Clinical effect of topical application of CpG oligodeoxynucleotide combined with OX40 monoclonal antibody for mouse model of hepatocellular carcinoma

Objective To investigate the clinical effect of topical application of CpG oligodeoxynucleotide ( CpG-ODN) combined with OX40 monoclonal antibody in the treatment of hepatocellular carcinoma and its therapeutic effect on distant homologous tumors. Methods H22 single cell suspension was subcutaneously injected into the axilla of the four limbs of BALB/c male mice to establish a tumor-bearing model. After seven days, 30 mice with a similar tumor volume were screened out and randomly divided into model control group, CpG group, and CpG + OX40 group, with 10 mice in each group, and drugs were injected into the tumor in the left lower limb. Ten normal mice in the same batch were selected as normal control group. Tumor volume was calculated, ELISA was used to measure the serum levels of interleukin-12 ( IL-12) and interferon-γ ( IFNγ) , and flow cytometry was used to measure the percentage of CD8+T lymphocytes in the spleen. The three groups were compared in terms of survival after treatment. Repeated measures analysis of variance and one-way analysis of variance were used for comparison of continuous data between multiple groups, and the least significant difference t-test was used for further comparison between two groups. The log-rank test was used to analyze survival rate for the model control group, CpG group, and CpG+ OX40 group, and survival curves were plotted. Results After treatment, the model control group had progressive growth of tumor, with significantly lower serum levels of IL-12 and IFNγ and percentage of spleen CD8+T lymphocytes than the normal control group ( all P <0. 05) . Compared with the model control group, the CpG group and the CpG + OX40 group had a significant reduction in tumor volume after intervention ( all P < 0. 05) . The CpG + OX40 group had a significantly lower growth rate of distant tumor than the CpG group and the model control group ( all P < 0. 05) , but there was no significant difference in distant tumor volume between the CpG group and the model control group ( P > 0. 05) . Compared with the model control group, the CpG group and the CpG + OX40 group had significant increases in serum levels of IL-12 and IFN-γ and percentage of spleen CD8+T lymphocytes ( all P < 0. 05) , which were significantly higher in the CpG +OX40 group than in the CpG group ( all P < 0. 05) . The CpG + OX40 group had a significantly higher survival rate than the model control group and the CpG group ( both P < 0. 05) , while there was no significant difference between the CpG group and the model control group ( P> 0. 05) . Conclusion OX40 monoclonal antibody combined with CpG-ODN can reduce liver tumor volume, effectively slow down the growth of distant tumors, and prolong the survival time of mice.