E2A-PBX1 fusion in adult acute lymphoblastic leukaemia: biological and clinical features.

Molecular and cytogenetic studies performed in 305 adult acute lymphoblastic leukaemia (ALL) patients enrolled in the gimema (Gruppo Italiano Malattie EMatologiche dell'Adulto) multicentric protocols identified an E2A-PBX1 fusion and/or t(1;19) in 10 patients (3.3%). All had common ALL, were mostly CyIg+ and were CD34/CD13/CD33-. Nine patients achieved a complete remission (CR); five patients showed a haematological relapse after 7 months (median). Four patients are alive in first CR with a median follow-up of 29 months; three patients are molecularly negative. This abnormality is frequently associated with early treatment failure. E2A-PBX1+ adult ALL should be considered for intensified treatment strategies and monitoring of minimal residual disease.