BACKGROUND: Immune checkpoint blockers (ICBs) have revolutionized cancer therapy, yet they remain largely ineffective in treating pancreatic ductal adenocarcinoma (PDAC). Moreover, ICBs can cause severe immune-related adverse events (irAEs), including fatal cardiac toxicity. Finally, obesity is a risk factor in PDAC that may differentially modulate ICB efficacy in a malignancy-dependent manner. METHODS: We investigated the mechanisms underlying irAEs induced by dual ICB therapy and sought to identify strategies to mitigate them while improving ICB efficacy in the obese setting. To this end, we used a clinically relevant mouse model that integrated key features of human PDAC: (1) high-fat diet-induced obesity, (2) an orthotopic PDAC, and (3) a therapeutic regimen combining chemotherapy (FOLFIRINOX) with ICBs (α-programmed cell death protein-1 + α-cytotoxic T-lymphocyte associated protein-4 antibodies). RESULTS: Obese mice developed cardiac irAEs and had elevated serum interleukin (IL)-1β levels after chemoimmunotherapy. IL-1β blockade not only prevented myocarditis and reduced cardiac fibrosis but also enhanced the antitumor efficacy of the combination of chemotherapy plus dual ICB therapy and significantly improved the overall survival of PDAC-bearing obese mice. CONCLUSIONS: Our findings provide the rationale and compelling data to test a Food and Drug Administration-approved anti-IL-1β antibody in combination with chemotherapy and dual ICB therapy in patients with pancreatic cancer with obesity.