This study investigates the safe dosage levels of an investigational medication alone and in combination with another investigational medication after a type of stem cell transplant. It focuses on patients with blood cancers like acute myeloid leukemia and myelodysplastic disorders. The study aims to understand the effects of these medications on transplant outcomes, including infection and disease response.

Participants will receive either the investigational medication alone or combined with another investigational medication. The study will monitor how the body responds to these treatments and observe any side effects. It will also examine how these treatments impact the success of the stem cell transplant.

• Who can participate: Adults with acute myeloid leukemia in remission or high-risk myelodysplastic disorders can participate. They must be undergoing a reduced-intensity allogeneic peripheral blood stem cell transplant.
• Study details: Participants will receive an investigational medication alone or with another investigational medication after their stem cell transplant. A placebo is not used in this study.