Intensive oral methotrexate protects against lymphoid marrow relapse in childhood B-precursor acute lymphoblastic leukemia

Purpose: To describe the use of combination chemotherapy, including divided-dose oral methotrexate (dMTX), for children with B-precursor acute lymphoblastic leukemia (ALL). dMTX produced prolonged MTX exposure on an outpatient basis. Patients and Methods: Two hundred forty-three patients were treated from January 1986 to May 1992. dMTX was given weekly during consolidation and biweekly for the first 16 months of continuation therapy with mercaptopurine (6-MP) and asparaginase (L-ASP). Initially, etaposide (VP-16) and cytarabine (Aro-C) pulses were included. Treatment continued for 30 months with single-dose weekly MTX replacing dMTX during continuation, part 2. Unexpected acute neurotoxicity was eliminated by the addition of leucovorin. VP-16 and Ara-C were omitted in the face of acute myelogenous leukemia (AML). Results: Two hundred thirty-nine patients entered remission: 16 had a lymphoid marrow relapse, two each with testicular or CNS relapse; 19 a CNS relapse; 16 secondary AML; three other second malignancies; two withdrew for transplant; three died in remission; 16 withdrew because of noncompliance, and nine withdrew with toxicity. Event-free survival (EFS) at 4 years was 73 ± 4%; 81 ± 4% for 150 patients with better risk features and 60 ± 7% for 93 with high-risk features. Lymphoid marrow relapse-free survival in the standard- and highrisk patients was 94 ± 3% and 86% ± 6%, respectively. The most common adverse event was secondary AML in the standard-risk group and isolated CNS relapse in the high-risk group. Conclusion: This therapy produced an overall EFS similar to other published regimens, but the pattern of failures is very different, with few patients having a lymphoid marrow relapse. These data suggest that highly effective therapy for children with ALL can be delivered on an outpatient basis using a regimen featuring repetitive dMTX.