Intensive Conditioning withTHI/Bu/Flu/Ara-C in Allo-HSCT for Myeloid Malignancies With Extramedullary Involvement

This study is a multicenter, single-arm, prospective phase II clinical trial that evaluates the efficacy and safety of an intensive conditioning regimen with thiotepa combined with busulfan, fludarabine, and cytarabine for allogeneic hematopoietic stem cell transplantation in the treatment of myeloid malignancies with extramedullary involvement. The conditioning regimen includes thiotepa at a dose of 5mg/kg/d from d -9 to d -8 (2 days), fludarabine at 30mg/m2/d from d -7 to d -3 (5 days), cytarabine at 1-1.5g/m2/d from d -7 to d -3 (5 days), and busulfan at 3.2mg/kg/d from d -5 to d -3 (3 days). Conditioning begins on day -9, and donor hematopoietic stem cell infusion is performed on day 0. All patients will undergo bone marrow examination on day 14 and day 28 post-transplant, followed by bone marrow examinations every 30 days within the first year after transplantation, and every 60 days within the second year after transplantation. If disease relapse is suspected during the follow-up period, bone marrow or extramedullary relapse site examinations will be conducted at any time. The primary study endpoints are the 1-year and 2-year progression-free survival (PFS) rates post-transplant. Secondary study endpoints include the incidence of acute graft-versus-host disease (GVHD) within 180 days post-transplant, cumulative relapse rates at 1 year and 2 years post-transplant, 1-year and 2-year overall survival (OS), graft-versus-host disease-free, relapse-free survival (GRFS), non-relapse mortality (NRM), cumulative incidence of chronic GVHD, and the incidence of Cytomegalovirus （CMV）and Epstein-Barr virus（EBV）reactivation within 1 year.