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. © 2004 Wiley‐Liss, Inc.