Resumen
Immunotherapy with checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis or Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) has shown only modest activity in neuroendocrine tumors (NET) and neuroendocrine carcinomas (NEC). By investigating the tumor immune microenvironment in NET/NEC with immunohistochemistry (IHC) and mRNA immunoprofiling, we found that they lack signs of an activation of an antitumor immune response like intratumoral T cell infiltration and expression of IFN? regulated genes. But NET and NEC expressed several immunosuppressive genes. This included chemokines, known to attract immunosuppressive myeloid cells but not antitumor effector cells, or genes with immunosuppressive functions. Some of those might be expressed by both tumor cells and immune cells, such as CD74, and represent potential therapeutic targets for immunomodulation.