Abstract Details

Title Myasthenia Gravis in a patient being treated with pembrolizumab in the absence of anti-acetylcholine receptor antibodies

Topic General Neurology

Presentation(s) General Neurology Posters (7:00 AM-5:00 PM)

Poster/Presentation
Number 053

Objective A report on a rare case of a cancer patient on pembrolizumab (Keytruda) immunotherapy developing myasthenia gravis in the absence of anti-acetylcholine receptor antibodies.

Background Myasthenia gravis is an antibody-mediated disease. In about 85% of myasthenia gravis patients with generalized muscle weakness, anti-acetylcholine receptor antibodies are present. Previously, there have been reports of patients developing myasthenia gravis while being treated with pembrolizumab. Almost all these patients were reported to have the presence of anti-acetylcholine receptor antibodies.

Design/Methods 77-year-old female arrived at the emergency room with complaints of pain in her left arm, shortness of breath, and dizziness. She had a known history of lung cancer for which she was being treated with pembrolizumab (Keytruda). She was started on bronchodilators and steroids. She developed progressive anemia from an ascending colon bleed. She continued to have dyspnea and progressive muscle weakness until she developed a neck drop. Differential diagnosis was broad with a concern for myasthenia gravis. Her labs were negative for anti-acetylcholine receptor antibody but due to her clinical presentation she was stared on IVIG, pyridostigmine (Mestinon), and steroids and she responded very well. Her respiratory status improved as did her muscle weakness from not being able to hold her head up to being able to sit in a chair for several hours by herself. After completing her course of IVIG, she was continued on maintenance therapy that included Mestinon and prednisone as she still had residual generalized weakness.

Results NA

Conclusions In patients being treated with Keytruda, atypical presentation of myasthenia gravis should be considered if a patient shows clinical presentation even in the absence of anti-acetylcholine receptor antibodies. This is confirmed with response to IVIG and pyridostigmine treatment.

Authors/Disclosures
Gaurav Kiri PRESENTER	Gaurav Kiri has nothing to disclose.
Liliana Montoya, MD (Neurology PA)	Dr. Montoya has nothing to disclose.

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