Risk Factors For Relapse After Allogeneic Hematopoietic Stem Cell Transplantation In Acute Myeloid Leukemia And A Preliminary Study On The Clonal Evolution Of Relapse

Part 1 Analysis of risk factors of relapse after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemiaObjectiveTo analyze the risk factors of relapse after allogeneic hematopoietic stem cell transplantation(allo-HSCT)in patients with acute myeloid leukemia(AML)and the effect of most frequent gene mutations on relapse after transplantation.MethodsRetrospective analysis of clinical data of 95 patients with AML(non-M3)who underwent allo-HSCT treatment and survived for more than 100 days in the Department of Hematology,affiliated Cancer Hospital of Zhengzhou University from January 2010 to May 2020.Analyze the influence of disease subtype,gender,age of transplantation,initial white blood cell count,gene mutation,chromosome,extramedullary disease prior to transplant,the cycle of induction therapy,the time of CR1 to transplant,disease status before transplantation,pretreatment,type of transplantation,gender of donor and recipient,stem cell source,acute GVHD(a GVHD),chronic GVHD(c GVHD),karyocyte number,CD34~+cell number,cytomegalovirus infection(CMV)and most frequent gene mutations(FLT3-ITD,TET2,DNMT3A,KIT,NPM1)on relapse after allo-HSCT.Results1.All patients were transplanted for the first time.13 patients(13.7%)were high leukocyte leukemia.59 patients(62.1%)had at least one gene mutation,and 14patients(14.7%)had more than 3 gene mutations.The most frequent gene mutations were FLT3-ITD(n=28/59,47.5%),TET2(n=16/59,27.1%),DNMT3A(n=9/59,5.3%),KIT(n=8/59,13.5%),and NPM1(n=8/59,13.5%).Chromosome karyotype abnormality in 33 patients(34.7%).8 patients(8.4%)had extramedullary disease prior to transplant.40 patients(42.1%)received more than 1 cycle of induction therapy.The time of CR1 to transplant was≥6 months in 34 patients(35.8%).The disease status before transplantation was first complete remission(CR1)in 76patients(80%),CR2 in 9 patients(9.5%),CR3 in 2 patients(2.1%),partial remission(PR)/non remission(NR)in 8 patients(8.4%).2.All patients were successfully reconstituted with hematopoietic reconstitution.The median time of neutrophil and platelet implantation was 13(9～24)d and 14(9～50)d,respectively.57.9%(55/95)of the patients developed a GVHD,including51 patients of I-II degree and 4 patients of III-IV degree.54.7%(52/95)of patients developed c GVHD,of which 5.3%(5/95)were generalized and 49.4%(47/95)were localized.The EBV infection rate was 34.7%(33/95),and the CMV infection rate was 49.4%(47/95).The incidence rate of hemorrhagic cystitis was 31.6%(30/95),the incidence rate of hepatic vein occlusive disease was 1.1%(1/95).3.By December 31,2020,34.7%(33/95)patients died,the median follow-up time was 28.2(3.7～114.7)months for all patients.25.3%(24/95)patients had leukemia relapse.The median time to relapse was 6.4(3.6～28.1)months.There were 19 patients of simple bone marrow relapse,3 patients of simple extramedullary relapse,2 patients of bone marrow with extramedullary relapse.The main sites of extramedullary relapse were central(n=3)and bone(n=2).One patient had extramedullary disease prior to transplant.Of the relapse patients,only 7 patients(29.2%)survived,and the median survival time after relapse was 5(0.2～41.6)months.4.Univariate analysis indicated that there were four risk factors related with the disease relapse(P<0.05),including disease status before transplantation,pretreatment,gender of donor and recipient,FLT3-ITD gene mutation.Multivariate analysis determined that disease status before transplantation(HR:2.070,95%CI:1.163-4.501,P=0.016)and FLT3-ITD gene mutation(HR:1.897,95%CI:1.002-3.592,P=0.049)were independent risk factors for relapse of the patients who had undergone transplantation.5.The 3-year OS rate and LFS rate of all patients were(63.8±5.2)%and(56.5±5.2)%,respectively.The 3-year OS rate and LFS rate of relapse and non-relapse patients were 20.3%and 76.7%,respectively.(P=0.000).The 3-year OS rate and LFS rate of CR1 patients before transplantation were higher than those of non-CR1patients(69%vs 39.8%P=0.023;63.6%vs 28.4%P=0.006).The 3-year OS rate of patients without FLT3-ITD mutation before transplantation was 67.7%,which was higher than that of patients with FLT3-ITD mutation(55.3%)(P=0.149).The 3-year LFS rate of patients without FLT3-ITD mutation before transplantation was 62.9%,which was higher than that of patients with FLT3-ITD mutation(41.7%)(P=0.038).Conclusions1.Non-CR1 status and FLT3-ITD mutation are risk factors for relapse after allo-HSCT in AML patients.2.Non-CR1 status is a risk factor for OS of AML patients after allo-HSCT.The prognosis of relapse patients after transplantation is poor.Part 2 Preliminary study on the clonal evolution of relapse acute myeloid leukemiaObjectiveTo analyze the characteristics of gene mutation in patients with AML during initial diagnosis and relapse,and to clarify the clonal evolution pattern of relapse.MethodsThis study included 22 patients with AML(non-M3)who were hospitalized and relapsed in the Department of Hematology,affiliated Cancer Hospital of Zhengzhou University from July 2016 to January 2020,including 6 patients of relapse after chemotherapy,4 patients of relapse after auto-HSCT and 12 patients of relapse after allo-HSCT.All patients were examined for 68 gene mutations associated with acute myeloid leukemia at initial diagnosis and relapse by next-generation sequencing technology(NGS).Results1.A total of 33 mutations were detected in 15 gene types in initial diagnosis patients,of which 17 patients(77.3%)had at least one gene mutation and 5 patients(22.7%)had more than 3 gene mutations.The most frequent gene mutations were FLT3-ITD(n=7),DNMT3A(n=4),NPM1(n=3),RUNX1(n=3),NRAS(n=3),TET2(n=3),and IKZF1(n=2).A total of 36 mutations in 15 gene types were detected in relapse patients,of which 20(90.9%)had at least one gene mutation and 4(18.2%)had more than 3 gene mutations.The most frequent gene mutations were FLT3-ITD(n=7),ABCB1(n=6),TET2(n=4),DNMT3A(n=3),KIT(n=2),RUNX1(n=2),CEBPA(n=2),NPM1(n=2)and IDH2(n=2).IDH1,PHF6,IKZF1 and ASXL1 mutations only appeared in initial diagnosis patients,while IDH2,TP53,BCOR and CSF3 R mutations only appeared in relapse.2.14 patients(63.6%)had gene mutation missing,and the mutations with high missing frequency were FLT3-ITD(n=3),DNMT3A(n=2),TET2(n=2),IKZF1(n=2)and NRAS(n=2).14 patients(63.6%)obtained new gene mutation,and the new gene mutations with higher frequency were ABCB1(n=6),FLT3-ITD(n=3),TET2(n=3),KIT(n=2)and IDH2(n=2).Patients with relapse after allo-HSCT were more likely to obtain and miss gene mutation than patients with chemotherapy and auto-HSCT.3.Comparing the characteristics of gene mutation between initial diagnosis and relapse patients,three clonal evolution patterns were found: 18.2%(n=4)patients had exactly the same gene mutation at initial diagnosis and relapse.18.2%(n=4)patients had completely different gene mutations at initial diagnosis and relapse.59.1%(n=13)patients missed one or more gene mutations or obtained new gene mutations on the basis of initial diagnosis gene mutations.Conclusions1.FLT3-ITD mutation is the most frequent at initial diagnosis and relapse.2.Some patients will obtain new gene mutations when they relapse,and most of these new mutations are related to poor prognosis.3.Patients with relapse after allo-HSCT are more likely to obtain and miss gene mutation than patients with chemotherapy and auto-HSCT.4.Monitoring the clonal evolution when the disease relapses by NGS,identify potential treatment targets,and provide new treatment ideas.