Toxicity and efficacy of intensive chemotherapy for children with acute lymphoblastic leukemia (ALL) after first bone marrow or extramedullary relapse

Background Approximately 25% of children newly diagnosed with acute lymphoblastic leukemia (ALL) will eventually experience leukemic relapse, with bone marrow being the most common site of recurrence. The ability to achieve a durable second remission is complicated by toxicity and resistant disease. We report a novel combination of chemotherapy for relapsed pediatric ALL. Procedure Thirty pediatric patients with relapsed medullary (n = 18) and extra‐medullary (n = 12) ALL were enrolled at three pediatric institutions. Following receipt of induction and the first Block A and Block B of intensification, each patient was evaluated for toxicity, efficacy in achieving remission, and long‐term survival. Additionally, minimal residual disease (MRD) detection by multidimensional flow cytometry (MDF) was performed. Results During induction, the major non‐hematopoeitic toxicities were mucositis (30% of patients) and bacteremia (50% of patients). Two patients (7%) died of toxicity during induction. Toxicity during intensification Block 1A and 1B was markedly reduced. Eight‐nine percent of patients with marrow disease achieved a remission following induction and intensification. The event‐free survival (EFS) for all patients at 2 and 4 years were 60% (95% CI: 42–78%) and 49% (95% CI: 30–68%), respectively. Conclusions This regimen for patients with relapsed ALL was successful in achieving a second remission for the majority of patients with acceptable toxicity. © 2004 Wiley‐Liss, Inc.