Optimized lipid nanoparticles for pulmonary delivery of CRISPR/Cas9 targeting KRAS G12S in lung cancer

KRAS G12S mutations in non-small cell lung cancer (NSCLC) remain refractory to current targeted therapies, with few clinical options and frequent resistance. While CRISPR/Cas9 enables mutation-specific gene disruption, its pulmonary application is limited by systemic clearance, hepatic tropism, and airway mucus barriers. Here, we present lipid nanoparticles (LNPs) specifically engineered for pulmonary delivery of Cas9 mRNA and KRAS G12S-targeting sgRNA, optimized through mRNA surrogate screening and orthogonal mixture design to guide lipid composition and Cas9:sgRNA weight-to-weight ratios. Two lead LNP formulations, A6 3:1 and A8 1:1, exhibited robust critical quality attributes, including particle sizes below 120 nm, low polydispersity, near-neutral zeta potential, and over 80 % encapsulation efficiency. Cryo-TEM revealed distinct morphologies correlated with enhanced transfection. In vitro, A8 1:1 achieved up to 90 % on-target gene editing in A549 cells and a 3.6-fold increase in apoptosis, while A6 3:1 induced a 3.7-fold apoptotic response. Both formulations efficiently traversed airway mucus in air-liquid interface cultures and preserved over 80 % cell viability across doses. In vivo, repeated pulmonary administration was well tolerated, with no signs of systemic toxicity or cytokine elevation in healthy or tumor-bearing mice. In an orthotopic A549-luc lung tumor model, intratracheal delivery of A6 3:1 and A8 1:1 modestly suppressed tumor growth, with histological evidence of tumor cell apoptosis for A8 1:1. Quantification confirmed a statistically significant increase of apoptosis in the A8 1:1 group, consistent with effective KRAS disruption in vivo. Overall, lead LNPs, particularly A8 1:1, enabled efficient and localized RNA-based gene editing that induced downstream apoptotic signaling, demonstrating a preliminary, yet promising, proof-of-concept for CRISPR/Cas9 therapy in NSCLC.