Inclusion Criteria: 

• Central histopathologic confirmation of the FL Grade 1 to 3a diagnosis must be obtained before study enrollment. Patients with FL grade 3b are ineligible. Follicular lymphoma subtyping is based on the World Health Organization (WHO) classification (Swerdlow, 2017). 
• Disease must have relapsed or must be refractory to ≥2 prior lines of systemic therapy, including an anti-CD20 antibody and an alkylating agent. Patients should in the opinion of the investigator require therapy for FL at the time of study enrollment. 
• Measurable disease on cross sectional imaging as defined in the protocol documented by diagnostic imaging (computed tomography (CT), or magnetic resonance imaging (MRI)).
• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. 
• Adequate bone marrow, hepatic, and renal function as defined in the protocol.

Exclusion Criteria:

• Primary central nervous system (CNS) lymphoma or known involvement by non-primary CNS Non-Hodgkin Lymphoma (NHL) (suspected CNS lymphoma should be evaluated by lumbar puncture, as appropriate, in addition to the mandatory head CT or MRI). 
• Treatment with any systemic anti-lymphoma therapy within 5 half-lives or within 28 days prior to first administration of study drug, whichever is shorter. 
• History of allogeneic stem cell transplantation.
• Prior treatment with any chimeric antigen receptor T-cell (CAR-T) therapy. 
• Continuous systemic corticosteroid treatment with more than 10 mg per day of prednisone or anti-inflammatory equivalent within 72 hours of start of study drug.
• History of neurodegenerative condition or CNS movement disorder.
• History of uncontrolled seizure disorder, defined as any seizure within 12 months prior to study enrollment.
• Another malignancy except FL in the past 5 years, with the exception of non-melanoma skin cancer that has undergone potentially curative therapy or in situ cervical carcinoma, or any other tumor that has been deemed to be effectively treated with definitive local control and with curative intent.
• Uncontrolled infection with human immunodeficiency virus (HIV), hepatitis B or hepatitis C infection; or other uncontrolled infection as defined in the protocol.
• Known hypersensitivity to both allopurinol and rasburicase.
• Note: Other protocol defined Inclusion/Exclusion criteria apply.