Inclusion Criteria

- Documentation of Disease

- Previously treated, histologically confirmed follicle center cell lymphoma,
World Health Organization (WHO) classification grade 1, 2, or 3a (> 15
centroblasts per high-power field with centrocytes present)

- Bone marrow biopsies as the sole means of diagnosis are not acceptable;
fine-needle aspirates are not acceptable for diagnosis

- Confirmed Cluster of Differentiation 20 (CD20) antigen expression by flow
cytometry or immunohistochemistry

- Measurable disease must be > 1 cm

- Prior treatment

- Patient must have had prior treatment with rituximab either alone or in
combination with chemotherapy.

- Last prior treatment regimen need not include rituximab.

- Patient must have a time to progression of ≥ 6 months from last rituximab dose
of last rituximab containing regimen.

- No corticosteroids within two weeks prior to study, except for maintenance
therapy for a non-malignant disease; maintenance therapy dose may not exceed 20
mg/day prednisone or equivalent

- Patients must be 18 years of age or older.

- Human immunodeficiency virus (HIV) Infection

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

- CD4+ cell count > 350/mm3

- Treatment sensitive HIV and, if on anti-HIV therapy, HIV viral load < 50
copies/mm3

- No history of Acquired Immunodeficiency Syndrome (AIDS)-defining conditions or
other HIV related illness

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

- Patients must not have known central nervous system (CNS) involvement

- Patients must not have known positivity for hepatitis B or C

- Patients must not have any currently active secondary malignancy except non-melanoma
skin cancer

- Patients must not have had deep vein thrombosis or pulmonary embolism within the past
3 months.

- Patients must not have had radioimmunotherapy within 12 months of study entry.

- Patients must not have other concurrent investigational or commercial agents or
therapies for lymphoma.

- Patients must not have current dialysis treatment.

- Patients must be non-pregnant and non-nursing.

- CYP3A4 Strong Inducers and Inhibitors

- Patients must not be on strong CYP3A4 inhibitors and/or inducers.

- Strong CYP3A4 Inhibitors prohibited are indinavir, nelfinavir, ritonavir,
clarithromycin, itraconazole, ketoconazole, nefazodone

- Strong CYP3A4 Inducers prohibited are carbamazepine, phenobarbital, phenytoin,
pioglitazone, rifabutin, rifampin, St. John's Wort, troglitazone

- Required Initial Laboratory Values

- Absolute neutrophil count (ANC) ≥ 1,000 mm³

- Total Bilirubin ≤ 2 times upper limit of normal (ULN) (unless due to Gilbert
disease or lymphoma)

- Creatinine ≤ 1.5 times ULN (unless due to lymphoma) OR creatinine clearance
(CrCl) ≤ 60 mL/minute

- Platelet count ≥ 75,000 mm³

- Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase
[SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase
[SGPT]) ≤ 2 x ULN