Myasthenia gravis and myocarditis induced by chemoimmunotherapy in locally advanced gastric cancer: A case report

The treatment strategy of patients with locally advanced gastric cancer has undergone notable changes since immune checkpoint inhibitors (ICIs) were developed. Although ICIs are generally well-tolerated, they can also cause serious adverse events, such as autoimmune diseases. In patients with gastric cancer and without a history of immune disease, the incidence of myasthenia gravis combined with myocarditis caused by ICI treatment is rare. Furthermore, cases of gastric cancer with ocular myasthenia gravis, without limb weakness or severe dyspnea, although with urination difficulties and symptoms of third-degree atrioventricular block have not been previously reported, to the best of our knowledge. The present study describes the case of a 72-year-old male patient with locally advanced gastric cancer that was treated with chemoimmunotherapy with oxaliplatin + tigio + sintilimab. At 19 days following only one cycle of therapy, the patient developed a left eyelid weakness and difficulty in urinating, as well as diplopia. At 5 days after the symptom of eyelid weakness, a third-degree atrioventricular block occurred. Hormone therapy, a temporary pacemaker and gamma-globulin therapy were administered, and the patient was discharged 1 month later with the resolution of myasthenia gravis and the atrioventricular block. At the final follow-up (1 month after discharge), the patient had a full recovery from myasthenia gravis and arrhythmias. Although some similar cases have been previously reported, the majority of patients with limb weakness and have eventually succumbed; moreover, clinical symptoms were identified at a late stage, and the disease evolution records were not detailed. Therefore, the present study describes the case of the patient and treatment strategy, also providing detailed laboratory indicators and clinical symptom evolution. This was performed with the aim to aid future research and the treatment of immune-related diseases.