Abstract LB172: Chemoradiation-induced tissue toxicity in oral cancer using 3D Epithelioids

Abstract Background: Oral mucositis is among the most prevalent side effects of head and neck cancer (HNC) therapy, impacting over 40% of patients treated with chemotherapy and 90% of those treated with chemoradiation. This widespread inflammation of the oral mucosa represents a major obstacle to the treatment and quality of life of HNC patients and is often a precursor of subsequent oral complications like dysphagia and infections. Although progress has been made in deciphering the mechanisms of oral mucositis, models to study this chemoradiotoxicity have been largely limited to tumor-bearing in vivo models which are both time and cost intensive. To overcome this, the Antoran lab has developed epithelioids, a novel in vitro system that recapitulates 3D epithelial structures from mouse and human tissues and can be extended to cancer epithelioids which recapitulate interactions between healthy and tumor cells along with the tumor microenvironment. Methods: The tongue and oral mucosa were excised from euthanized mice and the muscle layers were removed with forceps. Epithelium from both tissues was cut into small explants, plated on transparent six-well pored membrane trans wells, and incubated with keratinocyte typical media. Squamous cell carcinoma cells of varying aggressiveness were added in the center of each insert. Once confluent, the oral cancer epithelioids were treated with cisplatin, x-ray radiation, or both. Normal and tumor cell viability, proliferation, and recovery was observed using spinning disk confocal live imaging and immunofluorescent staining. Results & Discussion: Real-time live-cell imaging confirmed epithelial cell growth to confluency followed by tumor invasion. Following cisplatin, x-ray irradiation, or combination therapy, epithelioids showed increased markers of DNA-damage and repair such as yH2AX and 53BP1 respectively, apoptosis, and decreased epithelial barrier function as measured by dextran-FITC permeability assays. Relative to normal tissue in the cancer epithelioids, cancer tissue showed greater double-stranded DNA damage in response to chemoradiation. Conclusion: Our results suggest that cancer epithelioids are a promising in vitro alternative to more complex in vivo models and may be used for studying mechanisms of oral mucositis and potential therapeutic interventions of this side effect. Citation Format: George Morcos, Erini Terpsi Vitti, Ines Ferreira, Philippa Samella, David Fernandez-Antoran. Chemoradiation-induced tissue toxicity in oral cancer using 3D Epithelioids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB172.