Treatment of LEMS may vary depending upon the presence of associated cancer. If cancer is present, treatment first involves treatment directed at the cancer, this alone may result in relief of LEMS symptoms.
There is no cure for LEMS and treatment usually involves improving quality of life. Therefore, symptomatic treatment is the focus in the management of LEMS. The FDA recently approved a new drug for the symptomatic relief of symptoms associated with muscle weakness called Firdapse (amifampridine). It is a potassium channel blocker that works by increasing the release of acytelcholine. At this time, it is the only drug approved for the indication of LEMS. The medication has shown to have significant benefits such as improving muscle strength and CMAP. In addition, it is a well-tolerated medication.
If Firdapse alone does not improve symptoms, there are additional options that can be added in case of symptom progression. Mestinon is indicated for the treatment of MG, but is often used in combination with Firdapse to treat symptoms of autonomic dysfunction (dry mouth, dry eyes, constipation, impotence and, decreased sweating). In MG, Menstinon improves muscle strength, but in LEMS, it has only shown to improve symptoms of autonomic dysfunction.
In 2019, Ruzurgi (amifampridine) was approved to treat LEMS in patients 6 to less than 17 years of age. This is the first FDA approved treatment specifically for pediatric patients with LEMS.
Drugs that suppress the activity of the immune system (immunosuppressive drugs) are used in LEMS patients with more severe symptoms, e.g. prednisone (alone or in conjunction with azathioprine or cyclosporin). In some patients, a course of high dose immunoglobulins may prevent further disease progression.