Post Hoc MRI Analysis of Orbital Soft Tissue Volumes Pre- and Post-Teprotumumab in Patients with Chronic, Low-Activity Thyroid Eye Disease

A previous phase 4 trial (Chronic) evaluated teprotumumab treatment in patients with chronic, low-activity thyroid eye disease (TED). In the current study, volumetric changes in the orbital soft tissues, lacrimal glands, and full facial fat were evaluated following teprotumumab in a subset of patients from this chronic TED trial who underwent magnetic resonance imaging (MRI). This post hoc exploratory MRI analysis examined volumetric changes of extraocular muscles (EOMs), orbital fat (OF), lacrimal glands, and full facial fat pre- and post-teprotumumab (week 24) in patients from the phase 4 Chronic trial at one preselected trial site. Patients had a TED duration of 2–10 years, diagnosis of chronic, low-activity TED (clinical activity score ≤ 1), and received eight teprotumumab infusions administered once every 3 weeks. The study (more proptotic) and fellow orbit were evaluated separately and together via MRI. Of the six patients (female n = 5, male n = 1) undergoing MRI at baseline and week 24, the mean age and TED duration was 45.2 and 5.5 years, respectively. At baseline, patients had a mean proptosis of 25.25 mm (study orbits) and 24.00 mm (fellow orbits). Mean (%) changes from baseline (CFB) in total EOM and OF volumes in combined study and fellow orbits after 24 weeks of teprotumumab were − 1107.3 mm 3 (− 25.0%) and − 5017.1 mm 3 (− 34.6%), respectively. Mean (%) CFB in full facial fat and study and fellow lacrimal gland volumes were − 12,175.9 mm 3 (− 6.6%), − 116.7 mm 3 (− 21.9%), and − 150.5 mm 3 (− 26.4%), respectively. Proptosis response was observed in 100% (6/6) of study and 66.7% (4/6) of fellow orbits. MRI demonstrated that teprotumumab effectively reduces orbital soft tissue, facial fat, and lacrimal gland volumes in study and fellow orbits of patients with chronic, low-activity TED. ClinicalTrials.gov identifier NCT04583735.