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Satralizumab represents only the second targeted treatment for NMOSD and the first cleared for at-home administration.
The US Food and Drug Administration (FDA) has approved satralizumab for the treatment of adult patients with anti-aquaporin-4 (AQP4-IgG) antibody positive neuromyelitis optica spectrum disorder (NMOSD)
The approval, awarded to Genentech, is only the second targeted treatment for this patient population and the first eligible for at-home administration.
Marketed under the name Enspryng, the humanized monoclonal antibody targets and inhibits interleukin-6 receptor activity, which is thought to play a key role in the inflammation observed in NMOSD.
Novel recycling technology allows for a longer duration of antibody circulation, translating into a subcutaneous dosing regimen of every 4 weeks after an initial loading dose.
The approval pins satralizumab against the only other targeted treatment in this space, Alexion’s eculizumab (Soliris), which was approved with the same indication on June 27, 2019.
“For people with NMOSD, relapses can cause devastating, irreversible and disabling neurological effects,” Jeffrey Bennett, MD, PhD, professor of neurology and ophthalmology at the University of Colorado, and an investigator for the satralizumab pivotal clinical trials, said in a statement. “Having an approved therapy that can be administered subcutaneously in the home and has demonstrated an impact on the frequency of relapses is an important advancement for patients.”
Satralizumab’s approval was based on robust data from the phase 3 SAkuraStar and SAkuraSky clinical trials, which combined included more than 170 patients who were randomly assigned to receive satralizumab 120 mg or placebo.
In SAkuraSky, patients added treatment to baseline immunosuppressive therapy.
All patients received a loading dose of the study drug at baseline, week 2, and week 4, followed by 4-week treatment intervals.
The primary end point in both studies was time to protocol-defined relapse. Notably, both studies included a population of patients who were AQP4-IgG antibody positive and negative to accurately reflect clinical practice.
In SAkuraStar, 30% of patients treated with satralizumab monotherapy experienced relapse compared with 50% of those who received placebo (HR 0.45; 95% CI, 0.23–0.89; P =.018).
Among those who were AQP4-IgG antibody positive, a 74% reduction in relapse risk was observed.
In the overall satralizumab-treated population, 76.1% and 72.1% were relapse-free at 48 and 96 weeks, respectively, compared with 61.9% and 51.2% with placebo.
Data from the AQP4-IgG seropositive subgroup showed that 82.9% and 76.5% were relapse-free at 48 and 96 weeks compared with 55.4% and 41.1% with placebo, respectively.
In total, 92% (n = 58) of those in the satralizumab group experienced an adverse event compared with 75% (n = 24) of the placebo group. Serious AEs were similar between groups; only 1 event led to study drug discontinuation in the treatment group.
In SAkuraSky, the overall population saw a 62% reduction in the risk of relapse (HR 0.38, 95% CI, 0.16-0.88; P =.0184), while the group of AQP4-IgG seropositive patients experienced a 79% reduction in relapse risk (HR 0.21, 95% CI, 0.06-0.75; P =.0086).
Results showed 88.9% and 77.6% of patients in the total population were relapse-free at 48 and 96 weeks, respectively, compared with 66% and 58.7% of patients in the placebo group.
Among AQP4-IgG seropositive patients, 91.5% treated with satralizumab were relapse-free at 48 and 96 weeks compared with 59.9% and 53.3% of patients in the placebo group.
The most common AEs observed were upper respiratory tract infection, nasopharyngitis, and headache.
Genentech reports that the drug will be available in the US within 2 weeks. It is already approved and available in Japan, Canada, and Switzerland, with applications under review in the European Union and China.