Outcomes after Unrelated Cord Blood Transplantation in Children with Acute Lymphoblastic Leukemia. An Eurocord-Netcord Survey.

Unrelated cord blood transplantation (UCBT) is an alternative option to treat children with haematological diseases without an HLA-identical donor. We have analyzed a total of 323 children with ALL receiving an UCBT, from 1994 to 2004 in 99 transplant centres in 24 countries, mostly in Europe. Cumulative incidence with competing risk and KM estimates were used to calculate outcomes. Seventy six children were transplanted in CR1, 136 in CR2 and 111 in more advanced phase of the disease. Among those children poor cytogenetics were observed in 89% of children in 1CR, 33% in 2CR and 42% in advanced phase. Twenty percent of children transplanted in advanced phase had been previously autografted. The median age was 6.5 years at UCBT, median cell dose infused was 4.1x107/kg and the median follow time was 22 months (3–96). The cord blood was HLA identical (6/6) in 12% of the cases, 5/6 in 46%, 4/6 in 39% and 3/6 in 3%. All children received myeloablative conditioning regimen (TBI in 66%) and the majority (67%) received CsA+corticoids as GVHD prophylaxis. Cumulative incidence of neutrophil recovery at day 60, platelets recovery (>20.000) at day 180, acute (grade II–IV) and chronic GVHD were 76±5%, 54±5%, 42±3%, 14±2%, respectively. Overall 2 year-LFS was 36±3%. In a multivariate analysis, only CR1 or CR2 were associated with better LFS (HR=1.8; p<0.0001).

For those patients transplanted with poor cytogenetics, LFS at 2 years was 32±6% and it was 37% for CR1, 43% for CR2 and 0% for advanced phase of the disease. In conclusion, in these large series of high risk ALL patients, these results show that UCBT should be proposed as alternative source of allogeneic transplantation for children lacking an HLA identical donor, in earlier status of the disease.