Chimeric antigen receptor (CAR) T-cell therapy has revolutionized oncology through engineered targeting of molecules on previously untreatable cancers. However, less than half of patients on CAR T-cell therapy experience long-term disease control, and CAR T cells have not mediated sustained responses in solid tumors. Elucidating T-cell phenotype-function relationships is critical to informing future CAR T-cell therapy design and cancer treatment. Toward that end, my research integrates immunology, cellular engineering, and computational biology to characterize senescence in the context of CAR T cells, both in vitro and in patients treated with CAR T cells. Specifically, I aim to identify senescent markers correlated with CAR T-cell manufacturing, patient characteristics, and CAR T-cell treatment response, providing mechanistic insights for the development of increasingly effective cell therapies for the treatment of cancer.