Prostate cancer is the second most commonly diagnosed cancer and the fourth leading cause of cancer-related death in men in the developed countries worldwide. Various prostate-associated antigens (PAA), such as prostate-specific antigen (PSA), prostate-specific membrane antigen (PSMA), and prostate stem cell antigen (PSCA) have been shown to be overexpressed by prostate cancer cells as compared to normal counterparts. These antigens, therefore, represent possible targets for inducing specific immune responses against cancers expressing the antigens via the use of vaccine- based immunotherapy. The present disclosure provides (a) vectors comprising a multi-antigen construct encoding two, three, or more immunogenic PAA polypeptides； (b) compositions comprising the vectors, (c) methods relating to uses of the vectors and compositions for eliciting an immune response or for treating prostate cancers. In particular, the present invention provides a C68 vector comprising: (a) a C68 nucleotide sequence； and (b) a multi-antigen construct that comprises at least one nucleotide sequence encoding an immunogenic prostate-specific antigen (PSA) polypeptide, at least one nucleotide sequence encoding an immunogenic prostate-stem cell antigen (PSCA) polypeptide, and at least one nucleotide sequence encoding an immunogenic prostate-specific membrane antigen (PSMA) polypeptide, wherein the immunogenic PSA polypeptide is cytosolic PSA set out in SEQ ID NO:17.
