Azacitidine, Venetoclax, and Gilteritinib in Treating Patients With Recurrent/Refractory FLT3-Mutated Acute Myeloid Leukemia, Chronic Myelomonocytic Leukemia, or High-Risk Myelodysplastic Syndrome/Myeloproliferative Neoplasm

This study is testing a combination of three drugs — azacitidine, venetoclax, and gilteritinib — for people with certain types of blood cancer (acute myeloid leukemia or related conditions) that have a specific FLT3 gene mutation. The study includes newly diagnosed patients as well as those whose cancer has returned or not responded to prior treatment. **You may be eligible if...** - You are 18 or older - You have a diagnosis of AML (acute myeloid leukemia), CMML (chronic myelomonocytic leukemia), or high-risk myelodysplastic syndrome (MDS), with an FLT3 gene mutation - Depending on the study group (newly diagnosed vs. relapsed/refractory), you may or may not have had prior treatment - Your kidney, liver function, and heart rhythm (QTc) are within acceptable limits - You are able to swallow medications **You may NOT be eligible if...** - You have active central nervous system leukemia (cancer in the fluid around the brain) - You have HIV, active hepatitis B or C - You have serious heart failure (grade III-V) - You have a congenital long QT syndrome or severely abnormal heart rhythm - You are pregnant or breastfeeding - You have recently taken certain strong medications that interfere with this treatment Talk to your doctor to see if this trial is right for you.