Testing Treatment With Ipilimumab and Nivolumab Compared to Treatment With Ipilimumab Alone in Advanced Melanoma

Inclusion Criteria: * Patients must have pathologically confirmed melanoma that is either stage IV or unresectable stage III; patients may have primaries of cutaneous, mucosal or unknown origin; patients with uveal (ocular) primary are not eligible * Patients must have measurable disease per RECIST 1.1; all measurable lesions must be assessed by physical examination, computed tomography (CT) scans or magnetic resonance imaging (MRI) within 28 days prior to registration; if the only measurable disease is cutaneous or subcutaneous, lesions must be at least 10 mm in greatest dimension and able to be serially recorded using calipers and photographs; tests used to assess non-measurable disease must have been performed within 42 days prior to registration; all disease must be assessed and documented on the Baseline Tumor Assessment Form * Patients with central nervous system (CNS) metastases must have all lesions adequately treated with stereotactic radiation therapy, craniotomy, Gamma Knife (registered trademark) therapy, or whole brain radiotherapy, with no subsequent evidence of CNS progression; patients must not have required steroids for at least 14 days prior to registration; patients with a history of central nervous system metastases must have MRI of the brain within 42 days prior to registration * Patients must have had prior treatment with anti-PD1 or anti-PD-L1 agents and had documented disease progression per the treating physician either while on these agents or after…