A Study Investigating the Efficacy and Safety of Alcestobart (LBL-007) Plus Tislelizumab in Combination With Bevacizumab Plus Fluoropyrimidine Versus Bevacizumab Plus Fluoropyrimidine in Participants With Unresectable or Metastatic Colorectal Cancer

This is a Phase 1b/2 study to investigate the efficacy and safety of alcestobart (LBL-007) plus tislelizumab when administered in combination with bevacizumab plus fluoropyrimidine, and alcestobart in combination with bevacizumab plus fluoropyrimidine versus bevacizumab plus fluoropyrimidine to participants with colorectal cancer.

Inclusion Criteria: * Participant must have measurable disease as defined per RECIST((Response Evaluation Criteria in Solid Tumors) version 1.1 * Has a histologically confirmed colorectal adenocarcinoma with metastatic or unresectable disease (Stage IV as defined by American Joint Committee on Cancer \[AJCC\] 8th edition) * 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 * 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: * Participants whose disease has become resectable at the investigator's discretion during or after induction treatment are not eligible * 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 * Participants who have been treated with anti-epidermal growth factor receptor (EGFR) antibody in the induction treatment * Any prior therapy targeting T-cell stimulation or checkpoint pathways * Participants with B-raf proto-oncogene, serine/threonine kinase (BRAF)V600E mutations * 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.