New approaches to allogeneic hematopoietic stem cell transplantation in pediatric cancers.

About 30 years have passed since the first children underwent allogeneic hematopoietic stem cell transplantation (HSCT). Since then, there have been major improvements to identifying and expanding pools of donors, mobilizing and harvesting hematopoietic stem cells, conditioning therapies, transfusion medicine, antimicrobials, immunosuppression, and supportive care. These advances have broadened the application of HSCT to treat malignant and nonmalignant pediatric disorders. Currently, most children and young adults with cancer who undergo allogeneic HSCT are identified as having a malignancy that would be lethal if not for the biologic therapy that HSCT imparts, and remarkably, many of these patients can be cured. However, this cure still comes with costs, including infections, graft-versus-host disease, loss of potential, and psychosocial and financial stresses. New approaches are increasingly available that focus on immune modulation to reduce the burdens of HSCT while improving its therapeutic benefit.