Ch14.18/CHO is a monoclonal antibody. Monoclonal antibodies are made in the laboratory and are designed to bind to specific cancer cells. Ch14.18/CHO was designed to bind to neuroblastoma cells and other cancer cells that express the GD-2 antigen. The GD-2 antigen is expressed by virtually all neuroblastoma cells. An antigen is a substance that stimulates an immune response in the body by producing antibodies. Thus, when ch14.18/CHO binds to the neuroblastoma cells, the body's immune system is stimulated to attack and kill the neuroblastoma cells. Ch14.18/CHO is called chimeric, because it was genetically engineered to consist of 30% mouse-protein and of 70% human protein.