This study is looking at immune maintenance therapy for people with a kind of cancer called locally advanced head and neck squamous cell carcinoma. This therapy is being tested in patients who already had some treatments (like neoadjuvant immunotherapy and chemotherapy) before surgery and have shown a good response called MPR (Major Pathological Response). The trial aims to see how safe and effective this new therapy is. Participants should be between 18 and 80 years old and in good health overall. They shouldn't have severe autoimmune diseases or infections like HIV or hepatitis.

• The study is conducted at a single center and evaluates a new maintenance therapy.
• Participants must have a good response to prior treatments and meet health criteria.
• Excludes individuals with certain infections or those in other clinical trials.