Abstract 5970: Tumor vessel normalization by a novel anti-TIE2 antibody PMC-403 enhances the effectiveness of radiation therapy on cancer therapy

Abstract

Abstract Purpose: The delivery of drugs and immune cells into the tumor microenvironment is limited due to abnormal tumor vessel which is characterized as low oxygen concentration, low perfusion rate and leakage. It leads to diminish the efficacy radiation therapy. Traditional anti-angiogenesis strategies attempt to reduce the tumor vascular supply, but their success is restricted by insufficient efficacy or development of resistance. To solve the problem, we try to using PMC-403, which can normalize the abnormal condition of tumor vessel. Experimental procedures: Target selectivity: It was measured by Surface Plasmon Resonance (SPR) assay. Human TIE2 Cho-K1 cells or mouse TIE2 Cho-K1 cells were tested for species cross-reactive assay based on flow cytometry (FACS).In vitro studies: Human umbilical vein endothelial cells (HUVEC) were used for TIE2 signal pathway analysis with western blot assay and efficacy analysis with VEGF-induced vessel permeability assay.In vivo study: Glioblastoma model mice were employed for the assessment of tumor vessel normalizing activity of 1 mg/mouse PMC-403. CT26 colon cancer model mice were used to evaluate the anti-tumor efficacy of PMC403 (10 mg/kg) in combination with radiation therapy. Hypoxyprobe was used to measure the improvement of hypoxic conditions in tumor tissue. Summary of data: PMC-403 has a nanomolar range of affinity for both human or mouse TIE2 expressing cells. This contributed to dose-dependent ANG1-like TIE2 and FOXO1 phosphorylation and inhibited VEGF-induced vascular leakage, thereby contributing to ANG1-like vascular normalization. Moreover, similar to ANG-1, p-VEGFR2 and p-VE-Cadherin levels were significantly reduced by PMC-403, suggesting that PMC-403 can normalize blood vessels. In addition, PMC-403 stabilized abnormal tumor blood vessels in the glioblastoma mouse model and significantly reduced tumor growth and tumor hypoxia in the combination treatment (PMC-403 + radiation therapy) compared to radiation therapy alone, although the antitumor effect of PMC-403 alone was not effective in the same condition model. Conclusions: PMC-403, an anti-TIE2 monoclonal antibody, is a novel tumor vessel stabilizer. PMC-403 improved tumor microenvironment hypoxic condition that synergized with radiotherapy when it combined together for the anticancer therapy. These data strongly support the notion that PMC-403 can effectively treat tumors even with low doses of radiation by stabilizing tumor blood vessels. Citation Format: Eun-Ah Lee, Beom Yong Park, Nuri Kang, Cheon Ho Park, Weon Sup Lee. Tumor vessel normalization by a novel anti-TIE2 antibody PMC-403 enhances the effectiveness of radiation therapy on cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5970.