Abstract 358: EV-based delivery of chemically modified siRNA achieves MRTX1133-comparable efficacy in KRAS G12D-mutant pancreatic cancer.

Abstract Background: KRAS G12D-mutant pancreatic ductal adenocarcinoma (PDAC) remains largely incurable, with no clinically validated targeted therapies. RNA interference can selectively suppress mutant KRAS, yet current delivery technologies fail to achieve sustained, safe in vivo activity. We developed a shock wave-engineered extracellular vesicle (EV) platform (SWEET™) that enables efficient, stable encapsulation of KRAS G12D-targeting siRNA and overcomes key limitations of lipid nanoparticles (LNPs) and small-molecule inhibitors. Methods: We designed and screened a 105-member panel of chemically modified siRNAs engineered for high stability and reduced innate immune activation to identify potent and allele-specific KRAS G12D silencers. Optimized shock-wave engineering achieved >90% encapsulation and >85% nuclease resistance. Lead candidates were evaluated across PDAC cell lines, patient-derived organoids (PDOs), xenografts, biodistribution studies, toxicity models, and GMP-aligned scale-up workflows. Results: Five siRNAs exhibited single-digit nanomolar potency (IC50 < 10 nM). The lead, EV-siRNA #41, produced robust KRAS G12D knockdown and suppression of ERK/AKT signaling. In vivo, EV-siRNA #41 achieved markedly superior tumor accumulation relative to LNPs and induced significant tumor regression. Notably, a microdose of 25 μg EV-siRNA #41 produced antitumor efficacy comparable to or exceeding MRTX1133 at 30-60 mg/kg. PDO assays confirmed selective killing of KRAS G12D-mutant tumors with no effect on wild-type controls. Repeated-dose GLP toxicity studies established a high NOAEL without liver enzyme elevation or weight loss. GMP-aligned optimization increased EV yield from 1% to 7.5% with >80% loading efficiency. Conclusions: Shock wave-engineered EV delivery overcomes the major barriers of RNA therapeutics in PDAC. EV-siRNA #41 demonstrates potent, selective, and durable antitumor activity at microdose levels and outperforms both LNPs and a leading KRAS G12D inhibitor. These data position EV-siRNA #41 as a first-in-class, mutation-specific RNA therapeutic ready for IND-enabling development. Acknowledgments: This work was supported by the Korea Drug Development Fund (KDDF, Grant No. RS-2023-00282594), the Technology Development Program of the Ministry of Science and ICT (MSS, Grant No. RS-2023-00280797), and the Ultra-Gap Startup 1000+ Project for the promotion of ultra-gap startups, funded by the Ministry of SMEs and Startups of Korea in 2025 (Grant No. 20266766). Citation Format: Hyo Kyeong kim, Yujeong Choi, Kyoung Hwa Kim, Jae Hwan Kim, Shung Hyun An, Dae Ho Bae, Minyoung Lee, Jihwa Chung, Seok-Hyun Kim, Kihwan Kwon. EV-based delivery of chemically modified siRNA achieves MRTX1133-comparable efficacy in KRAS G12D-mutant pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 358.