Fluvoxamine combined with lenvatinib enhances anti-hepatocellular carcinoma immunity by promoting M1 macrophage and T-cell infiltration

This study aimed to investigate the synergistic antitumor activity of fluvoxamine combined with lenvatinib against hepatocellular carcinoma (HCC). Lenvatinib remains an approved targeted therapy for HCC but has limited single-agent efficacy with frequent resistance, partially driven by upregulated immunosuppressive programmed death-ligand 1 (PD-L1). Fluvoxamine, a clinical antidepressant, shows PD-L1 inhibitory and antitumor effects in some tumors, while its synergism with lenvatinib in HCC remains unclear. Wound healing assay, flow cytometry and Western blot were performed to evaluate the combination's effects on HCC cell migration, apoptosis and related protein expression. H22 tumor-bearing mouse models were established to assess in vivo antitumor efficacy. Immunofluorescence, Western blot and flow cytometry were used to detect tumor immune infiltration, PD-L1/VEGF-related protein expression, and systemic immune cell proportions. In vitro, the combination significantly inhibited HepG2 cell migration, promoted apoptosis, downregulated p-Stat3, MMP2, PD-L1, VEGF and BCL-2, and upregulated cleaved caspase-3 versus monotherapies. In vivo, it exerted more potent tumor growth inhibition without obvious toxicity, further downregulated PD-L1/VEGF, enhanced intra-tumoral T cell and M1 macrophage infiltration, and increased systemic T lymphocyte proportions. Fluvoxamine combined with lenvatinib exerts synergistic anti-HCC activity and is associated with enhanced antitumor immune infiltration, providing experimental evidence for novel clinical HCC combination therapies.