Animal experimental study on the therapeutic effect of palliative thermal ablation combined with PD-1 inhibitors in HCC treatment

Wang Fuan; Ma Yuan; Ji Jie; Lyu Penghua; Li Guiling

Abstract：Objective To investigate the safety and efficacy of palliative thermal ablation combined with immune checkpoint inhibitor PD-1 in the treatment of unresectable hepatocellular carcinoma.Methods Female SPF C57 BL/6 J mice aged 6-8 weeks were subcutaneously implanted with Hepa1-6 hepatocellular carcinoma cell lines to establish a subcutaneous liver metastasis model,and grouping experiments were performed when the tumor length reached 9-10 mm.Forty-five tumor-forming mice were equally divided into three groups,including a blank Control group(Control),a palliative ablation group,and a palliative ablation combined with a PD-1 treatment group.One month later,the mice were sacrificed,and the concentrations of Th1 cytokines(IL-2,IFN-γ,TNF-α)in peripheral blood were detected by ELISA.After the mice were sacrificed,the tumor tissues were dissected and removed.The size of the tumor tissues was measured by vernier calipers and hematoxylin and eosin staining(HE staining)was performed.In addition,immunohistochemistry was used to detect the expression of Ki67,PD-1,and PD-L1 in tumor tissues.Results Compared with the control group,the tumor volume and weight of the mice in the palliative ablation group and the palliative ablation+PD-1 group were reduced,and the reduction of tumor volume and weight in the palliative ablation+PD-1 group was the most obvious.Compared with the control group,the level of IL-2 in the blood of the palliative ablation group and the palliative ablation+PD-1 group showed an increasing trend,but the difference was not statistically significant;the level of IFN-γin the blood of the palliative ablation group also showed an increasing trend,but the difference was not statistically significant.There was no significant difference in the expression of PD-1 and PD-L 1 proteins in the tumor tissue of the control group and the palliative ablation group.Compared with the control group,the expression of PD-1 and PD-L 1 protein in the tumor tissue of the palliative ablation+PD-1 group was significantly decreased.Conclusions For the HCC subcutaneous tumor model in mice,palliative ablation combined with PD-1 inhibitor has a better anti-tumor effect than palliative ablation or blank control alone,and does not cause obvious immune adverse reactions.