Early Low‐Dose Rituximab for Mild‐to‐Moderate Thyroid Eye Disease: A Preliminary Evaluation of Efficacy and Safety

Background Thyroid eye disease (TED) is an autoimmune inflammatory condition linked to thyroid dysfunction, which can result in disfigurement and potential vision loss. Recently, immunomodulatory therapies such as rituximab have demonstrated potential benefit in managing TED. However, the optimal dosing and timing of rituximab administration remain uncertain. Objective This study aimed to assess the efficacy and safety of early, low‐dose rituximab therapy in patients with mild to moderate TED. Methods Eight untreated patients with mild to moderate TED were enrolled in the study. Weekly rituximab infusions at a low dose (100 mg weekly for 4 weeks) were administered, followed by a 16‐week follow‐up period. Thyroid function, thyrotropin receptor antibody (TRAb) levels, ophthalmic examinations, and adverse effects were evaluated at each visit. Additionally, orbital MRI, radionuclide orbital imaging, and clinical activity score (CAS) were performed before treatment and at the final follow‐up. Results The mean follow‐up duration was 16 weeks for the eight patients. Detailed baseline patient characteristics were recorded. CD3–CD20 levels decreased significantly after rituximab treatment, compared to baseline levels. TRAb levels also showed a statistically significant decline during the treatment period compared to the baseline levels ( p = 0.012). The CAS showed a significant decrease from baseline to 16 weeks post‐treatment ( p = 0.027). There were no significant differences in orbital MRI imaging before and after treatment yet. Nuclear medicine orbital imaging assessment indicated an improvement trend in orbital inflammatory activity among patients. Few adverse effects were observed during the therapy. Conclusions The preliminary exploratory study suggested that the early low‐dose rituximab treatment (100 mg weekly for 4 weeks) may be associated with immunological changes (TRAb reduction, B‐cell depletion) in patients with early progressive, mild‐to‐moderate TED. These hypothesis‐generating findings require validation in randomized, placebo‐controlled trials with adequate sample sizes and longer follow‐up.