The abscopal effect of Combination IRE with anti-PD-1 achieves local ablation and systemic control of PDAC

Irreversible electroporation (IRE) has shown promise for treating pancreatic ductal adenocarcinoma (PDAC), but whether IRE can induce an abscopal effect is not established. We demonstrated that the combination of IRE and anti-PD-1 antibody could trigger robust abscopal effects in preclinical models of metastatic PDAC. Data from multiple in vivo models, RNA-seq, scRNA-seq, and spatial immunofluorescence provide compelling evidence that IRE induced mitochondrial dysfunction and cellular stress, which triggered activation of the cGAS-STING pathway and subsequent systemic antitumor effects. IRE also led to inflammatory response characterized by tumor infiltration of myeloid cells and their polarization toward M1 state, turning immunologically "cold" tumors into "hot" tumors. Moreover, the presence of T cell/B cell clusters in tumors from mice treated with IRE plus PD-1 and the lack of antitumor efficacy in B cell knockout mice bearing orthotopic murine PDAC tumors indicate that B cells play an important role in IRE-mediated systemic antitumor immunity. SignificanceThis study shows that IRE plus a checkpoint inhibitor represents a promising therapeutic strategy for PDAC and supports advancing this treatment toward clinical translation. Our data also support potential combination strategies with immunomodulatory agents that can recruit and reprogram B cells to support T cell activation and cytotoxic effector functions.