BCG Vaccine and Its Derivatives: Potential, Practical Considerations, and Precautions in Human Cancer Immunotherapy

BCG vaccine is undergoing extensive clinical trials for cancer immunotherapy. These studies are based on its immunopotentiating and macrophage-activating properties. Efficacy of BCG vaccine probably depends on strain, proportion of viable organisms, absence of free soluble antigens, dose, route, and schedule of administration. BCG vaccine is most efficacious when administered in conjunction with or following intensive cytoreductive maneuvers such as surgery, radiotherapy, or chemotherapy. BCG vaccine has shown beneficial activity in acute myelogenous leukemia, malignant melanoma, colon cancer, lymphoma, head and neck cancer, and other tumors. Since BCG vaccine has toxic side effects, and since less than optimal preparations can be detrimental in terms of tumor control, progress in the development of BCG vaccine immunotherapy must be based on sound clinical trials, careful clinical and immunological evaluation of treated subjects, and continuing research on basic and applied aspects of its immunological and other biological activities.