We present a case of a 59-year-old male with a confirmed diagnosis of
small-cell lung cancer (SCLC). He had progressive disease even after four cycles of
cisplatin and
etoposide chemotherapy and 21 cycles of radiation. He was therefore started on
immunotherapy with
nivolumab every 2 weeks and
ipilimumab every 6 weeks. After 4 months of starting
immunotherapy, he reported extreme fatigue, muscular weakness, and poor appetite. He was diagnosed with
hypothyroidism, primary adrenal insufficiency, and
Lambert-Eaton Myasthenic Syndrome (LEMS). LEMS can be both a
paraneoplastic syndrome of SCLC and an adverse effect of
immunotherapy. Currently, there is no diagnostic test available to determine if a case of LEMS is a
paraneoplastic syndrome or
immunotherapy-related adverse effect. In our patient, we felt that LEMS was an
immunotherapy-related adverse effect rather being a
paraneoplastic syndrome. Our determination was based on the time of onset of
muscular weakness, presence of other
immunotherapy-mediated adverse events, and the appearance of symptoms in spite of SCLC that had been stabilized on
immunotherapy. Accordingly,
immunotherapy was stopped and a brief tapering course of
steroids was initiated. Our patient's
muscular weakness from LEMS responded well. His clinical improvement persisted even with radiologic progression of disease after cessation of
immunotherapy.