P098 A rare case of immunotherapy induced narcolepsy with cataplexy.

Abstract Background Narcolepsy is a rare disorder of central hypersomnolence which is often under diagnosed largely owing to a variable clinical phenotype. There is strong evidence that type 1 narcolepsy (NT1) is an immune-mediated disorder given the association with the class II Human Leukocyte Antigen (HLA) DQB1*06:02 allele. The advent of cancer immunotherapy, which augments the anti-tumour immune response, has been revolutionary in the management of many types of cancer. Unfortunately, owing to their mechanism of action these agents are frequently associated with immune related adverse effects (irAEs) which can involve any organ in the body. We report a case of NT1 manifesting following ipilimumab and nivolumab exposure. Case A 68 year old man presented with daytime hypersomnolence, fragmented nocturnal sleep and clear evidence of cataplexy captured on video after 7 months of ipilimumab/nivolumab for stage IV melanoma. He also experienced other irAEs (hepatitis, skin reaction, thrombocytopenia). MRI brain did not show intracerebral disease. An MSLT with diagnostic sleep study prior (>6 hours total sleep time) demonstrated a mean sleep latency of 1.15 minutes with 4 sleep onset REM periods. History and polysomnography did not suggest an alternative sleep disorder. HLA typing detected the HLA-DQB1*06:02 allele and lumbar puncture demonstrated an undetectable CSF orexin level. His hypersomnolence is well controlled with armodafanil 250mg daily but cataplexy remains difficult to control. Conclusions This is the second case report of NT1 following immunotherapy, illustrating a very rare but debilitating complication of this treatment, which oncologists and sleep physicians should be aware of.