CD274 and head and neck squamous cell carcinoma: The primary objective of the KESTREL study was to assess the overall survival (OS) of durvalumab monotherapy versus the EXTREME regimen in patients with R/M HNSCC whose tumors expressed high levels of PD-L1 (PD-L1 tumor cell [TC] ≥ 50%/immune cell [IC] ≥ 25%) [11].