Abstract 4679: FTO inhibition enhances the therapeutic index of radiation therapy in head and neck cancer

Despite the use of intensive combined modality therapy such as chemoradiation or surgery and radiation, the overall survival rate for patients with HPV-negative head and neck squamous cell carcinoma (HNSCC) remains poor. This underscores the unmet clinical need for the development of more effective drug-radiotherapy combinations to enhance the therapeutic index of radiation therapy (RT). The RNA demethylase enzyme FTO has emerged as a promising target for cancer therapy. However, its role as a radiosensitizer in HNSCC remains unknown. Here, we investigated the potential of targeting FTO to augment the effectiveness of RT in HPV-negative HNSCC. We found that genetic and pharmacologic inhibition of FTO enhanced the efficacy of RT in both human and mouse HNSCC tumor xenografts. Importantly, FTO inhibition did not increase radiation-induced oral mucositis. Mechanistically, FTO inhibition radiosensitizes HPV-negative HNSCC cells through amplifying DNA damage while reducing RAD51 foci formation, providing a molecular rationale for exploiting FTO inhibitors as radiation sensitizers in HNSCC. Collectively, our results suggest that therapeutic targeting of FTO may be an effective strategy to enhance the therapeutic index of RT for the treatment of HNSCC. Citation Format: Lu Ji, Leighton Pu, Hongbin Cao, Stavros Melemenidis, Subarna Sinha, Li Guan, Eyiwunmi E. Laseinde, Sara Richter, Rie Eyben, Kerriann Casey, Christina Kong, Edward Graves, Quynh Le, Erinn Rankin. FTO inhibition enhances the therapeutic index of radiation therapy in head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4679.