The present invention provides a cell which co-expresses a first chimeric antigen receptor (CAR) and second CAR at the cell surface, each CAR comprising: (i) an antigen-binding domain； (ii) a spacer (iii) a trans-membrane domain； and (iv) an endodomain wherein the antigen binding domains of the first and second CARs bind to different antigens, and wherein one of the first or second CARs is an activating CAR comprising an activating endodomain and the other CAR is an inhibitory CAR comprising a ligation-off inhibitory endodomain.
