Absence of biallelic TCR? deletion predicts induction failure and poorer outcomes in childhood T-cell acute lymphoblastic leukemia

Background The absence of biallelic TCR? deletion (ABD) is a characteristic of early thymocyte precursors before V(D)J recombination. The ABD was reported to predict early treatment failure in T-cell acute lymphoblastic leukemia (ALL). This study aimed to investigate its prognostic value in Taiwanese patients with T-cell ALL. Procedure. Forty-five children with T-cell ALL were enrolled from six medical centers in Taiwan. Quantitative DNA polymerase chain reaction (Q-PCR) was performed to check the status of TCR gamma deletion. The threshold for homozygous deletions by Q-PCR was defined as a fold-change <0.35. Results. ABD was found in 20 patients [20:45] who had higher incidences of induction failure than those without ABD (P = 0.03; hazard ratio [HR] = 8.13; 95% confidence interval [95% CI] 1.23-53.77) after multivariate regression analysis. Patents with ABD also had inferior EFS and OS (P = 0.071 and 0.0196, respectively). Multivariate Cox analysis indicated that the association between ABD and overall survival was independent of age and leukocyte count on presentation (P = 0.036; HR = 4.25; 95% CI = 1.10-16.42). Conclusions. The absence of TCRg deletion is a predictor of a poor response to induction chemotherapy for pediatric patients with T-cell ALL in Taiwan. Providing patients with T-cell ALL and ABD with alternative regimens may be worthwhile to test in future clinical trials. Pediatr Blood Cancer 2012;58:846-851. (C) 2011 Wiley Periodicals, Inc.