Abstract: This invention concerns an antibody which binds with high affinity to human single-chain intact, i.e. not internally cleaved, mature and/or zymogen forms of prostate specific antigen (SCINT PSA). The antibody does not bind to a nicked PSA (PSA-N), wherein said PSA-N has been formed by internal peptide bond cleavage(s) of SCINT PSA resulting in two-chain or multi-chain PSA. This invention further concerns an immunoassay and a method for differentiating patients with cancer of the prostate (PCa) from patients with benign prostatic hyperplasia (BPH) and/or healthy male subjects without PCa, patients with aggressive PCa from patients with indolent PCa and/or patients with clinically localized and/or organ confined PCa from patients with extraprostatic extension of PCa and/or PCa with metastatic spread to lymph nodes or bone marrow using said antibody.

Abstract: This invention concerns an antibody wherein said antibody does bind with high affinity to human single-chain intact, i.e. not internally cleaved, mature and/or zymogen forms of prostate specific antigen (SCINT PSA). The antibody, obtainable through immunization with an uncleaved form of PSA and selected by its differential reactivity with the intact and internally cleaved forms, does not bind to a nicked PSA (PSA-N), wherein said PSA-N has been formed by internal peptide bond cleavage(s) of SCINT PSA resulting in two-chain or multi-chain PSA.