Advancing therapeutic approaches for targeting KRAS in cancer treatment.

e16467 Background: PDAC is challenging to treat due to its dense stroma with 50% of cases driven by KRASG12D mutations. Recently discovered KRAS12D inhibitor, MRTX113 monotherapy in human trials faces resistance mechanisms that limits the clinical benefit due to immunosuppressive tumor microenvironment (TIME). This underscores the utmost need for combination strategies that target both KRASG12D and immune modulation, which is the central objective of this study. Therefore, this study determines the efficiency of combined inhibition of mutated KRAS G12D and Galectin-1 (Gal-1) inhibition to effectively suppress PDAC growth and progression. Methods: We have delivered KRAS G12D inhibiting siRNA (KRASsi-SP) using a superparamagnetic iron oxide nanoparticle (SPION) and used a galectin-1 inhibitor. Particles are investigated for size, physico-chemical characterization (Dynamic light scattering), hemocompatibility (hemolysis assay) and the complexation of siKRAS (gel retardation assay). Cellular internalization and uptake of the particles are investigated. I n vitro functional assays used include cell viability (MTT), migration (Boyden chambers), invasion (Matrigel), clonogenicity, Organoid formation, and in a KrasG12D;LSL-Trp53R172H syngeneic mouse model. Metagenomics using Illumina Miseq determined influence of treatment on microbial colonization. Results: Our study demonstrates that elevated Gal-1 expression correlates with PDAC progression and poor patient outcomes. Targeting Gal-1 effectively inhibits macrophage polarization and stromal activation, reduces monocytic myeloid-derived suppressor cells (M-MDSCs) and Treg recruitment, and enhances T cell infiltration in KRASG12D-driven pancreatic tumors using syngeneic ( Pdx1cre; LSL-KrasG12D; LSL-Trp53R172H ) mouse models. To address KRASG12D-driven PDAC, we developed an RNAi-based therapy formulated with our novel superparamagnetic iron oxide nanoparticle system (KRASsi-SP) for efficient systemic delivery. Preclinical data demonstrate that combining KRASsi-SP with a Gal-1 inhibitor significantly suppresses tumor growth and improves survival. This approach enhances CD8+ T cell infiltration, reduces MDSCs, and alters microbiota composition, identifying distinct probiotic and prebiotic species with potential immunomodulatory and antitumor effects. These findings support further investigation into Gal-1 inhibition and KRAS-targeted therapies as a strategy to enhance immunotherapy response in PDAC. Conclusions: The study introduces an innovative dual-target approach, combining KRASG12D RNAi therapy with Gal-1 blockade to simultaneously address both oncogenic signaling and immune suppression within the TIME. This combination has a potential to overcome the resistance mechanisms seen with KRASG12D-targeted monotherapies to target PDAC growth and improve patient survivability.