 - Active brain metastasis or leptomeningeal disease; patients with known brain metastases are allowed if metastases have been treated and there is no magnetic resonance imaging MRI evidence of progression for at least 12 weeks after treatment is complete and within 28 days prior to the first dose of nivolumab administration; there must also be no requirement for immunosuppressive doses of systemic corticosteroids 10 mgday prednisone equivalents for at least 2 weeks prior to study drug administration 