FDA Approves Amifampridine for Treatment of LEMS in Children

The US Food and Drug Administration recently announced it has granted approval for amifampridine (Ruzurgi) tablets, from Jacobus Pharmaceutical Company Inc., for the treatment of Lambert-Eaton myasthenia syndrome (LEMS) in patients between the age of 6 and less than 17 years old.

The approval marks the first for a treatment specifically for pediatric patients with LEMS — the only other approved treatment for LEMS is only approved for use in adults.

“We continue to be committed to facilitating the development and approval of treatments for rare diseases, particularly those in children,” said Billy Dunn, MD, director of the Division of Neurology Products in the FDA’s Center for Drug Evaluation and Research. “This approval will provide a much-needed treatment option for pediatric patients with LEMS who have significant weakness and fatigue that can often cause great difficulties with daily activities.”

LEMS is a rare autoimmune disorder that impacts the connection between nerves and muscles and causes weakness and other symptoms. LEMS may be associated with other autoimmune diseases, but more commonly occurs in patients with cancer. The prevalence of LEMS among pediatric patients is unknown, but an estimated 3 million people are impacted by the disease.

The effectiveness of amifampridine was demonstrated in a randomized, double-blind, placebo-controlled withdrawal study of 32 adult patients, all of which had been taking amifampridine for 3 months prior to entering the study. The study compared patients continuing on amifampridine to patients switched to placebo.

Effectiveness was measured by the degree of change in a test that assessed the time it took the patient to rise form a chair, walk 3 meters, and return to the chair for 3 consecutive laps without pause. Investigators found that patients who continued on amifampridine experienced less impairment than those on placebo. Scores from a self test to measure effectiveness indicated a greater perceived weakening in the patients switched to placebo.

The most common adverse events experienced by pediatric and adult patients were burning or prickling sensation, abdominal pain, indigestion, dizziness, and nausea. Adverse effects reported in pediatric patients were similar to those seen in adult patients. Patients should inform their health care professional if they have signs of hypersensitivity reactions such as hives, rash, itching, fever, swelling, or trouble breathing.

Amifampridine had previously received Priority Review and Fast Track Designations from the FDA. It also received the Orphan Drug designation.

The approval for a pediatric treatment for LEMS comes less than a year after the FDA approved amifampridine (Firdapse) tablets in Nov. 2018. Amifampridine demonstrated efficacy in a pair of clinical trials involving 64 adults patients that were administered either amifampridine or placebo.