Losartan, Pembrolizumab and Stereotactic Body Radiation Therapy for the Treatment of Patients With Locally Recurrent, Refractory or Oligometastatic Head and Neck Squamous Cell Carcinoma

This trial is testing a combination of three treatments — losartan (a blood pressure medication), pembrolizumab (an immunotherapy drug), and targeted radiation — for people with head and neck squamous cell carcinoma (a type of cancer in the mouth, throat, or neck area) that has come back, stopped responding to treatment, or spread to a small number of other sites. **You may be eligible if...** - You have been diagnosed with squamous cell carcinoma of the head and neck that has returned, is not responding to current treatment, or has spread to no more than 4 spots - Your cancer cannot be fully removed with surgery - You are 18 or older and in reasonably good physical health (able to carry out daily activities) - You have measurable cancer that can be seen on a CT or MRI scan - Your blood counts, liver, and kidney function are within acceptable ranges - You are willing to use contraception during the study and for up to 3 months after **You may NOT be eligible if...** - Your cancer started in the nasopharynx, salivary gland, or skin - You have previously been treated with a checkpoint immunotherapy drug (like nivolumab, atezolizumab, or similar) - You have significant heart, lung, or nerve problems unrelated to your cancer - You have had radiation to the head and neck in the past 6 months - You are currently taking blood pressure medications that work on the same pathway as losartan (ACE inhibitors or ARBs) - You have uncontrolled diabetes or active autoimmune disease requiring treatment Talk to your doctor to see if this trial is right for you.