Inclusion Criteria:

• Histologically or cytologically confirmed diagnosis of gastric or GEJ adenocarcinoma
• Metastatic disease or locally advanced, unresectable disease
• Participants who have measurable target lesion
• Participants with high carcinoembryonic antigen-related cell adhesion molecule (CEACAM5) expression as per central assessment on tumor biospsy
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Female participant who agrees to use effective contraceptive methods during and for at least 7 months after the last dose of treatment administration
• Male participant who agrees to use effective contraception methods during and for at least 4 months after the last dose of treatment administration
• Signed informed consent

Exclusion Criteria:

• Untreated brain metastases, leptomeningeal disease, or uncontrolled spinal cord compression
• Significant concomitant illness
• History within the last 3 years of an invasive malignancy other than that treated in this study
• Known uncontrolled infection
• Nonresolution of any prior treatment-related toxicity
• Unresolved corneal disorder or any previous corneal disorder considered by an ophthalmologist to predict higher risk of drug-induced keratopathy
• Use of contact lenses
• Radiographic evidence of major airway or blood vessel invasion or intratumor cavitation
• History of uncontrolled hereditary or acquired thrombotic disorder or history of aneurism
• Major surgery within 28 days prior to Day 1/first IMP infusion; subcutaneous venous access device placement within 7 days prior to Day 1; or postoperative bleeding complications or wound complications from a surgical procedure performed in the last 2 months
• History of gross hemoptysis (defined as bright red blood or ≥1/2 teaspoon) within 2 months before the first treatment administration
• Any arterial thrombotic event, including myocardial infarction, unstable angina, cerebrovascular accident, or transient ischemic attack, within 6 months before the first administration of treatment administration
• Uncontrolled arterial hypertension (systolic ≥150 mmHg or diastolic ≥90 mmHg) despite standard medical management.
• Serious or nonhealing wound, skin ulcer, or bone fracture within 28 days before the first administration of treatment administration
• Gastrointestinal (GI) perforation and/or fistulae within 6 months prior to first administration of treatment administration
• Significant bleeding disorders, vasculitis, or Grade 3-4 gastrointestinal (GI) bleeding within 3 months before the first administration of study intervention.
• Bowel obstruction, history or presence of inflammatory enteropathy or extensive intestinal resection Crohn's disease, ulcerative colitis, or chronic diarrhea
• Medical condition requiring concomitant administration of a medication with a narrow therapeutic window and metabolized by CYP450 or a strong CYP3A inhibitor
• Concurrent treatment with any other anticancer therapy
• Prior treatment targeting CEACAM5 or containing maytansinoid DM1 or DM4 or ramucirumab or taxane or targeting VEGF/VEGFR Poor organ function

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.