Abstract Details

Title Immune Checkpoint Inhibitor Related Myositis/Myasthenia Gravis Overlap Syndrome Treated with Eculizumab

Topic Autoimmune Neurology

Presentation(s) P3 - Poster Session 3 (12:00 PM-1:00 PM)

Poster/Presentation
Number 080

Objective To present a case of immune checkpoint inhibitor related myositis/myasthenia gravis overlap syndrome treated with eculizumab.

Background Immune checkpoint inhibitors (ICI), a common therapy for multiple cancer types, cause severe central and peripheral nervous system immune-related adverse neurotoxicity. Common peripheral nervous system manifestations include peripheral neuropathies, myositis, myasthenia gravis, and not uncommonly an overlap syndrome of myositis, myasthenia gravis and myocarditis. Treatment for ICI neurotoxicity often requires first line immunosuppressive therapies and discontinuation of the ICI but may require additional maintenance immunosuppression for aggressive disease.

Design/Methods A retrospective case report.

Results A 64-year-old male with metastatic hepatocellular carcinoma on durvalumab and tremelimumab presents with head drop, trouble breathing and proximal weakness. One week after he received his third cycle of his ICI he noticed weakness in his neck, proximal arm and legs, and trouble swallowing. Work up showed creatine kinase of 144 and positive acetylcholine receptor antibodies (7.5 nanomoles/Liter). EMG/NCS demonstrated a non-irritative myopathy affecting more proximal than distal muscles and repetitive nerve stimulation testing showed a decrement of 10% consistent with a superimposed postsynaptic neuromuscular junction disorder. Cardiac evaluation did not demonstrate myocarditis. He initially received multiple courses of intravenous immunoglobulin and high dose intravenous methylprednisolone with robust but transient improvements in symptoms, resulting in repeated hospitalizations intubation for respiratory failure. He was started on weekly plasmapheresis and started on eculizumab long-term while in the hospital, resulting in significant and sustained improvement in his symptoms.

Conclusions Immune checkpoint inhibitors can lead to neuromuscular immune-related adverse events with significant morbidity and mortality. ICI related myositis and myasthenia gravis overlap syndromes can result in severe respiratory distress and can been associated with potentially fatal myocarditis, making it crucial for providers to carefully screen for this triad. This case illustrates the benefit of plasmapheresis and complement blockade in such patients.

Authors/Disclosures
Sage T. Hewitt, MD (VUMC) PRESENTER	Dr. Hewitt has nothing to disclose.
Danfeng Wang, MD	No disclosure on file
Meryim Poursheykhi, MD (Vanderbilt University Medical CEnter)	Dr. Poursheykhi has nothing to disclose.
Shaily Patel, MD (Vanderbilt University Medical Center)	Dr. Patel has nothing to disclose.
Shailee S. Shah, MD	Dr. Shah has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon Therapeutics. Dr. Shah has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Shah has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Shah has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Shah has received publishing royalties from a publication relating to health care.

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