Clinical features and treatment outcome of childhood T-lineage acute lymphoblastic leukemia according to the apparent maturational stage of T-lineage leukemic blasts: a Children's Cancer Group study.
OBJECTIVE
Leukemic cells from T-lineage acute lymphoblastic leukemia (ALL) patients are thought to originate from T-lymphocyte precursors corresponding to discrete stages of T-cell ontogeny. Here we sought to determine the influence of leukemic cell apparent maturational stage on treatment outcomes in pediatric T-lineage ALL.


METHODS
From 1983 through 1993, 407 pediatric T-lineage ALL patients were enrolled onto two sequential series of risk-adjusted treatment protocols of the Children's Cancer Group. In the current analysis, T-lineage ALL patients were immunophenotypically classified as follows: CD7+ CD2- CD5- pro-thymocyte leukemia (pro-TL), CD7+ (CD2 or CD5)+ CD3- immature TL, and CD7+ CD2+ CD5+ CD3+ mature TL.


RESULTS
Similar induction outcomes of 91.4%, 97.1%, and 98.3% were obtained by the pro-, immature, and mature TL groups, respectively. Four-year event-free survival (EFS) was lower for pro-TL patients (57.1%; SD = 8.4%,) compared with immature and mature TL patients (68.5%; SD = 3.5%; and 77.1%; SD = 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 for pro-TL and immature TL versus mature TL, respectively. Highly significant differences were found for overall survival (P = .005, log-rank test; P = .009, log-rank trend test). Multivariate analysis confirmed that the prognostic influence of ontogeny grouping was independent of that of other prognostic factors.


CONCLUSIONS
Leukemic cells of the pro-TL maturation stage identify a small subgroup of T-lineage ALL patients who have a significantly worse EFS outcome than patients whose cells are of a more mature stage of development.
Uckun
F M
FM
Children's Cancer Group Acute Lymphoblastic Leukemia Biology Reference Laboratory, and Hughes Institute, St. Paul, MN 55113, USA. faith_uckun@mercury.IH.org
Gaynon
P S
PS
Sensel
M G
MG
Nachman
J
J
Trigg
M E
ME
Steinherz
P G
PG
Hutchinson
R
R
Bostrom
B C
BC
Sather
H N
HN
Reaman
G H
GH
D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D015993:Life Tables; D008213:Lymphocyte Activation; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000145:classification* / Q000276:immunology / Q000401:mortality; D011379:Prognosis; D013601:T-Lymphocytes / Q000276:immunology; D016896:Treatment Outcome