.7%) and a partial differentiation after 9 days. The patient received idarubicin (IDA) and steroid pulse because of the development of ATRA-like syndrome, and achieved CR 37 days after the initiation of As2O3. He received an additional 2 courses of As2O3 with IDA, and is in CR. These results demonstrated the therapeutic efficacy of As2O3 in treating ATRA and drug-resistant APL.