The Prognostic Impact Of Complex Gene Mutation In The Intermediate Risk Karyotype Acute Myeloid Leukemia

Many gene mutations were detected and overlapped in de novo acute myeloid leukemia (AML), but the prognosis of complex gene mutation remains to be unclear. In this study, we analyzed the prognostic impact of complex gene mutation in de novo AML patients with the intermediate risk karyotype.

We analyzed 143 samples from de novo AML patients with the intermediate risk karyotype diagnosed at Nippon Medical School Hospital from 2000 to 2012. Bone marrow or peripheral blood samples containing 20% or more blast cells were used for analyses. Mutation analyses were performed using PCR method for FLT3-ITD, FLT3-TKD and MLL-PTD, and direct sequence for NPM1, C/EBPα, DNMT3a, IDH1/2, TET2 and N/K-RAS.

The NPM1 (39.9%), DNMT3a (26.6%), FLT3-ITD (24.5%), IDH1/2 (18.9%), TET2 (17.5%), C/EBPα (14.7%), N/K-RAS (14.0%) and MLL-PTD (6.3%) mutations were detected in our cohort, respectively. When we performed prognostic analyses for mutations of these genes, DNMT3 mutation and FLT3-ITD were isolated as a poor prognostic factor in overall survival (OS) , respectively (DNMT3a mutation positive: n=39, 3yOS 17.9%. negative: n=104, 3yOS 33.2%. p=.0056) (FLT3-ITD positive: n=35, 3yOS 12.2%. negative: n=108, 3yOS 35.0%. p=.0077). Moreover, in the FLT3-ITD positive cases, OS of patients with DNMT3a R882 mutation was significantly shorter than those without R882 mutation (R882 positive: n=20, 3yOS: 0%. negative: n=15, 3yOS 25.0%. p<.0256). Interestingly, High rate of patients with FLT3-ITD (91.4%), NPM1 (89.5%), DNMT3a (92.1%), TET2 (84.0%), and IDH1/2 (88.9%) mutations were detected other overlapped mutations, respectively. The frequency of the overlapped mutations in patients with DNMT3a mutation, especially with mutations on R882, was significantly higher than those in patients without them (DNMT3a: p=.0001, R882: p<.0001). For total cohort, the rates of and OS and relapse free survival (RFS) in patients with three or more overlapping mutations (complex gene mutation: CGM) were significantly lower than those in patients without them (CGM+: n=36, 3yOS 5.6%. CGM-: n=107, 3yOS 37.7%. p<.0001) (CGM+: n=12, 3yRFS: 8.3%. CGM-: n=57, 3yRFS: 36.0%. p=.0013). Moreover, among the patients without FLT3-ITD, the rates of RFS and OS at 3 years in patients with complex gene mutation were significantly lower than those in patients without them (CGM+: n=11, 3yOS 5.6%. CGM-: n=96, 3yOS 37.7%. p<.0408) (CGM+: n=4, 3yRFS: 8.3%. CGM-: n=51, 3yRFS: 36.0%. p=.0179).

Our study revealed that the gene mutations appeared to be overlapped, and the complex gene mutation significantly affected the prognosis of de novo AML with the intermediate risk karyotype. Intriguingly the DNMT3a mutation may contribute to an occurrence of complex gene mutation by giving genetic instability to AML cells.

No relevant conflicts of interest to declare.