TRANSITIONAL PRE-B-CELL ACUTE LYMPHOBLASTIC-LEUKEMIA OF CHILDHOOD IS ASSOCIATED WITH FAVORABLE PROGNOSTIC CLINICAL-FEATURES AND AN EXCELLENT OUTCOME - A PEDIATRIC-ONCOLOGY-GROUP STUDY

The presenting characteristics and survival of children with the newly recognized transitional cell pre-B immunophenotype of acute lymphobla stic leukemia (ALL) are compared with those of children with pre-B ALL to determine the clinical significance of the new phenotype. Patients with transitional pre-B ALL (n = 17), defined by lymphoblasts express ing cytoplasmic and surface mu heavy chains without kappa or lambda li ght chains, have lower initial leukocyte counts (p = 0.02) and a highe r frequency of DNA indexes > 1.16 (p < 0.001) than patients with pre-B ALL (n = 501), whether or not cases with the unfavorable prognostic ( 1;19) translocation are included in the analysis. Patients with transi tional pre-B ALL lack FAB L3 morphology, bulky extramedullary disease, surface kappa or lambda chains, and the (8;14), (8;22), and (2;8) tra nslocations, features that characterize the syndrome of B-cell ALL. Th e 4-year relapse-free survival result for children with transitional p re-B ALL appears better than that for children with pre-B ALL (93.3 +/ - 17% versus 72.9% +/- 4.6%), but this difference is not statistically significant. We conclude that patients with transitional pre-B ALL ha ve a very favorable prognosis in the context of the therapy used in th is study.