Pulsed Dose Chemotherapy Plus Pembrolizumab in Recurrent/Metastatic HNSCC

This study tests a new chemotherapy dosing strategy — short, pulsed doses at regular intervals rather than continuous cycles — combined with the immunotherapy drug pembrolizumab, for head and neck squamous cell carcinoma (HNSCC) that has returned or spread and cannot be cured by surgery or radiation. **You may be eligible if...** - You have recurrent or metastatic squamous cell carcinoma of the head and neck that is no longer curable by local treatment - Your tumor tests positive for PD-L1 (CPS score greater than 1) - You are 18 or older and in acceptable overall health - Your blood counts and organ function meet the required thresholds **You may NOT be eligible if...** - You have active autoimmune disease or are on long-term immunosuppressants - You have had prior pembrolizumab or other anti-PD-1/PD-L1 immunotherapy - You have uncontrolled brain metastases - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.