Chimeric antigen receptor (CAR) T-cell therapy has been a game changer in the treatment of B-cell malignancies, although their manufacturing process is complex and needs lymphodepletion, thus limiting their use. Researchers from Capstan Therapeutics Inc. have recently published data regarding an in vivo engineering approach to generate CAR T cells using targeted lipid nanoparticles (LNPs) for mRNA delivery to specific T-cell populations for the treatment of cancer and B-cell-mediated autoimmune diseases.