Successful engraftment of mismatched unrelated cord blood transplantation following reduced intensity preparative regimen using fludarabine and busulfan

We conducted a pilot study to evaluate the feasibility of reduced-intensity cord blood transplantation (RI-CBT) using a non-total body irradiation (TBI) regimen in adult patients with advanced hematologic malignancies. Seventeen patients with a median age of 58 years (range, 38-74) underwent RI-CBT at Tsukuba Memorial Hospital between April 2004 and November 2005. Preparative regimens were fludarabine 30 mg/m(2) for 6 days, and busulfan 4 mg/kg for 2 days. Tacrolimus was used for prophylaxis of graft-vs-host disease (GVHD). Median numbers of infused total nucleated were 2.6 x 10(7)/kg (range, 2.0-3.3). HLA disparity was found in 2/6 antigens (n = 16) and 1/6 antigens (n = 1). Underlying diseases progressed despite preparative regimens in four patients. Of the remaining 13 patients, nine patients achieved engraftment at a median of day 18 (range, 17-28). Six of the nine patients with engraftment achieved complete donor-type chimerism by day 100. Six patients were alive in remission at median follow-up of 13.1 months (range, 1.0-19.0). This study demonstrated the feasibility of RI-CBT using a non-TBI regimen in adults. When disease progression is controlled by the preparative regimen, RI-CBT carries a clinically significant graft-vs-tumor effect. Further studies are required to identify patients who benefit from this regimen.