FDA Approves Alexion's Eculizumab for Neuromyelitis Optica Spectrum Disorder

Alexion Pharmaceuticals’ brand-name eculizumab (Soliris) gained its fourth approval, this time for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adult patients who are anti-aquaporin-4 (AQP4) antibody positive.

NMOSD mainly affects the optic nerves and spinal cord. NMOSD can be associated with antibodies that bind to the AQP4 protein; this binding appears to activate other components of the immune system, causing inflammation and damage to the central nervous system. NMOSD is believed to affect 4000 to 8000 patients in the United States. According to the National Institutes of Health, women are more often affected by NMOSD than men; African Americans are at greater risk of the disease than Caucasians.

The effectiveness of Soliris for the treatment of NMOSD was demonstrated in a clinical study of 143 patients with NMOSD who had AQP4 antibodies who were randomized to receive either Soliris or placebo. Compared to treatment with placebo, the study showed that treatment with Soliris reduced the number of NMOSD relapses by 94% over the 48-week course of the trial. Soliris also reduced the need for hospitalizations and the need for treatment of acute attacks with corticosteroids and plasma exchange.

It is the first FDA-approved treatment for the autoimmune disease; the application priority review and the use for NMOSD received orphan drug designation.

Eculizumab, first approved in 2007, is also approved for a rare blood disease called paroxysmal nocturnal hemoglobinuria; for atypical hemolytic uremic syndrome to inhibit complement-mediated thrombotic microangiopathy; and for the treatment of adults with myasthenia gravis. It carries a list price of approximately $500,000 per year.

Earlier this year, Alexion said it hopes to transition patients already receiving its eculizumab onto a newer drug, ravulizumab, in the future. Alexion’s chief commercial officer, Bryan Goff, said that the company is hoping for a 70% conversion from eculizumab to ravulizumab within the next 2 years ahead of biosimilar market entry. Currently, 2 biosimilar developers are targeting eculizumab: Amgen and Samsung Bioepis are both advancing their biosimilar candidates in phase 3 clinical trials.