A pediatric patient who underwent related bone marrow transplantation with reduced-intensity conditioning for near-haploid acute lymphoblastic leukemia

Abstract

A three-year-old boy was diagnosed as having B-cell precursor acute lymphoblastic leukemia (BCP-ALL). He was treated using the JPLSG ALL-B12 protocol and underwent allogeneic hematopoietic cell transplantation (HCT) during his first complete remission (CR1) because of a near-haploid karyotype (29 chromosomes). CR1 status was confirmed after induction therapy. The minimal residual disease (MRD) test showed a negative result after early intensive therapy. Moreover, he underwent bone marrow transplantation from his HLA 8/8 allele-matched father as the donor, with a reduced-intensity conditioning (RIC) regimen, consisting of 100 mg/m² fludarabine, 8000 mg/m² cytarabine, 180 mg/m² melphalan, and 3 Gy total body irradiation. He achieved neutrophil count recovery on day 18 and was discharged 80 days after HCT without severe adverse events. He is alive and disease-free 5.5 years after HCT. Although near-haploid BCP-ALL has a poor prognosis, patients with an MRD-negative status can survive with a good quality of life through HCT with RIC in CR1.