[A vaccine containing a clustered pancarcinoma carbohydrate antigen conjugated with keyhole limpet hemocyanin (KLH) with potential antineoplastic activity. Alpha-N-acetylgalactosamine (Tn) is a monosaccharide usually O-linked to serine or threonine residues of mucins found on most epithelial cancers with the highest expression on prostate cancer. This vaccine contains the Tn epitope cluster (c) that is synthesized by linking 3 copies of the Tn epitope on a threonine backbone to achieve the essential immunogenic structure. KLH is a hapten carrier and serves as an immunostimulant to improve immune recognition.Vaccination with Tn(c)-KLH vaccine may produce antibodies and elicit a cytotoxic T lymphocyte (CTL) response against those tumor cells expressing Tn antigen, resulting in decreased tumor growth. ( NCI )]