Background: Philadelphia chromosome-positive chronic myelogenous leukemia (CML) is a rare disease in children, and the optimal therapy is not clearly defined in these patients when a human leukocyte antigen-identical donor is not available. The present work focuses on the therapeutic efficacy and the toxicity of interferon (IFN) alpha 2b in combination with cytosine arabinosine (Ara-C) in patients younger than age 18 years enrolled in the randomized trial CML 91, which compared the efficacy of IFN and cytosine arabinoside (Ara-C) with IFN alone in 810 patients with CML in the chronic phase.
Patients and methods: Twelve patients younger than age 18 years were enrolled in the randomized trial CML 91. Hydroxyurea and IFN (5 million units/m2, once a day) were given as initial treatment in all patients. After randomization, six patients received IFN (5 million units/m2, once per day) and Ara-C (20 mg/m2 for 10 days each month) (IFN plus Ara-C group), and six patients received IFN alone (5 million units/m2 once per day) (IFN group).
Results: Six months after the beginning of the treatment, a complete hematologic response was obtained in all the patients in the IFN plus Ara-C group and in four patients in the IFN group. A major cytogenetic response was observed in three patients in the IFN plus Ara-C group and in two patients in the IFN group. Five patients from the IFN group who crossed over to receive Ara-C did not experience additional hematologic toxicity. Three patients in the IFN plus Ara-C group and two from the IFN group are alive, in major cytogenetic response, with a follow-up of 18 to 48 months.
Conclusion: The combination of IFN and Ara-C induces complete hematologic and major cytogenetic responses and is well tolerated in patients younger than age 18 years with CML. This combination may offer an alternative to bone marrow transplantation in children in the chronic phase of CML without a histocompatible donor.