Famitinib enhances the antitumor effect of radioimmunotherapy in murine lung cancer

Combining antiangiogenic therapy with radioimmunotherapy is believed to further improve antitumor efficacy, but there is still a lack of evidence to support this. This study aimed to investigate the role of the tumor vascular-targeted agent famitinib with a combination of radiotherapy and an immune checkpoint inhibitor in murine lung cancer.The effect of VEGFA and HIF1A on clinical prognosis and the tumor immune microenvironment was analyzed using public databases. Enrichment analyses of post-irradiation gene expression and mRNAs related to immunotherapy efficacy were carried out based on GEO datasets. A C57BL/6 mouse subcutaneous tumor model was used to evaluate the antitumor effects of different treatment schemes. The tumor immunophenotyping was identified by flow cytometry.We demonstrated that high level of VEGFA and HIF1A expression in lung cancer was related to poor prognosis and immunosuppressive tumor microenvironment. In a mouse model, the triple therapy of famitinib, radiotherapy and immunotherapy had the most dramatic antitumor activity. It significantly increased tumor infiltrating lymphocytes and reversed the immunosuppressive state of the tumor microenvironment in mice. Compared with radioimmunotherapy, the addition of famitinib further promoted the infiltration of CD8+ T cells and M1 type tumor associated macrophages, and reduced the number of myeloid suppressor cells. Therefore, triple therapy converted the immunosuppressive tumor microenvironment into an immunostimulatory one.Famitinib can synergize with radioimmunotherapy by regulating the tumor immune microenvironment in murine lung cancer.