Faculty Bibliography

This Phase I study of clofarabine with etoposide and cyclophosphamide for children with relapsed/refractory acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) was conducted to determine the maximum tolerated dose (MTD), dose-limiting toxicities and the recommended phase 2 doses (RP2Ds). All three drugs were administered for five consecutive days in induction and four consecutive days in consolidation, for a maximum of eight cycles. A total of 25 patients (20 ALL and 5 AML) were enrolled in five cohorts. An MTD was not reached. The RP2Ds of clofarabine, cyclophosphamide and etoposide were 40, 440 and 100 mg/m(2)/day, respectively. Complete remission (CR) was achieved in 10 patients (ALL: nine; AML: one), and CR without platelet recovery in six patients (ALL: two; AML: four) for an overall response rate of 64% (ALL: 55%; AML: 100%). Of the 16 responders, 9 patients proceeded to hematopoietic stem cell transplantation. In conclusion, the combination of clofarabine, etoposide and cyclophosphamide was well tolerated and effective in pediatric patients with relapsed/refractory leukemia. Of note, the phase II portion of the trial was amended after the occurrence of unexpected hepatotoxicity. The ongoing phase II study will evaluate the efficacy and safety of this regimen in ALL patients.

PURPOSE: Imatinib mesylate is a targeted agent that may be used against Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL), one of the highest risk pediatric ALL groups. PATIENTS AND METHODS: We evaluated whether imatinib (340 mg/m(2)/d) with an intensive chemotherapy regimen improved outcome in children ages 1 to 21 years with Ph+ ALL (N = 92) and compared toxicities to Ph- ALL patients (N = 65) given the same chemotherapy without imatinib. Exposure to imatinib was increased progressively in five patient cohorts that received imatinib from 42 (cohort 1; n = 7) to 280 continuous days (cohort 5; n = 50) before maintenance therapy. Patients with human leukocyte antigen (HLA) -identical sibling donors underwent blood and marrow transplantation (BMT) with imatinib given for 6 months following BMT. RESULTS: Continuous imatinib exposure improved outcome in cohort 5 patients with a 3-year event-free survival (EFS) of 80% +/- 11% (95% CI, 64% to 90%), more than twice historical controls (35% +/- 4%; P < .0001). Three-year EFS was similar for patients in cohort 5 treated with chemotherapy plus imatinib (88% +/- 11%; 95% CI, 66% to 96%) or sibling donor BMT (57% +/- 22%; 95% CI, 30.4% to 76.1%). There were no significant toxicities associated with adding imatinib to intensive chemotherapy. The higher imatinib dosing in cohort 5 appears to improve survival by having an impact on the outcome of children with a higher burden of minimal residual disease after induction. CONCLUSION: Imatinib plus intensive chemotherapy improved 3-year EFS in children and adolescents with Ph+ ALL, with no appreciable increase in toxicity. BMT plus imatinib offered no advantage over BMT alone. Additional follow-up is required to determine the impact of this treatment on long-term EFS and determine whether chemotherapy plus imatinib can replace BMT.