# Case Report and literature review: immune checkpoint inhibitor-associated myasthenia gravis and myocarditis

## TL;DR

A case report and literature review explore rare but severe side effects of immune checkpoint inhibitors, including myasthenia gravis and myocarditis.

## Contribution

The study reports a rare case of ICI-associated myasthenia gravis and myocarditis and reviews 45 similar cases to highlight clinical patterns and outcomes.

## Key findings

- ICI-associated myasthenia gravis and myocarditis is a rare but severe adverse event with poor prognosis.
- Prompt recognition and treatment with glucocorticoids and supportive care improved clinical outcomes in the reported case.
- Multiple immune-related adverse events can occur simultaneously following ICI therapy.

## Abstract

To investigate the clinical features of immune checkpoint inhibitor (ICI)-associated myasthenia gravis (MG) with concurrent myocarditis with the aim of enhancing our understanding. We retrospectively analyzed the clinical data of a patient diagnosed with ICI-associated MG and myocarditis, and reviewed the relevant literature. A 67-year-old man was admitted with a 4-day history of right-sided ptosis and blurred vision. His medical history included resection of adenocarcinoma in the right upper lung lobe over 18 years ago and a diagnosis of new lung cancer in the right lower lobe four months prior to presentation. In May 2025, lung cancer recurrence was identified but the patient declined any treatment at that time. In September 2025, following radiotherapy and a single dose of serplulimab (a programmed cell death protein 1 inhibitor, PD-1), the patient developed clinical symptoms including ptosis, a positive fatigue test, and a positive neostigmine test, suggestive of myasthenia gravis. Biochemical tests, electrocardiogram (ECG), and echocardiography indicated myocarditis. The clinical diagnosis was ICI-associated myocarditis. Management involved the discontinuation of immunotherapy, administration of glucocorticoids, and symptomatic supportive treatment, which led to clinical improvement. A literature review summarized 45 cases, indicating that this overlapping immune-related adverse event is rare and has a poor prognosis. Multiple adverse reactions to ICIs can occur simultaneously. Prompt recognition of symptoms and initiation of targeted and effective treatments are crucial for optimizing clinical outcomes.