Generic structure of a chimeric antigen receptor (CAR). These fusion receptors comprise a targeting moiety (in this example, an antibody-derived single chain antibody (scFv)), coupled via a hinge and transmembrane element to a bespoke modular signalling domain. This example shows a “third generation” CAR in which signalling is provided by CD3ζ together with costimulation provided by CD28 and a tumour necrosis factor receptor (TNFr), such as 4-1BB or OX40.