Tofacitinib for Glucocorticoid-Resistant Moderate-to-Severe Thyroid Eye Disease

Overview

Thyroid Eye Disease (TED), also known as Graves' orbitopathy, is an autoimmune condition that causes inflammation and tissue expansion behind the eyes, leading to bulging eyes (proptosis), double vision, and pain. Currently, intravenous glucocorticoids (steroids) are the standard first-line treatment. However, approximately 20-30% of patients do not respond to steroids, or cannot tolerate their side effects. This study aims to evaluate the safety and efficacy of Tofacitinib, an oral medication known as a Janus kinase (JAK) inhibitor, as a rescue therapy for these difficult-to-treat cases. Tofacitinib works by blocking specific signaling pathways (JAK-STAT) that drive inflammation and fibrosis in the eye socket. In this study, patients with moderate-to-severe active TED who are resistant to or intolerant of steroids will receive Tofacitinib tablets (5 mg twice daily) for 24 weeks. The researchers will assess whether the treatment can effectively reduce eye bulging and improve clinical activity scores.

Thyroid Eye Disease (TED) involves complex pathogenesis where orbital fibroblasts are activated by autoantibodies targeting the TSH receptor (TSHR) and the Insulin-like Growth Factor-1 receptor (IGF-1R). Current evidence suggests that TSHR and IGF-1R form a physical and functional complex that activates downstream signaling cascades, prominently the Janus Kinase/Signal Transducer and Activator of Transcription (JAK-STAT) pathway. The activation of STAT3, in particular, is a critical driver of hyaluronan synthesis, adipogenesis (fat expansion), and inflammation within the orbital tissue. While intravenous glucocorticoids (IVGC) are the standard first-line treatment, they primarily exert broad anti-inflammatory effects and may fail to adequately suppress the tissue remodeling (adipogenesis and fibrosis) driven by these specific signaling pathways. Consequently, a significant proportion of patients become "steroid-resistant." This study proposes the use of Tofacitinib, a small-molecule JAK inhibitor, as a targeted rescue therapy. By inhibiting the JAK-STAT pathway, Tofacitinib is hypothesized to suppress both the inflammatory cytokine release and the orbital tissue remodeling that persists despite steroid treatment. Participants will enter a 24-week treatment phase receiving oral Tofacitinib (5 mg twice daily). Clinical assessments will be performed at Baseline, Week 4, 12, 24, and a follow-up visit at Week 36. Key exploratory components of this study include: 1. Quantitative Orbital Imaging: Use of Orbital MRI to objectively measure changes in extraocular muscle volume and orbital fat volume to distinguish between anti-inflammatory and anti-remodeling effects. 2. Durability of Response: A 12-week post-treatment observation period (Weeks 24-36) to monitor for disease relapse or "rebound" phenomena after drug cessation. 3. Safety in Comorbidities: Close monitoring of coagulation profiles and lipid levels, given the known safety profile of JAK inhibitors, specifically in this population with potential metabolic comorbidities.