Pembrolizumab, Capecitabine, and Radiation Therapy in Treating Patients With Mismatch-Repair Deficient and Epstein-Barr Virus Positive Gastric Cancer

This phase II trial studies how well pembrolizumab works with capecitabine and radiation therapy in treating patients with mismatch repair deficient and Epstein-Barr virus positive gastric cancer. Monoclonal antibodies, such as pembrolizumab may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Radiation therapy uses high energy x-rays to kill tumor cells and shrink tumors. Giving pembrolizumab, capecitabine and radiation therapy may work better at treating gastric cancer.