Phase 2 Study of Oral IXAZOMIB in Adult Participants With Relapsed and/or Refractory Follicular Lymphoma

Inclusion Criteria:

* Male or female participants 18 years or older.
* Participants must have a pathologically confirmed diagnosis of non-Hodgkin lymphoma (NHL) (for the lead-in dose-finding phase) and FL (for phase 2).
* Participants must have radiographically or clinically measurable disease.
* Participants must be relapsed and/or refractory after at least 1 prior therapy (excluding radiation) with documented progressive disease at the time of enrollment.
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.
* Female participants who are post menopausal, surgically sterile, or agree to practice 2 effective methods of contraception or agree to practice true abstinence.
* Male participants who agree to practice effective barrier contraception or agree to practice true abstinence.
* Voluntary written consent.
* Suitable venous access.
* Appropriate clinical laboratory values as defined in the protocol.
* Recovered from toxicities of prior anticancer therapy.
* If the trial proceeds to the second step on the basis of the tandem 2-step design, participants must be confirmed PSMB1 positive at the central laboratory before treatment.

Exclusion Criteria

* Peripheral neuropathy that is greater or equal to Grade 2 or Grade 1 with pain.
* Female participants who are lactating and breastfeeding or have a positive serum pregnancy test during the Screening period.
* Autologous stem cell transplant within 6 months before Day 1 of Cycle 1, or prior allogeneic stem cell transplant at any time.
* Major surgery within 14 days before the first dose of study drug.
* Infection requiring systemic antibiotic therapy or other serious infection within 14 days before the first dose of study drug.
* Comorbid systemic illnesses or other severe concurrent disease that, in the judgment of the investigator, would make the participants inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
* Evidence of current uncontrolled cardiovascular conditions including uncontrolled hypertension, severe uncontrolled ventricular arrhythmias, unstable angina, New York Heart Association (NYHA) Class III or IV cardiac disease, or myocardial infarction within the past 6 months.
* Diarrhea greater than (\>) Grade 1 on the basis of the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) categorization.
* Systemic antineoplastic (including glucocorticoids \> the equivalent of 15 mg of prednisone daily), experimental, or radiation therapy within 21 days before the first dose of study drug.
* Prior treatment with rituximab or other unconjugated antibody treatment within 42 days (21 days if clear evidence of progressive disease or immediate treatment is mandated).
* Treatment with radioimmunoconjugates or toxin immunoconjugates within 12 weeks before the first dosing of study treatment.
* Systemic treatment with strong inhibitors of Cytochrome P450 1A2 (CYP1A2) or Cytochrome P450 3A (CYP3A), or strong CYP3A inducers within 14 days before the first dose of IXAZOMIB - Ongoing systemic therapy with corticosteroids.
* Central nervous system (CNS) involvement that is clinically uncontrolled or newly diagnosed in the last 4 months.
* Ongoing or active systemic viral infection, known human immunodeficiency virus (HIV) positive, known active hepatitis B virus or known active hepatitis C virus.
* Diagnosed or treated for another malignancy within 2 years before study enrollment or previously diagnosed with another malignancy and have any evidence of residual disease with the exception of nonmelanoma skin cancer or any completely resected carcinoma in situ.
* Platelet transfusions within 3 days before the 1st dose of study drug.
* Inability to swallow capsules, or inability or unwillingness to avoid taking anything by mouth except for water and prescribed medication for 2 hours before and 1 hour after dose of IXAZOMIB - Known allergy to boron or excipients in the formulation.