Mutation Characteristics And Prognosis Significance Of DNA Damage Repair Genes In Acute Myeloid Leukemia

Acute myeloid leukemia(AML)is a highly heterogeneous hematological malignancy characterized by clonal expansion and impaired differentiation of abnormal primitive myeloid cells in the bone marrow and peripheral blood.The accumulation of deoxyribonucleic acid(DNA)damage and the defect of DNA damage response(DDR)pathway would increase the frequency of gene mutations,lead to genomic instability,and ultimately increase the risk of canceration.The correlation between DNA damage repair and the occurrence,development,and prognosis of various solid tumors has been confirmed,but there is no research report on the occurrence and potential mechanism of DNA damage repair related mutations in AML by high throughput next generation sequencing(NGS)methodology.Objective:Explored the mutation characteristics and prognostic significance of DNA damage repair gene mutations in AML and provided new prognostic indicators and potential targets for targeted therapies of AML.Methods:Based on the Cancer Genome Atlas(TCGA),a targeted NGS panel was designed to cover 276 DNA damage repair genes.Bone marrow samples during initial diagnosis and remission period of 120 AML patients who were initial diagnosed and untreated in the Department of Hematology of the First Affiliated Hospital of Suzhou University from July 2018 to December 2019 were retrospectively collected.DNA was extracted separately,and 276 DNA damage repair gene mutations NGS panel were used to detect the mutation status of DNA damage repair genes,clarify mutation types,and summarize the gene mutation characteristics(incidence,mutation type,and mutation frequency).Collectd the pathological results from the bone marrow laboratory,treatment plans,and follow-up data of all patients at initial diagnosis,and analyzed the impact of DNA damage repair gene mutations on patient survival.Kaplan Meier curve was used to describe survival,Cox univariate and multifactorial regression was used to investigate the influencing factors of overall survival(OS)and progression free survival(PFS)in patients,and to explore the correlation between DNA damage repair gene mutations and involved pathways and the prognosis of AML.Results:1.Designd a targeted NGS panel covering 276 DNA damage repair genes,with mutated genes involved in 9 damage repair pathways:Base excision repair(BER),Nucleotide excision repair(NER),Direct damage reverse/repair(DR),Mismatch repair(MMR),Homology dependent recombination(HDR)Non homologous end joining(NHEJ),Fanconi anemia(FA)pathway,Translesion DNA synthesis(TLS)and key DDR related pathways.2.The sequencing results of 276 DNA damage repair gene mutations showed that the overall positive detection rate of mutations in patients was 99%.9%of patients had a single gene mutation,12%had two gene mutations,and 78%had three or more gene mutations.From the perspective of the source of mutations in patients,the incidence of somatic mutation was 47%,and the incidence of germline mutation was 88%.There were a total of 22 genes with a mutation frequency of 5%or more.According to the clinical significance of gene mutations,they were divided into three categories:pathogenic(P),likely pathogenic(LP),and non pathogenic(NP).At the age of 50,the incidence of somatic pathogenic mutations is 8.4%in the<50 year old group and 24.3%in the ≥50 year old group.The chi square test showed a statistical difference in the incidence of mutations between the two groups(P<0.05).The univariate Kaplan Meier survival curve showed that age≥ 50 years old and presence of somatic DNA damage repair gene mutations predicted worse OS and PFS;AML patients with favorable risk classification and chemotherapy followed by allogeneic hematopoietic stem cell transplantation(allo-HSCT)had comparative advantages in OS and PFS.3.Cox multivariate regression analysis showed that age at initial diagnosis≥ 50 years old,intermediate and adverse ELN risk classification and presence of somatic DNA damage repair gene mutations were independent risk factors for poor OS and PFS in AML patients(P<0.05);Chemotherapy followed by allo-HSCT was a good independent prognostic factor for AML patients(P<0.05).4.The results of subgroup analysis showed that among AML patients with somatic DNA damage repair gene mutations,those with HDR pathway gene mutations had poorer OS and PFS compared to those without this pathway gene mutations(P<0.05);Among AML patients with single germline DNA damage repair gene mutations,those with NHEJ pathway gene mutations had poorer OS and PFS compared to those without this pathway gene mutations(P<0.05).Conclusions:1.Successfully designed exonic targeted NGS panel covering 276 DNA damage repair genes.2.Described for the first time the mutation profile of AML DNA damage repair genes.3.Age at initial diagnosis≥ 50 years old,ELN risk classification in the intermediate and adverse groups and presence of somatic DNA damage mutations were confirmed as poor prognostic factors in OS and PFS of AML patients;Allo-HSCT significantly improved survival in such patients.4.Among 276 DNA damage repair genes panel,somatic DNA damage repair mutations involving the HDR pathway and single germline DNA damage repair mutations involving the NHEJ pathway suggested poor prognosis in AML patients.