Patients receive bortezomib IV over 3-5 seconds on days 1, 4, 8, and 11. Courses repeat every 3 weeks in the absence of disease progression or unacceptable toxicity. Patients with complete response (CR) receive 2 courses beyond documentation of CR. Patients with stable disease receive a maximum of 4 courses. Patients with partial response (PR) continue therapy until disease progression or for 2 courses beyond documentation of stable PR.