The US Food and Drug Administration (FDA) has approved Genentech’s Enspryng (satralizumab-mwge) for adults with thyroid eye disease (TED), making it the first subcutaneous treatment approved for the condition. The interleukin-6 receptor (IL-6R) inhibitor can be self-administered at home following training, with maintenance dosing every 4 weeks.

The approval was based on results from the phase 3 SatraGO-1 and SatraGO-2 trials, which enrolled 258 patients with active or chronic TED across 19 countries.

SatraGO-2 met its primary endpoint, with 52.9% of patients receiving satralizumab achieving a proptosis response at week 24, compared with 23.4% receiving placebo. Diplopia improvement was reported in 60.7% and 25.8% of patients, respectively. Results were consistent in the overall population, including patients with chronic TED.

SatraGO-1 did not meet its prespecified primary efficacy endpoint at week 24.

No new safety signals were identified in either trial. The drug carries warnings for serious infections, elevated liver enzymes, and decreased neutrophil counts.

Satralizumab is a monoclonal antibody that inhibits IL-6 signaling through binding to soluble and membrane-bound IL-6 receptors. The FDA previously approved the drug in 2020 for adults with aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder.