ERO1A drives immunosuppression and attenuates response to immune checkpoint blockade

Immunophenotyping of tumor microenvironment (TME) is crucial for immunotherapy efficacy in patients with solid tumours. However, strategies to characterize TME are largely limited with huge heterogeneity. We show that endoplasmic reticular oxidoreductase-1α (ERO1A) induces an immune-suppressive TME and resistance to PD-1 blockade by promoting endoplasmic reticulum (ER) stress response. Single-cell RNA sequencing analyses confirm that ERO1A is correlated with immunosuppression and dysfunction of CD8+ T cell along anti-PD-1 treatment. Ablation of Ero1a in tumours promotes the infiltration of lymphocytes as well as cytotoxicity of CD8+ T cells and enhances response to anti-PD-1 treatment in mouse models. To dissect the cellular and molecular changes of the TME during immunotherapy, we performed scRNA-seq analyses of tumours from wild type mice (n=5) and Ero1a KO mice (n=5).