 - Arm I: Patients receive bevacizumab IV over 30-90 minutes on day 1 of courses 1-5 and on days 1, 22, and 43 of course 6; rituximab IV over 2-4 hours on days 2 and 3 of course 1 and on day 1 of courses 2-6; and pentostatin IV over 30 minutes and cyclophosphamide IV over 30 minutes on day 2 of course 1 and on day 1 of courses 2-6. Patients also receive pegfilgrastim subcutaneously SC on day 3 of course 1 and on day 2 of courses 2-6. Treatment repeats every 21 days for 6 courses in the absence of disease progression or unacceptable toxicity. 