New-onset (Grade 2-3) moderate to severe symptoms: rule out infectious or other causes; consult neurologist, obtain brain MRI and lumbar puncture
For ipilimumab: Anticipate standard ipilimumab dosage holds/discontinuations; administer corticosteroids at dosage of 1-2 mg/kg/d prednisone equivalents (or 2-4 mg/kg if necessary)
For nivolumab: Withhold nivolumab for new-onset moderate to severe neurologic symptoms; evaluate as described above; if other etiologies are ruled out, administer corticosteroids and permanently discontinue nivolumab for immune-mediated encephalopathy