• Tumor response rate [ Time Frame: baseline to measured progressive disease ] [ Designated as safety issue: No ]
  

• Progression-free survival [ Time Frame: baseline to measured progressive disease ] [ Designated as safety issue: No ]
  
• Time to response [ Time Frame: baseline to date of confirmed response ] [ Designated as safety issue: No ]
  
• Duration of response [ Time Frame: time of response to progressive disease ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

All patient must:

1. Have had a histologically confirmed diagnosis of Grade 1 or 2 FL, according to World Health Organization classification (Harris et al. 1999), at the original time of diagnosis. Pathology must be confirmed locally prior to enrollment at the investigational site.
2. Have Ann Arbor Stage III or IV disease.
3. Must be chemo-naive OR have relapsed disease after receiving only one prior chemotherapy regimen. The chemotherapy must have been completed at least 6 months prior to first dose of study treatment. Relapse after one prior course of single-agent rituximab treatment (in the chemo-naive setting) is also allowed if completed at least 6 months prior to first dose of study treatment.
4. Patients must not require cytoreductive therapy for at least 3 months from first dose of study treatment, in the opinion of the investigator.
5. Previous radiation therapy is allowed, but should have been limited and must not have included whole pelvis radiation. Patients must have recovered from the toxic effects of the treatment prior to study enrollment (except for alopecia). Prior radiotherapy must be completed 30 days before study entry. Lesions that have been irradiated cannot be included as sites of measurable disease unless clear tumor progression has been documented in these lesions since the end of radiation therapy.

Exclusion Criteria:

Patients will be excluded from the study if they meet any of the following criteria:

1. Are unable to swallow tablets.
2. Are unable to discontinue use of carbamazepine, phenobarbital, and phenytoin.
3. Are receiving concurrent administration of any other antitumor therapy.
4. Are pregnant or breastfeeding.
5. Have a serious concomitant systemic disorder (including active bacterial, fungal, or viral infection) that, in the opinion of the investigator, would compromise the patient's ability to adhere to the protocol.