Long-term follow-up of HLA-A2+ patients with high-risk, hormone-sensitive prostate cancer vaccinated with the prostate specific antigen peptide homologue, PSA146-154

Twenty eight HLA-A2+ patients with high-risk, locally advanced or metastatic, hormone-sensitive prostate cancer were immunized with a peptide homologue of prostate specific antigen, PSA146-154, between July 2002 to September 2004 and monitored for clinical and immune responses. Fifty percent of the patients developed strong PSA146-154-peptide specific delayed type hypersensitivity skin responses, tetramer and/or IFN-γ responses within one year. Thirteen patients had stable or declining serum levels of PSA one year post-vaccination. A decreased risk of biochemical progression was observed in patients who developed augmented tetramer responses at six months compared to pre-vaccination levels (p=0.02). Thirteen patients have died while 15 patients remain alive with a mean overall survival of 60 months (95% CI, 51 to 68 months) per Kaplan-Meier analysis. A trend towards greater overall survival was detected in men with high-risk, hormone-sensitive CaP who developed specific T-cell immunity following vaccination with PSA146-154 peptide.