Clinical trial of low dose cytosine arabinoside in the treatment of acute promyelocytic leukemia.

The purpose of this study is to determine the efficacy of low dose cytosine arabinoside (LD Ara-C) as an alternative treatment to conventional cytotoxic induction chemotherapy in childhood acute promyelocytic leukemia (APL). Four children with APL in poor medical condition prior to chemotherapy were treated with LD Ara-C (10 mg/m2/12 h) for 3 weeks. In three patients, the second course was administered after a resting period of two weeks. Subsequent conventional cytotoxic induction chemotherapy was applied in patients who did not enter complete remission (CR). After induction of CR, maintenance chemotherapy with a conventional monthly multi-drug regimen was applied. CR in one patient and partial remission (PR) in two patients were obtained after two courses of LD Ara-C. Patients who did not enter CR after LD Ara-C entered on subsequent conventional chemotherapy. There were no major complications such as intracranial hemorrhage and sepsis; myelosuppression was not as severe as in conventional chemotherapy; there was clinical and laboratory improvement in coagulopathy. We concluded that LD Ara-C may be an alternative treatment to the conventional chemotherapy in children with APL, especially in whom conventional cytotoxic induction chemotherapy is thought to increase the risk of serious complications and early fatality during induction chemotherapy.