Detection of circulating antibodies to linear peptide antigens derived from ANXA1 and DDX53 in lung cancer.

The EarlyCDT®-Lung test was the first autoantibody-based diagnostic tool for lung cancer, which was developed with a panel of recombinant protein antigens. To confirm whether the antibody test developed with linear peptide antigens has a similar power to that developed with the whole protein molecules, the present work was then undertaken to develop an in-house enzyme-linked immunosorbent assay with linear peptide antigens derived from annexin A1 (ANXA1) and DEAD box protein 53 (DDX53), which have been used to develop the EarlyCDT®-Lung test. A total of 272 patients with non-small cell lung cancer (NSCLC) and 227 control subjects matched in age and smoking history were recruited. Student's t test showed that the levels of circulating IgG to ANXA1-derived peptide antigens were significantly higher in patients with NSCLC than control subjects (t = 5.66, P < 0.0001), in which the increased anti-ANXA1 IgG levels were observed only in patients at stages I, II, or III, but not in those at stage IV. However, the levels of circulating IgG to DDX53-derived peptide antigens were not significantly altered in NSCLC (t = 1.78, P = 0.076). Receiver operating characteristic analysis showed that the sensitivity against specificity of >90% was 23.7% for ANXA1 IgG assay and 13.8% for DDX53 IgG assay. This work suggests that the linear peptide antigen derived from ANXA1 may be suitable for the development of diagnostic tool for lung cancer although further screening is needed to identify more such peptide antigens derived from tumor-associated antigens.