Lymphoblastic Leukaemia in Infants

Overview

The therapeutic results in children with acute lymphoblastic leukaemia (ALL)are improving continu-ously with modern treatment protocols of combined chemotherapy.Approximately 75 %children andadolescents can be cured from their leukaemia.Among infants younger than one year ALL is a raredisease.Typical infant ALL originates from very early precursors of B cells with a specific genotype,large leukaemic mass on diagnosis and high risk of early relapse.Between 1990 –2000,671 children andadolescents 0 –18 years old were diagnosed with ALL in the Czech Republic.Only 24 (3.6 %)of them wereinfants.Boys (n 16)predominated over girls (n 8)and 10 infants were younger than 6 months.ALLdeveloped from very early precursors of B cells (pro-B ALL)in 16 children,cALL was diagnosed in 7and T-ALL in one child,respectively.Cytogenetic and molecular genetic investigation revealed trans-location t(4;11)/fusion gene MLL-AF4 in 11 (45.8 %)patients.Fifteen children were treated according tothe protocol ALL-BFM 90,ALL-BFM 95 was used in one child and age-tailored schedules POG 9407 andInterfant 99 were used in 5 and 3 children,respectively.Therapeutic results were analyzed in 21 childrenbecause the follow-up of 3 children on the Interfant 99 protocol was too short.The 5-year event-free-survival (EFS)was 33 %(SE 10 %)with a median follow-up of 7.9 years.Children with ALL andt(4;11)/MLL-AF4 had a significantly inferior outcome (EFS 10 %)in comparison to children without thistranslocation (EFS 55 %;p 0,01).Boys achieved better therapeutic results (EFS 45 %)than girls (EFS12 %;p 0,007).The explanation of this difference is the higher incidence of t(4;11)in girls.Anotherimportant risk factor in our group was a slow early treatment response in 33 %infants.Poor responseto early therapy is found only in 10 %older children.Infant ALL is a rare disease with a worse prognosisthan ALL in older children due to the different biological properties of the leukaemic cells.

Key words:
acute lymphoblastic leukaemia,infants,t(4;11),fusion gene MLL-AF4