CD28 and neoplasm: For example, mutating specific sites in the CD28 domain can benefit the safety and persistence of CAR‐T cells.[38] CD3ζ truncated signaling containing only one immunoreceptor tyrosine activation motif showed better anti‐tumor effect and persistence in animal models.[39] Further, modifying the hinge and transmembrane regions can affect the signal transmission and regulate cytokine secretion of CAR‐T cells.[40]