Cancer immunotherapy mobilizes the body's own sophisticated defenses to target and kill cancer cells. Despite its enormous promise, immunotherapy is only effective in a subset of cancers in a small group of patients. Dr. Han is investigating the role of the immune system's T cells in human colorectal cancer, which has limited treatment success with immunotherapy. He is using unique tools to improve our fundamental understanding of tumor immunity and to directly test a new therapeutic approach based on his hypothesis that our bodies produce T cells capable of specifically targeting a patient's tumors. His proposed research explores a strategy to identify these T cells and use genetic engineering to enable them to realize their full potential. He anticipates his findings will be applicable to other types of cancers as well.