Abstract 6692: Intermittent fasting-remodeled gut microbiota improves anti-tumor immunity in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) has become the third leading cause of cancer-related death in the United States with high resistance to therapies, presentation at late stages and aggressive biology. Immunotherapy has revolutionized cancer therapy by offering survival benefit in many solid malignancies, however, it is still not effective in pancreatic cancer. Host factors are crucial modulators of responses to immunotherapy. The roles of gut microbiome in modulating the immune system and determining cancer outcomes have been well established. Eating patterns can alter the gut microbiota and metabolic output, both of which affect anti-tumor immune responses. Intermittent fasting (IF), a form of dietary restriction which is characterized by limited feeding with unlimited calorie consumption during a certain time window. IF has been shown to affect gut microbiota composition, modulate immunity, and metabolic processes. Despite the well-known beneficial role of fasting in pancreatic conditions, including pancreatitis and diabetes, its effect in the treatment of pancreatic cancer has not been explored. Our study found that IF reverses immunotherapy resistance in PDAC. IF can reshape gut microbiota composition and reprogram the metabolism of host. We found that IF improves anti-tumor immunity through modulating gut microbiota. Depletion of gut microbiota can abrogate the beneficial effect of IF on anti-tumor response, while fecal microbiota transplantation from mice exposed to IF can sensitize the anti-tumor effects of immunotherapy. Using 16S rRNA sequencing, metabolic profiling and transcriptomic sequencing, our findings elucidate the mechanism of IF-remodeled gut bacteria influencing metabolic molecules which drive immune cells activation. Our study suggests that IF-based interventions have potential utility for the prevention and treatment of PDAC. Citation Format: Le Li, Vidhi Chandra, Olivereen Le Roux, Rian Morgan Howell, Virginia Tahan, Nagireddy Putluri, Joseph Petrosino, Arun Sreekumar, Jay K. Kolls, James White, Florencia McAllister. Intermittent fasting-remodeled gut microbiota improves anti-tumor immunity in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6692.