Matched unrelated donor transplantation versus haploidentical transplantation with post-transplant cyclophosphamide in children with acute myeloid leukemia: a PDWP-EBMT study.

In children with acute myeloid leukemia (AML) who lack an HLA identical sibling, the donor can be replaced with an HLA matched unrelated donor (MUD) or a haploidentical donor (haplo). We compared outcomes of patients <18 years with AML in first and second complete remission (CR1 and CR2) undergoing a hematopoietic stem cell transplantation (HCT) either with a MUD with anti-thymocyte globuline (ATG) (n=420) or a haplo HCT with PT-CY (n=96) after a myeloablative conditioning regimen (MAC) between 2011 and 2021, reported to EBMT. A matched pair analysis was performed to adjust for differences among groups. The final analysis was performed on 253 MUD and 95 haplo-HCTs. In the matched cohort, median age at HCT was 11.2 and 10 years and median year of HCT was 2017 and 2018, in MUD and haplo- HCT recipients, respectively. The risk of grade III-IV aGvHD was significantly higher in the haplo group (HR=2.33, 95%CI1.18-4.58, p=0.03). No significant differences were found in 2 years overall survival (OS; 78.4%vs71.5%; HR 1.39, 0.84-2.31, p=0.19), leukemia-free-survival (LFS; 72.7%vs69.5%; HR1.22, 0.76-1.95, p=0.41), CI of relapse (RI; 19.3%vs19.5%; HR=1.14, 0.62-2.08, p=0.68) non-relapse-mortality (NRM; 8%vs11%; HR=1.39, 0.66-2.93, p=0.39) and graft versus host free-relapse free survival (GRFS; 60.7%vs54.5%, HR=1.38, 0.95-2.02, p=0.09) after MUD and haplo-HCT respectively. Our study suggests that haplo-HCT with PT-CY is a suitable option to transplant children with AML lacking a matched related donor.

Successful HLA-identical hematopoietic stem cell transplantation in a patient with purine nucleoside phosphorylase deficiency.

PNP deficiency is an autosomal recessive metabolic disorder characterized by severe combined immunodeficiency, autoimmune hemolytic anemia, and by a complex of neurologic manifestations including ataxia, developmental delay, and spasticity. PNP protein catalyzes the phosphorolysis of deoxyinosine and deoxyguanosine. It is found in most tissues of the body but is expressed at the highest levels in lymphoid tissues. This tissue distribution explains why the lymphoid system is predominantly affected in PNP deficiency. We describe a five-yr-old boy with muscular hypertonia, impaired growth, autoimmune hemolytic anemia, and neutropenia who underwent HSCT from his HLA-identical sister. One yr post-HSCT, the boy developed normal immunological functions, and his neurological status improved.