Lambert-Eaton Myasthenic Syndrome in Small Cell Lung Cancer
Dr. Ticiana Leal from Emory University's Winship Cancer Institute and Dr. Wade Iams from Tennessee Oncology introduce their discussion on Lambert-Eaton myasthenic syndrome (LEMS) in patients with small-cell lung cancer (SCLC). This paraneoplastic syndrome affects approximately 3% of patients with SCLC but remains undiagnosed in up to 90% of cases, representing a significant clinical challenge where symptoms often overlap with expected disease progression or treatment-related adverse effects in busy oncology settings.
Dr. Leal discusses the updated NCCN guidelines recommending VGCC antibody testing for patients with suspected neurologic paraneoplastic syndromes like cancer-associated LEMS, asking about the impact of these guideline changes on awareness and testing rates in community and academic settings. Dr. Iams acknowledges the guidelines help somewhat but emphasizes that broader awareness of the diagnosis and specific available treatments remain more significant factors in improving recognition.
Dr. Leal introduces amifampridine, an FDA-approved oral potassium channel blocker that increases acetylcholine release at neuromuscular junctions for treating LEMS, including cancer-associated cases.
Dr. Leal addresses the complex interaction between cancer-associated LEMS as an autoimmune condition and standard SCLC therapies, particularly immunotherapy agents like checkpoint inhibitors and newer treatments like tarlatamab T-cell engagers.
Dr. Leal addresses diagnostic challenges with newer therapies, particularly tarlatamab's potential neurologic side effects including immune effector cell-associated neurotoxicity syndrome (ICANS), which can manifest as weakness and create diagnostic overlap concerns with cancer-associated LEMS symptoms.