Haploidentical stem cell transplantation for children with high-risk leukemia

Background The Chilean population is ethnically diverse, and more than 50% of children referred for hematopoietic stem cell transplantation (HSCT) lack a suitable donor. Procedure To expand the donor pool, we assessed the feasibility, tolerance, and efficacy of using a haploidentical (HI) donor and a reduced-intensity conditioning regimen for high-risk pediatric leukemia. This study was facilitated by technology transfer from St. Jude Children's Research Hospital over the 2 preceding years. Results Between March 2006 and April 2009, 10 patients (median age, 9.8 years) received T cell-depleted grafts at Calvo Mackenna Hospital in Santiago. Median cell doses were CD34+: 7.45 x 106/kg (range, 4.0020.20 x106/kg); CD3+: 0.88 x 105/kg (0.111.35 x 105/kg); and CD56+: 71.30 x 106/kg (31.50131.80 x 106/kg). Nine patients experienced complete engraftment; six of the nine remain alive and clinically well 1350 months post-HSCT. Three patients died after bone marrow relapse, while only one died of transplant-related causes. Virus reactivation was the main post-transplant complication: 5/10 had positive CMV PCR but none had CMV disease. One patient developed acute GvHD?>?grade II and only one had chronic GvHD. Conclusions HI-HSCT is feasible in our setting, offers a rational treatment option, and expands the donor pool significantly for children with high-risk leukemia in a developing country. This information is especially relevant to other ethnically diverse populations that are poorly represented in international donor registries. Pediatr Blood Cancer 2012; 59: 895901. (C) 2012 Wiley Periodicals, Inc.