Dose-Expansion Study of Low Dose Post-Transplant Cyclophosphamide/Tacrolimus/Ruxolitinib for Graft-versus-Host Disease (GVHD) Prophylaxis in Myeloablative Allogeneic Peripheral Blood Stem Cell Transplantation

This study tests a specific combination of drugs — low-dose cyclophosphamide, tacrolimus, and ruxolitinib — given after a stem cell transplant from a donor to prevent graft-versus-host disease (GVHD), a serious complication where the donor's immune cells attack the patient's body. **You may be eligible if...** - You are 18 or older - You have acute leukemia (with fewer than 5% blast cells in bone marrow) or a myelodysplastic syndrome - You are receiving a stem cell transplant from a matched related or unrelated donor using peripheral blood stem cells - Your heart, lung, kidney, and liver function meet specified thresholds - You have a Karnofsky performance score of at least 70% **You may NOT be eligible if...** - You have had a prior bone marrow or stem cell transplant - You have active cancer in the brain or spinal fluid - You have an uncontrolled infection (bacterial, viral, or fungal) - You have active or poorly treated tuberculosis - You have uncontrolled HIV with detectable viral load, or active hepatitis B or C - You had a heart attack, stroke, or dangerous blood clot in the past 6 months - You have severe heart failure - You are pregnant or breastfeeding - You have previously been treated with ruxolitinib or immune checkpoint inhibitor drugs within the past 6 months Talk to your doctor to see if this trial is right for you.