The Inhibitory Effect Of Combined Blocking TGF-β/PD-1 On Ovarian Cancer And Its Immune Mechanism

Background : Epithelial ovarian cancer(EOC),as a common malignant tumor in gynecology,due to the insidious onset,lack of specific symptoms and screening methods,about 80% of patients are advanced at the time of presentation,and the fatality rate is still the highest among gynecological tumors.In the past two decades,immune checkpoint suppression therapy has been widely used in the treatment of various malignant tumors including cervical cancer and endometrial cancer,and has achieved good anti-tumor efficacy,but not in ovarian cancer.Transforming growth factor β(TGF-β)can affect the tumor microenvironment,promote tumor cell invasion and inhibit the function of various immune cells through a variety of different pathways,thereby promoting tumor metastasis.These mechanisms suggest that inhibition of transforming growth factor signaling may be a promising strategy to enhance the effect of immune checkpoint inhibition.Recent studies have shown that inhibition of TGF-β can enhance the anti-tumor effect of immune checkpoint inhibitors in a variety of malignancies by improving the tumor immunosuppressive microenvironment,so we speculate that the combined blocking of TGF-β/PD-1 in ovarian cancer can also achieve good results.Object:To investigate the effect of combined blocking TGF-β/PD-1 on tumor growth and immune cells and immune factors in the tumor microenvironment.Methods:The expression and prognostic value of PD-1 and TGF-β in tumor tissues were analyzed by the TCGA ovarian cancer transcriptome database;Cultured ID8 mice ovarian cancer cell lines,purchased C57BL/6 immunocompetent mice,and established a mouse model of homlogous ovarian cancer.Twenty-four mice were randomly divided into 4 groups: Control group,Anti PD1 group,Anti TGF-β group,Anti PD1 + TGF-βgroup.The tumor volume of each group was measured,the tumor suppression rate was calculated,the tumor tissue HE staining was performed,and the organ index was calculated.The tumor tissue was processed into a single-cell suspension and the content of CD4+ T cells,CD8+ T cells,Tregs cells,and cytokine GZMB expression were measured by flow cytometry.Results:1.Database analysis displayed that PD1 and TGF-β were highly expressed in ovarian tumor tissues(P<0.001;P=0.006),and the expression of PD1 in ovarian cancer tissues was significantly positively correlated with TGF-β(Spearman r=0.507,P<0.001).High expression of TGF-β predicted a poor prognosis(P=0.036),and high expression of PD1 had a good prognostic trend,but did not achieve a statistical difference.Immunoinfiltration analysis showed that the high expression of TGF-β was highly correlated with the infiltration of various immunosuppressive cells such as macrophages,Treg cells and dendritic cells.2.Compared with the Control group,the effect of inhibiting tumor growth in the combination group was stronger than that in the anti TGF-β group(P<0.001),and there were no side effects such as weight loss and hepatosplenomegaly;the effect of tumor inhibition in the anti PD1 group was not obvious(P>0.05)3.CD8+/CD4+ T cells in the combination group were significantly higher than those in the Control group(P=0.006),while the anti TGF-β group and anti There was no significant difference between PD1 group and Control group(P>0.05),the proportion of Tregs cells in anti PD1 group,anti TGF-β group and combination group decreased sequentially,and there were statistical differences compared with the control group(P<0.05),and the secretion of GZMB in anti PD1 group,anti TGF-β group and combination group was statistically different(P<0.05),but anti There was little difference between PD1 and anti TGF-β(P>0.05).Conclusion: Combined blocking of TGFβ/PD1 has good anti-ovarian cancer efficacy,and its possible immune mechanism is to increase the proportion of activated CD8+ T cells and the secretion of GZMB in the tumor microenvironment,while reducing the proportion of inhibitory Tregs cells,and ultimately improving the tumor suppressor immune microenvironment.Therefore,combined blockade of TGFβ/PD1 can be used as a new strategy for ovarian cancer immunotherapy.