A pilot study of reduced intensity conditioning and allogeneic stem cell transplantation from unrelated cord blood and matched family donors in children and adolescent recipients

Reduced intensity (RI) allogeneic stem cell transplantation (AlloSCT) was initially demonstrated in adults following HLA-matched family and unrelated adult donor AlloSCT. There is little information about RI AlloSCT in children. We report results of a pilot study of RI AlloSCT in 21 recipients (⩽21 years). Age: median 13 (0.5–21) years, 8F:13M, 14 unrelated cord blood units (UCB) (10 4/6, 4 5/6), two related BM (6/6, 5/6), four related PBSC (2 6/6, 2 5/6), and one related BM+PBSC (6/6). RI: fludarabine, busulfan (n=14); fludarabine, cyclophosphamide (n=4); fludarabine, melphalan (n=1); total body irradiation, fludarabine, cyclophosphamide (n=1); or fludarabine, cyclophosphamide, and etoposide (n=1). Graft-versus-host disease prophylaxis: FK506 0.03 mg/kg/day and mycophenolate mofetil 15 mg/kg/q 12 h. UCB median nuc/kg and CD34/kg was 4.3 × 107/kg (0.9–10.8) and 1.9 × 105/kg (0.3–6.9), and related BM/PBSC median nuc/kg and CD34/kg was 8.3 × 108 (4.7–18.9) and 5.0 × 106/kg (4.6–6.4). Maximal chimerism following unrelated cord blood transplantation, 100% × 7, 98% × 1, 95% × 2, 55% × 1, and 0% × 3; related PBSC/BM, 100% × 5, 65% × 1, and 55% × 1. Graft failure occurred in 5/21 (24%). In summary, RI AlloSCT in children is feasible and tolerable (⩽25% GF) and results in ⩾85% of recipients initially achieving ⩾50% donor chimerism.