Effectiveness Study of Nivolumab Compared to Placebo in Prevention of Recurrent Melanoma After Complete Resection of Stage IIB/C Melanoma

The purpose of this study is to determine the effectiveness of nivolumab adjuvant immunotherapy compared to placebo in adults and pediatric participants after complete resection of Stage IIB/C melanoma with no evidence of disease (NED) who are at high risk for recurrence.

Inclusion Criteria: * Had a negative sentinel lymph node biopsy * Participant has not been previously treated for melanoma * ECOG 0 or 1 * Participants must have been diagnosed with histologically confirmed, Resected, Stage IIB/C cutaneous melanoma Exclusion Criteria: * History of ocular or mucosal melanoma. * Pregnant or nursing women * Participants with active known or suspected autoimmune disease * Known history of allergy or hypersensitivity to study drug components * Prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, anti-CTLA-4 antibody, or agents that target IL-2 pathways, T-cell stimulators, or checkpoint pathways Other protocol defined inclusion/exclusion criteria apply.