The invention relates to a method for enhancing an endogenous immune response-mediated elimination of a population of cancer cells in a host. The method comprises the steps of administering to the host a composition comprising an immunogen conjugated to a vitamin receptor-binding ligand selected from the group consisting of a vitamin, or an analog or a derivative thereof, and administering to the host a therapeutically effective amount of radiation wherein the amount of radiation can range from about 0.5 to about 10 Gy per dose.