This is a global, randomised, Phase III, multicentre, open-label study evaluating the efficacy, safety and the degree of added benefit of the Surovatamig (AZD0486) plus rituximab combination compared to Investigator's choice of 3 standard immunochemotherapy regimen, conducted in participants with untreated FL.

The study consists of 2 sequential parts.

1. Safety Run-in - this part will compare dose levels of Surovatamig (AZD0486) in combination with rituximab in order to establish the RP3D.

2. Phase III - The Phase III part will assess the superiority of Surovatamig (AZD0486) at RP3D in combination with rituximab, compared to Investigator's choice between 3 standard chemoimmunotherapy regimens. Phase 3 consists of 3 arms

   1. Arm A: treatment with Surovatamig plus rituximab Schedule A
   2. Arm B: treatment with Surovatamig plus rituximab Schedule B
   3. Arm C (Comparator arm): one of the following standard regimens per Investigator's choice: R-CVP + rituximab maintenance, R-CHOP + rituximab maintenance or B-R + rituximab maintenance

Inclusion Criteria:

1. Participant must be at least 18 years of age, inclusive, at the time of signing the ICF.
2. Histologically confirmed diagnosis of classic FL per WHO 2022 classification
3. ECOG performance status of 0 to 2
4. No prior systemic lymphoma-directed therapy
5. Need for systemic treatment meeting at least 1 GELF criteria
6. FDG-avid and measurable disease
7. Stage II to IV and FLIPI 2-5 [Phase III only]
8. Adequate liver, hematological, renal and cardiac function.

The above is a summary, other inclusion criteria details may apply

Exclusion Criteria:

1. Follicular large B-cell lymphoma (WHO 2022 classification), formerly Follicular lymphoma Grade 3B (WHO 2016 classification) or suspicion for histologic transformation to high-grade/aggressive lymphoma
2. Contra-indication to BR, RCVP, and R-CHOP
3. Participants with or history of CNS lymphoma
4. History of a clinically relevant CNS medical condition or pathology that required treatment in the preceding year, is currently symptomatic or that which the treating investigator considers to have the potential to interfere with the evaluation of safety
5. Presence of >5000 circulating lymphoma cells
6. Active or uncontrolled infection (including EBV) requiring systemic therapy and which places participant at unacceptable risk if he/she were to participate in the study. If a participant has a history of COVID-19 within 1 month of C1D1 or contracts COVID while on study treatment, participant must have 2 consecutive negative tests (PCR testing is preferable) performed at least 48 hours apart prior to resuming dosing. All symptoms related to COVID-19 infection should have fully resolved before initiating or resuming treatment
7. Known history of hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS)

The above is a summary, other exclusion criteria details may apply

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

When a request has been approved AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. A Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information