The purpose of this study is to assess the efficacy, safety, and immunogenicity of ABP 206 compared with Nivolumab in Subjects with Treatment-Naïve Unresectable or Metastatic Melanoma.

Eligible subjects will be randomized (1:1) to receive investigational product (ABP 206 or nivolumab).

All subjects will be treated until disease progression, unacceptable toxicity, or subject withdrawal of consent for a maximum of 24 months of treatment.

The total duration of study participation for each subject will be approximately 26 months.

Key Inclusion Criteria:

• At least 18 years of age.
• Histologically confirmed unresectable or metastatic melanoma.
• Subject has no prior systemic treatment for advanced disease.
• Subject must have measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST version 1.1).
• Tumor tissue from site of unresectable or metastatic melanoma must be available for biomarker analyses in order to be randomized.
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1.

Key Exclusion Criteria:

• Subject has had any prior systemic anti-cancer therapy for the treatment of advanced melanoma.
• Known hypersensitivity to monoclonal antibodies or to any of the excipients of the study drug.
• Subject has active central nervous system (CNS) metastases not previously treated.
• Ocular melanoma.
• Subject has active or known immune-mediated disorders.
• Subject has had prior treatment with PD-1/PD-L1 and cytotoxic T lymphocyte- associated protein 4 inhibitors, or other antibodies targeting immune checkpoint pathways.
• Subject has medical conditions requiring systemic immunosuppression with either corticosteroids or other immunosuppressive medications within 14 days of the first dose of investigational product.

Other protocol-defined inclusion/exclusion criteria apply.

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues, and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data-sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data-sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.

The study is double-blinded; therefore, the investigators, study personnel (with the exception of the data monitoring committee, authorized unblinded sponsor and contract research organization staff, and unblinded site pharmacy staff) and the study subjects will remain blinded to treatment allocation. ABP 206 and nivolumab will be coded and labeled to protect blinding.