1. 1Division of Oncology and Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
2. 2Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
3. 3Foundation Medicine, Inc., Cambridge, Massachusetts.
4. 4Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania and the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.