Abstract 6667: Dual inhibition of PIKfyve and KRAS/MAPK targets metabolic vulnerabilities of pancreatic ductal adenocarcinoma

Abstract Background: Pancreatic Ductal Adenocarcinoma (PDAC) exists within a harsh, nutrient-depleted microenvironment, and is known to use lysosomal processes, such as autophagy, for maintenance of metabolic function. PIKfyve is a lipid kinase that serves as the single source for PI(3, 5)P2, a molecule critical for the process of autophagy. Considering the role of PIKfyve in autophagy, we hypothesized it to be crucial for PDAC pathophysiology. Methods & Results: To evaluate the significance of PIKfyve in PDAC, we employed RNA-ISH and found that PIKfyve was significantly higher expressed in PDAC tissue compared to normal surrounding cells. Performing viability screens across multiple PDAC cell lines, we observed that they were highly sensitive to PIKfyve inhibitors apilimod and ESK981. This data suggested that PIKfyve is crucial for PDAC development. We then performed a metabolism-focused CRISPR screen with the selective pressure of PIKfyve inhibition to assess the metabolic role of PIKfyve in PDAC. From this, we identifiedthe function of the de novo fatty acid synthesis pathway as necessary for PDAC survival following PIKfyve perturbation. In addition to this pathway being essential upon PIKfyve inhibition, we also noticed dramatic upregulation of fatty acid synthesis genes FASN and ACACA following the activation of SREBP1, a transcriptional regulator of lipogenesis. To determine if this shift translated to a metabolic phenotype, we performed targeted lipidomics and observed a significant increase in sphingolipids. KRAS, mutated in the majority of PDAC cases, is known to be a major driver of metabolic homeostasis through MAPK signaling. De novo fatty acid synthesis is one such pathway controlled by KRAS signaling; we noticed decreased expression of FASN and ACACA along with sphingolipids following KRAS/MAPK inhibition. Specifically, KRAS/MAPK inhibition attenuated the increase in FASN and ACACA as well as lipidomic reprogramming seen with PIKfyve inhibition. We investigated the in vivo potential of this combination using a syngeneic orthotopic model of PDAC. Notably, all but one mouse were cured when treated with both ESK981 and MEK inhibitor trametinib. Then employing a KPC model, we observed that mice treated with both ESK981 and MEK inhibitor selumetinib had an increased median survival time by over 5 times. Taken together, the concurrent targeting of PIKfyve and KRAS-MAPK disrupts lipid homeostasis and has potent antitumor effects, holding promise as a therapeutic treatment strategy. Citation Format: Jasmine P. Wisniewski, Caleb Cheng, Sydney Peters, Rüya Pakkan, Pietro Morlacchi, Jennifer P. Morton, Yuanyuan Qiao, Costas A. Lyssiotis, Arul M. Chinnaiyan. Dual inhibition of PIKfyve and KRAS/MAPK targets metabolic vulnerabilities of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6667.