Primary Objective: Measure the overall response rate for immunotherapy given with quad-shot radiotherapy.~Secondary Objective(s)~Measure the response rate at the target lesion.~Measure the response rate at non-target sites in patients with non-target sites.~Evaluate the durability of response at the target lesion.~Evaluate progression-free survival.~Evaluate overall survival.~Assess the tolerability of the combination of quad-shot radiotherapy with immunotherapy in order to assess the feasibility of this treatment regimen.~Exploratory Objective: Evaluate the effect of quad- shot administration on increasing the immune activation by treatment with pembrolizumab and investigate possible mechanisms.~OUTLINE: Patients receive standard of care pembrolizumab intravenously (IV) over 30 minutes every 3 weeks. Cycles repeat every 3 weeks in the absence of disease progression or unacceptable toxicity. Patients also undergo quad-shot radiation therapy twice daily (BID) on 2 consecutive days between cycles 2-3 or 3-4, 6-7, and 11-12 of pembrolizumab treatment and in the last week of pembrolizumab treatment.~After completion of study treatment, patients are followed up at 1 and 2 months for adverse events monitoring. Patients will be followed until death for monitoring survival study endpoints. Frequency of visits will be established by the treating physician and will be done in person or over the phone.
This is a single-arm, non-randomized pilot study to evaluate the efficacy and tolerability of combination quad-shot palliative radiotherapy with immunotherapy for advanced/recurrent/metastatic head and neck cancer.