Syngeneic Blood and Marrow Transplantation: A Report of 94 Cases From Chinese Society of Blood and Marrow Transplantation (CSBMT).

Abstract 4295

Syngeneic blood and marrow transplantation (BMT) has been applied in the treatment of many malignant or nonmalignant hematologic disorders with no or minimal and transient graft-versus-host disease (GVHD), much less transplant-related mortality (TRM) in contrast to allogeneic BMT, and lower relapse rate compared with autologous BMT. However, limited data in a single BMT center is not sufficient for statistical analysis. To evaluate the clinical outcomes of syngeneic BMT, CSBMT has performed a cooperative survey among BMT centers in mainland, Taiwan, and Hong Kong. From January 1964 to May 2009, 94 transplants from syngeneic donors have been performed in 32 BMT centers. The median age was 20 (1.5 to 51) years old. The diagnosis included AML (29 cases), SAA (26 cases), ALL (17 cases), CML (12 cases), lymphoma (3 cases), MDS (4 cases), neuroblastoma (2 cases), and large granular lymphocytosis (1 case). The main conditioning regimens were CYTBI or BUCY for malignant diseases, none or CY plus ATG for SAA. Bone marrow (BM, 34) or peripheral blood (PB, 49) or both BM and PB (11) as grafts were used. Five patients (SAA 2, AML 3) underwent the same donor's syngeneic BMT twice. One patient with large granular lymphocytosis and 1 case with SAA underwent the same donor's syngeneic BMT thrice. The median follow-up time was 28 months (1 month to 45 years). The median time for white blood cells > 1.0 × 10⁹/L, and platelets > 20 × 10⁹/L was 11 (2-30) days, 13 (0-122) days, respectively. Two patients (2.1%) had grade I acute GVHD (aGVHD), and 4 cases (4.3%) had grade II aGVHD. However, only one patient's specimen was consulted by pathologist. All aGVHD was controlled easily with low-dose steroid. No chronic GVHD was noted. Three-year disease-free survival (DFS) for the patients with nonmalignant disorders was 88.5%. Among them, the longest survivor was living and well for 45 years after transplant. Three-year DFS for the patients with malignant diseases was 62.9%. The overall survival rates at 3 years were 87.9%, and 69.5% for nonmalignant, and malignant diseases, respectively. 22 of 94 patients died after BMT (nonmalignant 3, malignant 19). The only cause of death for the patients with nonmalignant disorders was rejection. Relapse was the main cause of death in patients with malignancies (17/19). TRM was 2.1%. In conclusion, syngeneic BMT is a safe and effective therapeutic option for both nonmalignant and malignant hematologic disorders. Syngeneic donor, if available, should be the first choice in all cases of AA and hematological malignancies in general. The longest survivor of 45 years post-BMT is presented in this series. The good results and advantage of syngeneic BMT cast light on the potential utility of stored autologous placental-cord blood which is shared by the identical twin through the same placenta.