Inclusion Criteria:

1. Participant must have measurable disease as defined per RECIST version 1.1
2. Has a histologically confirmed colorectal adenocarcinoma with metastatic or unresectable disease (Stage IV as defined by American Joint Committee on Cancer [AJCC] 8th edition)
3. No prior systemic therapy for colorectal cancer (CRC) in the metastatic setting except for the induction treatment of first-line therapy. Note: Local regional treatment performed during induction systemic treatment is allowed
4. Participants who have completed the first-line induction treatment, with an overall response of stable disease or better. The duration of induction treatment should be completed within approximately 6 months. The first dose of study treatment needs to occur within 2 weeks (for 2-week regimen) or 3 weeks (for 3-week regimen) to 6 weeks after Day 1 of the last cycle of induction therapy

Exclusion Criteria:

1. Participants whose disease has become resectable at the investigator's discretion during or after induction treatment are not eligible
2. Progressive disease occurred less than 6 months from completion of any prior neoadjuvant therapy (ie, chemotherapy with or without radiotherapy) or adjuvant therapy (ie, chemotherapy with or without radiotherapy), whichever occurred later
3. Participants who have been treated with anti-epidermal growth factor receptor (EGFR) antibody in the induction treatment
4. Any prior therapy targeting T-cell stimulation or checkpoint pathways
5. Participants with B-raf proto-oncogene, serine/threonine kinase (BRAF)V600E mutations
6. Have locally or centrally confirmed microsatellite instability-high (MSI-H) by polymerase chain reaction (PCR) method or dMMR by immunohistochemistry (IHC) method

Note: Other protocol defined criteria may apply.