The purpose of this study is to evaluate the efficacy of Pumitamig versus Pembrolizumab in participants with previously untreated advanced Non-Small Cell Lung Cancer and PD-L1 ≥ 50%.

DRUG: Pumitamig

Specified dose on specified days

DRUG: Pembrolizumab

Specified dose on specified days

Inclusion Criteria

• Participants must have a histologically or cytologically confirmed diagnosis of Non-Small Cell Lung Cancer (NSCLC) (squamous and nonsquamous) with Stage IIIB/IIIC or Stage IV disease.
• Participants must have a programmed death ligand-1 (PD-L1) expression ≥ 50%.
• Participants must have measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.
• Participants must have no prior systemic anti-tumor therapy for locally advanced or metastatic NSCLC.
• Participants must have an Eastern Cooperative Oncology Group (ECOG) Performance Status 0-1.

Exclusion Criteria

• Participants must not have any documented actionable genomic alteration (AGA) for which first-line (1L) approved therapies are indicated.
• Participants must not have any symptomatic untreated central nervous system (CNS) metastases, leptomeningeal metastases (carcinomatous meningitis) or spinal cord compression.
• Participants must not have any significant cardiovascular impairment as evidenced by uncontrolled hypertension (despite optimal medical treatment), congestive heart failure, active coronary disease (within 6 months prior to randomization), ventricular arrhythmias, or major thrombotic or embolic events or major hemorrhagic events (within 6 months prior to randomization), or significant risk of pulmonary hemorrhage.
• Participants must not an active autoimmune disease.
• Other protocol-defined Inclusion/Exclusion criteria apply.