Nivolumab +/- Relatlimab Prior to Chemoradiation With II/III Gastro/Esophageal Cancer

This is a Phase IB study assessing the safety of 2 cycles of induction (Arm A) nivolumab or (Arm B) 2 cycles of induction nivolumab prior to concurrent chemoradiation plus nivolumab (Arm A) or nivolumab/relatlimab (Arm B) before surgical resection in operable stage II/III esophageal/gastroesophageal junction cancer. Approximately 32 patients will be enrolled on study with 16 enrolled on Arm A and if no unexpected toxicities then an additional 16 patients will be enrolled on Arm B.