The FDA has accepted Roche’s sBLA for Enspryng (satralizumab) in thyroid eye disease and granted Priority Review, supported by Phase III trials showing improvements in eye bulging, inflammation, and double vision.
Written By: Kalyani Boharapi,
M.Pharm (Reg. Affairs)
Reviewed By: Pharmacally Editorial Team
The US Food and Drug Administration (FDA) has accepted Roche’s supplemental Biologics License Application (sBLA) for Enspryng (satralizumab) and granted Priority Review for the treatment of thyroid eye disease (TED). The regulatory submission is supported by results from the global Phase III SatraGO-1 (NCT05987423) and SatraGO-2 (NCT06106828) trials, which evaluated the IL-6 receptor inhibitor in adults with moderate-to-severe TED. The FDA is expected to issue its decision by 15 October 2026
If approved, Enspryng could become the first disease-modifying therapy for TED that patients can self-administer at home as a subcutaneous injection, offering an alternative to currently available infusion-based treatments.
Targeting the inflammatory pathway driving TED
Thyroid eye disease, also known as Graves’ ophthalmopathy, is a rare autoimmune disorder that causes inflammation of the tissues surrounding the eyes. The condition can lead to eye bulging (proptosis), double vision (diplopia), pain, eyelid retraction, and, in severe cases, vision-threatening complications. The disease affects approximately 155 people per 100,000, and about half of patients with hyperthyroidism develop at least mild TED.
Enspryng is a humanized monoclonal antibody that blocks the interleukin-6 (IL-6) receptor, reducing inflammatory signaling involved in autoimmune disease. The therapy is already approved in around 90 countries for neuromyelitis optica spectrum disorder (NMOSD), where it has established a well-characterized safety profile.
Phase III trials demonstrated clinically meaningful improvements
The identically designed, randomized, placebo-controlled SatraGO-1 and SatraGO-2 studies enrolled 258 patients across 19 countries with active, moderate-to-severe TED. Participants were randomized 1:1 to receive Enspryng or placebo.
The primary endpoint measured the proportion of patients achieving at least a 2 mm reduction in proptosis at Week 24.
SatraGO-2 met its primary endpoint, with 53% of patients receiving Enspryng achieving a clinically meaningful reduction in eye bulging compared with 23% in the placebo group, demonstrating statistical significance.
In SatraGO-1, 49% of patients receiving Enspryng achieved the primary endpoint versus 31% with placebo. Although this difference did not reach statistical significance, the study provided supportive evidence consistent with the overall clinical program.
Across both trials, Enspryng also improved key secondary outcomes. Between 78% and 90% of treated patients achieved reductions in Clinical Activity Score (CAS), reflecting decreased inflammation, while 44% to 61% experienced improvements in double vision (diplopia).
Safety findings remained consistent with Enspryng’s established profile in NMOSD. Investigators reported no new safety signals during either study.
Expanding treatment options for thyroid eye disease
Roche said the Priority Review reflects the potential of IL-6 inhibition to address the underlying immune mechanisms driving TED while offering the convenience of at-home administration. The company believes the therapy could expand treatment options for patients who need an effective, well-tolerated alternative to existing therapies.
Beyond TED, Roche continues to evaluate Enspryng across multiple autoimmune neurological disorders. The company recently reported positive Phase III results in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and plans regulatory submissions later this year. Enspryng is also under investigation for autoimmune encephalitis, further extending its potential role across IL-6-mediated autoimmune diseases.
What this means for patients
Patients with thyroid eye disease may soon have access to an at-home injectable treatment that helps treat the underlying cause of the disease, rather than just relieving symptoms. Enspryng improved eye bulging, inflammation, and double vision, while maintaining a well-established safety profile with no new safety concerns reported. If approved, patients could receive treatment at home instead of making regular hospital visits, making long-term care more convenient and accessible.
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About the Writer
Kalyani Boharapi (LinkedIn) is a pharmacy professional and healthcare writer currently pursuing an M.Pharm in Regulatory Affairs at Dr. D. Y. Patil College of Pharmacy, with interests in pharmaceutical regulations, drug development, and healthcare innovation. She has academic exposure to dossier preparation, scientific writing, and regulatory documentation. Kalyani has also completed certification courses in Generative AI, AI in Pharma, and Bioinformatics, and actively participates in pharmaceutical conferences to stay updated with emerging trends and advancements in the healthcare and pharmaceutical industry.