Based on progress to date, Dr. Ferguson was awarded a new grant in 2014 to fund an optional third year of this fellowship. Neurofibromatosis type I is a rare genetic disorder that affects about 100,000 people in the United States alone. Of children with this disease, 25-40% form slow growing tumors called plexiform neurofibromas. These tumors can cause disfigurement, disability, and even death, depending on their location. To date, there is no effective therapy to treat these tumors. This project is testing drugs, already developed by pharmaceutical companies, that block growth in other cancers, for plexiform neurofibromas. The purpose of this study is to find a life-saving treatment for children with these tumors.