IL6R and congenital rubella syndrome: CAR T cells and T‐cell recruiting bsAbs are functionally closely related, and thus, it is not surprising that, besides efficacy, both reagent types share similar toxicity profiles: Despite their tumor‐targeting properties, they induce off‐tumor T‐cell activation, which frequently results in a cytokine release syndrome (CRS) (Maude et al, 2014; Frey & Porter, 2016) that may be successfully treated by steroids or, as approved very recently, the anti‐IL6R antibody tocilizumab (Le et al, 2018).