6814 Durability of Teprotumumab for the Treatment of Thyroid Eye Disease (TED) in Clinical Trials

Abstract Disclosure: G.J. Kahaly: Consulting Fee; Self; Amgen Inc. Research Investigator; Self; Amgen Inc. P.S. Subramanian: Consulting Fee; Self; Amgen Inc. Research Investigator; Self; Amgen Inc. E. Conrad: Employee; Self; Amgen Inc. Stock Owner; Self; Amgen Inc. R.J. Holt: Employee; Self; Amgen Inc. Stock Owner; Self; Amgen Inc. T.J. Smith: Consulting Fee; Self; Amgen Inc, Viridian, Minghui, Lassen, Lundbeck. Other; Self; US patents covering the use of IGF-1 receptor inhibitors in TED which are held by UCLA and the Lundquist Institute. Introduction: Teprotumumab has demonstrated efficacy for the treatment of thyroid eye disease (TED). To assess durability of responses to teprotumumab over the longer term, pooled clinical trial data were assessed beyond the 24-week treatment period for patients in phase 2, OPTIC, and OPTIC-X studies who received a full course of teprotumumab. Methods: Observed rates for clinical activity score (CAS, ≥2 point improvement), EUGOGO-recommended composite response, diplopia (≥1 Gorman grade improvement), proptosis (≥2 mm improvement), and Overall responder status (≥2 mm improvement proptosis and ≥2 point improvement CAS) were assessed and pooled from study baseline to Week 24 (formal study) and up to Week 72 (51 weeks post-final teprotumumab infusion). Graves’ ophthalmopathy quality-of-life (GO-QOL) scores were also examined. Additional therapies for TED administered up to Week 120 (i.e., 99 weeks post-therapy) were assessed for evidence of persistent benefit from Week 24 through Week 120. Studies differed in the timing of follow-up visits. Data were not available at every time point for all patients. Results: Response rates among patients receiving a full (8-infusion) course of teprotumumab (N=112) were largely maintained 51 weeks after the final teprotumumab infusion at study Week 72: CAS 52/57 (91.2%); composite 51/57 (89.5%); diplopia 35/48 (72.9%); proptosis 38/56 (67.9%); and Overall 37/56 (66.1%). The mean reduction in proptosis was 2.68 (SD 1.92) mm (N=56), mean GO-QOL reduction was 15.22 (SE 2.82, N=56), and disease inactivation (CAS ≤1) was detected in 40/57 (70.2%). Post-teprotumumab treatment, 17.9% (19/106) of reporting patients received additional TED treatment (systemic steroids or teprotumumab) and/or remedial periocular surgery as of 99 weeks after the last dose (to study Week 120). Conclusions: At Week 72, nearly one-year posttherapy, responses to teprotumumab were similar to those at Week 24 formal study end. Both CAS and ophthalmic composite responses were observed in 90% of observed patients. Diplopia and proptosis responses were seen in almost 70%. Additionally, 82% of patients did not require additional treatment for TED nearly two years after therapy completion. Public Presentation: 6/2/2024