This may be an advantage of A20-4G CAR T cells since clinical studies of the 4G CAR T cells targeting CD19 found that low levels of IFN-γ might be beneficial to limit CAR T cell-mediated cytokine release syndrome (CRS) (10, 15), which was often observed in patients who received CAR T cell therapy (48, 49). Here, CD19 is linked to congenital rubella syndrome.