RecruitingBiological interventionA Study of 2141-V11 in People With Esophageal, Gastric, or Gastroesophageal Junction AdenocarcinomaThe purpose of this study is to find out whether adding the drug 2141-V11 to standard treatment (anti-PD-1 immunotherapy with or without 5-FU) is a safe treatment approach for participants with advanced esophageal, gastric, or gastroesophageal junction adenocarcinoma