Abstract
Liver cancers are often diagnosed at advanced stages and are the fourth leading cause of cancer death globally. Liver metastases, particularly from colorectal cancer, occur in 66% of patients. Immunotherapies for these cancers are limited by immunosuppressive tumor microenvironments. To address this, phospholipid-free small unilamellar vesicles (PFSUV) are developed to deliver the toll-like receptor 7 agonist Imiquimod (IMQ) to hepatocytes. PFSUV consists of 83 mol% cholesterol and 17 mol% Tween80, with IMQ encapsulated in these 75-nm particles. Intravenous administration of PFSUV-IMQ sustained liver IFN-α levels over 24 h while reducing systemic exposure. In a CT26 liver metastasis model, PFSUV-IMQ combined with Oxaliplatin reduced tumor size, increased CD8+ T cell infiltration, and enhanced tumor apoptosis. In an HCA-1 liver cancer model, the same treatment decreased tumor burden, increased apoptosis, and reduced lung metastases. Flow cytometry revealed increased CD86+/MHC-II+ dendritic cells and IFN-γ+ CD8+ T cells in treated tumors. RNA-seq shows enrichment of innate immune activation genes after a single dose. These findings suggest that targeted IMQ delivery activates the tumor immune microenvironment, leading to reduced tumor burden in liver cancer and metastasis models.