Eculizumab for Neuromyelitis Optica Spectrum Disorder

A new study from the 2019 National Organization for Rare Diseases (NORD) and Orphan Products Breakthrough Summit is shining additional light on the safety and effectiveness of eculizumab in the treatment of neuromyelitis optica spectrum disorder(NMOSD).

Conducted by an international team of investigators, interim results of the open-label extension study backed the safety and efficacy results of the PREVENT core study.

In an effort to expand on information obtained from the phase 3, randomized, time-to-event PREVENT study, investigators performed an open-label extension study using patients from PREVENT study, which was used as the core study in the analysis. Results presented at NORD 2019 were a combined analysis of the PREVENT study and an interim analysis from the extension study.

The population for the analysis was 137 patients who had received at least one dose of eculizumab. Of the patients included, 96 received eculizumab for the first time during the core study and 41 received eculizumab for the first time during the extension study after previously receiving placebo.

Most of the patients in the study(91%) were female and the mean age of patients at the first dose of eculizumab was 44.5 years. Mean annualized relapse rate (ARR) in the 24 months prior to screening in the core study was 2.01 (SD, 0.95) and the median Expanded Disability Status Scale score at first dose was 4.0. Investigators noted patients included in the analysis had a median follow-up time of 107.9 weeks and the study included a total follow-up of 282.3 patient-years.

Results of the analysis revealed the rates of adverse events and serious adverse events per 100 patient-years were 763.1 and 37.6, respectively, when including NMOSD relapses. When excluding NMOSD relapses, rates were 758.5 and 32.9, respectively.

Headache, upper respiratory tract infection, and nasopharyngitis were the most commonly reported adverse events. Pneumonia(2.9%), urinary tract infection(2.9%), and optic neuritis(2.2%) were the most commonly reported serious adverse events. Investigators noted there were no cases of meningococcal infection and incidence of adverse events did not increase with longer treatment duration.

Of the 137 patients treated with eculizumab, 8(5.8%) experienced an adjudicated relapse. In regard to relapses, only 1 patient had 2 relapses and both occurred in the extension study. Additionally, 6 patients had optic neuritis and 2 had myelitis.

The estimated proportion of patients in the study who were relapse-free at 192 weeks was 93.9% (95% CI, 87.5 to 97.1%) and the adjudicated ARR was 0.032 (95% CI, 0.017-0.062).

This study, “Long-term Safety and Effectiveness of Eculizumab in Neuromyelitis Optica Spectrum Disorder,” was presented at NORD Summit 2019.