Outcomes of Unrelated Umbilical Cord Blood Transplantation Using a Conditioning Regimen of TBI/Ara-c/CY without ATG for Adolescent and Adults Patients with High-Risk Hematologic Malignancies

Abstract 4525

To retrospectively analyze the curative efficacy of umbilical cord blood transplantation (UCBT) using total body irradiation (TBI)-based myeloablative conditioning regimen without antithymocyte globulin (TBI/Ara-c/CY w/o ATG) in adolescent and adult patients with high-risk hematological malignancies.

Outcomes of forty-five consecutive adolescent and adult patients with high-risk hematological malignancies treated with TBI-based myeloablative UCBT without ATG in a single center between September 2006 and February 2012 were retrospectively analyzed. The conditioning regimen included TBI/Ara-c/CY:TBI 12GY (four fractionated) + Ara-C 8g/m² (two days fractionated) + CY 120mg/kg (two days fractionated), and rhG-CSF was administered for myeloid leukemia by continuous infusion at a dose of 5μg·kg⁻¹·d⁻¹. Infusion of G-CSF was started 24 hours before the first dose of Ara-C and stopped at the completion of the last dose. The patients included 31 males and 14 females, with a median age of 21 years (range: 14–40) and a median weight of 58 kg (range: 42–76). Of those, 17 patients (37.8%) had advanced disease. Double UCB grafts were used for 16 patients, while single UCB graft was used for 29 patients. The median number of nucleated cells infused was 3.57 (1.94∼6.76)×10⁷/kg and the median CD34⁺cells infused was 2.11 (0.71∼4.95)×10⁵/kg. All patients received a combination of cyclosporine (CSA) and mycophenolate mofetil (MMF) for graft-versus-host disease (GVHD) prophylaxis.

All patients successfully engrafted. The median times to neutrophil (ANC≥0.5×10⁹/L) and platelet (PLT PLT≥20×10⁹/L) recovery were 19 days (range: 13–35 days) and 36 days (range: 24–90 days) respectively after transplantation in 40 evaluable patients. Acute GVHD occurred in 21 patients and the cumulative incidences of gradeII-‡W and grade III-‡W acute GVHD were 24.4% and 11.1%, respectively. Chronic GVHD occurred in five of 40 evaluable patients (12.5%). Of the 45 patients, 9 (20%) had relapse. After a median follow-up of 25.1 months (range: 6–65.1) among survivors, treatment-related mortality (TRM) within 100 days and within one year was 8.9% and 24.4%, respectively. The main causes of death were pneumonia and severe acute GVHD. The probability of three-year disease-free survival and overall survival (OS) was 53.3% and 57.8%, respectively.

The TBI/Ara-c/CY myeloablative conditioning regimen has been well tolerated by patients at our institution and seems to be able to establish sustained donor cell engraftment and decrease the risk of transplant-related death. For high risk patients and patients with advanced disease, this conditioning regimen could reduce relapse and chronic GVHD, indicating the feasibility of TBI/Ara-c/CY as a conditioning regimen for CBT in adolescent and adult patients with hematologic malignancies.