Dual Drug-Loaded Enzyme-Responsive Liposomes Exert Specific Modulation on Liver Cancer Cells and Tumor-Associated Macrophages In Vitro

Background: Hepatocellular carcinoma (HCC) is a highly lethal malignancy and remains a major contributor to global cancer mortality. In situ vaccination (ISV) holds great potential for HCC therapy. Still, its efficacy is severely limited by intrinsic antigen scarcity and the tumor-associated macrophage (TAM)-mediated inhibition of dendritic cell (DC) maturation and T cell activation. In particular, the M2 TAM-HCC cell crosstalk may further aggravate ISV suppression. Moreover, as an internal organ tumor, HCC requires systemic administration of ISV agents, which often cause severe off-target toxicity. Methods: To address these challenges, we developed secretory phospholipase A2 (sPLA2)-responsive liposomes co-loaded with the TLR7/8 agonist R848 and the ICD inducer doxorubicin (DOX) via a sequential remote loading method, termed sP-Lips@DR. Results: Incorporation of cholesterol (CHOL) significantly improved DOX encapsulation, and the sequential loading method enabled efficient co-encapsulation of both R848 and DOX. sP-Lips@DR responds to an sPLA2-overexpressed, mildly acidic microenvironment in HCC, enabling selective drug release. In addition, sP-Lips@DR exhibited sPLA2-responsive cytotoxicity toward H22 cells and macrophage phenotypic shift. Furthermore, sP-Lips@DR could disrupt the crosstalk between M2-like macrophages and H22 cells in an sPLA2-responsive manner. Conclusions: Overall, the preparation and in vitro evaluation of sP-Lips@DR demonstrate their potential to enhance ISV efficacy in HCC, providing a solid foundation for future in vivo investigations.