Lenalidomide and Rituximab in Treating Patients With Recurrent and/or Refractory Multiple Myeloma

DISEASE CHARACTERISTICS:

• Histologically confirmed CD20+ multiple myeloma

• CD20+ disease defined as co-expression of CD20 on ≥ 25% of the clonal plasma cell population as defined by immunohistochemical or flow cytometric staining of a bone marrow or plasmacytoma specimen obtained at study entry

• For flow cytometry, this is determined by calculating the frequency of CD20+ CD138+ double-positive cells within the total CD138+ plasma cell population

• For immunohistochemistry, this is determined by dual staining for CD20 and the involved clonal light chain (kappa or lambda), with a determination of the percent double-positive (≤ 25% or ≥ 25%)

• Symptomatic multiple myeloma that has relapsed or progressed after at least 1 prior anti-myeloma therapeutic regimen

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2

• Life expectancy > 16 weeks (4 months)

• ANC ≥ 1,500/μL (unless low ANC due to multiple myeloma)

• Platelets ≥ 100,000/μL (unless low platelets are due to multiple myeloma)

• Serum bilirubin ≤ 2.0 mg/dL

• AST, ALT, and alkaline phosphatase < 3 times upper limit of normal

• Serum creatinine ≤ 2.5 mg/dL

• Able to understand the investigational nature of lenalidomide and rituximab combination therapy and to give informed consent

• Not pregnant or nursing

• Negative pregnancy test

• Fertile patients must use effective double-method contraception at least 28 days before, during, and for at least 28 days after completion or discontinuation of study treatment

• Able to take acetylsalicylic acid (ASA) (325 mg) daily as prophylactic anticoagulation (patients intolerant to ASA may use warfarin or low molecular weight heparin)

• Prior malignancies with a disease free interval of ≥ 5 years allowed

• No history of thromboembolic disease within the past 6 months, regardless of anticoagulation

• No myocardial infarction within the past 6 months

• No New York Hospital Association class III or IV heart failure

• No uncontrolled angina

• No severe uncontrolled ventricular arrhythmias

• No active hepatitis B or C infection

• No HIV 1or 2 positivity

• No acute ischemia or active conduction system abnormalities as evidenced by ECG

• No history of hypersensitivity reactions to lenalidomide, thalidomide, or rituximab

• No other medical condition or laboratory evaluation that, in the treating physician's or principal investigators' opinion, makes the patient unsuitable to participate in this clinical trial

• No concurrent active malignancy other than nonmelanoma skin cancers or carcinoma-in-situ of the cervix

PRIOR CONCURRENT THERAPY:

• At least 3 weeks since prior therapy, including radiotherapy

• Prior lenalidomide or thalidomide allowed

• No prior rituximab