A Clinical Study to Test if an Investigational Treatment Called BNT314 When Used in Combination With Another Investigational Treatment Pumitamig (BNT327) and Chemotherapy, is Beneficial and Safe for Patients With Advanced Colorectal Cancer

This randomized, multi-site, three-part study will test a new treatment called BNT314, which is designed to help the body's own defense to fight cancer in combination with another new treatment (pumitamig, which is a cancer immunotherapy drug also known as BNT327 and PM8002) and chemotherapy in participants with metastatic colorectal cancer (mCRC).

Key Inclusion Criteria: * Have unresectable histologically confirmed adenocarcinoma of the colon or rectum. * Have confirmed non-microsatellite instability-high (non-MSI-H)/pMMR mCRC per Food and Drug Administration (FDA)/European Commission (EC) approved test or based on local testing. * Have measurable disease defined by RECIST v1.1. * Must provide a tumor tissue sample (formalin-fixed, paraffin-embedded or tissue slides) collected before C1D1 for enrollment. A newly obtained tumor sample is preferred. If it is not feasible to obtain a recent tumor sample, participants can provide archival tumor tissue (less than 2 years prior treatment). * Have Eastern Cooperative Oncology Group Performance Status of 0 or 1. * Have a life expectancy of ≥12 weeks. * Have an adequate organ and bone marrow function within ≤7 days of Day 1 as defined in the protocol. * Have had an adequate previous treatment washout period before randomization/enrollment as defined in the protocol. Inclusion criteria applicable to only protocol-specific cohorts: * Have histologically confirmed metastatic colorectal cancer and radiographically documented disease progression after ≥2 prior lines of systemic therapy for metastatic disease as defined in the protocol. * Have progressed following first-line chemotherapy as specified in the protocol. * Have not received prior systemic therapy for MSS/pMMR mCRC. Participants who received chemotherapy, radiotherapy, or chemoradiotherapy with curative intent for non-metastatic disease in the neoadjuvant or adjuvant setting are eligible for the study if therapy was completed at least 6 months prior to initiation of study treatment. Other cohort-specific inclusion criteria apply. Key Exclusion Criteria: * Confirmed MSI-H/deficient mismatch repair mCRC (per FDA/CE approved test or based on local testing). * Prior treatment with epithelial cell-adhesion molecule or 4-1BB targeted or immunotherapy. * Prior treatment with immune checkpoint inhibitors or programmed death-ligand 1 (PD\[L\]-1)/vascular endothelial growth factor bispecific antibody. * Is a candidate to locoregional treatment (including surgical resection, stereotactic radiation therapy or tumor ablation) with potential to induce complete or near complete response and prolonged tumor control (sometimes described as "radical" intent), per investigator's assessment. * Have uncontrolled or significant cardiovascular disease as specified in the protocol. * Have left ventricular ejection fraction \