A cancer vaccine, containing epitopes of the gangliosides GD2 and GD3 conjugated with the immunostimulant keyhole limpet hemocyanin (KLH), with potential antineoplastic activity. Vaccination with GD2 lactone/GD3 lactone-KLH conjugate bivalent vaccine may elicit antibodies against tumor cells expressing either epitope, resulting in complement-mediated cytotoxicity (CMC) and antibody-dependent cell-mediated cytotoxicity (ADCC). Located primarily in the nervous system, gangliosides, such as GD2 and GD3, are cell membrane components involved in cellular recognition and cell-cell communication.