Prevalence and prognostic value of IDH1 and IDH2 mutations in childhood AML: a study of the AML-BFM and DCOG study groups

Mutations in the NADP(+)-dependent isocitrate dehydrogenase genes 1 and 2 (IDH1 and IDH2) have recently been found in adult acute myeloid leukemia (AML) patients with a prevalence rising up to 33%. To investigate the frequency of IDH1/2 mutations in pediatric AML, we characterized the mutational hotspot (exon 4) of these genes in diagnostic samples from 460 pediatric AML patients. Our analysis identified somatic IDH1/2 mutations in 4% of cases (IDH1 R132 n = 8; IDH2 R140 n = 10) and the minor allele of single-nucleotide polymorphism (SNP) rs11554137 in 47 children (10.2%). IDH mutations were associated with an intermediate age (P = 0.008), FAB M1/M2 (P = 0.013) and nucleophosmin1 mutations (P = 0.001). In univariate analysis, IDHmutated compared with IDHwildtype patients showed a significantly improved overall survival (OS; P = 0.032) but not event-free survival (EFS; P = 0.14). However, multivariate analysis did not show independent prognostic significance. Children with at least one minor allele of IDH1 SNP rs11554137 had similar EFS (P = 0.27) and OS (P = 0.62) compared with major allele patients. Gene expression profiles of 12 IDHmutated were compared with 201 IDHwildtype patients to identify differentially expressed genes and pathways. Although only a small number of discriminating genes were identified, analysis revealed a deregulated tryptophan metabolism, and a significant downregulation of KYNU expression in IDHmutated cases. Leukemia (2011) 25, 1704-1710; doi:10.1038/leu.2011.142; published online 7 June 2011