Flower-Shaped Lipid Nanoparticles Evade Apolipoprotein E-Mediated Liver Tropism for Safe and Enhanced Cytokine-Based Cancer Immunotherapy

Lipid nanoparticles (LNPs) are effective carriers for intratumoral delivery of cytokine-encoding mRNA, but their clinical use is limited by apolipoprotein E (ApoE)-mediated hepatic tropism, which causes off-target cytokine expression and hepatotoxicity. Here, we reprogrammed LNP morphology by partially substituting native cholesterol with a TLR7/8 agonist-conjugated analog (R-Chol), generating flower-shaped LNPs (RLNPs) with reduced ApoE adsorption. Upon intratumoral injection, RLNPs maintained efficient tumor transfection while markedly decreasing liver accumulation and IL-12 mRNA-induced hepatotoxicity. Hydrodynamic modeling indicated that the distinct surface curvature of RLNPs constrained ApoE binding. RLNPs were further functionalized with CD47-SIRPα blocking peptide (IL-12 mRNA@CRLNPs), eliciting potent M1 macrophage-driven immune activation in orthotopic 4T1 tumors. When embedded in a photo-cross-linkable hydrogel (mCRLNP@HAMA gel) and combined with αPD-L1, this platform achieved sustained postoperative delivery, thereby preventing tumor recurrence and ensuring prolonged systemic safety. These findings highlight cholesterol structural tuning as a strategy to control LNP morphology and biodistribution, advancing safe and translational cytokine-based cancer immunotherapy.