SIL-TAL1 Rearrangement is Related with Poor Outcome: A Study from a Chinese Institution

SIL-TAL1 rearrangement is common in T-cell acute lymphoblastic leukemia (T-ALL), however its prognostic implication remains controversial. To investigate the clinical characteristics and outcome of this subtype in Chinese population, we systemically reviewed 62 patients with newly diagnosed T-ALL, including 15 patients with SIL-TAL1 rearrangement. We found that SIL-TAL1 + T-ALL was characterized by higher white blood cell count ( P  = 0.029) at diagnosis, predominant cortical T-ALL immunophenotype ( P  = 0.028) of the leukemic blasts, and a higher prevalence of tumor lysis syndrome (TLS, P <0.001) and disseminated intravascular coagulation (DIC, P <0.001), which led to a higher early mortality ( P  = 0.011). Compared with SIL-TAL1 − patients, SIL-TAL1 + patients had shorter relapse free survival ( P  = 0.007) and overall survival ( P  = 0.002). Our NOD/SCID xenotransplantation model also demonstrated that SIL-TAL1 + mice models had earlier disease onset, higher leukemia cell load in peripheral blood and shorter overall survival ( P <0.001). Moreover, the SIL-TAL1 + mice models exerted a tendency of TLS/DIC and seemed vulnerable towards chemotherapy, which further simulated our clinical settings. These data demonstrate that SIL-TAL1 rearrangement identifies a distinct subtype with inferior outcome which could allow for individual therapeutic stratification for T-ALL patients.