Maintenance rituximab treatment lowers NMOSD relapse frequency
Study shows treatment remains effective after relapse
Maintenance treatment with rituximab significantly reduced the number of relapses per year in people with neuromyelitis optica spectrum disorder (NMOSD), and it remained effective after patients experienced relapses, according to a study from China.
Relapses more frequently occurred within the first year after rituximab initiation, and their frequency decreased with further treatment doses during maintenance therapy.
The study, “Rituximab maintenance treatment outcomes in patients with relapsing neuromyelitis optica spectrum disorder: a monocentric retrospective analysis,” was published in Acta Neurologica Belgica.
NMOSD is a progressive autoimmune disease that primarily affects the spinal cord and the optic nerves, the nerves that relay signals between the eyes and the brain, leading to issues with vision and muscle control. It is commonly characterized by relapses, when symptoms suddenly worsen, followed by periods of remission in which symptoms ease. Each new relapse can cause damage that accumulates over time, leading to increasing disability.
Rituximab (sold as Rituxan and others) is an antibody-based therapy designed to eliminate B-cells, immune cells that produce antibodies that play a key role in the development of NMOSD. The treatment, approved to treat certain cancers and autoimmune diseases, is commonly used off label in NMOSD to prevent relapses and ease disability.
Relapse after rituximab
Some patients experience relapses after receiving rituximab. Little has been known about their clinical characteristics and subsequent treatments after relapse.
To fill that gap in knowledge, researchers in China retrospectively analyzed data from people with NMOSD who were positive for antibodies against the aquaporin-4 protein, the most common self-reactive antibody in NMOSD.
The analysis looked at 147 patients who had received at least one 500 mg rituximab dose as part of their maintenance treatment between 2011 and 2022. Thirty-seven of them relapsed, and 30 continued on rituximab maintenance therapy after their relapses. These 30 patients were all female, with a mean age at disease onset of 44. The median follow-up period was 6.6 years.
Among the initial group of 147 patients, rituximab treatment significantly reduced the frequency of relapses by 83.8%, from 0.99 per year to 0.16 per year. In patients who continued on rituximab treatment after they relapsed, the frequency of relapses decreased from 1.04 per year before the treatment to 0.46 per year, a 44.2% reduction.
“We observed a significant decrease in the [annualized relapse rate] compared to before the RTX maintenance therapy in 30 relapsing NMOSD patients, suggesting that RTX treatment is still effective even during periods of disease activity,” the researchers wrote.
Of the 35 relapses registered after rituximab initiation — 25 patients relapsed once, and five relapsed twice — most were due to inflammation in the spinal cord (48.6%) or optic nerve (28.6%). Most patients (51.4%) relapsed after their first rituximab dose.
The average duration from the last rituximab dose to relapse was 6.2 months, with most patients (88.6%) experiencing a relapse in the first 12 months after treatment initiation.
While on rituximab maintenance treatment, patients who experienced a relapse had a median increase of 0.5 points in their Expanded Disability Status Scale (EDSS) scores, a validated scale used to monitor disability levels. About a third of the relapsing episodes led to no changes in EDSS scores.
“Relapses after RTX [rituximab] therapy were mild and could be well-controlled by repeated RTX infusions in most patients with NMOSD,” the researchers wrote, adding that further studies are needed to confirm rituximab’s benefits.
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