Clinical features, early treatment responses, and outcomes of pediatric acute lymphoblastic leukemia in China with or without specific fusion transcripts: a single institutional study of 1,004 patients.

Acute lymphoblastic leukemia (ALL) with distinct fusion transcripts has unique clinical features. In this study, the incidence, clinical characteristics, early treatment response, and outcomes of 1,004 Chinese pediatric ALLs were analyzed. Patients with TEL-AML1 and E2A-PBX1 fusion genes or other B cell precursor ALLs (BCP-ALL) had favorable clinical features, were sensitive to prednisone, had low minimal residual disease (MRD), and an excellent prognosis, with a 5-year event-free survival (EFS) of 84-92%. T-ALL was associated with a high WBC, increased age, more central nervous system involvement, a poor prednisone response, and high MRD, with a 5-year EFS of 68.4 ± 5.2%. Patients with BCR-ABL and MLL rearrangements usually had adverse clinical presentations and treatment responses, and a dismal prognosis, with 5-year EFS of 27.3 and 57.4%, respectively. We also showed that BCR-ABL and MLL rearrangements, the prednisone response, and MRD were independent prognostic factors. Interestingly, the BCH-2003 protocol resulted in a better outcome for E2A-PBX1(+) patients than the CCLG-2008 protocol. Intermediate and late relapses were more common in TEL-AML1(+) patients and other BCP-ALLs compared with other subgroups (P = 0.018). Therefore, this study suggests that a fusion gene-specific chemotherapy regimen and/or targeted therapy should be developed to improve further the cure rate of pediatric ALL.