Chimeric antigen receptor T-cell therapy, or CAR T, is a relatively new type of therapy approved to treat several types of aggressive B cell leukemias and lymphomas. Many patients have strong responses to CAR T; however, some have only a short response and develop disease progression quickly. Unfortunately, it is not completely understood why these patients have progression. In an article published in Proceedings of the Royal Society B, Moffitt Cancer Center researchers use mathematical modeling to help explain why CAR T cells work in some patients and not in others.