Haplo-Cord HSCT for AML/MDS

This study aims to investigate the clinical efficacy of haploidentical-cord blood hematopoietic stem cell transplantation in patients with acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS), and to analyze the impact of different engraftment patterns (haploidentical engraftment versus cord blood engraftment) on clinical outcomes. By comparing the efficacy of haploidentical-cord blood transplantation in different subtypes of AML and MDS, this research will explore its unique advantages and comparative effectiveness relative to conventional transplantation strategies, so as to provide new evidence for clinical practice. Specific research objectives I. To evaluate the efficacy of haploidentical-cord blood hematopoietic stem cell transplantation for AML and high-risk MDS, including the speed of hematopoietic recovery, immune tolerance, and long-term survival rates. II. To compare the effects of different engraftment patterns (haploidentical engraftment vs. cord blood engraftment) on quality of life, immune tolerance, early complications, and long-term prognosis. III. To identify the clinical advantages and indications of haploidentical-cord blood transplantation through data analysis, and to provide a theoretical basis for clinical decision-making. Novelty of the Study I. Innovation in Hematopoietic Stem Cell Infusion Schedule The present study employs a sequential infusion strategy: haploidentical stem cells are infused on Day 0, and umbilical cord blood cells are infused on Day +6 after transplantation.In contrast to the conventional approach used at most domestic and international centers (including the uzhou Protocol), in which both stem cell sources are infused simultaneously on Day 0, the current protocol delays cord blood infusion. This design confers potential advantages for immune reconstitution and long-term cord blood engraftment. II. Unique Myeloablative Conditioning Regimen The conditioning regimen used in this study is as follows: Fludarabine 25 mg/m² for 5 days, Cytarabine 2 mg/m² for 5 days, intravenous Busulfan 3.2 mg/kg for 3 days, ATG 5 mg/m² for 2 days, Melphalan 60 mg/m² for 2 days, and CTX 50.0 mg/kg daily for 2 days. (For patients in complete remission (CR) with negative MRD before transplantation, Fludarabine and Cytarabine are administered for 3 days instead of 5 days.) Distinct from regimens at other centers, our team administers cyclophosphamide within the critical window after haploidentical stem cell infusion but before cord blood infusion, establishing a novel sequential conditioning model. This approach balances myeloablative intensity and immunomodulation, creating a favorable environment for subsequent long-term cord blood engraftment. III. Engraftment Outcomes and Clinical Value Preliminary clinical experience demonstrates that haplo-cord sequential transplantation following the FA5Cy2Bu3 conditioning regimen combined with low-dose ATG/PTCY can achieve long-term cord blood engraftment in approximately 50% of patients. By comparison, other domestic protocols (e.g., the Suzhou Protocol) rarely result in sustained cord blood engraftment. Achievement of long-term cord blood engraftment is clinically meaningful for reducing relapse rates, lowering the incidence and severity of graft-versus-host disease (GVHD), and improving patient prognosis. These outcomes represent a key advantage of the present protocol.