The Outcome Of AML Patients With MLL Gene Rearrangement Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Objective1.To summarize the clinical and prognostic characteristics of AML patients with MLL gene rearrangement(MLL-r AML)undergoing allogeneic hematopoietic stem cell transplantation(allo-HSCT)and to explore the potential factors.2.To investigate the role of EVI1 gene quantification in MLL-r AML patients after allogeneic hematopoietic stem cell transplantation.Methods1.We retrospectively analyzed the clinical characteristics,treatment response and survival of 119 MLL-r AML patients from September 2009 to January 2019.2.Reverse transcription-polymerase chain reaction(RT-PCR)analysis was performed to measure copies of common EVI1 gene from 96 cDNA samples at diagnosis,57 cDNA samples at one month before allo-HSCT and 54 cDNA samples at 100 days post allo-HSCT.Then we compared the differences of clinical characteristics,gene mutations and survival between the EVI1-high and EVI1-low groups,so as to investigate the prognostic value of EVI1 gene quantification in MLL-r AML patients after allogeneic hematopoietic stem cell transplantation.Results1.A total of 47 MLL-r AML patients underwent allo-HSCT from September 2009 to May 2016.There were 24 males and 23 females in this study.The median age was 30(15-58)years old and 36(76%)patients were FAB-types M4/M5.On the whole,45 patients were identified with 11q23 translocations,and 2 patients with normal karyotype were MLL partial tandem duplication.According to their different chromosome karyotypes,the 47 patients were divided into three groups:16 cases of t(6;11),15 cases of t(9;11),and 16 cases of other types.There were 38 patients in CR,3 patients in PR and 6 patients in NR before transplant.Eight patients underwent sibling-matched allogeneic stem cell transplantation,while 39 patients underwent haploid-matched allogeneic stem cell transplantation.With a median follow-up time of 19 months(3-73 months),the 2-year overall survival(OS),disease-free survival(DFS),relapse incidence and transplant-related mortality(TRM)were 64.4%,47.3%,41.0%and 17.9%,respectively.There was no significant difference on OS among the three cohorts(χ2=1.509,P=0.472).Univariate analysis revealed non-CR status before transplant and female donor were the unfavorable prognostic factors for OS and DFS(P<0.05),while positive minimal residual disease(MRD)was prognostic factor for poor DFS and high relapse incidence(P<0.05).Our multivariate analysis revealed that age at transplant(>45 years old)was an independent risk factor on OS[HR=4.45(95%CI 1.31～15.10),P=0.016].Positive MRD before transplant was a negative prognostic factor on DFS[HR=4.24(95%I/1.24-14.50),P=0.021]and relapse incidence[HR=5.49(95%CI 1.37～21.99),P=0.016].The multivariate analysis also confirmed higher TRM in patients who were in non-CR states before transplant[HR=10.37(95%CI1.04～103.11),P=0.046].2.We detected the quantification of EVI1 gene in 96 MLL-r AML patients from September 2009 to January 2019.Seventy(73%)patients were defined as EVI1-high and the remainder EVI1-low.EVI1-high MLL-r AML patients were characterized by high WBC counts(median,33.89×109/L vs 8.3×109/L,P=0.046),lowplatelet counts(median,34×109/L vs 87×109/L,,P<0.001),low myeloblast(median,78%vs 88%,P=0.002)and commonly had t(6;11)(41%vs 15%,P=0.032).Next generation sequencing was performed in samples of 32 EVI1-high and 12 EVI1-low patients.A significant difference was observed in the SETD2 gene mutation between the EVI1-high and EVI1-low groups(0%vs 50%,P<0.001).PTPN11 and FLT3-ITD mutations were found in 6 and 4 patients in the EVI1-high group,respectively,whereas these two mutations were not found in the EVI1-low group OP=0.16,P=0.56).EVI1-high MLL-r AML patients had worse 2-year OS(49.8%vs 79.7%,P=0.01)and 2-year progression-free survival(PFS)(40.2%vs 68.1%,P=0.014)than EVI1-low patients.In 57 MLL-r AML patients undergoing allo-HSCT,poorer 2-year PFS(48.6%vs 72.4%,P=0.039)and higher cumulative incidence of relapse(CIR)(33.2%vs 11.1%,P=0.035)were observed in the EVI1-high patients.Similarly,poorer 2-yaer OS(49.7%vs 84.4%,P=0.026)and 2-year PFS(47.1%vs 73.5%,P=0.021)as well as higher 2-year CIR(34.2%vs 10.9%,P=0.023)were observed in the pre-EVI1+group.Multivariate analysis showed>2 induction regimens for CR was unfavorable independent prognostic factor for OS[HR=2.77(95%CI 1.19～6.46),P=0.018]and PFS[HR=3.10(95%CI 1.3～^7.03),P=0.007].Pre-EVI1+was the sole independent factor of high CIR[HR=4.97(95%CI 1.12～22.04),P=0.035].EVI1+at 100 days post allo-HSCT was associated with significantly higher 2-year CIR(P=0.017).Conclusions1.Allo-HSCT was an effective treatment for MLL-r AML patients.Age at transplant(>45 years old),non-CR states at transplant and positive MRD before transplant were negative prognostic factors in allo-HSCT for MLL-r AML patients.2.High EVI1 expression was common in t(11q23)AML patients,especially in t(6;11)AML patients.SETD2 mutation was only found in EVI 1-low MLL-r AML patients.Pre-EVI1+had a significant negative influence on the prognosis of allo-HSCT with MLL-r AML,which was an independent prognostic factor of CIR.>2 induction regimens for CR was unfavorable independent prognostic factor for OS and PFS.The quantification of EVI1 gene could likely be used as an additional marker for the early prediction of relapse in allo-HSCT MLL-r AML patients.