GADD45β Loss Ablates Innate Immunosuppression in Cancer.

Abstract

T-cell exclusion from the tumor microenvironment (TME) is a major barrier to overcoming immune escape. Here, we identify a myeloid-intrinsic mechanism governed by the NF-κB effector molecule GADD45β that restricts tumor-associated inflammation and T-cell trafficking into tumors. In various models of solid cancers refractory to immunotherapies, including hepatocellular carcinoma and ovarian adenocarcinoma, <i>Gadd45b</i> inhibition in myeloid cells restored activation of proinflammatory tumor-associated macrophages (TAM) and intratumoral immune infiltration, thereby diminishing oncogenesis. Our results provide a basis to interpret clinical evidence that elevated expression of <i>GADD45B</i> confers poor clinical outcomes in most human cancers. Furthermore, they suggest a therapeutic target in GADD45β for reprogramming TAM to overcome immunosuppression and T-cell exclusion from the TME.<b>Significance:</b> These findings define a myeloid-based immune checkpoint that restricts T-cell trafficking into tumors, with potentially important therapeutic implications to generally improve the efficacy of cancer immunotherapy. <i>Cancer Res; 78(5); 1275-92. ©2017 AACR</i>.