MLL-NEGATIVE INFANT ACUTE LYMPHOBLASTIC LEUKEMIA. CLINICAL CHARACTERISTICS AND POSSIBILITIES FOR CHEMOTHERAPY OPTIMIZATION

Abstract

MLL-negative (mixed lineage leukemia – MLL) acute lymphoblastic leukemia (ALL) diagnosed in the first year of life is rare. Although infant ALL is often assumed to be fatal, no studies have been published on outcome of MLL-negative infant ALL. The present study reports the clinical characteristics and outcome of 60 patients with MLL-negative infant ALL treated with the series of Moscow-Berlin (MB) protocols, a regimen with reduced chemotherapy. MLL-negative ALL by infants with age < 6 months at the diagnosis was characterized by a higher white blood cell count, splenomegaly and prevalence of girls compared with older infants. Induction failure rate was 3.4 % for the whole group of patients and was not significantly different between infants with less or more 6 month old. EFS and OS for the whole group of patients were 62 ± 7 % and 59 ± 7 % with relapse rate of 28.7 %. But relapse rate was significantly higher in MLL-negative infant ALL patients with age < 6 month compared of that of pts with age  6 month (cumulative incidence was 60.7 ± 16.5 % vs 19.1 ± 6.7 %, p < 0.005). EFS and OS of MLL-negative infant ALL patients were significantly worse compared of that for the old infants (10 ± 9% vs 79 ± 7 % for EFS). The treatment according new MB regimens significantly improve the outcomes for the whole group and also for children with < 6 months age at the diagnosis.