[Eculizumab led to beneficial clinical course in a patient with generalized myasthenia gravis who developed COVID 19-associated pneumonia].

A 74-year-old woman developed myasthenia gravis (MG) at the age of 32. She had a thymoma removed the following year, but her MG symptoms did not stabilize, and she required frequent hospitalization for fast-acting treatment (FT). She started eculizumab in March of two years ago and was followed up on an outpatient basis as her MG symptoms became milder. In February of this year, she was admitted to our hospital due to mild COVID-19-associated pneumonia with general malaise and fever. Her COVID-19-associated pneumonia was treated with intravenous sotrovimab, dexamethasone, and unfractionated heparin, and oral therapy for MG stayed the same. Eculizumab was not administered during hospitalization due to the combination of stable MG symptoms and the fact that the drug is not paid for by the Japanese insurance system. The patient's MG and COVID-19-associated pneumonia were not severe during hospitalization. However, the risk of myasthenic crisis and death is high when patients with MG develop COVID-19-associated pneumonia. Several reports suggest that the condition of patients with eculizumab-treated MG who develop COVID-19-associated pneumonia is not severe, and that that inhibition of the complement pathway with eculizumab is effective for COVID-19-associated pneumonia. Complement deposition in organ microvessels has been observed in patients with COVID-19, which suggests that complement overload may be a risk factor for COVID-19-associated pneumonia. Excessive complement activation may be involved in the pathogenesis; thus, eculizumab may function by inhibiting this pathway. In this case, eculizumab was discontinued while the patient had COVID-19-associated pneumonia, however, CH50, which is an indicator of complement, was suppressed during hospitalization due to the COVID-19-associated pneumonia. Therefore, eculizumab may have interfered with this course of events. This case demonstrates that eculizumab may be safe for and tolerated by patients with MG and COVID-19-associated pneumonia, but more cases need to be accumulated to support this conclusion.