Alexion Pharmaceuticals has obtained approval from Japan’s Health, Labour and Welfare Ministry (MHLW) to expand the use of Soliris (eculizumab) to prevent relapse in anti-aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD), including neuromyelitis optica.

NMOSD is a rare, complement-mediated disorder of the central nervous system. It causes relapses that lead to disability, paralysis and even premature death.

Soliris works by inhibiting the C5 protein in the terminal part of the complement cascade, which may lead to rare disorders in abnormal functioning.

The drug already holds approval to treat paroxysmal nocturnal hemoglobinuria (PNH) in adults and atypical hemolytic uremic syndrome (aHUS) in children.

It is claimed to be the first drug to secure Japanese approval for NMOSD.

MHLW approval comes from comprehensive data of Phase III PREVENT study and an ongoing long-term extension study, ECU-NMO-302.

During the randomised, double-blind placebo-controlled PREVENT trial, Alexion’s drug was observed to prolong the time to the first relapse and reduce relapse risk.

Of the total participants treated with the drug, 98% were relapse-free versus 63% on placebo at 48 weeks. Also, all 25% of patients on Soliris monotherapy, without other immunosuppressive therapies, were relapse-free at 48 weeks.

The drug’s effects were observed to sustain through 144 weeks of treatment. Trial data showed that the safety profile of the drug was consistent with that of other studies and real-world use in approved indications.

Alexion Pharmaceuticals executive vice-president and research and development head John Orloff said: “We are pleased that the Japanese health authorities have approved Soliris as a new treatment for patients suffering from this complex and unpredictable disease.

“Nearly all patients treated with SOLIRIS were relapse-free at 48 weeks in Phase III PREVENT study, providing new hope for Japanese patients with NMOSD and their clinicians.”

Soliris also has approval in the US and the European Union to treat NMOSD in adults with AQP4.