AB8939 in Patients With Relapsed/Refractory Acute Myeloid Leukemia

This study is testing a new drug called AB8939 for people with acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS) — a blood cancer of the bone marrow — that has returned or stopped responding to previous treatments. **You may be eligible if...** - You have been diagnosed with AML and are eligible for second or third-line treatment - Or you have high-risk MDS that did not respond to at least two prior treatments - You are in good enough physical condition to participate (ECOG score of 1 or less for the escalation phase, 2 or less for expansion) **You may NOT be eligible if...** - You are eligible for a standard of care treatment - You are eligible for a bone marrow transplant at this time - You have a specific subtype of AML called acute promyelocytic leukemia (APL/M3) - You have leukemia that has spread to the brain or spinal fluid - You had a stem cell transplant within the past 100 days - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.