There are 2 phases in this study: Phase 1 (dose escalation) and Phase 2 (dose expansion). The goal of Phase 1 of this clinical research study is to find the highest tolerable dose of DS-3032b that can be given in combination with low-dose cytarabine (LDAC) to patients with relapsed (has come back)/refractory (has stopped responding to treatment) acute myeloid leukemia (AML). The goal of Phase 2 is to learn if the dose of DS-3032b and LDAC found in Phase 1 can help to control the disease. The safety of this drug combination will also be studied in both phases. This is an investigational study. DS-3032b is not FDA approved or commercially available. It is currently being used for research purposes only. LDAC is FDA approved and commercially available for the treatment of AML. It is considered investigational to give DS-3032b in combination with LDAC to treat AML. The study doctor can explain how the study drugs are designed to work. Up to 32 participants will be enrolled in this study. All will take part at MD Anderson.