SOX2 autoantibodies as noninvasive serum biomarker for breast carcinoma.

BACKGROUND A clear association has been established between antibodies to the transcription factor sex-determining region Y (SRY)-box 2 (SOX2) and small cell lung cancer. In light of the pathologic role of SOX2 and its aberrant expression in breast cancer, we measured serum SOX2 autoantibodies (SOX2-Abs) in breast cancer patients. METHODS The presence of SOX2-Abs was determined by an indirect enzyme-linked immunosorbent assay (ELISA) in sera from 282 patients with breast cancer, 78 patients with benign breast disease, and 194 healthy women. RESULTS SOX2-Abs were more prevalent in patients with breast cancer (18.4%) compared with healthy women (2.6%, P < 0.0001), and patients with benign breast disease (6.4%, P = 0.011). The concentrations of circulating SOX2-Abs were found to discriminate between breast cancer patients and healthy controls (P < 0.001) and between breast cancer patients and those with benign breast disease (P < 0.001). In addition, measurement of SOX2-Abs was more effective than assays of serum tissue polypeptide-specific antigen, carcinoembryonic antigen, carbohydrate antigen (CA) 125, and CA 15-3 in distinguishing between malignant and benign breast disease. In breast cancer patients, the prevalence of SOX2-Abs was associated with a higher tumor grade (P = 0.021) and positive nodal status (P = 0.021). CONCLUSION The presence of SOX2-Abs in breast cancer may be of clinical value. IMPACT This study provides the first evidence for the presence of circulating SOX2-Abs in breast cancer and shows their potential clinical application.