PDCD1 and neoplasm: Furthermore, editing of immune checkpoint regulators, including CISH (cytokine-inducible SH2-containing protein), PD1 (programmed cell death protein 1), TIGIT (T cell immunoreceptor with Ig and ITIM domains), and A2AR (adenosine A2A receptor), has been shown to restore anti-tumor activity and improve in vivo persistence (33–37).