Breaking barriers for T cells by targeting the EPHA2/ TGF-[beta]/COX-2 axis in pancreatic cancer

EPHA2 expression defines T cell exclusion Although antibodies that block immune checkpoints have revolutionized the management of some tumors with tumor-infiltrating lymphocytes (TILs), most cancer patients still fail to respond [...]
Pancreatic ductal adenocarcinoma is projected to become the second-leading cause of cancer-related death and is largely resistant to immunotherapies. The tumor microenvironment, largely composed of heterogeneous myeloid cells, creates a physical, metabolic, and immunosuppressive barrier that prevents T cells from infiltrating cancer beds. In this issue of the JCI, Markosyan and colleagues have reported a tumor-intrinsic mechanism that excludes T cells from the vicinity of tumor cells. They showed that a receptor tyrosine kinase, ephrin-A receptor 2 (EPHA2), regulates prostaglandin endoperoxide synthase 2 (PTGS2) (encodes COX-2) expression in a TGF-[beta] signaling-dependent manner. Genetic ablation of Epha2 or Ptgs2 in preclinical models or pharmacological inhibition of COX-2 elicited the transformation of this immunosuppressive microenvironment into a T cell-permissive milieu. Consequent T cell relocation rendered this immunoresistant malignancy responsive to combinations of checkpoint blockers and CD40 agonists. Because the association between T cell infiltration and the EPHA2/TGF-[beta]/COX-2 axis is supported by independent clinical data, these results provide a rationale for ensuing clinical trials aimed at incorporating pancreatic cancer into the range of immunotherapy- responsive tumors.