Indeed, the supra-carcinoids also presented levels of immune checkpoint receptors and ligands (including PDL1 and CTLA4) similar—or higher—than those of LCNEC and SCLC, as well as upregulation of other immunosuppressive genes such as HLA-G, and interferon gamma that is speculated to promote cancer immune-evasion in immunosuppressive environments42,43. Here, CTLA4 is linked to carcinoid tumor.