Salvage UCBT with Short-Term Melphalan-based Reduced-Intensity Conditioning for Primary Graft Failure after Upfront UCBT for Fulminant Aplastic Anemia

Umbilical cord blood transplantation (UCBT) is a potential option for patients with very severe aplastic anemia (VSAA) when no suitable related or unrelated donor is available. However, the high incidence of graft failure following UCBT remains a major challenge. The optimal conditioning regimen for UCBT in aplastic anemia (AA), particularly for salvage UCBT after graft failure following an initial transplant, remains undetermined. We report the cases of two adolescent patients with fulminant aplastic anemia who successfully underwent salvage UCBT, conditioned by a short-term melphalan-based regimen for primary graft failure after initial UCBT. The regimen comprised fludarabine (30 mg/m²) on days -4 to -2, melphalan (40 mg/m²) on days -3 and -2, and total body irradiation (2 Gy) on day -1. Neutrophil engraftment occurred in both cases approximately three weeks after salvage UCBT. One patient developed grade 1 acute graft-versus-host disease (GVHD) and mild chronic GVHD, while the other experienced no GVHD. Both patients have normal complete blood counts more than two years after salvage UCBT. These cases suggest that a short-term melphalan-based regimen may be a viable conditioning option for salvage UCBT in cases of primary graft failure.