Decitabine and Venetoclax Treatment as Maintenance Therapy in Patients Post Allograft Stem Cell Transplant

The goal of this interventional clinical trial is to determine if low doses of gentle chemotherapy after bone marrow transplant may prevent relapse and promote an increase in survival and decrease in side effects in participants with acute myeloid leukemia and myelodysplastic syndromes. The main question it aims to answer is whether or not providing a new, gentler way of administering chemotherapy will help control leftover cancer with minimal side effects. This treatment involves decitabine and venetoclax. Participants will receive standard post-transplant care. Participants will be administered decitabine once per week with normal transplant follow up visits, and then will take a venetoclax pill about 6 to 8 hours later. Participants will meet their study team at the beginning, midway, and at the end of the trial to receive bone marrow testing. Participants will receive treatment until either one year of therapy, relapse, or recurrent dose limiting toxicity (DLT) despite dose reduction.