A trivalent cancer vaccine containing the ganglioside lactones GM2, GD2 and GD3 conjugated with the immunostimulant keyhole limpet hemocyanin (KLH), with potential antineoplastic activity. Vaccination with GM2 lactone/GD2 lactone/GD3 lactone-KLH conjugate trivalent vaccine may elicit antibodies against tumor cells expressing any of these epitopes, resulting in an antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells expressing these gangliosides. GM2, GD2 and GD3 are tumor associated antigens (TAAs) that are overexpressed in a variety of tumor cell membranes.