Narcolepsy type 1 following immune checkpoint inhibitor therapy for metastatic melanoma

Narcolepsy is a rare disorder of central hypersomnolence which is often under-recognised owing to a variable clinical phenotype. Narcolepsy type 1 (NT1) is caused by loss of hypothalamic hypocretin (orexin) secreting neurons, which function to maintain wakefulness. There is strong evidence that NT1 is an immune-mediated disorder associated with the class II human leucocyte antigen DQB1*06:02 allele. Immune checkpoint inhibitors have revolutionised the treatment of many cancers; however, through their mechanism of action, they are associated with immune-related adverse effects. We describe a complex case of NT1 following ipilimumab and nivolumab exposure for management of metastatic melanoma.