Inclusion Criteria:

- Histologically confirmed mantle cell lymphoma meeting the following criteria:

- Diagnosis confirmed by initial biopsy or at time of relapse

- No bone marrow biopsy as sole means of diagnosis

- May be used in conjunction with nodal biopsies

- No fine needle aspirates

- CD5-positive, CD23-negative, and cyclin D1-positive by flow cytometry or
immunohistochemistry

- Measurable disease, defined as any tumor mass > 1cm by physical examination, CT scan,
MRI, or conventional radiograph

- No nonmeasurable disease only, including any of the following:

- Bone lesions (should be noted, if present)

- Ascites

- Pleural or pericardial effusion

- Lymphangitis cutis or pulmonis

- Bone marrow (involvement by non-Hodgkin lymphoma should be noted)

- Received prior therapy with at least 1 regimen, which may have been single- or
multi-agent, and consisted of traditional cytotoxic and/or biologic agents

- Must have progressive or refractory disease following initial regimen

- Refractory disease defined as stable or progressive disease as best
response to prior therapy, or complete or partial response as initial
response followed by disease progression within 6 months

- No known CNS involvement by lymphoma

- ECOG performance status 0-2

- ANC ≥ 1,000/μL (≥ 500/μL if marrow involvement)

- Platelet count ≥ 75,000/μL

- Total bilirubin ≤ 2 times upper limit of normal (ULN) (unless attributable to Gilbert
disease)

- Creatinine ≤ 1.5 times ULN (unless attributable to non-Hodgkin lymphoma) AND
estimated creatinine clearance ≥ 30 mL/min (patients on dialysis are not eligible)

- Not pregnant or nursing

- Negative pregnancy test

- Fertile women must use effective double-barrier contraception during and for at least
28 days after completion of lenalidomide therapy

- Men must use effective contraception during and for 28 days after completion of
lenalidomide therapy, even if they have undergone a successful vasectomy

- No peripheral neuropathy ≥ grade 3 within the past month

- Patients with HIV infection are eligible, provided they meet the following criteria:

- CD4-positive cell count > 350/mm^3

- Must have treatment-sensitive HIV and, if on anti-HIV therapy, HIV viral load <
50 copies/mm^3

- No history of AIDS-defining conditions or other HIV-related illnesses

- No concurrent zidovudine or stavudine because of overlapping toxicities with
protocol therapy

- No deep vein thrombosis (DVT) and/or pulmonary embolism (PE) within the past 3 months
* Patients with a distant history (> 3 months prior to study entry) of DVT/PE are
eligible, provided they receive concurrent prophylactic aspirin or low molecular
weight heparin, unless contraindicated

- LVEF ≥ 45% by MUGA scan or ECHO

- No New York Heart Association class III or IV congestive heart failure

- No myocardial infarction within the past 6 months

- No known positivity for hepatitis A, B, or C

- No concurrent dexamethasone or other steroidal antiemetics

- No concurrent hormones used as chemotherapy or other chemotherapeutic agents except
for steroids given for adrenal failure (hormones administered for non-disease related
conditions [e.g., insulin for diabetes or birth control pills])

- No prior bortezomib or lenalidomide

- Prior autologous stem cell transplantation (SCT) allowed

- No prior allogeneic SCT allowed

- No prior radioimmunotherapy within the past 12 months

- More than 2 weeks since prior corticosteroids, except maintenance therapy for a
non-malignant disease

- Maintenance therapy dose may not exceed20 mg/day prednisone or equivalent

- No other concurrent investigational or commercial agents or therapies for lymphoma