Excellent outcome of acute lymphoblastic leukaemia with TCF3-PBX1 rearrangement in Hong Kong

OBJECTIVE:The aim of this study was to review clinical outcomes and prognosis of paediatric patients with acute lymphoblastic leukaemia (ALL) with TCF3-PBX1 rearrangement. PATIENTS:All children in Hong Kong diagnosed with ALL with TCF3-PBX1 rearrangement over the past two decades were included. METHODS:Six hundred and twenty-four newly diagnosed patients with ALL from four consecutive studies were enrolled from 1997 to 2016. Patients carrying TCF3-PBX1 rearrangement and patients at intermediate risk without the gene expression were compared for clinical characteristics, overall survival and event-free survival (EFS). RESULTS:The TCF3-PBX1 rearrangement was detected in 30 of 624 patients (4.8%). Results were consistent across the consecutive clinical trials employed in the past two decades. Compared with 239 intermediate risk patients without TCF3-PBX1 rearrangement, the 5-year overall survival and EFS for patients with TCF3-PBX1 rearrangement was superior, with both at 100% (P = 0.12 and P = 0.029). CONCLUSION:This population-based study over the past 20 years demonstrated that patients with TCF3-PBX1 rearrangement had favourable EFS compared with other intermediate risk patients treated with a similar chemotherapy backbone.