Innovations in chimeric antigen receptor T cell (CAR T) therapies demonstrate expanding applications beyond oncology. The first allogeneic CD19-directed CAR T-cell treatment was administered to a multiple sclerosis (MS) patient, marking a pioneering approach to progressive neurodegeneration. Separate advances report promising in vivo CAR T cell production strategies poised to streamline manufacturing and broaden accessibility. These developments could transform therapeutic options for autoimmune diseases and difficult-to-treat cancers, addressing critical unmet medical needs.