Abstract LB279: The combination therapy with B7-H3 antibody drug conjugates for effective radiation treatment

Abstract

Abstract Purpose: Antibody-drug conjugate (ADC) is a promising treatment modality because it enables effective tumor-specific delivery of anticancer drugs by targeting cancer antigens with antibodies. By using ADC, each treatment can be used at an optimal dose, thereby minimizing side effects, and maximizing treatment effects. The ADC used in this experiment targets B7-H3, and the B7-H3 protein is highly expressed in various cancer types. Recent studies have shown that B7-H3 is increased by radiation in various cancer cells. This study aims to demonstrate the efficacy of the B7-H3 ADC and confirm its combined effect with radiotherapy. Method: In vitro, colony forming assay, CCK-8 assay, FACs and western blotting were performed in JIMT-1 and HCT116 cell lines. In vivo, JIMT-1, HCT116 and Colon PDX models were developed to monitor tumor growth and survival rate. Biodistribution was performed through the IVIS (In Vivo Imaging System) spectrum. Result: The B7-H3 ADC used in the experiment was developed by combining DUBA as a toxin with anti-B7-H3 antibody In in vitro experiments, the combined treatment of radiation and B7-H3 ADC reduced cell viability via apoptosis more effectively than treatment alone. In the in vivo mouse models, we observed that the combined treatment of radiation and B7-H3 ADC was more effective in inhibiting tumor growth than the single treatment groups. The survival rate of the mice was also improved when the radiation was combined with B7-H3 ADC treatment compared to the other treatment groups alone. In the biodistribution results, the accumulation of B7-H3 ADC-Cy7 was further enhanced when irradiated. Conclusion: The results show that B7-H3 ADC can be used as a promising therapeutic agent and the combined treatment with radiation can obtain an improved anticancer effect than the single treatment, suggesting another cancer treatment method. Citation Format: Gawon Son, Eunjin Ju, Jin Park, Seolhwa Shin, Eunjeong Ko, Miri Kwon, Hyewon Lee, Beomseok Seo, Sangkwang Lee, Seoksoon Park, Seongyun Jeong, Siyeol Song, Eunkyung Choi. The combination therapy with B7-H3 antibody drug conjugates for effective radiation treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB279.