Romiplostim Versus rhTPO for Platelet Engraftment After Transplant in MDS and AA

This is a prospective, single-center, randomized, open-label, parallel-controlled Phase II clinical trial. The primary objective is to provide a preliminary efficacy estimate and evaluate the safety of romiplostim compared to recombinant human thrombopoietin (rhTPO) for promoting platelet engraftment following allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with myelodysplastic syndrome (MDS) or aplastic anemia (AA). Study Design and Population: The study will enroll approximately 74 patients to achieve 66 evaluable subjects, randomized in a 1:1 ratio to the romiplostim group or the rhTPO group. Randomization will be stratified by the underlying disease (MDS vs. AA). Eligible patients are aged 18-65 years, diagnosed with MDS or severe/very severe AA (SAA/VSAA), and are candidates for allo-HSCT from a matched sibling, haploidentical, or unrelated donor (including cord blood). Key inclusion criteria require a platelet count \<20×10⁹/L with transfusion dependence between day +4 and day +10 post-transplant. Major exclusion criteria include uncontrolled active infection, significant history of thrombosis, active transplant-associated thrombotic microangiopathy (TA-TMA), pre-transplant bone marrow fibrosis ≥ MF-2 grade, and known allergy to the study drugs. Interventions: Experimental Group (n≈33): Romiplostim administered subcutaneously at a starting dose of 5.0 µg/kg once weekly, beginning on transplant day +4. Subsequent doses (from day +18) will be adjusted weekly based on platelet counts. Active Control Group (n≈33): rhTPO administered subcutaneously at a fixed dose of 15000 U once daily, beginning on transplant day +4. Treatment for both groups continues until the platelet count is ≥50×10⁹/L without transfusion support for 7 consecutive days, until day +60 post-transplant, or for a maximum of 8 weeks, whichever occurs first. All patients will receive standardized transplant supportive care. Endpoints: Primary Endpoints: Platelet engraftment time, defined as the first of three consecutive days with a platelet count ≥20×10⁹/L without platelet transfusion in the preceding 7 days. Incidence of ≥ Grade 3 adverse events (AEs) within 100 days post-transplant, with specific focus on graft-versus-host disease (GVHD) and thrombotic events. Secondary Endpoints: Platelet engraftment rate at day 60 (≥50×10⁹/L), total platelet transfusion units from day 0 to 60, overall survival (OS), progression-free survival (PFS), and non-relapse mortality (NRM). Exploratory Endpoints: Immune reconstitution (lymphocyte subsets), megakaryocyte-related biomarkers, and a pharmacoeconomic evaluation. Oversight and Safety: An Independent Data Safety Monitoring Committee (DSMB) will be established to periodically review accumulated safety data. Safety will be actively monitored through weekly clinical and laboratory assessments during the treatment period, with specific focus on thrombotic events, GVHD, and potential clonal evolution. The study will be conducted at the Department of Hematology, The First Affiliated Hospital of Soochow University, China, following approval by its institutional Ethics Committee.