New Integrated Data Show Promise for Novel Thyroid Eye Disease Drug

New pooled data from Phase 2 and Phase 3 clinical trials further reinforce that teprotumumab-trbw significantly improves proptosis (eye bulging) and diplopia (double vision) for thyroid eye disease (TED) in patients in different subgroups, with most maintaining a long-term response. The results were published recently in The Lancet Diabetes & Endocrinology. Teprotumumab-trbw is a fully human monoclonal antibody (mAb) and a targeted inhibitor of the insulin-like growth factor-1 receptor (IGF-1R). Horizon Therapeutics plc is marketing the drug as TEPEZZA®

“This integrated analysis comprises one of the largest controlled study populations reported to date in people living with Thyroid Eye Disease, which allowed us to evaluate a variety of patient subgroups, including those whose symptoms were considered more severe,” says Endocrine Society member George Kahaly, MD, PhD, professor of medicine and endocrinology and metabolism, Johannes Gutenberg University Medical Center and primary author of the paper. “Of most importance, the data clearly show that TEPEZZA mitigates varying levels of disease severity, including proptosis and diplopia, which are the most progressive and difficult findings to treat, and that improvements continue for the long term.”

In this report, treatment study outcomes and follow-up off-treatment data were integrated from two 24-week multicenter, double-masked, placebo-controlled clinical trials where patients were randomized to receive TEPEZZA (n=84) or placebo (n=87) once every three weeks for a total of eight infusions. The final treatment study visit was at Week 24, which was three weeks after the final infusion. Responses were also evaluated at seven weeks and 51 weeks after the final dose of TEPEZZA. Responses were analyzed for proptosis and diplopia, as well as a post-hoc analysis of a combined outcome measure: the “ophthalmic composite outcome.” The composite outcome is calculated as the percentage of patients with clinical improvement in one eye in at least two of the following: 1) proptosis, 2) diplopia, 3) eyelid swelling, 4) lid aperture, 5) globe motility, and 6) Clinical Activity Score, without deterioration of at least two of these outcomes in either eye.

 New Study Findings

  • There was no evidence for acute disease rebound (increase in percentage of patients no longer meeting proptosis, diplopia or ophthalmic composite outcome) seven weeks after the last dose of TEPEZZA.
  • Proptosis (87 percent; 62/71), diplopia (66 percent; 38/58) and ophthalmic composite outcome (92 percent; 66/72) responses were observed seven weeks after the last dose of TEPEZZA.
  • A post-hoc analysis of the composite ophthalmic outcome indicated that 81 percent (68/84) of TEPEZZA patients versus 44 percent (38/87) of placebo patients were responders at Week 24.
  • Proptosis (67 percent; 38/57), diplopia (69 percent; 33/48) and composite outcome response (83 percent; 48/58) were observed 51 weeks after the last dose of TEPEZZA for those who had long-term off-treatment data available.

 Efficacy in Difficult-to-Treat Patients at Week 24

  • In a post-hoc analysis, TEPEZZA-treated patients with more severe disease (those with ≥3 mm of proptosis and/or inconstant or constant diplopia) and those with less severe disease at baseline both experienced significant improvements in proptosis and diplopia.
    • In patients with more severe disease, those treated with TEPEZZA had a proptosis response of 79 percent (50/63) compared to 17 percent (11/65) of those who received placebo (P<0.0001), and a diplopia response of 68 percent (38/56) compared to 31 percent of those who received placebo (15/49) (P<0.0001).
    • In patients with less severe disease, those treated with TEPEZZA had a proptosis response of 71 percent (15/21) compared to 9 percent in those who received placebo (2/22) P<0.0001, and a diplopia response of 80 percent (8/10) compared to 30 percent in placebo (3/10) (P=0.015).
  • In post-hoc analyses, patients who received TEPEZZA in both the lower baseline CAS subgroup (4 or 5) and the higher CAS subgroup (6 or 7) demonstrated statistically significant improvements compared with placebo in proptosis and diplopia. Overall response and CAS of 0 or 1 response also improved.
  • Post-hoc analysis from the Phase 3 study demonstrates that in patients treated with teprotumumab, those with higher (≥10 IU/L) or lower (<10 IU/L) serum thyrotropin-binding inhibitory immunoglobulin (TBII) baseline levels both had a proptosis response (mean reduction of -3.65 mm and -3.01 mm, respectively) with no treatment difference between the two groups (p=0.43). In patients with higher baseline TBII, 71 percent (10/14) of patients who received TEPEZZA experienced an improvement in diplopia compared to 23 percent (3/13) of patients who received placebo (p=0.0046).

 Adherence and Safety

  • Nearly 91 percent of patients in the TEPEZZA treatment group (76/84) and the placebo treatment group (79/87) completed the randomized, double-masked treatment period.
  • There were no new safety concerns identified in the follow-up period or as part of the pooled analysis that had not been identified in the 24-week treatment period. Of those patients who experienced adverse events, most were mild to moderate (grade 1 or 2) in intensity during the follow-up period. There were no serious adverse events related to TEPEZZA treatment during the follow-up period, as assessed by trial investigators.
  • No anti-drug antibodies were reported that impacted safety or efficacy.
  • Of the most commonly reported adverse events with TEPEZZA, muscle spasm (18 percent, 95 percent CI 7.3–28.7), hearing loss (10 percent) and hyperglycemia (8 percent, 95 percent CI 1.7–15.0) had the greatest risk difference from placebo. Hearing impairment events were all classified as nonserious and all patients continued in the study without event worsening or discontinuing treatment.

“These comprehensive data enlighten our understanding of how TEPEZZA improves Thyroid Eye Disease symptoms in both the short- and longer-term,” says Saba Sile, MD, study author and executive director, clinical development, ophthalmology, Horizon. “We will apply these learnings as we continue to study TEPEZZA in the broader Thyroid Eye Disease population and report findings in a larger, more diverse patient population in the future.”