Good steroid response in vivo predicts a favorable outcome in children with T-cell acute lymphoblastic leukemia

BACKGROUND: Improved outcome of children with acute lymphoblastic leukemia (ALL) who received intensive chemotherapy was observed by the Italian Association for Pediatric Hematology Oncology (AIEOP). To verify if this improved outcome was also extended to T-cell acute lymphoblastic leukemia (T-ALL) patients after introduction of intensive chemotherapy, treatment responses of 2011 patients, including 184 with T-ALL treated over the decade 1982-1991, were analyzed. Further, the potential use of the association of presenting clinical and biologic features with treatment outcome to determine risk factors that might be useful for planning risk-directed therapeutic studies was analyzed. METHODS: Of the 2011 children consecutively entered on the three sequential AIEOP trials ('82, '87, and '88), 1528 (76%) had successful immunologic studies of the bone marrow blasts. One hundred eighty-four (12%) had T-ALL. During these studies, four consecutive high-risk ALL treatment protocols (i.e., 8303, 8503, 8703, and 8803) were used. Because the treatment schedule in protocols 8503 and 8703 were almost identical, those patients were grouped together for the purpose of survival analysis. The 137 boys and 47 girls ranged in age from 16 months to 15.5 years (median, 7.8 years) at diagnosis, and 38% had a mediastinal mass. The rates of treatment response i.e. complete remission (CR) and event free survival (EFS) rates were compared for patients with T-ALL or B-cell progenitor ALL, overall and by individual study. Presenting features and early response to steroid monotherapy were also tested as possible prognostic factors. RESULTS: Overall, the CR rate was 94%, and the 7-year survival (SE) was 51.9% (4.2). T-ALL patients had a significantly worse outcome than B-lineage ALL patients 7-year EFS 40.4% (5.2) vs. 61.7% (1.7), P 50 x 10(9)/l (P = 0.04). The EFS for patients with T-ALL and good steroid response [63% (3.0) was comparable with that of the unselected B-lineage ALL patients. CONCLUSIONS: EFS for patient with T-ALL has steadily increased in consecutive AIEOP ALL trials. However T-ALL patients still have a significantly worse EFS compared with patients with B-lineage ALL. Patients with T-ALL and a poor in vivo response to steroid monotherapy represent a particularly high risk treatment group.