CD3E and cancer: Thus, the two top targets, CD19 and CD3E, are responsible for the engineered retargeting of T cells, either as CAR-T cells (Ruella and Gill, 2015; Ruella and June, 2016; Smith et al., 2016) or T-cell redirecting bispecific antibodies (Lum and Thakur, 2011; Satta et al., 2013; Suzuki et al., 2015), to kill cancer cells.