A Study to Compare the Efficacy of Nivolumab and Relatlimab Plus Chemotherapy vs Pembrolizumab Plus Chemotherapy for Stage IV/Recurrent Non-squamous Non-small Cell Lung Cancer With PD-L1 Expression ≥ 1%

Prior treatment

• Participants with known BRAFV600E mutations, that are sensitive to available targeted inhibitor therapy; participants with known activating rearranged during transfection (RET) mutations or neurotrophic tyrosine receptor kinase (NTRK) fusion gene alterations are excluded. Participants with unknown or indeterminate BRAF mutation, activating RET mutations or NTRK fusion gene alterations are eligible.
• Participants must not have concurrent malignancy requiring treatment.
• Participants must not have had prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, or anti-CTLA-4 antibody, or other antibody or drug targeting T-cell co-stimulation or checkpoint pathways.

Other illness

• Participants must not have an active autoimmune disease.
• Participants must not have history of interstitial lung disease or pneumonitis that required oral or intravenous (IV) glucocorticoids to assist with management.
• Participants must not have a history of myocarditis.

Lab values

• Participants with epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), or ROS-1 mutations that are sensitive to available targeted inhibitor therapy. Participants with unknown EGFR, ALK, or ROS-1 status are excluded.

Other

• Participants must not be pregnant and/or breastfeeding.
• Participants must not have untreated central nervous system (CNS) metastases.
• Participants must not have leptomeningeal metastases (carcinomatous meningitis).
• Other protocol-defined Inclusion/Exclusion criteria apply.

• Participants must have histologically confirmed Stage IV or recurrent Non-small Cell Lung Cancer (NSCLC) of non-squamous (NSQ) histology with no prior systemic anti-cancer therapy given as primary therapy for advanced or metastatic disease.
• Participants must have measurable PD-L1 ≥ 1% Tumor Cell (TC) score by the investigational PD-L1 immunohistochemistry (IHC) assay VENTANA PD-L1 (SP263) CDx Assay conducted by central laboratory during the screening period prior to randomization.
• Participants must have measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) per RECIST v1.1 criteria.
• Participants must have an Easter Cooperative Oncology Group (ECOG) performance status of ≤ 1 at screening.
• Participants must have a life expectancy of at least 3 months at the time of randomization.