CLINICAL-FEATURES AND TREATMENT OUTCOME OF CHILDHOOD T-LINEAGE ACUTE LYMPHOBLASTIC-LEUKEMIA ACCORDING TO THE APPARENT MATURATIONAL STAGE OFT-LINEAGE LEUKEMIC BLASTS - A CHILDRENS CANCER GROUP-STUDY

Purpose: Leukemic cells from T-lineage acute lymphoblastic leukemia (A LL) patients are thought to originate from T-lymphocyte precursors cor responding to discrete stages of T-cell ontogeny. Here we sought to de termine the influence of leukemic cell apparent maturational stage on treatment outcomes in pediatric T-lineage ALL. Patients and Methods: F rom 1983 through 1993, 407 pediatric T-lineage ALL patients were enrol led onto two sequential series of risk-adjusted treatment protocols of the Children's Cancer Group. In the current analysis, T-lineage ALL p atients were immunophenotypically classified as follows: CD7(+)CD2(-)C D5(-) pro-thymocyte leukemia (pro-TL), CD7(+)(CD2 or CD5)(+)CD3(-) imm ature TL, and CD7(+)CD2(+)CD5(+) CD3(+) mature TL. Results: Similar in duction outcomes of 91.4%, 97.1%, and 98.3% were obtained by the pro-, immature, and mature TL groups, respectively, Four-year event-free su rvival (EFS) was lower for pro-TL patients (57.1%; SD = 8.4%,) compare d with immature and mature TL patients (68.5%; SD = 3.5%; and 77.1%; S D = 4.0%, respectively) with an overall significance of .05 (log-rank test) or .04 (log-rank trend test), Relative hazards rates (RHR) were 2.11 and 1.22 far pro-TL and immature TL versus mature TL, respectivel y, Highly significant differences were found for overall survival (P = .005, log-rank test; P = .009, log-rank trend test), Multivariate ana lysis confirmed that the prognostic influence of ontogeny grouping was independent of that of other prognostic factors, Conclusion: Leukemic cells of the pro-TL maturation stage identify a small subgroup of T-l ineage ALL patients who have a significantly worse EFS outcome than pa tients whose cells are of a more mature stage of development. (C) 1997 by American Society of Clinical Oncology.