MUC1 and neoplasm: Previous attempts at vaccination strategies targeting up-regulated tumor antigens have been largely unsuccessful for many tumor types; however, a recent trial of MVA-5T4 encoding mucin 1 in advanced non–small cell lung cancer demonstrated improvement in progression-free survival (PFS). Such vaccines work by inducing the intracellular expression of their respective transgene, allowing the tumor antigen to be processed by major histocompatibility complex classes I and II pathways.