Purpose

Thyroid eye disease (TED) is a complex orbital inflammatory disease that can lead to significant morbidity, including facial disfigurement and sight-threatening complications. Interleukin-6 (IL-6) and its receptor (IL-6R) play a key role in the pathogenesis of TED. Satralizumab, a humanized monoclonal antibody that targets IL-6R, was designed using innovative antibody recycling technology, which allows for longer duration of circulation and subcutaneous dosing. Here, we present Week (W)24 results from the phase 3 SatraGO-1/2 trials.

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Methods

SatraGO-1 (NCT05987423) and SatraGO-2 (NCT06106828) are identical, global, phase 3 trials evaluating the efficacy and safety of satralizumab in patients with moderate-to-severe active TED or chronic inactive TED. Participants were randomized 1:1 to receive subcutaneous satralizumab or placebo at W0, W2, and W4 and then Q4W through W20. The primary endpoint was the proportion of participants with active TED with a proptosis response (≥ 2-mm reduction in proptosis from baseline in the study eye) at W24.

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Results

The proportion of participants with active TED with a proptosis response was higher for satralizumab (SatraGO-1/2; 49/53%) vs placebo (31/23%; P=0.0715/0.0011). The proportion of participants with active TED with diplopia reduction (≥1-grade reduction) was higher for satralizumab (SatraGO-1/2; 44/61%) vs placebo (34/26%; P=0.3371/0.0044). The proportion of participants with active TED with Clinical Activity Score (CAS) reduction (≥2-point reduction) was higher for satralizumab (SatraGO-1/2; 78/90%) vs placebo (55/63%; P=0.0120/0.0009). Clinical benefits were also observed in the overall (active + inactive) TED population. Overall, the incidence of serious adverse events and treatment discontinuations was low and there were no serious infections.

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Conclusion

Satralizumab showed clinically meaningful improvements across key efficacy endpoints and had a favorable safety profile in patients with TED. Satralizumab is the first IL-6R inhibitor with convenient subcutaneous dosing demonstrating efficacy for both active and inactive TED.

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Additional Authors

First name	Last name	Base Hospital / Institution
César	Briceño	Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania
Oluwatobi	Idowu	Genentech, Inc.
Laura	Brockwell	Roche Products Ltd.
Thorsten	Ruf	F. Hoffmann-La Roche Ltd.
Thomas	Kuenzel	F. Hoffmann-La Roche Ltd.
Christopher	Brittain	Genentech, Inc.
Giulio	Barteselli	Genentech, Inc.

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