This study is exploring a new medicine, **emavusertib (CA-4948)**, for treating **Acute Myelogenous Leukemia (AML)** and **Myelodysplastic Syndrome (MDS)**. AML and MDS are types of blood cancers that affect how blood cells develop. This study is in two phases: Phase 1, to find the best dose of the medicine, and Phase 2, to see how well it works in treating cancer. Participants need to have certain types of genetic changes in their cancer, like **FLT3** or **SF3B1** mutations. They should have tried 1 or 2 other treatments before. The medicine is taken as a pill twice a day for 28 days each cycle. If the medicine works and is safe, participants can continue taking it. **Key Points:** - **Visit Requirement:** Regular visits for taking the medicine and monitoring are necessary. - **Study Length:** Each treatment cycle is 28 days, and participants can continue as long as it's safe and beneficial. - **Eligibility:** Participants must have tried other treatments and meet specific health conditions. This study is open for adults who are willing to comply with the study requirements and have a life expectancy of at least three months.