Safety Run-In:~To evaluate the safety of the addition of pembrolizumab (anti PD-1 immunotherapy) to re-irradiation with SBRT for patients with recurrent or new second primary head and neck squamous cell carcinoma (HNSCC).~Phase II:~To compare progression-free survival (PFS) for patients with recurrent or new second primary head and neck squamous cell carcinoma with SBRT re-irradiation with or without pembrolizumab.~OUTLINE:~Safety Run-In: Patients receive SBRT over 2 weeks and then receive pembrolizumab every 3 weeks for up to 2 years.~Phase II: Patients are randomized to 1 of 2 treatment arms.~ARM I: Patients receive SBRT over 2 weeks and then receive pembrolizumab every 3 weeks for up to 2 years.~ARM II: Patients receive SBRT over 2 weeks. Arm II patients who experience progressive disease within 2 years after the start of SBRT will be allowed to cross over to receive pembrolizumab for up to 2 years.~After the completion of study treatment, patients are followed up every 6 months for 3 years.
This phase II trial with a safety run-in component will evaluate whether the addition of pembrolizumab to Stereotactic Body Radiation Therapy (SBRT) re-irradiation will improve the progression-free survival for patients with recurrent or new second primary Head and Neck Squamous Cell Carcinoma (HNSCC).