Clinical Efficacy of Haplo-HSCT of ATG Combined with PTCy for Children with Myelodysplastic Syndrome

Abstract

To investigate the efficacy and safety of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in combination of ATG and post-transplant cyclophosphamide (PTCy) -induced immune tolerance after transplantation in treatment of childhood myelodysplastic syndromes(MDS）. From July 2016 to November 2020, a total of 8 children with MDS receiving the haploidentical allo-HSCT combined with ATG and PTCy-induced immune tolerance after transplantation in our hospital were enrolled, whose clinical data were retrospected and analyzed. Median age at diagnosis of the 8 children (1 male and 7 females) was 6.4 (range, 10 months to 15 years) years old. The median medical history of MDS was 2.7 years (range, 3 months to 8 years). Among the 8 patients, 7 cases were diagnosed with refractory cytopenia of childhood and one with refractory anemia with excess of blasts. The HSC donors were father, mother or brother of patients and HLA matching in 6-9/12 loci were identical. All the donors were healthy and didn't carry the same pathogenic genes as the recipients. The median age of donors was 36.4 (range, 25 to 49) years old. The median mononuclear cell (MNC) number of the graft was 19.8, ranging in (13.2-47.3)×108/kg, and the median CD34+ cell number was 11.8×106/kg, ranging in (5.0-18.3)×106/kg. Graft-versus-host disease prophylactic regimen was started on day 3 and 4 after transplantation, in which cyclophosphamide (50 mg/kg·d) was administered by intravenous infusion. From day 5 after transplantation, low-dose tacrolimus was administered by intravenous infusion and mycophenolate mofetil was administered orally. The median time of neutrophil and platelet engraftment was 12.6 (rang, 11 to 15) days and 13.3 (rang, 11 to 18) days, respectively. All the patients achieved full donor chimerism on neutrophil engraftment after transplantation. The median follow-up time was 1 032 (rang, 747 to 1 536) days. Both overall survival rate and disease-free survival rate were 100%. Haplo-HSCT combined with ATG and PTCy-induced immune tolerance after transplantation is a safe and effective treatment for children with MDS.