The US Food and Drug Administration (FDA) has approved satralizumab-mwge (Enspryng)for adults with thyroid eye disease (TED), making it the first and only approved at-home subcutaneous treatment for the condition, according to a Genentech press release.
The interleukin-6 receptor inhibitor can be self-administered or administered by a caregiver following training, with maintenance injections given every 4 weeks.
The October 15 approval expands the indication for satralizumab-mwge, which initially was approved in 2020 for aquaporin-4 antibody–positive neuromyelitis optica spectrum disorder. The supplemental biologics license application received priority review.
The approval was supported by the phase 3 SatraGO-1 (NCT05987423) and SatraGO-2 (NCT06106828) trials, which enrolled a total of 258 adults across 19 countries. The identically designed, double-masked, placebo-controlled studies evaluated patients with active, moderate-to-severe, and chronic TED, with participants randomized 1:1 to satralizumab-mwge or placebo.
The primary end point was the proportion of patients with active TED achieving a reduction in proptosis of at least 2 mm from baseline at week 24.
SatraGO-2 met its primary end point, with a proptosis response observed in 52.9% of satralizumab-treated patients versus 23.4% of those receiving placebo. Diplopia improved in 60.7% of satralizumab-treated patients versus 25.8% of those receiving placebo. SatraGO-1 did not meet its prespecified primary end point, with a proptosis response observed in 49.0% of patients receiving satralizumab-mwge versus 31.2% receiving placebo.
According to Genentech, results in SatraGO-2 were consistent across the overall study population, including patients with active and inactive TED. The studies did not directly compare satralizumab-mwge with other approved treatments.
The trials identified no new safety signals, with low rates of serious adverse events and treatment discontinuation. No serious infections occurred in the satralizumab groups during the 24-week assessment.
Satralizumab-mwge is administered subcutaneously, with loading injections at weeks 0, 2, and 4, followed by maintenance dosing every 4 weeks.
Existing US prescribing information requires screening for hepatitis B and tuberculosis, and assessment of liver transaminases before initiation, with monitoring for infections, elevated liver enzymes, and reduced neutrophil counts during treatment. Contraindications include hypersensitivity, active hepatitis B infection, and active or untreated latent tuberculosis. Treatment should be delayed during active infection.
Sources: Genentech, Ophthalmology, Daily Med
