When it comes to unexplained muscle weakness and fatigue in SCLC patients
Leave no stone unturned
Your patients may also have Cancer-Associated LEMS, which can make it difficult to get out of a chair or climb stairs
LEMS=Lambert-Eaton myasthenic syndrome;
SCLC=small cell lung cancer;
VGCC-Ab=voltage-gated calcium channel antibody.
Scroll down to read more about National Comprehensive Cancer Network® (NCCN®)
recommendations and an FDA-approved treatment
Cancer-Associated Lambert-Eaton myasthenic syndrome (LEMS) is the most common antibody-mediated neurologic paraneoplastic syndrome in SCLC1
Cancer-Associated LEMS is a progressive, debilitating, and treatable immune-mediated disease2,3
Symptoms of Cancer-Associated LEMS are caused by the production of anti-voltage-gated calcium channel (VGCC) antibodies that impair signal transmission at the neuromuscular junction5
It is speculated anti-VGCC antibodies, as well as other soluble components in patients with Cancer-Associated LEMS, may inhibit SCLC tumor cell proliferation4
- Clinical data suggest that the immune response associated with LEMS may suppress tumor activity, thus prolonging survival times of LEMS patients with cancer6
- LEMS diagnosis can be confirmed with an anti-VGCC antibody test—a simple, readily available, inexpensive blood test7
- Testing for LEMS is important: The weakness associated with LEMS in patients with Cancer-Associated LEMS may be treatable8,9
Symptoms of Cancer-Associated LEMS:
Include the classic triad of proximal muscle weakness, autonomic dysfunction, and hyporeflexia or areflexia10,11
- Proximal leg muscle weakness
- Proximal arm muscle weakness
- Dry mouth
- Impotence
- Constipation
- Areflexia
- Orthostatic hypotension
Are progressive, leading to worsening weakness and the loss of mobility2,10
May be mistaken for cancer or the side effects of cancer treatment12,13
Estimated prevalence of patients with co-occurring SCLC and LEMS
An analysis of claims data suggests that > 90% of LEMS cases associated with SCLC may be undiagnosed14
LEMS presents with symptoms SCLC patients commonly experience, such as fatigue, weakness, and restricted mobility2,12
- It is difficult to clinically differentiate these SCLC symptoms from LEMS—a VGCC test can help confirm the diagnosis7,15
- Some case studies suggest immune checkpoint inhibitor (ICI) therapy could exacerbate neurologic symptoms for patients with neurologic paraneoplastic disease16
- SCLC patients with suspected LEMS pattern of weakness (either on or not on chemotherapy) may benefit from LEMS testing10,17
If symptoms of weakness are caused by LEMS, an FDA-approved therapy is available.3
Patients with SCLC and Cancer-Associated LEMS exhibit more favorable survival rates than those with non-LEMS SCLC, with an overall median survival of 17 months compared with 7 months (P < 0.0001)8
Overall Median Survival Rate8
There is a simple and inexpensive test to confirm LEMS in your patients with SCLC7
When Cancer-Associated LEMS is suspected, anti-VGCC antibody testing is one method to confirm the diagnosis7
VGCCs are transmembrane protein structures that play a pivotal role in neuromuscular signal transmission10,18
Multiple types of VGCCs have been described in both the central and peripheral nervous systems18
Currently, anti-VGCC antibody testing may not be a standard part of paraneoplastic panels
Catalyst Pharmaceuticals provides free anti-VGCC antibody testing
In collaboration with a national diagnostic lab provider, Catalyst offers no-cost anti-VGCC antibody testing (both VGCC-P/Q type and VGCC-N type) for patients who have symptoms suggestive of Cancer-Associated LEMS
You can also get the test request form by calling 1-833-422-8259 or contacting a Catalyst Representative below
The NCCN recommends considering a comprehensive antibody panel for patients with SCLC and a suspected paraneoplastic neurologic syndrome19
Learn about the only clinically proven, FDA-approved treatment for LEMS
References:
- Gandhi L, Johnson BE. Paraneoplastic syndromes associated with small cell lung cancer. J Natl Compr Canc Netw. 2006;4(6):631-638.
- Harms L, Sieb JP, Williams AE, et al. Long-term disease history, clinical symptoms, health status, and healthcare utilization in patients suffering from Lambert Eaton myasthenic syndrome: results of a patient interview survey in Germany. J Med Econ. 2012;15(3):521-530.
- National Organization for Rare Disorders (NORD) website. Rare disease database: Lambert-Eaton myasthenic syndrome. Accessed March 14, 2025. https://rarediseases.org/rare-diseases/lambert-eaton-myasthenic-syndrome/
- Maddison P, Gozzard P, Grainge MJ, et al. Long-term survival in paraneoplastic Lambert-Eaton myasthenic syndrome. Neurology. 2017;88:1-6.
- Tarr TB, Wipt P, Meriney SD, et al. Synaptic pathophysiology and treatment of Lambert-Eaton myasthenic syndrome. Mol Neurobiol. 2015;52(1):456-463.
- Kesner VG, Shin JO, Dimachkie MM, Barohn RJ. Lambert-Eaton myasthenic syndrome. Neurol Clin. 2018;36(2):379-394.
- Gilhus NE. Lambert-Eaton myasthenic syndrome; pathogenesis, diagnosis, and therapy. Autoimmune Dis. 2011;2011:973808.
- Lipka AF, Boldingh MI, van Zwet EW, et al. Long-term follow-up, quality of life, and survival of patients with Lambert-Eaton myasthenic syndrome. Neurology. 2020;94(5):e511-e520.
- Yoon CH, Owusu-Guha J, Smith A, Buschur P. Amifampridine for the management of Lambert-Eaton myasthenic syndrome: a new take on an old drug. Ann Pharmacother. 2020;54(1):56-63.
- Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011;10(12):1098-1107.
- Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011; Appendix:1-4.
- Bebb DG, Murray C, Giannopoulou A, et al. Symptoms and experiences with small cell lung cancer: a mixed methods study of patients and caregivers. Pulm Ther. 2023;9:435-450.
- Schoser B, Eymard B, Datt J, et al. Lambert-Eaton myasthenic syndrome (LEMS): a rare autoimmune presynaptic disorder often associated with cancer. J Neurol. 2017;264(9):1854-1863.
- Morrell D, Drapkin B, Shechter G, et al. Lambert-Eaton myasthenic syndrome is underrecognized in small cell lung cancer: an analysis of real-world data. Presented as a poster at the International Association for the Study of Lung Cancer (IASLC) – WCLC Annual Meeting 2023. September 9-12, 2023, Singapore.
- Sanders DB. Lambert-Eaton myasthenic syndrome: diagnosis and treatment. Ann NY Acad Sci. 2003;998:500-508.
- Kunii E, Owaki S, Yamada K, et al. Lambert-Eaton myasthenic syndrome caused by atezolizumab in a patient with small-cell lung cancer. Intern Med. 2022;61:1739-1742.
- Briggs S, Gozzard P, Talbot DC. The association between Lambert–Eaton myasthenic syndrome and small cell lung carcinoma. Immunotargets Ther. 2013;2:31-37.
- Catterall WA. Voltage-gated calcium channels. Cold Spring Harb Perspect Biol. 2011;3:a003947.
- Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Small Cell Lung Cancer Version 4.2025 © National Comprehensive Cancer Network, Inc. 2025. All rights reserved. Accessed March 14, 2025. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.
