ABSTRACT
Objective To evaluate the safety and efficacy of an further optimized pretreatment protocol for the treatment of severe aplastic anemia (SAA) by haploidentical peripheral hematopoietic stem cell transplantation. Methods From July 2009 to July 2019, 26 SAA patients in the Affiliated Hospital of North China University of Technology were treated with haploidentical peripheral blood stem cell transplantation. The "Beijing protocol" of haploid transplantation for treating SAA is modified busulfan (BU)/cyclophosphamide (CY) + rabbit anti thymocyte globulin (ATG) regimen. We based on it and further refined it. Here's how it works: (1) According to the different volumes of hematopoietic tissue in bone marrow biopsy before transplantation, different methods for clearance of residual hematopoietic cells were established in SAA patients. If bone marrow hematopoietic tissue volume<10%, the bone marrow was pretreated with Beijing protocol of BU/CY+ATG. If 10% ≤ bone marrow hematopoietic tissue volume ≤25%, the dose of BU for 1 day was added on the basis of the original protocol: Increase the dose of BU to 9.6 mg/kg (intravenous drip in 3 days), which became a modified BU/CY+ATG transplantation preconditioning protocol. (2) According to the diagnosis of the disease, the transplantation pretreatment was designed: Patients with SAA-PNH syndrome or with PNH alone were treated with further modified BU/CY+ATG transplantation preconditioning protocol, and the BU dose was set as 9.6 mg/kg (intravenous drip in 3 days). Transplantation way: The "Beijing protocol" is use of bone marrow plus peripheral blood hematopoietic stem cell. Based on it, the protocol was modified to simple peripheral blood hematopoietic stem cell transplantation. Results 22 of 26 SAA patients underwent hematopoietic reconstruction. The patients were followed up until December 2019, and the results were as follows: During a median follow-up period of 48 (5-122) months, 5 patients died, 4 of whom suffered transplant-related deaths (15.4%, 4/26), and 1 of whom was due to central nervous system infection (3.8%, 1/26). The 3-year overall survival rate (OSR) was 84.2%, the 3-year progression-free survival (PFS) was 72.6% (SAA I: 100.0%, SAA-PNH: 100.0%, SAA II: 72.2%). Conclusions The further improved BU/CY+ATG transplantation preconditioning scheme is safe and effective in SAA with haploid peripheral blood stem cell transplantation. It is suitable not only for SAA I, SAA II, but also for patients with PNH clone, thus being worth wider clinical aplplication.