Cooperating Mutations of IDH1,IDH2, JAK2^V617F, NPM1, FLT3-ITD,C-KIT Genes in Chinese Patients with De Novo Acute Myeloid Leukemias

Acute myeloid leukemia (AML) is a heterogeneous group of aggressive disease with complex process,gene mutations play an important role in AML pathogenesis. Several genes have been identified in AML,such as FLT3, c-KIT, NPM1 and JAK2. Indeed, some mutations have revealed prognosis subgroups and modified the therapeutic management of these leukemias. Recently,novel mutations in IDH1(amino acid R132)and IDH2 (R140 and R172)have been found in patients with AMLs,but the frequency and impact on biological and prognostic features in Chinese patients with AMLs remain unknown. We aimed at studying the potential significance of IDH1 and IDH2 mutations in AML and analyzed their interaction with other mutations in Chinese patients with de novo AMLs.

We searched 163 Chinese patients with de novo AML for mutations in the IDH1,IDH2, JAK2, NPM1, FLT3-ITD,C-KIT genes.Female/male ratio was 98/65 and age ranged from 17.0–74.0years (median, 41.0years).Genomic DNA was extracted from diagnostic marrow specimens,FLT3 internaltandem duplication(FLT3 –ITD) and JAK2^V617F mutations were screened using polymerase chain reaction (PCR),c-KIT, NPM1 and IDH genes were assessed by PCR followed by direct sequencing, according to previously described protocols.

Overall, IDH mutations were found in 25 patients (15.3%) —IDH1 in 7 patients (4.29%) and IDH2 in 18 patients (11.04%). A total of 4 types of IDH1 mutations were identified(c.395G>A, p.R132H,n=4 Gc.394C>A, p.R132S,n=1 Gc.394C>G, p.R132G,n=1 Gc.315C>T, n=1),six out of the seven patients with the missense mutations and the overall frequency of missense mutations in IDH1 was 3.68% (6/163). Both synonymous substitution (c.315C>T; rs11554137) in IDH1 and IDH2^R140 mutation occurred in one patient. No mutated cases had both IDH1 and IDH2 missense mutations, suggesting that the mutations are mutually exclusive. IDH2 mutations caused changes of R140 (c.419G>A,p.R140Q,n=18), R172 mutation was not found in our study. The NPM1 mutation in exon 12 was present in 18.35% (n=29 29/158), 25 cases had FLT3-ITD(15.8% 25/158),One case had frame insertion/deletions of c-KIT in exon 8,7 cases had the substitution of a single amino acid in exon 17(4.57%,7/153),none of them had JAK2^V617F mutation. IDH- mutated cases showed a higher frequency of concurrent NPM1 mutation compared with wildtype cases (48.3% 14/29 vs 10.8% 11/129), IDH mutations were also more frequent in FLT3-ITD mutation vs FLT3-ITD wildtype (44.0% 11/25 vs 10.5%14/133).10 patients had both FLT3-ITD and NPM1 mutations, concurrent mutations in NPM1, FLT-ITD were detected in 5 cases with the IDH mutation. None of all cases had both IDH and C-KIT mutations. IDH mutations were more often in cytogenetically normal AML cases(20.5% 15/73 vs5.8% 3/52. Patients with IDH mutations were older (51:40 P=0.003), whereas, there were no differences in sex,WBC and platelet count for IDHmut and IDHwt.

Our results show that IDH mutations, especially IDH^R140 were frequent genetic alterations in Chinese patients with de novo AMLs, and associated with older age, normal karyotype at diagnosis.There was strong association of IDH mutations with NPM1 and FLT3-ITD mutations, suggesting that IDH mutations may act cooperatively in leukemogenesis.

No relevant conflicts of interest to declare.