- Brain metastases are allowed if they have been adequately treated with radiotherapy or surgery and have been stable for at least three months prior to registration; eligible subjects should be neurologically asymptomatic; there is no magnetic resonance imaging (MRI) evidence of progression for a minimum of 4 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 mg/day prednisone equivalents) for at least 2 weeks prior to study drug administration