993PDASSOCIATION OF HUMAN PAPILLOMAVIRUS (HPV) AND P16 STATUS WITH EFFICACY AND SAFETY DATA IN THE PHASE III RADIOTHERAPY (RT)/CETUXIMAB (CET) REGISTRATION TRIAL FOR LOCOREGIONALLY ADVANCED SQUAMOUS CELL CARCINOMA OF THE HEAD AND NECK (LASCCHN)

• In a 5-year review of the data, the phase 3, randomized trial of RT ± cetuximab for LA-SCCHN, also called the Bonner trial, showed that RT + cetuximab signi cantly improved locoregional control (LRC) and overall survival (OS) compared with RT alone1,2 • A recent subgroup analysis of the Bonner trial suggested that both patients with p16+ and patients with p16− oropharyngeal cancer (OPC) had improved OS and LRC when cetuximab was added to RT – An interaction test did not reveal a statistically signi cant difference between the p16+ and p16− OPC cohorts; accordingly, while p16 was con rmed as a prognostic biomarker, it may not predict response to cetuximab. These results should be interpreted with caution due to the relatively small sample size3 – p16 status has been widely used as a surrogate marker of HPV status in OPC4 • In this subgroup analysis, we evaluated the effect of HPV status on OS and LRC in patients with p16+ OPC, comparing cetuximab + RT with RT alone • When used as the curative modality for LA-SCCHN, RT causes mucositis and dysphagia in a majority of patients, which can lead to treatment breaks and suboptimal responses – These toxicities are exacerbated when chemotherapy is added to RT5 – Mucositis and dysphagia were not affected by adding cetuximab to RT in the Bonner trial1,2 • In the present subgroup analysis, we evaluated the effect of adding cetuximab to RT on mucositis and dysphagia in patients with p16+ or p16− OPC