LNP-Delivered CAR-mRNA Enables in Vivo CAR-Macrophage Production for TYRP1-Targeted Therapy of Choroidal Melanoma

Purpose To develop a macrophage-targeted therapy for choroidal melanoma using lipid nanoparticles (LNPs) that deliver TYRP1-CAR mRNA to reprogram tumor-associated macrophages.Methods B16-F10 cells were injected into the subretinal space of C57BL/6 mice to establish choroidal melanoma. F4/80-antibody-conjugated MPLA-LNPs encapsulating TYRP1-CAR mRNA were administered via intravitreal injection on days 3 and 6. Macrophage phenotype, CAR expression, and tumor progression were assessed using immunofluorescence, flow cytometry, and bioluminescence imaging. Safety was evaluated through blood biochemistry and histology.Results Tumor-associated macrophages exhibited predominantly M2 phenotype. MPLA-LNPs promoted M1 polarization and generated functional TYRP1-CAR-expressing macrophages in situ. The F4/80/MPLA-LNP-CAR mRNA treatment significantly reduced tumor burden (bioluminescence and tumor weight), increased M1 macrophage infiltration, and extended survival compared to controls. No systemic toxicity was observed in hematological, biochemical, or histological analyses.Conclusions We demonstrate that macrophage-targeted MPLA-LNP delivery of TYRP1-CAR mRNA in a murine choroidal melanoma model reprograms tumor-associated macrophages toward an M1 phenotype, suppresses tumor growth, and prolongs survival through combined antigen-specific targeting and microenvironment remodeling.