A peptide-based cancer vaccine, consisting of amino acid residues 29 through 37 of T cell receptor gamma alternate reading frame protein (TARP) with a leucine-to-valine substitution at position 9, with potential immunostimulatory and antineoplastic activities. Upon administration, TARP 29-37-9V peptide vaccine may induce a cytotoxic T-lymphocyte (CTL) response against TARP-expressing tumor cells, which may result in decreased tumor cell proliferation. The leucine-to-valine substitution at position 9 of this peptide improves its immunogenicity. The nuclear protein TARP is commonly expressed on prostate and breast cancer cells and is highly immunogenic.