The Cord Blood Transplantation Study (COBLT)

Background:

Compared to other stem cell sources, cord blood is easier and safer to procure, has no donor attrition, a limitless supply, reduced viral transmission, less acute and chronic graft-versus-host-disease, is rich in hematopoietic progenitor cells, and immaturity of T-cell-mediated immunity. However, cord blood also has delayed neutrophil and platelet engraftment, a prolonged immune reconstitution, uncertain graft-versus-tumor activity, and cell doses from single cord blood units are a limiting factor for larger recipients.

Design:

The Cord Blood Transplantation (COBLT) Study was comprised of three cord blood banks, seven core transplant centers and a data coordinating center. Funding was initiated in 1996 and the first two years of the project focused on the establishment of three cord blood banks and the development of validated Standard Operating Procedures for the recruitment of cord blood donors and collection, processing, testing and storage of umbilical cord blood units (UCBUs). The transplant protocol and Manual of Procedures for the clinical trial were also developed during this time by the original seven participating transplant centers. Additional centers were recruited to reach accrual goals and the transplant protocol was initiated at 26 participating institutions.

Objectives:

The transplant center protocol was a phase II multicenter trial to determine if banked unrelated donor umbilical cord blood could serve as an adequate hematopoietic stem cell source for adults and children with malignancies, immune deficiencies, inherited marrow failure, or inborn errors of metabolism. The largest strata studied pediatric patients with various leukemias. Each participating transplant center used the same patient selection criteria, preparative regimen for patients in the same class, initial graft-versus-host disease (GvHD) prophylaxis, indications for the use of cytokines, definitions for events and complications, and methods for evaluating immune reconstitution. The main study evaluated the impact of HLA 3/6 and 4/6 matching on outcome. The primary endpoint was 180-day disease free survival after UCBU transplantation. Secondary endpoints included engraftment, the frequency and severity of acute and chronic GvHD with stratification by degree of HLA match, overall survival, and immunologic reconstitution. Search activity was initiated in November 1998 and the first UCBU transplant was in March 1999. Enrollment in the COBLT transplant protocol ended December 31, 2003 with the accrual of 364 transplant recipients.