Safety and efficacy of umbilical cord blood (UCB) transplantation using a low-dose total body irradiation (TBI) containing regimen for hematologic malignancies

INTERVENTION: Conditioning regimen with fludarabine 25mg/m2 for 5 days, melphalan 40mg/m2 for 2 days and TBI at a dose of 2 Gy on day‐1 are used. GVHD prophylaxis consists of tacrolimus given at 0.03mg/kg/day as continuous intravenous infusion from day‐1 and mycophenolate mofetil at 750mg orally given three times a day from day 0. UCB unit with more than 2.5 x 10^7/kg of cryopreserved total nucleated cell dose, which is serologically matched for greater than 4 of 6 HLA antigens is used. CONDITION: Hematologic malignancies with an indication for allogeneic hematopoietic stem cell transplantation PRIMARY OUTCOME: Day 60 survival rate of patients with successful engraftment after transplantation SECONDARY OUTCOME: (1) Overall survival and progression free survival at day 100; (2) Non‐relapse mortality at day 100; (3) Rate of primary graft failure, secondary graft failure; (4) Time to hematopoietic recovery and achievement of complete donor T‐cell chimerism ; (5) Incidence and severity of acute GVHD and chronic GVHD; (6) Regimen‐related toxicity; (7) Rate of relapse; (8) Incidence of bacterial, fungal and viral infection; (9) Immune reconstitution after transplantation INCLUSION CRITERIA: (1) Patients with hematologic malignancies who are incurable by conventional treatments and therefore have an indication for allo‐HSCT Eligible diseases; (a)AML 1. First CR with high risk 2. Second CR or greater 3. Relapse or failure to achieve CR by the first induction chemotherapy (b)MDS 1. Poor prognosis MDS with IPSS scores of int‐2 or higher 2. Patinets with transfusion‐dependent MDS who require RBC transfusion over 2 units per week or platelet transfusion over 10 units per week (c)CML 1. Second CP or greater 2. First CP or tyrosine kinase inhibitor failure (d)Malignant lymphoma 1. Indolent lymphoma (including CLL) First relapse/progression,or greater, regardless of sensitivity to prior chemotherapy (e)ALL (including Ph positive ALL) 1. CR (2) Patients lacking a 5/6 or 6/6 HLA‐A/B/DR serologically matched related donor (3) Patients lacking an HLA‐A/B/DR serologically matched unrelated donor, pa