Patients receive bevacizumab IV over 30-90 minutes on days 1 and 15 and irinotecan hydrochloride IV over 90 minutes on day 16 or 17 for course 1. Patients receive bevacizumab and irinotecan hydrochloride on days 1 and 15 for all subsequent courses. Treatment repeats every 4 weeks for up to 24 courses in the absence of disease progression or unacceptable toxicity.