Tislelizumab and Metronomic Capecitabine as Maintenance in High-risk Locoregionally-advanced Nasopharyngeal Carcinoma

This study is testing a maintenance treatment approach for patients with high-risk, locally advanced nasopharyngeal carcinoma (a cancer at the back of the nose and throat). After completing standard treatment, patients receive tislelizumab (an immunotherapy) plus low-dose capecitabine (an oral chemotherapy) to help prevent the cancer from coming back. **You may be eligible if...** - You are 21 years or older - You have been diagnosed with locally advanced nasopharyngeal carcinoma considered to be high-risk - You have completed standard chemoradiation treatment - You are in reasonably good health (ECOG 0-1) - Women of childbearing age must use highly effective contraception and have a negative pregnancy test **You may NOT be eligible if...** - You have previously received an anti-PD-1 or anti-PD-L1 immunotherapy - You have serious autoimmune disease, active infections, or uncontrolled medical conditions - You are pregnant or breastfeeding - You have significant liver, kidney, or heart problems Talk to your doctor to see if this trial is right for you.