NY-ESO-1 protein expression and humoral immune responses in prostate cancer

BACKGROUND. Due to restricted expression in normal tissues cancer/testis (C/T) antigens represent candidate molecules for immunotherapy of cancer. NY-ESO-1 is a well-studied C/T antigen with unknown expression and immunogenicity in prostate cancer (PC) patients. METHODS. NY-ESO-1 expression was determined by immunohistochemistry and humoral immune responses against NY-ESO-1 assessed by enzyme-linked immuno-sorbent assay (ELISA) and Western blotting. Protein expression and serological responses were correlated with clinical findings and survival. RESULTS. NY-ESO-1 expression was found in biopsies from 2 of 66 localized PC and 7/48 hormone refractory prostate cancer (HRPC) patients, respectively. Anti-NY-ESO-1 antibodies were detected in sera from 1 of 112 localized PC and 18 of 95 HRPC patients. Two of four HRPC patients with NY-ESO-1 positive biopsies had mounted a serological response. Positive anti-NY-ESO-1 titers were correlated with poor survival in HRPC patients. CONCLUSIONS. NY-ESO-1 is expressed in a subset of HRPC patients and, together with other C/T antigens, may serve as a target antigen for development of immunotherapy of PC. Spontaneous serological responses against NY-ESO-1 may be associated with poor survival. (C) 2004 Wiley-Liss, Inc.