Amgen has reported positive top line results from its Phase III subcutaneous Tepezza (teprotumumab-trbw) trial in adults with moderate-to-severe active thyroid eye disease (TED).

Delivered using an on-body injector (OBI), the subcutaneous formulation achieved efficacy comparable to the already approved intravenous (IV) Tepezza.

The Phase III randomised, double-masked, multi-centre, placebo-controlled, parallel-group trial met its primary endpoint, demonstrating a statistically significant 77% proptosis response rate at 24 weeks.

The average reduction in proptosis, a secondary endpoint, was reported as 3.17mm at week 24.

Additional secondary endpoints were met, including significant improvements in overall responder rate, clinical activity score (CAS) of 0 or one, diplopia change and response rates, and improvements in Graves' Ophthalmopathy quality of life (GO-QoL) appearance subscale.

A numerical trend favouring Tepezza OBI was observed in visual function on the GO-QoL, though it lacked statistical significance.

Safety outcomes for subcutaneous Tepezza matched the IV formulation. Mild-to-moderate injection site reactions did not require interruption or stopping of treatment. The most common adverse events included diarrhoea, ear discomfort, muscle spasms, nausea, tinnitus, and weight decrease.

TED is a rare, progressive autoimmune disease that can cause proptosis, double vision, and other ophthalmic complications.

The trial included participants with a diagnosis of moderate-to-severe TED within the previous 15 months and proptosis of 3mm or greater from baseline.

Dosing occurred every two weeks via the OBI across 12 total administrations, and participants with existing hearing impairment were included.

Amgen research and development executive vice-president Jay Bradner said: “These results extend and support the best-in-class efficacy of Tepezza for people living with thyroid eye disease, now with subcutaneous administration delivering IV-level efficacy.

“With a well-understood mechanism and established impact in the clinic, we can evolve how the medicine is delivered to potentially reach even more patients through a more convenient subcutaneous option.”

In September 2025, Amgen and Kyowa Kirin announced initial top line findings from the Phase III ASCEND trial assessing the investigational T-cell rebalancing therapy, rocatinlimab, aimed at treating adults and adolescents with moderate to severe atopic dermatitis.