Durvalumab for Extensive-Stage of Small-Cell Lung Cancer With Lambert-Eaton Myasthenic Syndrome.

Durvalumab is an immune checkpoint inhibitor (ICI) of anti-programmed cell death protein 1 ligand antibody. ICI-combined chemotherapy has recently become a standard regimen for extensive-stage of small-cell lung cancer (ES-SCLC). SCLC is well known to be the most likely tumor associated with Lambert-Eaton myasthenic syndrome (LEMS), a rare autoimmune disease of a neuromuscular junction disorder. Although LEMS has been reported to be induced by ICI as immune-mediated adverse events, it remains unknown whether ICI can deteriorate preexisting paraneoplastic syndrome (PNS) of LEMS. Our rare case was successfully treated by durvalumab plus chemotherapy without exacerbation of preexisting PNS of LEMS. We report a 62-year-old female with ES-SCLC and preexisting PNS of LEMS. She started carboplatin-etoposide in combination with durvalumab. This immunotherapy achieved nearly complete response. However, multiple brain metastases were found after two courses of maintenance durvalumab. Her symptoms and physical examinations of LEMS improved despite of no significant change in compound muscle action potential amplitude in the nerve conduction study. The titer of anti-P/Q-type voltage-gated calcium channel (VGCC) antibody decreased from 1,419.2 to 263.5 pmol/L during the immunotherapy. In conclusion, ICI in combination with platinum doublet chemotherapy is still challenging but may be a treatment option for ES-SCLC patients complicated with PNS of LEMS.