A Study On Clinical Implications Of Gene Mutations In The Lower-risk Myelodysplastic Syndrome Patients

ObjectivesThis study aims to investigate the clinical implications of gene mutations in the lower-risk Myelodysplastic Syndrome(MDS)patients and develop a new molecular prognostic model.MethodsThe records of 176 patients with lower-risk(low or intermediate-1 risk)MDS in The First Affiliated Hospital,College of Medicine,Zhejiang University from January 1,2009 to October 30,2016 were retrospectively analyzed.The clinical variables included age,gender,blood cell counts,bone marrow blast percentage,bone marrow proliferative degree,bone marrow fibrosis grade,karyotypes and WHO subtypes.Genomic DNA was extracted from bone marrow mononuclear cell samples and then screened by Sanger or High-Throughput Sequencing for 15 MDS-related genes,including DNMT3A,SF3B1,SRSF2,IDH1,IDH2,ASXL1,EZH2,JAK2,TET2,CBL,ETV6,TP53,NRAS and RUNX1.The relationships between clinical variables and different gene mutation were evaluated.And the correlation of different mutations were also analyzed.To determine the contribution of mutation status and specific location of the mutation to overall survival,univariable analyses were performed.A validation of the MD Anderson Lower-Risk Prognostic Scoring System(LR-PSS)was applied to this cohort.The multivariable analyses were also performed,including LR-PSS classification and candidate mutation status.In addition,a new model,called LR-PSSM that incorporates mutational data to the LR-PSS was generated.ResultsThis cohort included 176 patients.The median follow-up and overall survival were 38.1 months,15.0 months,respectively.The median age was 57;and the ratio of male to female was 1.29(99/77).Abnormal cytogenetic clones was present in 19.3%(34/176)of the patients in this cohort,whereas clonal evidence combining metaphase karyotyping with DNA sequencing,was detected in 51.7%(91/176)of the patients.The relatively high frequency of gene mutation were as follows:SF3B1(3.10%,21/160),TET2(12.5%,7/56),U2AF1(10.4%,17/163),ASXL1(9.5%,7/74),TP53(7.0%,5/71),RUNXI(6.7%,4/60),SRSF2(6.3%,11/174).There was a significant correlation between the number of mutant genes and age(P=0.008).With the increase of age,the number of mutant genes also raised.ASXL1 mutation was related to age stratification(P=0.003).ASXL1 mutation tended to elderly patients.TET2 and ASXL1 mutation were associated with gender(P=0.041,P=0.017).TET2 mutation tended to female patients while ASXL1 mutation was inclined to male patients.U2AF1 and EZH2 mutation were related to bone marrow proliferative degree(P=0.030),bone marrow fibrosis grade(P=0.003),respectively.U2AF1 mutation tended to hyperplasia or extremely hyperplasia;EZH2 mutation tended to high grade of reticular fiber staining.A strong association was found between SF3B1 mutation and refractory anemia with ring sideroblasts(r=0.359,P<0.001).Cooperative relationships were observed between the following six gene mutation pairs:IDH1 and NRAS(r=0.70,P<0.00);ASXL1 and RUNX1(r=0.40,P<0.001);JAK2 and SRSF2(r=0.57,P<0.001);JAK2 and EZH2(r=0.57,P<0.001);IDH2 and SRSF2(r=0.28,P<0.001);IDH2 and DNMT3A(r=0.44,P<0.001).SRSF2 mutant cases had significantly worse overall survival compared to wild-type cases(median OS:19.8 months VS 58.4,P=0.032).Patients with U2AF1(P=0.055),TP53(P=0.064),TET2(P=0.069)mutation tended to poor overall survival in univariate analyses.Different locations of U2AF1 mutation were also associated with overall survival(P=0.024).The patients with U2AF1-S34 mutation(median OS:17.5 months)had the worst prognosis,followed by U2AF1 wild type(median OS:20.9 months),and U2AF1-Q157 mutation(median OS:29.1 months).Patients with SF3B1-K700 mutation tended to show better prognosis than those with SF3B1-non K700 mutation(median OS:57.8 months VS 25.7,P=0.066).Lower-Risk MDS Prognostic Scoring System(LR-PSS)was validated in this cohort.Patients were grouped into three categories:category 1(5.7%)with a median survival of 91.9 months;category 2(58%)with a median survival of 46.0 months and category 3(35.8%)with a median survival of 23.1 months.A new model,called LR-PSSM was generated by adding SRSF2 mutation status to LR-PSS.The patients were stratified into three groups.Moreover,the median overall survival was 105.3,46.0,23.1 and 12.0,respectively.ConclusionWith the increase of age,the number of mutant genes also raised.ASXL1 mutation tended to elderly and male patients whereas TET2 mutation is relatively common in female patients.Patients with U2AF1 mutation was related to hyperplasia or extremely hyperplasia;EZH2 mutation tended to high grade of reticular fiber staining.SF3B1 mutation showed a strong association with refractory anemia with ring sideroblasts.Univariable and multivariable analysis suggested SRSF2 mutation was an independent risk factor for overall survival in the lower-risk MDS patients.Patients with U2AF1,TP53,TET2 mutation may suggest adverse prognosis.Different locations of gene mutation may be associated with overall survival.This cohort validated the LR-PSS model,similar to that reported in the literature.A new model,called LR-PSSM was constructed by adding SRSF2 mutation status to LR-PSS.The LR-PSSM model may help to identify patients with lower risk MDS and poor prognosis who may benefit from early intervention.It may also be beneficial to select very low-risk patients and estimate their survival time more accurately.The new model still needs to be validated by large samples and other centers.