Alpha Radiation Emitters Device (DaRT) in Combination With Check Point Inhibitor for the Treatment of Recurrent Unresectable or mHNSCC

This study tests a combination of two treatments — radioactive seed implants (called DaRT, which emit low-level radiation directly into a tumor) and immune checkpoint inhibitor drugs — for head and neck cancers that have come back or spread and cannot be surgically removed. **You may be eligible if...** - You are 18 or older with confirmed squamous cell carcinoma of the head and neck that has returned or spread - Your tumor can be targeted with the DaRT seed implant - You are in reasonably good health (ECOG performance status 0–2) - Your blood counts and kidney/liver function are within acceptable ranges - Your expected survival is more than 6 months **You may NOT be eligible if...** - You have poor organ function (kidney, liver, heart, or bone marrow) - You have certain serious infections like HIV or hepatitis - You have uncontrolled autoimmune diseases - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.