Assessment of chimerism and immunomodulation to prevent post-transplantation relapse in childhood acute myeloblastic leukemia: is it the right approach?

Relapse of acute myeloblastic leukemia (AML) after first allogenic hematopoietic stem-cell transplantation (allo-HSCT) is a fatal complication. Sixty-five children transplanted for AML were included in a prospective national study from June 2005 to July 2008 to explore the feasibility of preemptive immune modulation based on the monitoring of blood chimerism. Relapse occurred in 23 patients (35%). The median time between the last complete chimerism and relapse was 13.5 days (2-138). Prompt discontinuation of cyclosporin and the administration of donor lymphocyte infusions (DLIs) based on chimerism monitoring failed as a preemptive tool, either for detecting relapse or certifying long-term remission.