Rituximab for thyroid eye disease.

PURPOSE To assess the efficacy and safety of rituximab-mediated B-lymphocyte depletion as treatment for thyroid eye disease (TED). METHODS Prospective, open-label, interventional clinical trial evaluating 12 patients with TED and Clinical Activity Scores (CAS) (VISA [vision, inflammation, strabismus and appearance/exposure] classification) of 4 or greater followed for 1 year after rituximab (1000 mg) treatment, administered intravenously on days 1 and 15. CAS, peripheral B-lymphocyte levels, thyroid autoantibody levels, and thyroid function tests were recorded at baseline, 4 weeks, 8 weeks, 12 weeks, 24 weeks, 36 weeks, and 52 weeks after the second infusion. The primary endpoint was a change from baseline in CAS. Thyroid-stimulating immunoglobulin and thyroid-stimulating hormone levels were also monitored over the 12-month postinfusion observation period. RESULTS CAS scores demonstrated a statistically significant decrease from baseline at each of the follow-up visits. Thyroid-stimulating immunoglobulin and thyroid-stimulating hormone levels demonstrated no statistically significant change from baseline. B-cell depletion was observed within 1 month after rituximab treatment, and peripheral B-lymphocyte counts started to increase 36 weeks after the infusion. B-cell depletion was well tolerated, and there were no adverse effects of the rituximab infusions. CONCLUSIONS CAS scores were significantly reduced over time in this group of 12 patients and appeared to be associated with rituximab infusion. The variable natural history of TED makes it difficult to definitively assign efficacy. The results support the continued investigation of rituximab for TED in a larger placebo-controlled trial.