This study is testing a new drug called Infigratinib for people with certain types of stomach cancer, including gastric cancer (GC) and gastroesophageal junction (GEJ) adenocarcinoma. These cancers are where the stomach and esophagus meet. The study is for patients whose cancer did not respond to at least two other treatments. Infigratinib targets cancer cells with a specific change in a gene called FGFR2. Participants must be 18 or older, have a confirmed diagnosis, and be willing to provide a tumor sample. They should have a good performance status (able to do daily activities) and a life expectancy of 3 months or more.

• Study involves taking Infigratinib for safety and effectiveness testing.
• Participants need to have failed at least two prior treatments.
• There are specific health requirements and restrictions to join the study.