Circulating IgG antibody against FOXP3 may be a potential biomarker for lung cancer

Background: Forkhead box P3 (FOXP3) has been found to be overexpressed by a range of cancer cells and correlated with prognosis of tumors. This finding raises the possibility that the development of anti-FOXP3 antibody test may be useful for clinical application. Objective: The present work was designed to test whether circulating autoantibody to FOXP3 was altered in lung cancer. Methods: 271 patients with non-small cell lung cancer (NSCLC) and 227 in control subjects matched in age, gender and smoking history were recruited. Circulating anti-FOXP3 IgG antibody was tested using an in-house enzymelinked immunosorbent assay. Results: Student’s t-test showed that the levels of IgG autoantibody to FOXP3 were significantly higher in patients with NSCLC than control subjects (t = 7.67, P < 0.0001). Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve (AUC) was 0.70 (95% CI 0.65 - 0.75, SE ± 0.024), in which patients at stage 2 had the highest AUC of 0.75 (95%CI 0.67 - 0.81, SE ± 0.037), with a sensitivity of 31.4% against a specificity of 90.3%. Analysis of quality control samples gave an inter-assay deviation of 13.3% among 45 plates tested. Conclusions: Circulating IgG autoantibody to FOXP3 may be a potential biomarker for lung cancer.