Up to 20 pediatric patients will receive therapy. The previously established bevacizumab dose of 15 mg/kg will be administered by intravenous infusion on day 1 at the start of every 3-week course. Intravenous vincristine will be given on day 1, oral irinotecan on days 1-5, and oral temozolomide on days 1-5. Courses will be repeated as frequently as every three weeks in patients who do not have evidence of disease progression and who have adequate recovery from previous courses. Cephalosporin antibiotics will be used to reduce irinotecan-associated diarrhea.