However, two phase III studies (EAGLE and KESTREL) investigating the efficacy of durvalumab or durvalumab combined with tremelimumab (anti-CTLA-4 mAb) versus the standard of care or the EXTREME treatment regimen failed to demonstrate an improvement in the OS of patients with R/M HNSCC (AstraZeneca communication https://www.astrazeneca.com/media-centre/press-releases/2021/update-on-kestrel-phase-iii-trial-for-imfinzi.html (accessed on 21 September 2022) [56]. This evidence concerns the gene CTLA4 and head and neck squamous cell carcinoma.