Allogeneic stem cell transplantation without preconditioning in a child with therapy-related myelodysplastic syndrome: A case report

Infants with mixed-lineage leukemia (MLL)-rearranged leukemia are usually refractory to standard induction therapy and are not immediate candidates for allogeneic hematopoietic stem cell transplantation (allo-HSCT). Chromosome 11q23 translocations, resulting in MLL rearrangement, have been well characterized in infant acute lymphoblastic leukemia (ALL). While t(4;11) ALL continues to have carry a bleak prognosis, patients with therapy-related myelodysplastic syndrome (t-MDS) have a shorter median overall survival than those compared with de novo MDS. We describe a child with t-MDS who evolved from MLL-rearranged ALL and was successfully treated with HSCT without toxic preconditioning. MDS diagnosis was based on morphological characteristics of bone marrow dysplasia in patients with clinical manifestations evidence of hematopoiesis impairments by different combinations of anemia, leukopenia, neutropenia, and thrombocytopenia. Although the best donor for allo-HSCT is generally considered an human leukocyte antigen-matched sibling, only ~ 30% of patients have a suitable sibling. HSCT from an unrelated donor is a suitable option for patients with t-MDS who do not have matched sibling donors. Allo-HSCT without recipient preconditioning could be a promising treatment option for t-MDS, especially for patients with recurrent or persistent infections. Cytogenetics, prognosis, and treatment of t-MDS are briefly discussed. Preconditioning before allo-HSCT seriously damages immune function. This work reviews our experience with a patient with t-MDS following ALL complicated by recurrent infections, and highlights our choice to omit preconditioning from allo-HSCT.