Small Cell Lung Cancer Treated by Atezolizumab Without the Exacerbation of Lambert-Eaton Myasthenic Syndrome: a Case Report

Background. In the treatment of lung cancer, cancer immunotherapy with immune checkpoint inhibitors (ICIs) may cause or exacerbate immune-related adverse events (irAEs) in patients with pre-existing autoimmune diseases. Case. A 72-year-old man was referred to our hospital with complaints of fever and back pain. After a thorough medical examination, he was diagnosed with extensive stage small cell lung cancer (SCLC) complicated by Lambert-Eaton myasthenic syndrome (LEMS) and obstructive pneumonia. After receiving carboplatin/etoposide plus atezolizumab therapy, he is currently on maintenance therapy with atezolizumab. Conclusion. Although there are several reports of LEMS as an irAE caused by ICI therapy, we report a case of SCLC complicated by LEMS, in which the patient was treated with atezolizumab, and in which both LEMS and SCLC had an uneventful course.