CPI-455

Colorectal cancer (CRC), as a fatal cancer, is one of the most common cancers worldwide. Although the standard treatment for colorectal cancer is well researched and established, long-term patient survival remains poor, and mortality remains high. Therefore, more and more effective treatment options are needed. To evaluate the efficacy of bevacizumab, the histone demethylase inhibitor IOX1, or their combination for the treatment of colorectal cancer, we examined the effects of IOX1, bevacizumab, and IOX1 combined with bevacizumab on cell activity, proliferation, and migration of colorectal cancer cell lines HCT116, RKO, and CT26 by CCK8, colony formation assay, wound healing assay, and transwell assay. The effects of the drugs alone as well as in combination on apoptosis in colorectal cancer cell lines were examined by flow cytometry and further validated by Western blotting for apoptosis-related proteins. The antitumor effects of treatment alone or in combination on colorectal cancer cells were examined in animal models. Mice were injected subcutaneously with CT26 cells and the growth and immune infiltration in tumor tissues were detected by IHC after drug treatment. We found that IOX1 could effectively inhibit the activity of CRC cells and had a significant inhibitory effect on the proliferation and migration of CRC cells. The apoptosis rate increased in a dose-dependent manner after IOX1 treatment on colorectal cancer cells, and the expression of apoptosis-related proteins changed accordingly. Further combination with bevacizumab revealed that the combination had a more significant effect on the proliferation, migration, and apoptosis of CRC cells than either IOX1 or bevacizumab alone. In vivo experiments have found that both alone and combination drugs can inhibit the growth of mouse tumors, but the effect of combination inhibition is the most obvious. Combination therapy significantly inhibited the expression of proliferative marker (Ki67) in tumor xenograft models, and increased content of antigen-specific CD4⁺, CD8⁺T cell growth, and granzymeB (GZMB), which is associated with T cell cytotoxicity, was detected in combination therapy. Immunoassays suppressed the expression of relevant PD-1 and decreased. The anticancer drug bevacizumab and the histone demethylase inhibitor IOX1 may inhibit colon cancer cell growth by regulating apoptosis. The inhibitory effect of combination therapy on tumor growth may be achieved, in part, through upregulation of infiltration-mediated tumor immunity by T lymphocytes. The combination of IOX1 and bevacizumab produced significant synergistic effects. This study aims to provide a new direction for CRC combination therapy.