Horizon Therapeutics plc announced the release of positive topline data from its phase 4 study evaluating teprotumumab-trbw (Tepezza) for the treatment of adults with chronic/low clinical activity score (CAS) thyroid eye disease (TED).
Refresh me on Tepezza.
Approved by the FDA in 2020, Tepezza is the first and currently only treatment indicated for the treatment of TED.
The recommended dosage consists of a 10 mg/kg intravenously injected into the arm followed by a second 20 mg/kg injection every 3 weeks for 7 additional infusions.
Now talk about this trial.
The randomized, double-masked, placebo-controlled, parallel-group, multicenter trial (NCT04583735) enrolled 62 patients with chronic (inactive) TED and low CAS. Patients were administered eight infusions of either Tepezza (n = 42) or a placebo (n = 20) for 24 weeks.
Investigators sought to measure the effectiveness of Tepezza versus a placebo in the change of proptosis measurements in the study eye from baseline to Week 24.
What determined patient eligibility?
Patients were required to have an initial diagnosis of TED between 2 and 10 years prior to the start of the trial as well as a CAS of ≤1 in both eyes for at least 1 year prior to screening.
Other optional criteria included patients with no progression in proptosis, no progression in diplopia, and no new inflammatory TED symptoms for at least 1 year before screening.
Further, patients were excluded from the study if they had a history of orbital decompression surgery, orbital irradiation, or strabismus surgery.
Findings?
Week 24 topline data, based on an intent-to-treat method, found the study met its primary endpoint, with the Tepezza-treated patients having a statistically significant reduction in proptosis from baseline (compared to placebo-treated patients).
In addition, in the pre-specified per-protocol analysis, there was an increase in differences between the Tepezza- and placebo-treated patients.
Give me some numbers.
Tepezza-treated patients achieved a 2.41 mm proptosis reduction from baseline at Week 24, while placebo-treated patients reached 0.92 mm.
Similarly, 62% of Tepezza patients displayed a clinically meaningful proptosis improvement (≥ 2 mm) compared to only 25% of placebo patients.
Significance?
According to Horizon’s Elizabeth H.Z. Thompson, PhD, executive vice president, research and development, the data supports previous findings of Tepezza significantly reducing proptosis in TED patients, regardless of disease activity or duration.
“[It] underscores what we learned from our initial trials and what we have seen through more than 3 years of real-world use of Tepezza,” she stated.
What’s next?
According to Clinical Trials, the study’s estimated completion date is October 15, 2023. Stay tuned for further data!
This article has been corrected as of 5/1. Tepezza is intravenously administered via the arm, not the eye.