The five-year survival rate for patients with head and neck squamous cell carcinoma (HNSCC) has remained at ~50% for the past 30 years despite advances in treatment.EBC-46 is a novel diterpene ester developed by QBiotics Pty Ltd that induces HNSCC cell death in vitro.The aims of this study were to identify a human HNSCC xenograft that responds poorly to intratumoural injection of EBC-46, improve efficacy of EBC-46 treatment by altering different administration parameters, and confirm the molecular mechanism of HNSCC cell ii