TNF-α Blockade Improves Immunotherapy Efficacy by Altering the Tumor Microenvironment and Enhancing Tumor-Specific T Cell Function in Pancreatic Ductal Adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDA) is a particularly lethal malignancy with a 5-year survival rate of 9%. A recent phase 1 clinical trial suggests CD40 agonist has antitumor activity in some patients. We developed an orthotopic PDA mouse model to track tumor specific CD8 T cells, identify critical antitumor mechanisms, and determine pathways of immunotherapy resistance. Here, we exploit this model to uncover a novel combination immunotherapy that includes CD40 agonist, PD-L1 blockade and TNF-α neutralization (e.g., 4PT). Interfering with TNF-α significantly improves overall mouse survival and cure rate compared to CD40+PDL1 only (4P). Critically, 4PT enhanced the generation of tumor-specific long-lived effector and central memory T cells. TNF-α neutralization significantly reduced T cell exhaustion, as indicated by reduced Lag-3 and increased IFN-γ production by intratumoral tetramer+ CD8 T cells. Additionally, 4PT increased CD4+Foxp3− T cell frequency and decreased CD4+Foxp3+ T cells as compared to 4P-treated mice, consistent with enhanced antitumor CD4 T cell reactivity in the absence of chronic TNF-α signaling. Lastly, abrogating Tnfr1 significantly reduced splenic and intratumoral Ly6G+ granulocytes following 4P. Thus, disrupting TNF-α via genetic deletion or monoclonal antibodies alters the tumor microenvironment to promote highly functional tumor-specific CD8 T cells. We conclude that perturbation of TNF-α-mediated chronic inflammation is an appealing approach to enhance immunotherapy efficacy for pancreatic cancer patient treatment. Supported by NIH 1R01CA249393-01A1