High-frequency irreversible electroporation synergizes with PD-1/PD-L1 inhibitor BMS-1 and TLR7/8 agonist R848 to potentiate liver cancer antitumor immunity

Abstract

BACKGROUND

High-frequency irreversible electroporation (H-FIRE), a second-generation tumor ablation therapy, has demonstrated efficacy and safety in treating liver cancer. However, its clinical application is hindered by the risk of residual disease and metastasis resulting from incomplete ablation, while H-FIRE’s inherent capacity to induce immunogenic cell death (ICD) provides a potential direction for optimizing its efficacy.

AIM

To leverage H-FIRE’s ICD capacity, and investigate the efficacy and safety of H-FIRE combined with immunotherapy in the treatment of liver cancer.

METHODS

A murine subcutaneous hepatocellular carcinoma model was established using hepatoma 22 cells. Mice were randomized into eight groups: Control, BMS-1, R848, BMS-1 + R848, H-FIRE, H-FIRE + BMS-1, H-FIRE + R848, and H-FIRE + BMS-1 + R848. Treatments comprised: Intraperitoneal BMS-1 and intratumoral R848 administered every 2 days (4 total doses); H-FIRE ablation performed once when tumors reached 7-8 mm in long diameter. Efficacy was assessed by monitoring survival, primary tumor volume, primary tumor cell proliferation and damage-associated molecular patterns expression, immune microenvironment alterations in primary tumors and spleens, distant secondary tumor apoptosis, and treatment safety.

RESULTS

H-FIRE robustly induced ICD in primary liver tumors. Notably, the triple-combination therapy (H-FIRE + BMS-1 + R848) exerted the most potent antitumor efficacy: It significantly reduced primary tumor burden relative to all other monotherapy or dual-combination groups, with a mean tumor volume of 305.3 ± 35.0 mm³ in the triple-combination group. This therapeutic benefit was further confirmed by markedly extended overall survival, with median survival times of 17, 24.5, 25, 28.5, 28.5, 33.5, 37.5, and 53 days, respectively. Mechanistically, the triple-combination strategy was accompanied by enhanced tumor cell apoptosis and suppressed cell proliferation, underscoring its multi-faceted antitumor effects. In primary tumors and spleens, this combination markedly increased proportions of CD3+ CD4+ T cells, CD3+ CD8+ T cells, CD11c+ CD80+ CD86+ dendritic cells, F4/80+ CD11b+ CD86+ M1 macrophages, and the M1/M2 macrophage ratio. Conversely, it reduced proportions of CD4+ CD25+ FOXP3+ regulatory T cells and F4/80+ CD11b+ CD206+ M2 macrophages, with no significant toxicity observed. Furthermore, the triple therapy effectively promoted apoptosis and inhibited growth in distant secondary tumors.

CONCLUSION

The triple therapy synergistically reverses local and systemic immune tolerance, eliciting robust anti-tumor immunity. This strategy not only effectively inhibits primary and secondary tumor progression but also exhibits favorable safety, underscoring its potential as a novel combinatorial cancer treatment.

Keywords: Liver cancer; High-frequency irreversible electroporation; Programmed death-1/programmed death-ligand 1 inhibitor; Toll-like receptor 7/8 agonist; Antitumor immunity

Core Tip: High-frequency irreversible electroporation potently triggers immunogenic cell death within tumors. In combination with BMS-1 and R848, this multimodal strategy not only curbs tumor progression but also dynamically reprograms the immunosuppressive tumor microenvironment. Specifically, it augments the infiltration of CD3+ CD4+ and CD3+ CD8+ T cells, CD11c+ CD80+ CD86+ dendritic cells, and F4/80+ CD11b+ CD86+ M1 macrophages, while depleting immunosuppressive subsets such as CD4+ CD25+ FOXP3+ regulatory T cells and F4/80+ CD11b+ CD206+ M2 macrophages. Consequently, the regimen induces a pronounced abscopal effect and fosters robust, systemic antitumor immunity, underscoring its translational potential as an innovative combination immunotherapy.