FDA approves first treatment for rare neuromuscular disorder of children

The U.S. Food and Drug Administration today approved first treatment for a rare neuromuscular disorder of children. Ruzurgi (amifampridine) tablets have been approved for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in patients 6 to less than 17 years of age. The FDA granted the approval of Ruzurgi to Jacobus Pharmaceutical Company, Inc.

This is the first FDA approval of treatment specifically for pediatric patients with LEMS. The only other treatment approved for LEMS is only approved for use in adults.

LEMS is a rare autoimmune disorder that affects the connection between nerves and muscles and causes weakness and other symptoms in affected patients. In people with LEMS, the body’s own immune system attacks the neuromuscular junction (the connection between nerves and muscles) and disrupts the ability of nerve cells to send signals to muscle cells. LEMS may be associated with other autoimmune diseases, but more commonly occurs in patients with cancer such as small cell lung cancer, where its onset precedes or coincides with the diagnosis of cancer. LEMS can occur at any age. The prevalence of LEMS specifically in pediatric patients is not known, but the overall prevalence of LEMS is estimated to be three per million individuals worldwide.

“We continue to be committed to facilitating the development and approval of treatments for rare diseases, particularly those in children,” said Billy Dunn, M.D., 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.”

Use of Ruzurgi in patients 6 to less than 17 years of age is supported by evidence from adequate and well-controlled studies of the drug in adults with LEMS, pharmacokinetic data in adult patients, pharmacokinetic modeling and simulation to identify the dosing regimen in pediatric patients and safety data from pediatric patients 6 to less than 17 years of age.

The effectiveness of Ruzurgi for the treatment of LEMS was established by a randomized, double-blind, placebo-controlled withdrawal study of 32 adult patients in which patients were taking Ruzurgi for at least three months prior to entering the study. The study compared patients continuing on Ruzurgi 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 from a chair, walk three meters, and return to the chair for three consecutive laps without pause. The patients that continued on Ruzurgi experienced less impairment than those on placebo. Effectiveness was also measured with a self-assessment scale for LEMS-related weakness that evaluated the feeling of weakening or strengthening. The scores indicated a greater perceived weakening in the patients switched to placebo.

The most common side effects experienced by pediatric and adult patients taking Ruzurgi were burning or prickling sensation (paresthesia), abdominal pain, indigestion, dizziness, and nausea. Side effects reported in pediatric patients were similar to those seen in adult patients. Seizures have been observed in patients without a history of seizures. Patients should inform their health care professional immediately if they have signs of hypersensitivity reactions such as rash, hives, itching, fever, swelling or trouble breathing.

The FDA granted this application Priority Review and Fast Track designations. Ruzurgi also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.