Immune Checkpoint Inhibition-Related Myasthenia-Myositis-Myocarditis Responsive to Complement Blockade

Area of Science:

• Oncology
• Immunology
• Neurology

Background:

• Immune checkpoint inhibitors (ICIs) offer significant cancer treatment benefits but can induce immune-related adverse events (irAEs).
• Neuromuscular irAEs, such as myositis and myasthenia gravis (MG), present serious challenges due to high morbidity and mortality.

Observation:

• A 47-year-old woman with breast cancer developed severe tetraparesis, dysphagia, and myalgia during ICI therapy.
• The patient had a prior diagnosis of MG with thymoma, presenting as a myasthenia-myositis-myocarditis overlap syndrome.

Findings:

• Despite ICI discontinuation and standard treatments, the patient showed no clinical response.
• A muscle biopsy revealed complement deposition, guiding the use of eculizumab.
• Eculizumab therapy resulted in prompt improvement of muscle strength and cardiac function.

Implications:

• Early diagnosis and targeted therapy, guided by muscle biopsy, are crucial for managing refractory neuromuscular irAEs.
• Identifying specific treatment targets, like complement deposition, can overcome limitations of standard approaches.
• Further research into patient-tailored strategies is essential to improve outcomes for neuromuscular irAEs.