Additional Study Information: This study is being done to answer the following question: What is the highest dose of BAY 1895344 and FOLFIRI chemotherapy (irinotecan, 5-fluorouracil, which is also known as 5-FU, and leucovorin) in combination that can be safely and tolerably taken in patients with advanced gastrointestinal cancer? This is the first time that these drugs will be tested together in humans. We are doing this study because we want to find out if this approach is better or worse than the usual approach for your cancer. The usual approach is defined as care most people get for advanced gastrointestinal cancer. Cancers include esophageal cancer, colon and rectal cancer, and stomach cancer.