Study of Duvelisib in Combination With Rituximab vs Rituximab in Subjects With Previously Treated Follicular Lymphoma

Inclusion Criteria:

* Diagnosis of CD20-positive FL:

  * Histology grades 1, 2 or 3a
  * Biopsy-confirmed histopathological diagnosis of FL. Biopsy specimen should be obtained ≤2 years prior to randomization, unless medically contraindicated
* CD20 immunophenotyping performed ≤2 years prior to randomization
* First or subsequent relapse following at least one induction therapy regimen containing rituximab in combination with an anthracycline or rituximab in combination with an alkylating agent
* Patients in first relapse must be chemoresistant or intolerant to chemotherapy
* No response or disease progression ≤ 24 months from start of last previous therapy
* At least 1 measurable disease lesion \>1.5 cm in at least one diameter by CT/CT-PET or magnetic resonance imaging (MRI) in an area of no prior radiation therapy, or in an area that was previously irradiated that has documented progression

Exclusion Criteria:

* Clinical evidence of other indolent forms of lymphoma (e.g., marginal zone lymphoma \[MZL\], small lymphocytic lymphoma \[SLL\])
* Transformation to a more aggressive subtype of lymphoma or grade 3b FL
* Refractory to rituximab: defined as disease progression while receiving or within 6 months of completing either weekly rituximab induction therapy, or rituximab-based chemoimmunotherapy induction
* Intolerance to rituximab or severe allergic or anaphylactic reaction to any humanized or murine monoclonal antibodies
* Prior allogeneic hematopoietic stem cell transplant (HSCT)
* Known Central Nervous System (CNS) lymphoma; subjects with symptoms of CNS disease must have a negative CT scan and negative diagnostic lumbar puncture
* Prior treatment with a PI3K inhibitor or BTK inhibitor
* History of tuberculosis within the preceding two years
* Ongoing systemic bacterial, fungal, or viral infections at randomization (defined as requiring IV antimicrobial, antifungal or antiviral agents)
* Subjects on antimicrobial, antifungal or antiviral prophylaxis are not specifically excluded if all other I/E criteria are met
* Prior, current, or chronic hepatitis B or hepatitis C infection, positive result for hepatitis B surface antigen (HBsAg) or hepatitis B core antibody (HBcAb) or hepatitis C virus antibodies (HCV Ab)
* History of stroke, unstable angina, myocardial infarction, or ventricular arrhythmia requiring medication or mechanical control within the last 6 months