CD19 and congenital rubella syndrome: In the severe combined immunodeficiency (SCID)-beige mouse model, Sterner et al. found that GM-CSF inhibition not only reduced CRS severity but also enhanced CAR-T-cell functions in xenografts.24 Furthermore, compared with CD19 CAR-T cells, GM-CSF-deficient CD19 CAR-T cells maintained normal functions and enhanced antitumor activity and improved overall survival.