The therapeutic response and clinical outcome of adults with ALL1(MLL)/AF4 fusion positive acute lymphoblastic leukemia according to the GIMEMA experience.

The clinical outcome of 21 adults with ALL1(MLL)/AF4 positive acute lymphoblastic leukemia enrolled in the GIMEMA LAL 2000 trial and of 25 patients entered into the previous 0496 study is reported. LAL 2000 included more intensive consolidation and transplants. Complete remission rates were 90% and 88% in the LAL 2000 and 0496 trials, respectively. Fifteen patients were transplanted (5 autologous, 10 allogeneic). At 36 months, overall and disease free survivals were 32.9%, 31.8%, 28% and 27.3%, in LAL 2000 and 0496 trials, respectively. Relapses remained the main reason of failure occurring in 10 and 16 of the 19 and 22 responding patients. In the LAL 2000 study, 4 relapses were observed before transplant. Thus, ALL1(MLL)/AF4 abnormality characterized a subset of patients with adverse prognosis in which the overall strategy adopted in the LAL 2000 study, rather than transplants per se, failed to improve the patient clinical outcome.