Teprotumumab effective long term, during retreatment for thyroid eye disease
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Teprotumumab is effective in reducing proptosis in people with thyroid eye disease more than 2 years after treatment, and initial nonresponders to teprotumumab may benefit from a second series of infusions, according to a speaker.
“Responding to initial teprotumumab (Tepezza, Horizon Therapeutics) therapy may benefit during long-term follow-up,” George J. Kahaly, MD, PhD, a professor of medicine, endocrinology and metabolism at Johannes Gutenberg University Medical Center in Mainz, Germany, said during a presentation at the American Thyroid Association annual meeting. “Though 72% of those with longer thyroid eye disease duration who were treated with teprotumumab for the first time received no additional thyroid eye disease therapy during the follow-up, a small cohort of patients required additional therapy.”
As Healio previous reported, teprotumumab was effective at reducing proptosis in people with thyroid eye disease during the phase 3 OPTIC trial. Of 34 participants in OPTIC who were responders to teprotumumab at 24 weeks, 19 remained responders at 72 weeks. The 72-week responders were contacted at 96 and 120 weeks to see if they required any further treatment for thyroid eye disease since the last contact in OPTIC, with 90% saying they did not need any additional therapy.
“This demonstrates some degree of durability,” Terry J. Smith, MD, the Frederick G.L. Huetwell Professor of Ophthalmology and Visual Sciences and professor of internal medicine at the University of Michigan Medical School, told Healio. “At least a large fraction of responders will go on to experience a long-term continued response over the duration of the observational period.”
Second course of teprotumumab effective
In the open-label extension OPTIC-X trial, researchers analyzed retreatment with teprotumumab in those who were initially responders, but had an exacerbation of their thyroid eye disease, as well as the efficacy of a second course of infusions in people who did not receive or respond to the first series of 8 infusions.
Nine participants who initially responded to teprotumumab but experienced a flare-up of their thyroid eye disease after the trial were enrolled to receive a second course of infusions every 3 weeks for 24 weeks. At 24 weeks, 62.5% had a proptosis reduction of at least 2 mm, with a cumulative proptosis reduction of 3.3 mm compared with OPTIC baseline.
A second course of teprotumumab was also given to five people who were nonresponders in OPTIC: Two were responders at the end of the second course, one was a nonresponder, and two did not undergo measurements at week 24. The group had a proptosis reduction of 2.5 mm at 24 weeks of OPTIC-X compared with OPTIC baseline.
Teprotumumab in long-term thyroid eye disease
Researchers also enrolled 37 nonresponders from the OPTIC trial’s placebo group to receive an infusion of teprotumumab every 3 weeks up to 24 weeks in OPTIC-X. The group had thyroid eye disease for about 1 year, compared with the initial OPTIC group receiving teprotumumab who had been diagnosed with thyroid eye disease about 6 months prior to treatment.
The placebo nonresponders had a 3.5 mm reduction in proptosis with 89.2% of the group responding to teprotumumab. Of 23 participants with diplopia, 60.9% had at least a one Gorman grade improvement at 24 weeks. All three figures were similar to those observed in the teprotumumab group in the phase 3 OPTIC trial.
Researchers were not able to determine specifically why those who did not respond to teprotumumab in OPTIC would become responders in OPTIC-X, according to Smith, and additional studies are needed to examine this.
“We don’t have the important discriminators to stratify patients in terms of either responding to an initial series of infusions or those who, after the initial series failed, might go on to respond later,” Smith told Healio. “There is always the potential that some of those who didn’t respond initially but respond later, might have been relatively late responders to the initial course of infusions. The study was designed in such a way to not allow discriminating between those two possibilities.”
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Kahaly G, et al. OP-33. Presented at: American Thyroid Association Annual Meeting; Sept. 30-Oct. 3, 2021 (virtual meeting).
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