Mantle cell lymphoma (MCL) remains difficult to treat by standard treatment approaches. Novel drugs have shown promising results in early clinical evaluations. In the current trial, we investigate a combination of bortezomib (a proteasome inhibitor), rituximab (a monoclonal antibody), and dexamethasone in patients with MCL, who have already been pretreated by standard chemotherapy and show again signs of disease progression. The study objectives include remission rates, safety of this drug combination, and survival time.

Description of the treatment regimen: Bortezomib: 1.3 mg/m2 as i.v. bolus injection, given on days 1, 4, 8, and 11 of each treatment cycle; Rituximab: 375 mg/m2 infusion, day 1 of each cycle; Dexamethasone: 40 mg per day orally (days 1 - 4) of each treatment cycle. Treatment will be given for a total of 6 cycles (every 21 days), followed by maintenance treatment with rituximab (375 mg/m2 every two months for 4 times)

Inclusion Criteria:

• mantle cell lymphoma at stage II - IV, previously treated with at least one line of prior therapy (CHOP or CHOP-like), measurable disease, age 19 - 75 years, adequate cardiac, liver and renal function tests, patient's written informed consent

Exclusion Criteria:

• second malignancy, evidence for CNS involvement, clinically significant peripheral neuropathy (grade II or higher), HIV positivity, pregnancy