Inclusion Criteria:

• Age >= 18 years.
• Must have received prior therapy for their WM and have relapsed or refractory WM. Any number of prior therapies is acceptable.
• Measurable disease, defined as presence of immunoglobulin M (IgM) paraprotein with a minimum IgM level of > 2 times the upper limit of each institution's normal value is required and over 10% of lymphoplasmacytic cells in the bone marrow.
• ECOG Performance Status (PS) 0, 1, or 2.
• The following laboratory values obtained 14 days prior to registration
• ANC >= 1 x109/L
• PLT >= 75 x109/L
• Total bilirubin ≤ 2.0 mg/dL (If total is elevated check direct and if normal patient is eligible.)
• AST <= 3 x upper limit of normal (ULN)
• Creatinine <= 2 x ULN
• Ability to provide informed consent.
• Life expectancy >= 12 weeks.

Exclusion Criteria:

• Uncontrolled infection.
• Other active malignancies.
• CNS involvement.
• Cytotoxic chemotherapy ≤ 3 weeks, or biologic therapy ≤ 2 weeks, or corticosteroids ≤ 2 weeks, prior to registration. Patients may be receiving chronic corticosteroids if they are being given for disorders other than WM such as auto-immune diseases. Plasmapheresis is not considered as an active therapy and can be used at the physician's discretion.
• Other concurrent chemotherapy, immunotherapy, radiotherapy, or any ancillary therapy considered investigational.
• Any of the following:
• Pregnant women
• Nursing women
• Men or women of childbearing potential who are unwilling to employ adequate contraception (condoms, diaphragm, birth control pills, injections, intrauterine device (IUD), or abstinence, etc.)
• Known to be HIV positive.
• Radiation therapy ≤ 2 weeks prior to registration.