Safety and Efficacy of SHR2554 Combined With Other Antitumor Therapies in Gastric or Gastro-oesophageal Junction Adenocarcinoma

This study is testing whether a drug called SHR2554 (an EZH2 inhibitor) combined with other cancer treatments is safe and effective in people with stomach or gastroesophageal junction cancer. **You may be eligible if...** - You are 18 or older - You have stomach cancer or cancer where your stomach meets your esophagus (gastroesophageal junction) - You have at least one measurable tumor on scans - Your overall health is good enough to participate (ECOG 0 or 1) - You are willing to provide a tumor tissue sample **You may NOT be eligible if...** - You have difficulty swallowing pills - You have previously been treated with an EZH2-targeting drug - You have serious heart conditions or uncontrolled brain metastases - You have significant nerve damage in your hands or feet Talk to your doctor to see if this trial is right for you.