RecruitingPhase 2Drug trialA Study of Ruxolitinib for Preventing Graft-Versus-Host Disease in People With a Hematologic Malignancy Who Will Receive a Stem Cell TransplantThe researchers are doing this study to compare 2 different GVHD prevention (prophylaxis) approaches. The researchers will see which approach is good or more effective at preventing chronic GVHD until 1 year after allogeneic hematopoietic stem cell transplantation (allo-HCT).