A Study With Combinations of Anti-LAG-3 and Anti-PD-1 Antibodies in Adult Participants With Advanced or Metastatic Melanoma (Harmony Head-to-Head)

Key Inclusion Criteria:

• Participants with histologically confirmed unresectable stage III and stage IV (metastatic) melanoma per American Joint Committee on Cancer (AJCC), eighth revised edition.
• Participants must not have received prior systemic therapy for unresectable or metastatic melanoma as described in the protocol.
• Measurable disease per RECIST version 1.1.
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤1
• Adequate bone marrow, hepatic, and kidney function
• Known B-Rapidly Accelerated Fibrosarcoma protein (BRAF) V600 mutation status or submitted sample for BRAF V600 mutation assessment as described in the protocol

Key Exclusion Criteria:

Medical Conditions:

• Uveal, acral or mucosal melanoma.
• Ongoing or recent (within 2 years) evidence of an autoimmune disease that required systemic treatment with immunosuppressive agents as described in the protocol.
• Uncontrolled infection with human immunodeficiency virus (HIV), hepatitis B (HBV), or hepatitis C virus (HCV) infection; or diagnosis of immunodeficiency that is related to, or results in chronic infection. Mild cancer-related immunodeficiency (such as immunodeficiency treated with gamma globulin and without chronic or recurrent infection) is allowed.

Prior/Concomitant Therapy:

• Prior immune checkpoint inhibitor therapy other than anti-PD1/PD-L1 as described in the protocol
• Systemic immune suppression as described in the protocol.

Other Comorbidities:

• Participants with a history of myocarditis.
• Troponin T (TnT) or troponin I (TnI) >2x institutional upper limit of normal (ULN).
• Active or untreated brain metastases or spinal cord compression as described in the protocol.

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply.