The Clinical Value Of Monitoring Serum MGMT Autoantibodies In Patients With Glioma Using A Peptides Microarray

Background and purpose:Tumor-specific autoantibodies found in the serum of cancer patients have been identified as early markers of tumor diagnosis,predicting the risk of recurrence and identifying potential markers of therapeutic response.This study aimed to investigate serum 06-methylguanine-DNA methyltransferase(MGMT)autoantibodies were used as glioma diagnostics to predict the risk of recurrence and to assess novel biomarkers of resistance for glioma and to predict B-cell linear epitopes of MGMT proteins ere detected by MGMT microarray.Methods:1.MGMT protein were cut into overlapped peptides to build a peptide library and a stable MGMT peptide measuring scheme based peptides microarray was established.2.Collection of serum samples:A total of 180 serum samples from glioma patients with different WHO grades and 311 serum samples from healthy volunteers were collection in this study.Serum samples were collected at 3 time points:preoperative,30 days after surgery and at glioma recurrence.3.The response of MGMT autoantibodies in the serum of patients with preoperative glioma and healthy control group was detected by using the peptides microarray.4.The cut-off values of each peptide were determined as the SNR which yields maximum difference of positive response rate between glioma and healthy normal group.5.The changing regularity of MGMT autoantibodies were then studied use the serum sample of different time points with glioma patients.6.Univariate and multivariate analysis methods were used to predict the risk of recurrence and to analyze the correlation between the status and level of MGMT autoantibody in serum of preoperative glioma patients and postoperative chemotherapeutic with temozolomide of glioma patients.7.The predicted B-cell epitope series by bioinformatics were compared with the high-response peptides serum in glioma to predict the B-cell linear epitope sites recognized by the MGMT peptides autoantibody,and to explore its potential application prospect.Results:1.The MGMT peptide autoantibody can be detected in the serum of glioma patients,and 5 high response MGMT peptide autoantibodies(MGMT-02,MGMT-04,MGMT-07,MGMT-10,MGMT-18)in the glioma group were identified.2.Receiver operating characteristic(ROC)analyses showed that combination of five peptides was the most efficient at discriminating glioma from healthy controls compared with single autoantibody measurements.ROC of combination five peptides diagnosis model have increase to 0.81(95%confidence interal,0.69-0.87),the overall sensitivity of 75%,specificity of 83%.Especially in High-grade glioma group,the ROC was 0.84(95%confidence interval 0.78-0.90),with an overall sensitivity of 75%and a specificity of 89%.3.The levels of MGMT autoantibodies decreased on the 30th day after operation,and when the tumor recurred,the MGMT autoantibody level increased and reached the preoperative level.4.Univariable and multivariable analyses revealed that the only preoperative autoantibodies to MGMT-02 peptide were independently correlated with recurrence-free survival(p<0.05),but not related to WHO grades,age,gender and ki-67 expression of glioma(p>0.05).Preoperative seropositive(SNR value 5.5-20)patients were more likely than seronegative patients to have shorter recurrence times and to be resistant to chemoradiotherapy or chemotherapy with temozolomide,except seropositive(SNR value≥20)patients.Monitoring the levels of preoperative serum autoantibodies to MGMT-02 peptide was useful for identifying patients with glioma and predicting patients at high risk of recurrence and chemoradiotherapy resistance with temozolomide.5.The predicted B cell epitope compared with five amino acid sequence of peptides,each peptides with 12 or more for the same amino acid sequence,we found 5 high response MGMT peptide autoantibodies in the glioma group might be useful for the development of new monoclonal antibodies and peptide cancer vaccines that target different epitopes of MGMT.Conclusion:In this retrospective study,we provided evidence for the occurrence of autoantibodies to the MGMT peptide in glioma serum,and 5 highly responsive peptides have been identified in the glioma group.Our observations indicate that MGMT autoantibody could be used for diagnosis,prediction the risk of recurrence and chemotherapy resistance of glioma.We identified five highly responsive peptides that might be useful for the development of new monoclonal antibodies and peptides cancer vaccines that target different epitopes of MGMT.