EC359 enhances trametinib efficacy in Ras/Raf-driven ovarian cancer by suppressing LIFR signaling

Ovarian cancer (OCa) remains the most lethal gynecologic malignancy in the United States, with low-grade serous and mucinous subtypes frequently driven by KRAS mu-tations. These mutations activate downstream MAPK and PI3K/AKT signaling path-ways, contributing to tumor progression and resistance to therapy. Although the MEK inhibitor trametinib is used to target these pathways, its efficacy is limited in KRAS-mutant OCa due to compensatory activation of the leukemia inhibitory factor (LIF)/LIF receptor (LIFR) axis. In this study, we evaluated the therapeutic potential of combining trametinib with EC359, a selective LIFR inhibitor, in Ras/Raf-driven OCa models. EC359 significantly reduced cell viability, clonogenic survival, and induced cell death via ferroptosis in vitro. Mechanistic studies revealed that EC359 suppressed trametinib-induced activation of LIFR downstream signaling. RNA-seq analysis showed that combination therapy downregulated mitochondrial translation and MYC target genes while upregulating apoptosis-related genes. In vivo, EC359 and trametinib co-treatment significantly reduced tumor growth in Ras- and Raf-mutant xenograft models without inducing toxicity. These findings demonstrate that LIFR signaling is a critical driver in Ras/Raf-mutant OCa and that dual inhibition of the MEK and LIFR pathways offers a promising strategy to enhance therapeutic efficacy and overcome resistance in KRAS-mutant OCa. Overall design: RNA-seq profiling of OVCAR8 cells treated with vehicle, EC359 (150 nM), trametinib (100 nM), or the combination of both agents for 7 hours. Three replicates for each condition were performed.