Chimeric antigen receptor (CAR) T cells are a type of immunotherapy that uses genetically engineered T cells from patients to treat cancer. While a one-time treatment has the potential to generate long-term protection from relapse, CAR T cells often fail due to poor persistence. Dr. Mi recently studied samples from patients with durable remissions of leukemia and found that rare persistent CAR T cells share a distinct set of molecular and cellular features. She will now define the properties of persistent CAR T cells across multiple blood cancers, trace their T cell origins and evolutionary dynamics using novel technologies, and experimentally evaluate her findings in preclinical models. These studies could illuminate how CAR T cells change over time in patients and help guide development of future cellular therapies with more durable effects for patients with different types of cancers.