FDA Approves Genentech's Enspryng as Subcutaneous Treatment for Thyroid Eye Disease

The U.S. Food and Drug Administration has approved Enspryng (satralizumab-mwge) for the treatment of adults with thyroid eye disease (TED), Genentech announced on October 15. The company said Enspryng is the first and only subcutaneous treatment for the condition that can be given at home, by the patient or a caregiver after training from a healthcare provider.

Enspryng, developed by Chugai, a member of the Roche Group, is a humanized monoclonal antibody that binds the interleukin-6 receptor and inhibits IL-6 signaling, a pathway involved in inflammation. The approval followed a priority review and is the drug's second U.S. indication; it was approved for neuromyelitis optica spectrum disorder (NMOSD) in 2020.

Mixed results across two Phase III trials

The approval is based on the pivotal Phase III SatraGO program, made up of two identically designed randomized, placebo-controlled, multicenter trials, SatraGO-1 (NCT05987423) and SatraGO-2 (NCT06106828). Together they enrolled 258 patients from 19 countries, who were randomized 1:1 to Enspryng or placebo. The primary endpoint was the share of participants with active, moderate-to-severe TED who achieved at least a 2 mm reduction in proptosis, or eye bulging, in the study eye at week 24.

Genentech said SatraGO-1 did not meet its prespecified primary efficacy endpoint at week 24. SatraGO-2 did: 52.9% of patients with active TED in the Enspryng group had a proptosis response, compared with 23.4% in the placebo group. Diplopia, or double vision, was reduced in 60.7% of Enspryng patients versus 25.8% on placebo in that population. The company said results in SatraGO-2's overall population, which included both active and chronic patients, were consistent.

Genentech described the program's results as a whole as clinically meaningful and said no new safety signals were identified, with a safety profile consistent with the drug's known profile in NMOSD. Full results were presented at the American Society of Ophthalmic Plastic and Reconstructive Surgery Fall Scientific Symposium in October 2025.

Statements

"Today's FDA approval of Enspryng provides an important new option for people with thyroid eye disease, who have long faced limited treatment choices," said Levi Garraway, Genentech's chief medical officer and head of Global Product Development.

César A. Briceño, a clinical trial investigator and associate professor of ophthalmology at the Scheie Eye Institute, University of Pennsylvania, said: "Treating thyroid eye disease requires balancing efficacy, safety, and the practical realities of long-term treatment." He added that a subcutaneous option could reduce "the logistical burden associated with infusion-based therapies."

Christine Gustafson, chief executive of the TED Community Organization, a patient group, said in the company's release: "Until now, our community has had very limited choices."

The disease and what comes next

TED, also known as Graves' ophthalmopathy, is an inflammatory autoimmune disease affecting the eyes and the tissue around them. Genentech said it affects about 155 of every 100,000 people and most commonly occurs in people with hyperthyroidism. Symptoms include redness and swelling, eyelid retraction, proptosis, double vision and pain.

Genentech said Enspryng is approved for NMOSD in about 90 countries. The FDA granted priority review in September 2026 to a supplemental Biologics License Application for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), with a decision expected in January 2027, and the drug is also being studied in autoimmune encephalitis, the company said.