The invention relates to methods and compositions for causing the selective targeting and killing of tumor cells. Through a combination of ex vivo gene therapy protocols and cell enchment, tumor cells are engineered to express an &alpha； (1,3)galactosyl epitope and optionally the tumor associated antigens mesothelin and carcinoembryonic antigen. After administration of the compositions of the invention to patients, the production of increased antibody titers to certain cell-surface markers, including mesothelin, calreticulin, and carcinembryonic antigen (CEA) positively correlates with an increased overall survival.
