CD274 and head and neck squamous cell carcinoma: The efficacy of NK cells in HNSCC was and is being investigated in various clinical trials, that include the use of off-the-shelf NK products combined with monoclonal antibodies (clinical trials.gov NCT05674526), autologous and ex vivo expanded NK cells (clinical trials.gov NCT00717184) with or without bispecific antibodies (clinical trials.gov NCT05099549) as well as genetically modified NK cells expressing anti-PD-L1 (clinical trials.gov NCT04847466) or anti-NKG2D-ligand CARs (clinical trials.gov NCT03415100).