Reduced Intensity Umbilical Cord Blood Transplantation(RI-UCBT) in Adult Patients with Graft Failure or Relapse after First Allogeneic Transplantation.

Background: Graft failure, graft rejection, or disease relapse post allogeneic hematopoietic stem cell transplantation(HSCT) is life-threatening and serious complication that necessitate consideration for a second transplantation. Graft failure has been more frequently reported in patients with aplastic anemia with T-cell depletion of the graft, in cord blood transplants, or when unrelated or HLA-mismatched related donors were used. In second allogeneic stem cell transplant setting, current questions include suitable stem cell source, additional conditioning, immunosuppression, and the use of a different donor, still remain unknown. We performed a feasibility study of reduced intensity umbilical cord blood transplantation (RI-UCBT) in adult patients with graft failure or disease relapse after first allogeneic transplantation.

Patients and Methods: Nine patients (median age, 53 years; range 17–68) with advanced hematological diseases [AML (n=4), ALL (n=2), MDS (n=2), ATL (n=1)] who showed relapse or graft failure after first allogeneic transplantation underwent RI-UCBT with single cord blood unit at Toranomon Hospital between May 2003 and February 2004. Eight cases were in non-CR at transplant. A median time from first to second transplant was 226 days (range 31–475). The median number of mononuclear cells transfused was 2.3 x 10⁷ /kg (range 1.8–3.5). HLA disparities were as follows; 5/6 in two cases, 4/6 in seven cases. Conditioning regimen mainly consisted of fludarabine 25 mg/m2 on days -7 to −3, melphalan 40mg/m² (n=8) or busulfan 4mg/kg(n=1) day −3 to −2, and 4 Gy total body irradiation on day −1. Graft-versus-host disease (GVHD) prophylaxis was composed of ciclosporin alone (n=6) and tacrolimus alone (n=3).

Results: All of them achieved primary neutrophil engraftment (>500/μL) after a median of 22 days (range, 15–32) and achievement of donor T-cell chimerism was confirmed. Four cases developed grade II-IV GVHD, and one case developed limited chronic GVHD. Of all the nine cases received RI-UCBT, seven died from relapse (n=4), sepsis (n=2), and TMA (n=1). Two survived without relapse for +232 and +81 days, respectively.

Discussion: Although the number of patients is small and the follow-up period is short, our results corroborate that RI-UCBT for graft failure or relapse post first transplant is tolerated and may be worth considering for further evaluation. Neutrophil engraftment was achieved, however, disease relapse rate and treatment-related mortality is high. The management of disease status and development of ideal conditioning regimen will be the focus of future investigation.