Since acquiring rare disease specialist Horizon Therapeutics for $27.8 billion in 2023, Amgen has struggled to grow sales of its biggest acquisition, the thyroid eye disease (TED) treatment Tepezza.
But with a new patient-friendly route of administration, a California biotech company may have found a way to increase demand for Tepezza, the only drug on the market to treat inflammatory exophthalmia.
A phase 3 study in patients with moderate to severe TED showed that subcutaneous injection of Tepezza via systemic injector (OBI) can provide comparable performance to current routes of administration, which include eight intravenous (IV) infusions (each lasting 60 to 90 minutes) spaced three weeks apart.
The trial met its primary endpoint, with Tepezza OBI demonstrating a statistically significant and clinically meaningful proptosis response rate of 77%, compared to 20% in the placebo group, according to Amgen’s Monday press release.
Patients were considered to have responded if their exophthalmos (proptosis) decreased by 2 mm or more from baseline without worsening after 24 weeks.
As a key secondary endpoint, Tepezza OBI resulted in an average reduction of 3.17 mm in proptosis at week 24, compared to an average reduction of 0.80 mm in the control group.
“These results extend and confirm Tepezza’s best-in-class efficacy for people living with thyroid eye disease, now delivering IV-level efficacy through subcutaneous administration,” Jay Bradner, director of research and development at Amgen, said in the release. “With well-understood mechanisms and established efficacy in the clinic, we can advance how we deliver the drug to even more patients through more convenient subcutaneous delivery options.”
Amgen did not disclose regulatory plans in the release. A spokesperson said the company would submit its results to regulators, but added: “It is too early to comment on the timing of approval as it depends on a number of regulatory factors.”
Horizon’s 2020 FDA approval of Tepezza IV was supported by results from a Phase 3 trial that showed an 83% response rate (also defined as a 2 mm reduction in exophthalmos over 24 weeks), compared to a 10% reduction in the placebo group.
In its second full year on the market in 2022, Tepezza’s sales reached $1.96 billion. Sales have been sluggish ever since. Last year, Amgen reported sales of $1.9 billion.
There may be competition for Tepezza. Massachusetts-based Viridian Therapeutics faces an FDA decision date of June 30 on its TED candidate Verigrotag, which is administered as an infusion five times over 12 weeks.
Last week, Viridian also scored a Phase 3 win with injected TED prospect Elegrobert, but the results did not impress investors. The response rate in this study was 54% for the drug candidate, compared to 18% for the placebo group. Elegrobart showed an average reduction of 2.33 mm over 24 weeks, compared with 0.81 mm for placebo.
“We believe Viridian’s Verigrotag and Elegrobert have the potential to capture a significant share of the TED market,” William Blair analyst Lachlan Hanbury-Brown said in a note to investors. “We believe BerigloTag offers a competitive profile compared to the current standard of care, Tepezza, and believe that its more convenient dosing and diplopia benefits in chronic TED should lead to meaningful commercial opportunities.”
Last year, Michigan-based Sling Therapeutics shared results from a Phase 2B/3 TED trial of its oral challenge drug, lincitinib, a former Astellas Pharma property, but the data suggested the therapy fell short of Tepezza’s efficacy, with a response rate of 52%.
Amgen added on Monday that it has completed a Phase 3b/4 trial for Tepezza IV to meet FDA post-marketing requirements. The purpose of this study was to evaluate the tolerability and efficacy of three treatment periods (4, 8, and 16 infusions) and assess the need for retreatment.
The company said the observed risk profile is “consistent” with the known profile of current dosing regimens, and those results will be submitted to regulatory authorities and presented at an upcoming medical conference.
Editor’s note: Comments from William Blair analyst Lachlan Hanbury-Brown were added to this article after it was first published.
