Sadelain and his team study gene transfer in hematopoietic stem cells and T cells, the regulation of transgene expression, the biology of chimeric antigen receptors, and therapeutic strategies to enhance immunity against cancer. Sadelain is a recognized leader in the conceptualization and design of synthetic receptors for antigen, which he named chimeric antigen receptors (CARs). T cells can be engineered to express a CAR to acquire the ability to recognize and destroy cancer cells. Sadelain has referred to CAR T cells as a “living drug.” A CAR typically comprises an antibody fragment (scFv) to recognize the cancer and a modular signaling domain to activate the T cell and promote T cell multiplication and persistence. CAR T cells are made by extracting a cancer patient’s T cells, inserting a CAR into the cell using a vector such as a gamma-retroviral or lentiviral vector, and then re-infusing the cells. Sadelain's current research makes use of genome editing, which he showed enhances CAR T cells when the CAR is expressed from the TRAC locus.