Chitosan–PEG Nanoparticles for Co-Delivery of Paclitaxel and KRAS G12D-Directed siRNA to Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies due to limited responsiveness to chemotherapy and the high prevalence of oncogenic Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. Co-delivery of cytotoxic agents and small interfering RNA (siRNA) is a potential combination strategy, but the two cargos have distinct physicochemical and intracellular-delivery requirements. Here, we developed a chitosan–polyethylene glycol (CP)-based polymeric nanoparticle platform for the cotreatment of paclitaxel (PTX) and small interfering RNA (siRNA) targeting KRAS G12D mutation. PTX was first modified to PTX-COOH through an ester-containing succinate linker and then covalently conjugated to the polymer backbone through amide bond formation, enabling stable nanoparticle formation and subsequent electrostatic complexation with siRNA. The CP-PTX-siRNA nanoparticles demonstrated efficient cellular uptake, while luciferase knockdown by CP-siRNA supported functional siRNA delivery by the CP carrier. In KRAS G12D–mutant pancreatic cancer cells, PTX- and KRAS-targeting siRNA-coloaded nanoparticles resulted in enhanced cytotoxicity compared to single-agent treatments and free drug combinations, with combination index values below 1 indicating calculated synergy under the tested in vitro conditions. Because KRAS knockdown and a non-targeting siRNA control were not assessed in PANC-1 cells, the enhanced cytotoxicity cannot be attributed specifically to KRAS silencing. Across multiple drug-to-siRNA ratios, nanoparticle formulations consistently improved treatment potency. Together, these results support CP-PTX-siRNA nanoparticles as a modular and biocompatible platform for combined PTX/siRNA delivery. This approach provides a versatile strategy for combining chemotherapeutic agents with RNA-based therapeutics in PDAC, supporting further development of these polymeric nanocarriers for combination cancer therapy.