In this elegant study, the capacity of CAR-T cells to kill eosinophils was similar to that of benralizumab, but at the same time, these CAR-T cells were designed to continuously secrete an IL-4 mutein that binds to IL-4Rα, the receptor for IL-4 and IL-13, and, as such, behaves like dupilumab, a blocking anti-IL-4Ra antibody used in asthma. The gene discussed is IL4R; the disease is asthma.