Graft failure following reduced-intensity cord blood transplantation for adult patients.

We reviewed the medical records of 123 adult reduced-intensity cord blood transplantation (RI-CBT) recipients to investigate the clinical features of graft failure after RI-CBT. Nine (7.3%) had graft failure, and were classified as graft rejection rather than primary graft failure; they showed peripheral cytopenia with complete loss of donor-type haematopoiesis, implying destruction of donor cells by immunological mechanisms rather than poor graft function. Three of them died of bacterial or fungal infection during neutropenia. Two recovered autologous haematopoiesis. The remaining four patients underwent a second RI-CBT and developed severe regimen-related toxicities. One died of pneumonia on day 8, and the other three achieved engraftment. Two of them died of transplant-related mortality, and the other survived without disease progression for 9.0 months after the second RI-CBT. In total, seven of the nine patients with graft failure died. The median survival of those with graft failure was 3.8 months (range, 0.9-15.4). Graft failure is a serious complication of RI-CBT. As host T cells cannot completely be eliminated by reduced-intensity preparative regimens, we need to be aware of the difficulty in differentiating graft rejection from other causes of graft failure following RI-CBT. Further studies are warranted to establish optimal diagnostic and treatment strategies.