Prostate cancer biomarker annexin A3 detected in urines obtained following digital rectal examination presents antigenic variability

Annexin A3 (ANXA3) is a potential marker for prostate cancer (PCa). We aimed to develop robust immunoassays suitable for quantifying ANXA3 in urine samples obtained following digital rectal examination (DRE) in order to facilitate the diagnostic performance evaluation of this marker. Anti-ANXA3 monoclonal antibodies were generated and their epitopes mapped. Two different ANXA3 assay prototypes were established on the VIDAS® automated immunoanalyser and analytical validation was carried out using post-DRE urine samples obtained from patients with PCa (n=23) or benign prostate hyperplasia (n=31). The assays had the same capture antibody (TGC44) but different detection antibodies (13A12 or 5C5), recognizing novel distinct epitopes. Both had a lower limit of quantification