First Successful Allogeneic Hematopoietic Stem Cell Transplantation in Children with Chronic Myeloid Leukemia, Preceded by Imatinib Prior Transplantation.

Objectives: Although very rare in children, chronic myeloid leukemia (CML) can be cured by hematopoietic stem cell transplantation (HSCT). However, the 5-year survival probability following allogeneic HSCT is only about 50–60% in childhood CML. With imatinib successful in CML patients, the impact of imatinib treatment on subsequent allogeneic hematopoietic stem cell transplantation (HSCT) remains unclear. Imatinib therapy prior to HSCT has not been reported in children. Herein we describe imatinib induction preceding HSCT in three children newly diagnosed. Methods: Imatinib was administered as induction in three boys, aged 11, 14, 15 years, newly diagnosed in the chronic phase. Between induction and cytogenetic remission, two patients received HSCT from matched unrelated donors (MUD) and one received HSCT from matched sibling donor. Busulphan and cyclophosphamide were utilized as a conditioning regimen. Cyclosphorin A and methotrexate were both used as graft versus host disease (GVHD) prophylaxis. Anti-thymocyte globulin was added for MUD cases. Results: Successful engraftment and neither severe liver toxicity nor acute GVHD were encountered. All three cases show cytogenetic remission, with chronic GVHD well controlled in one. We monitored each patient’s status for minimal residual disease by real-time quantitative polymerase chain reaction. Absence of detectable minimal residual disease was found in two patients at 28 and 63 months after HSCT. At present, all of these three patients have good quality of life. Conclusions: As first-line therapy, imatinib appears useful for providing a bridge to HSCT in children with CML. Further study is warranted to determine impact of imatinib prior transplantation on child CML.