There has been much recent excitement about immunotherapy and the use of genetically engineered chimeric antigen receptor (CAR) T cells. Historically, CAR T cell immunotherapy has aimed to boost the immune system by giving immune cells the information they need to better recognize tumor cells as foreign and attack them. New work led by Hans-Guido Wendel, MD, of Memorial Sloan Kettering Cancer Center (MSK), and collaborator Karin Tarte of the University of Rennes, France, illustrates an untapped potential of CAR T cells to act as targeted delivery vehicles that can function as “micro-pharmacies” for precise therapeutic delivery.