Engineered immune cells, known as CAR T cells, have shown the world what personalized immunotherapies can do to fight blood cancers. Now, investigators have reported highly promising early results for CAR T therapy in a small set of patients with the autoimmune disease lupus. Penn Medicine CAR T pioneer Carl June, MD, and Daniel Baker, a doctoral student in Cell and Molecular Biology in the Perelman School of Medicine at the University of Pennsylvania, discuss this development in a commentary published today in Cell.