Pembrolizumab-induced myasthenia gravis with myositis in a patient with lung cancer.

In the new era of cancer immunotherapy, clinical research has uncovered diverse and unpredictable immune-related adverse events. Here, we report the first case of pembrolizumab-induced myasthenia gravis (MG) and myositis in a patient with lung cancer. The patient developed symptoms after the second infusion of pembrolizumab and was successfully treated with systemic corticosteroid therapy. With the accelerated development of immune checkpoint inhibitors as mono- or combination therapies for various malignancies, clinicians should closely monitor patients for important immune-related adverse events, such as MG, especially during the early phase of the treatment.