[Clinical Characteristics and Treatment Efficacy of Children with SIL/TAL1 Positive T-Cell Acute Lymphoblastic Leukemia].

OBJECTIVE: To investigate the clinical features, treatment and prognosis of children with SIL-TAL1 fusion gene positive T-cell acute lymphoblastic leukemia (T-ALL).

METHODS: The data of 101 children with T-ALL were collected from April 2005 to November 2012 in Beijing Children's Hospital. The common clinical features, early treatment response, minimal residual disease (MRD), event-free survival (EFS) and relapse-free survival (RFS) were compared between children with SIL-TAL1 positive and negative T-ALL. The treatment efficacy in children with SIL-TAL1 positive T-ALL was compared between BCH-2003 and CCLG-2008 protocol.

RESULTS: Out of 101 cases, 22 cases (21.9%) of T-ALL carried SIL-TAL1 fusion gene. The distribution of sex, age, response to prednisone and central nervous system (CNS) involvement were no significant different at diagnosis between SIL-TAL1 positive and negetive patients. However, the WBC count in SIL-TAL1 positive cases were significantly higher than that of SIL-TAL1 negative cases at diagnosis (P<0.05). Additionally, MRD levels were not significantly different between children with SIL-TAL1 positive or negative T-ALL at 3 time points including: after the remission induction therapy, before delayed intensive therapy II and before maintenance therapy. However, the number of cases with high MRD levels before consolidation therapy were more in SIL-TAL1 positive group than that in SIL-TAL1 negative group (P<0.05). The cases with high MRD levels before delayed intensive therapy I was more in SIL-TAL1 negative group than that in the SIL-TAL1 positive group (P>0.05). Besides, there were no significant differences in 5-year EFS and RFS between the two groups. The risk of 22 children with SIL-TAL1 positive acute T-ALL was again stratified according to the typing stemdard in CCLG-2008 protocol, as a result, the risk in BCH-2003 group (10 cases) was significantly higher than that in BCH-2008 group (12 cases) (P<0.05), but no significant difference was found in common clinical features, early treatment response, MRD levels and treatment efficacy.

CONCLUSIONS: Although WBC level was significantly higher in SIL-TAL1 positive group than that in SIL-TAL1 negative group, the treatment efficacy in SIL-TAL1 positive group was similar to SIL-TAL1 negative group. Meanwhile, the children with SIL-TAL1+ T-ALL may respond poorly to early intensive therapy, the BCH-2003 protocol may be more suitable for the patients with this subtype of leukemia.