Two clinical trials have shown positive topline data that add to the growing body of evidence supporting the efficacy and safety of teprotumumab-trbw for the treatment of Thyroid Eye Disease (TED). Horizon Therapeutics is marketing the drug as TEPEZZA, the first medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of TED – a serious, progressive and vision-threatening rare autoimmune disease.
The OPTIC Phase 3 confirmatory clinical trial and the OPTIC-X open-label extension clinical trial are part of Horizon’s development program to evaluate the safety and efficacy of TEPEZZA in people living with TED. The OPTIC Phase 3 confirmatory clinical trial included a 24-week treatment period and a 48-week off-treatment follow-up period. The OPTIC 24-week treatment period evaluated patients who received TEPEZZA or placebo once every three weeks for a total of eight infusions. The primary endpoint was a 2 mm or more reduction of proptosis from baseline in the study eye (without deterioration in the fellow eye) at Week 24. At Week 24 of OPTIC, proptosis responders entered into a 48-week off-treatment follow-up period, without receiving additional TED treatment, including TEPEZZA.
OPTIC-X evaluated the safety and efficacy of TEPEZZA in TED patients who were enrolled in OPTIC and were either proptosis non-responders at Week 24 of OPTIC, or were proptosis responders at Week 24 but relapsed during the 48-week off-treatment follow-up period. Non-responders were defined as patients who did not achieve at least a 2 mm proptosis improvement from baseline at Week 24 of OPTIC. Relapse was defined as patients who lost at least 2 mm of their Week 24 proptosis improvement during the 48-week off-treatment follow-up period – even if their proptosis was still substantially better than at baseline of OPTIC – or who had a substantial increase in the number of inflammatory signs or symptoms without worsening proptosis. Patients could qualify as relapsing at any point during the 48-week off-treatment follow-up period of OPTIC.
Topline data include the following:
- 89% of patients (33/37) who received placebo during the OPTIC trial and then entered OPTIC-X and received TEPEZZA achieved the primary endpoint of a 2 mm or more reduction in proptosis at Week 24 (average reduction of -3.5 mm). This is consistent with results from the OPTIC trial, where 83% of TEPEZZA patients (n=41) had a proptosis reduction of 2 mm or more at Week 24 (average reduction of -3.3 mm).2
- The results for other OPTIC-X endpoints, including diplopia and Clinical Activity Score (CAS), are similar to what was observed in OPTIC.
- These patients who received placebo in OPTIC and their first course of TEPEZZA in OPTIC-X had a TED diagnosis for an average of one year and as long as 16 months, compared with an average of six months in the OPTIC trial.
- In the OPTIC 48-week off-treatment follow-up period, the majority of TEPEZZA patients who were proptosis responders at Week 24 in OPTIC maintained their proptosis response at Week 72 (19/34; 56%) without receiving additional TED treatment. Of the 15 patients who did not qualify as maintaining a proptosis response, eight patients were at least 2 mm better than baseline at the time of their last assessment in the OPTIC 48-week off-treatment follow-up period. The 15 patients include four who prematurely discontinued the study, two who had worsened slightly but not enough to qualify as relapsed for OPTIC-X and nine who met the OPTIC-X criteria for relapse prior to Week 72 of the off-treatment follow-up period (eight of whom entered OPTIC-X for retreatment and one who did not enroll in OPTIC-X).
- Similar durability from Week 24 to Week 72 was demonstrated for other endpoints in the OPTIC 48-week off-treatment follow-up period, including diplopia and CAS.
- For relapsed patients who were retreated with an additional course of TEPEZZA, more than 60 percent had a 2 mm or more proptosis improvement from OPTIC-X baseline at Week 24.
- Only five patients had not achieved a proptosis response after completing a full course of TEPEZZA in OPTIC. Of these, two achieved a 2 mm or more proptosis reduction in OPTIC-X after an additional course of TEPEZZA.
- There were no new safety concerns in OPTIC-X or the OPTIC 48-week off-treatment follow-up period, including in patients who received additional TEPEZZA treatment.
“Data from OPTIC-X provide evidence supporting the potential for TEPEZZA to meaningfully reduce proptosis in patients who have had TED for a longer period of time than what was originally studied in the Phase 2 and Phase 3 clinical trials,” says Elizabeth H.Z. Thompson, PhD, group vice president, development and external search, research and development at Horizon. “It is also promising to see that there are patients who may benefit from additional therapy with TEPEZZA, and the data suggest that they can experience these improvements without added safety concerns. We look forward to continuing our development program and further understanding the efficacy and safety of TEPEZZA among patients who are at various stages of their TED journey, from early diagnosis to chronic (inactive) patients.”
“The similarity in results between those who received TEPEZZA in the OPTIC trial and those who transitioned from placebo in OPTIC to TEPEZZA in OPTIC-X is remarkable,” says Raymond Douglas, MD, PhD, the trial’s co-principal investigator and director of the Orbital and Thyroid Eye Disease Program, Cedars-Sinai Medical Center. “Previously, people diagnosed with TED had no FDA-approved treatments and could expect to experience many years of life-altering symptoms while undergoing multiple surgeries in an attempt to restore their vision. Data from the OPTIC and OPTIC-X clinical trials, as well as observations from our real-world use of TEPEZZA following the FDA approval, have provided very compelling reasons to completely change expectations for people living with TED.”
Read more about the effects of thyroid eye disease and the patient experience with TED here.