Abstract B074: Comparative analysis of next-generation KRAS inhibitors in patient derived pancreatic cancer organoids

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a five-year survival rate below 10%. Due to aggressiveness and lack of early detection methods, patients are often diagnosed at an advanced stage, leaving few therapeutic options. This emphasizes the need for a deeper understanding of the molecular landscape of PDAC and for developing novel therapeutic approaches. One of the key mutations that drives tumor growth and survival is found in the KRAS gene, which is mutated in over 90% of PDAC cases. While the KRAS p.G12C mutation is rare in PDAC, it represents a targetable alteration. The inhibitors Sotorasib and Adagrasib are approved for treatment of KRAS p.G12C-mutant non-small cell lung cancer (NSCLC). Early clinical trials show that monotherapy initially benefits PDAC patients, however, most eventually progress due to resistance mechanisms. Combination therapies are considered to overcome resistance and are thus valuable therapeutic approaches. In this study, we screen five KRAS inhibitors in six KRAS-mutant PDAC patient derived tumor organoids (PDTOs) to identify potential targets for combination therapy. Out of those six PDTOs, four harbored KRAS p.G12C mutations, one carried a KRAS p.G12D mutation, and one was KRAS wild type with a BRAF alteration. The tested inhibitors included the approved KRAS p.G12C OFF inhibitor Sotorasib, the second generation KRAS p.G12C OFF inhibitors Divarasib (GDC-6036) (phase III) and D3S-001 (phase II), the KRAS p.G12C ON inhibitor Elironrasib (RMC-6291) (phase II), and the tricomplex pan-RAS ON inhibitor Daraxonrasib (RMC-6236). Whole-exome sequencing confirmed the presence of the KRAS p.G12C mutation and enabled characterization of the mutational landscape. We comparatively assessed dose–response profiles after 72 h of treatment and defined a therapeutic window in which KRAS p.G12C PDTOs show a clear pharmacologic response at minimal drug toxicity. Consistent with effective target engagement, preliminary Western blot analyses demonstrated that treatment with concentrations within this range leads to a rapid pathway inhibition, evidenced by loss of pERK signaling. Using bulk RNA-sequencing, we characterized the transcriptomic changes induced by these inhibitors. Beyond confirmed on-target pathway inhibition (KRAS, PI3K, mTOR), treated organoids showed reduced metabolic signaling, a shift toward a more epithelial, ciliated phenotype and a pronounced interferon/antigen-presentation signature. This apparent gain in immunogenicity points to immune-based combination strategies as a promising direction for future work.