Symbiotic-GI-03: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Adult Participants With Metastatic Colorectal Cancer

Inclusion Criteria: * Histological or cytological confirmed colorectal adenocarcinoma. * Evidence of Stage IV metastatic disease. * No prior systemic therapy for metastatic disease. * Eastern Cooperative Oncology Group performance status (ECOG) 0-1 * At least one measurable lesion according to RECIST 1.1 per Investigator assessment. * Adequate hepatic, liver, and renal function Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Locally confirmed BRAF V600E mutation * Locally confirmed microsatellite instability (MSI)-high or DNA mismatch repair deficiency (dMMR) colorectal cancer * Participants with known active symptomatic CNS lesions, including leptomeningeal metastasis, brainstem, meningeal, or spinal cord metastases or compression * Clinically significant risk of hemorrhage or fistula * Major surgery or severe trauma within 4 weeks prior to the first dose, or planned major surgery during the study * History of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation * Any Grade ≥3 bleeding/hemorrhage events within 28 days of Cycle 1 Day 1, or prior history of clinically significant bleeding events * Clinically significant cardiovascular disease, or other comorbidities, within 6 months prior to first dose * Participants with active autoimmune diseases requiring systemic treatment within the past 2 years * Evidence of non-infectious or drug-induced interstitial lung disease (ILD) pneumonitis