FDA approves first at-home therapy for thyroid eye disease

The first at-home subcutaneous treatment for thyroid eye disease met its primary end point in 1 of 2 phase 3 trials.

By
Mouj Hijazi
October 16, 2026
2 min

MDSpire News

Overview

On October 15, 2026, the FDA 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. Approval was supported by two phase 3 trials: SatraGO-2 met its primary endpoint, whereas SatraGO-1 did not meet its prespecified primary endpoint. The trials reported no new safety signals during the 24-week assessment.

Background

TED is an autoimmune disease involving inflammation and tissue remodeling around and behind the eyes; symptoms can include proptosis, diplopia, pain, and vision impairment. The supplied guideline context describes care as based on disease activity and severity, with coordinated endocrinology and ophthalmology management. Satralizumab-mwge is an interleukin-6 receptor inhibitor previously approved in 2020 for aquaporin-4 antibody–positive neuromyelitis optica spectrum disorder. Its TED approval expands its indication and introduces an at-home subcutaneous option for adults.

Data Highlights

Trial or measure	Satralizumab-mwge	Placebo	Result
SatraGO-2: proptosis response at week 24	52.9%	23.4%	Trial met its primary endpoint
SatraGO-2: diplopia improvement	60.7%	25.8%	Reported improvement
SatraGO-1: proptosis response at week 24	49.0%	31.2%	Trial did not meet its prespecified primary endpoint
Combined enrollment	258 adults across 19 countries		Two identically designed, double-masked, placebo-controlled phase 3 trials

Key Findings

The FDA approval applies to adults with TED and was announced on October 15, 2026; the supplemental biologics license application received priority review.
SatraGO-1 and SatraGO-2 enrolled 258 adults across 19 countries and evaluated active, moderate-to-severe, and chronic TED. Participants were randomized 1:1 to satralizumab-mwge or placebo.
The primary endpoint 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 endpoint: proptosis response occurred in 52.9% with satralizumab-mwge and 23.4% with placebo; diplopia improved in 60.7% and 25.8%, respectively.
SatraGO-1 did not meet its prespecified primary endpoint; proptosis response occurred in 49.0% with satralizumab-mwge and 31.2% with placebo. The trials did not directly compare satralizumab-mwge with other approved treatments.
Administration includes loading injections at weeks 0, 2, and 4, followed by maintenance injections every 4 weeks. The source reports no new safety signals, low rates of serious adverse events and treatment discontinuation, and no serious infections in satralizumab groups during the 24-week assessment.

Clinical Implications

After training, satralizumab-mwge may be self-administered or administered by a caregiver, with maintenance dosing every 4 weeks. The prescribing information described in the source calls for screening for hepatitis B and tuberculosis and assessing liver transaminases before treatment, with monitoring for infection, elevated liver enzymes, and reduced neutrophil counts; treatment should be delayed during active infection.

Conclusion

Satralizumab-mwge is now an FDA-approved at-home subcutaneous treatment option for adults with TED. The supporting phase 3 results differed between the two trials, with SatraGO-2 meeting and SatraGO-1 not meeting its prespecified primary endpoint.