The Pharmacology of CAR T Cell Therapy for Autoimmune Disease

For decades, autoimmune disease treatment depended on long-term immunosuppression, which seldom yields lasting immune tolerance and carries cumulative toxic risks. Recent cell therapies, including chimeric antigen receptor (CAR) T cells, regulatory T cells, and mesenchymal stromal cells, have induced deep remission in refractory diseases, often persisting after treatment withdrawal and indicating benefits beyond short-term inflammation suppression. However, traditional dose-exposure-response pharmacokinetic/pharmacodynamic frameworks are insufficient to account for the in vivo expansion, trafficking, and phenotypic evolution of living cellular products. Here we propose that, in autoimmune diseases, cell-based therapies exemplified by CAR T cells should be reframed from exposure-control pharmacology to state-transition pharmacology. Through endogenous expansion and immune networks, therapeutic cells may shift the immune system from a pathological toward a tolerant steady state. Because toxicities may reflect the amplification or persistence of intended mechanisms, future work requires quantitative metrics of immune state transitions and programmable strategies for precise functional control.