Improved Post-Transplant Cyclophosphamide Regimen for Pediatric with Refractory Acute Myeloid Leukemia

Haploidentical stem cell transplantation (HSCT) is a potentially curative therapy for patients refractory acute myeloid leukemia (AML). Graft-versus-host disease (GVHD) is a major barrier to achieve success for patients with HSCT. High dose cyclophosphamide given after HSCT for patients with hematologic malignancies increases neither the relapse nor the non-relapse mortality (NRM). However, few data described outcomes for refractory pediatric AML. From 2015 to 2018, 26 pediatric patients with primary induction failure /relapsed AML were treated in our institution with modified myeloablative regimen, post-transplant cyclophosphamide (PTCy), which has been used as GVHD prophylaxis. The modified sequential regimen consisted of idarubicin (IDA) 10 mg/m2 for 2 days, total body irritation (TBI) 9Gy, divided into 3 fractions and for 3 days, the dose for lung was 6Gy in total followed by thymoglobulin (2.5 mg/kg/d) which was administered for 3 days, etoposide (VP-16, 300 mg/m2) which was infused intravenously for one day, cladribine (10 mg/m2/d) which was administered for 3 days. In our study, results showed that 1 and 2-year overall survival (OS) were both 88.5%, the NRM at 1-year and 2-years were both 3.9%, cumulative incidence of relapse was 8% at 1- year and 12% at 2- years. Leukemia- free survival (LFS) at 1 and 2 years was 88.5% and 84.6%, respectively. No patients developed chronic GVHD (cGVHD) and acute GVHD (aGVHD, grade III-IV), and aGVHD (grade I-II) was 23.1 %. Clinical Trial Number: and registered at the Clinical Trial gov. (http://clinicalTrails.gov) (Identifier: ClinicalTrails.gov, ID: NCT03654703). Funding Statement: The authors declare no funding support. Declaration of Interests: The authors declare no competing financial interests. Ethics Approval Statement: The protocol was approved by the ethics review committee of each institution.