RecruitingPhase 3Drug trialA Global Study of Volrustomig (MEDI5752) for Participants With Unresected Locally Advanced Head and Neck Squamous Cell Carcinoma Following Definitive Concurrent ChemoradiotherapyThe main purpose of this study is to assess the efficacy and safety of volrustomig compared to observation in participants with unresected locally advanced head and neck squamous cell carcinoma (LA-HNSCC) who have not progressed after receiving definitive concurrent chemoradiotherapy (cCRT).