What are the key results from Amgen’s (NASDAQ:AMGN) Phase 3 trial for the subcutaneous formulation of TEPEZZA (teprotumumab-trbw)?

Amgen announced positive topline results from its Phase 3 trial evaluating a subcutaneous formulation of TEPEZZA for moderate-to-severe active Thyroid Eye Disease (TED). The treatment achieved a 76.7% proptosis response rate, significantly outperforming the 19.6% response in the placebo group. Additionally, the subcutaneous TEPEZZA group showed a mean proptosis reduction of -3.17 mm, compared to -0.80 mm in the placebo group (p<0.0001).

How does the subcutaneous formulation of TEPEZZA differ from the current intravenous version?

The subcutaneous formulation of TEPEZZA provides a more convenient delivery method compared to the current intravenous (IV) version, which requires patients to spend several hours at an infusion center. The subcutaneous option allows for at-home or clinic-based administration without sacrificing efficacy, offering a potentially more accessible treatment option for patients with TED.

What was the primary endpoint of the Phase 3 clinical trial for subcutaneous TEPEZZA?

The primary endpoint of the trial was the proptosis response rate, which measures the reduction in the outward bulging of the eye, a key symptom of Thyroid Eye Disease (TED). The subcutaneous TEPEZZA formulation demonstrated a significantly higher proptosis response rate (76.7%) compared to the placebo group (19.6%) at week 24.

How does the subcutaneous TEPEZZA perform in terms of proptosis reduction?

The subcutaneous TEPEZZA treatment group achieved a mean proptosis reduction of -3.17 mm, significantly greater than the -0.80 mm reduction observed in the placebo group. This highlights the drug's potential for effectively reducing eye bulging in patients with moderate-to-severe active TED.

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Amgen’s subcutaneous TEPEZZA meets primary endpoint in Phase 3 TED trial

Written by Brie CarterPublished Apr 6, 2026, 12:00 AMLast Updated Jul 7, 2026, 12:01 PM

Amgen (NASDAQ:AMGN) has announced positive topline results from its Phase 3 clinical trial evaluating a subcutaneous formulation of TEPEZZA (teprotumumab-trbw) for adults with moderate-to-severe active Thyroid Eye Disease (TED).

The trial, which utilized an automated on-body injector for drug delivery, successfully met its primary endpoint.

Data revealed a 76.7% proptosis response rate in patients receiving subcutaneous TEPEZZA, compared to just 19.6% in the placebo group at week 24.

Furthermore, the treatment group showed a mean proptosis reduction of -3.17 mm, significantly outperforming the -0.80 mm reduction observed in the placebo arm (p<0.0001).

The development of a subcutaneous option represents a potential shift in the treatment landscape for TED, a rare and vision-threatening autoimmune condition.

Currently, TEPEZZA is administered via intravenous (IV) infusion, which typically requires patients to spend several hours at an infusion center.

The new on-body injector is designed to provide a more convenient, at-home or clinic-based administration route without sacrificing efficacy.

Safety data from the Phase 3 trial remained consistent with the known profile of IV TEPEZZA.

The most common adverse events reported by at least 10% of participants included muscle spasms, tinnitus, weight decrease, ear discomfort, nausea, and diarrhea.

No new safety signals were identified during the 24-week study period.

Amgen acquired TEPEZZA through its $27.8 billion acquisition of Horizon Therapeutics in 2023.

The drug is a cornerstone of Amgen’s rare disease portfolio, and the introduction of a subcutaneous version is a key component of the company's strategy to defend its market share and expand the addressable patient population.