For the 12 breast cancer patients who were given monthly PANVAC vaccinations, a poxviral vaccine containing transgenes for MUC-1, CEA, and 3 T-cell costimulatory molecules, the side effects were some mild injection-site reactions, and 33% patients showed stable disease (SD) and 8% had a complete response (CR). The gene discussed is MUC1; the disease is breast cancer.