Pembrolizumab, INCB081776, and Radiation Therapy for Head and Neck Squamous Cell Carcinoma

This study tests a three-drug combination — pembrolizumab (an immunotherapy), INCB081776 (a drug that helps the immune system attack cancer more effectively), and targeted radiation therapy — in patients with head and neck squamous cell carcinoma (a type of cancer affecting the mouth, throat, or voice box) that has spread or returned and cannot be cured. **You may be eligible if...** - You have been diagnosed with head and neck squamous cell carcinoma that has spread or returned after prior treatment - Your cancer cannot be treated with surgery or other curative approaches - You have at least one measurable tumor - Prior cancer treatments were completed at least 14 days ago (or 28 days for antibody therapies) **You may NOT be eligible if...** - You have active autoimmune disease requiring systemic treatment - You are on long-term steroids or other immune-suppressing drugs - You have active infections such as HIV or hepatitis B/C that are not controlled - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.