A Study to Compare the Efficacy and Safety of Golcadomide in Combination With Rituximab (Golca + R) vs Investigator's Choice in Participants With Relapsed/Refractory Follicular Lymphoma Who Have Received at Least 1 Prior Line of Systemic Therapy (GOLSEEK-4)

Participant has histologically confirmed FL (Grade 1, 2, 3a or classic FL) as assessed by local pathology. Adequate fresh tumor biopsy tissue or archived tumor biopsy from the latest relapse if available with corresponding pathology report for retrospective central pathology confirmation of relapse, is required. Evaluation from fine needle aspirate is not permitted.

Relapsed or refractory disease:

1. Relapsed FL is defined as relapse after an initial response of CR or PR to the most recent prior therapy.
2. Refractory FL is defined as best response of SD or PD or a response that lasted less than 6 months to the most recent prior therapy.

Eastern Cooperative Oncology Group (ECOG) 0-2 (ECOG 3 authorized if it is due to lymphoma and not comorbidities).

Participant must have positron emission tomography (PET)-positive disease with at least one PET-positive lesion and measurable disease on cross section imaging by CT, as defined by Lugano classification.

Participants with an indication for anti-lymphoma treatment as per investigator assessment based on modified Groupe d'Etude des Lymphomes Folliculaires (GELF) criteria.

Participant has received at least 1 or more prior lines of systemic therapy with one line consisting of a combination including an anti-CD20 monoclonal antibody (eg, rituximab, obinutuzumab) and an alkylating agent (eg, cyclophosphamide, bendamustine). Prior treatment with radiation therapy does not count as a line of therapy for eligibility.

Lab parameters:

1. Absolute neutrophil count (ANC) ≥ 1,000 cells/mm3 (1.0 x 109 /L),
2. PLT count ≥ 75,000 cells/mm3 (75 x 109 /L)
3. Hb ≥ 7.5 g/dL

estimated glomerular filtration rate (eGFR) ≥ 30 ml/min/1.73m².

Serum aspartate transaminase (AST/SGOT) or alanine transaminase (ALT/SGPT) ≤ 2.5 x upper limit of normal (ULN). In case of documented liver involvement by lymphoma, ALT/SGPT and AST/SGOT must be ≤ 5.0× ULN.

Serum total bilirubin ≤ 1.5 × ULN (corresponding to mild dysfunction as per National Cancer Institute Organ Dysfunction Working Group [NCI ODWG] criteria). In case of documented liver involvement by lymphoma, serum total bilirubin must be ≤ 3.0 × ULN (corresponding to moderate dysfunction as per NCI ODWG criteria). For cases of Gilberts syndrome, serum total bilirubin≤ 5.0 × ULN

Adequate cardiac function for participants receiving anthracycline-based chemotherapy, defined as left ventricular ejection fraction (LVEF) ≥ 45% as assessed by echocardiogram (ECHO) as standard of care or multi-gated acquisition scan (MUGA)