Second umbilical cord blood transplantation for relapsed adverse-risk acute myeloid leukemia patient with near-homozygous HLA haplotypes.

Transplantation involving human leukocyte antigen (HLA) haplotype-homozygous individual is a rare circumstance, and for the unidirectional HLA mismatches in some cases, its transplant prognosis exhibits certain characteristics. This report details a case of an adverse-risk acute myeloid leukemia (AML) patient with near-homozygous HLA haplotypes who underwent double units unrelated umbilical cord blood transplant (dUCBT) twice. Molecular relapse was detected 1 year and 2 years after the first transplantation, and complete remission (CR) was regained by drug therapy (venetoclax and azacitidine) on both occasions. A second transplantation was performed after hematologic relapse occurred 3 years later. The patient remained clinically stable for one year after CR again, without graft-versus-host disease symptoms. This case suggests that second UCBT for relapsed adverse-risk AML with near-homozygous HLA haplotypes is feasible.