Anti-tumor Activity Of PD-1 Monoclonal Antibody And Anti-angiogenesis Combined Chemotherapy In Mice With Triple-negative Breast Cancer

Objective In order to enable more triple-negative breast cancer patients to benefit from immune checkpoint blocking therapy,and at the same time to solve the limitations of anti-angiogenic drug therapy,this project intends to use triple-negative breast cancer tumor-bearing mouse models,through PD-1 After treatment with inhibitors,bevacizumab and albumin-bound paclitaxel,observe the tumor growth of tumor-bearing mice,and analyze the expression of VEGF,Cleaved caspase-3,Bax,and Bcl-2 proteins in the tumor microenvironment,To initially explore whether bevacizumab can improve the normalization of tumor blood vessels and further enhance the mechanism of the drug’s anti-tumor effect,which is intended to provide a new theoretical basis for finding the best immunological combination therapy.Methods A mouse model of triple-negative breast cancer was constructed,and the mice were randomly divided into tumor formation group(control group),bevacizumab group(Bev group),albumin-bound paclitaxel group(Nab-PTX),bevacizumab Anti-albumin-bound paclitaxel group(Bev+Nab-PTX group),PD-1inhibitor+bevacizumab+albumin-bound paclitaxel group(PD-1inhibitor+Bev+Nab-PTX).According to grouping regulations,mice were injected intraperitoneally to observe the changes of tumor bodies in tumor-bearing mice.The neovascularization was developed by CD31 by immunofluorescence method to mark the change of tumor microvessel density.Immunohistochemistry and Western blot were used to detect the expression of VEGF,Cleaved caspase-3,Bax,and Bcl-2 protein in mouse tumor tissues in each group.All data were statistically analyzed using SPSS 22.0(SPSS Inc.,Chicago,USA)software.Results 1.Tumor suppression: The treatment group has different degrees of tumor suppression.The combined treatment group has slower growth of transplanted tumors than the single-agent group.The combined treatment group with PD-1 inhibitor has the best tumor suppression effect on the 16 th day(P<0.05).2 The inhibitory effect of each treatment group on tumor angiogenesis in tumor-bearing mice:(1)Microvessel density(MVD): The tumor microvessel density in each treatment group decreased compared with the control group,and the three-drug combination group had the best effect.②Expression of VEGF: Western Blot experiment report: each treatment group can inhibit the expression of VEGF,and the inhibitory effect of the combination group with PD-1 inhibitor is the most significant(P<0.05).However,the results of immunohistochemistry did not fully show the absolute advantage of the three-drug superposition.3.The effect of each treatment group on apoptotic proteins in tumor tissues of tumor-bearing mice: Western Blot results: Compared with the control group,the expression of pro-apoptotic factors cleaved caspase3 and BAX were up-regulated in the treatment group,and the expression of anti-apoptotic factor Bcl2 was decreased.The above results were most obvious in the combination group with PD-1 inhibitor,and the difference was statistically significant(P<0.05).The results of immunohistochemistry also reflected the better pro-apoptosis effect of the combined drug group,but the absolute advantage of the three-drug superposition did not fully highlight.Conclusion PD-1 inhibitor,bevacizumab combined with albumin-bound paclitaxel has a synergistic anti-tumor effect.This combination scheme is superior in terms of inhibiting tumor growth,promoting tumor cell apoptosis and anti-tumor angiogenesis The combination group of bevacizumab and albumin-bound paclitaxel.