Endocrine Abstracts

Background: Thyroid eye disease (TED) is an autoimmune inflammatory disease associated with Graves’ disease. Rituximab (a monoclonal antibody that depletes B-cells), has recently been shown to be effective in treating TED. There is evidence to support an association with increased TRAbs and TED severity, and one study has demonstrated a fall in TRAbs with rituximab therapy. The aim of this study was to assess the clinical efficacy of low dose rituximab in patients with TED, and correlate this with TRAb level.

Methods: A retrospective study of patients with moderate to severe active TED who received low dose rituximab (100 mg) at the Oxford Joint Thyroid Clinic (Ox-TED). 14 patients were identified between 2016 and 2018. All patients were initially treated with 100 mg rituximab and 500 mg intravenous (IV) methylprednisolone. Patients were subsequently treated with further 100 mg rituximab (2 patients), further IV methylprednisolone or steroid-sparing agents if clinically indicated. Disease severity scores, B-cell counts and TRAb levels were collected at baseline and following treatment.

Results: Clinical activity scores significantly decreased from baseline to follow up (11.78 to 6.8, P=0.01). B-cell depletion was seen in all 11 patients with B-cell count recorded following treatment, P<0.001. Cumulative steroid dose was 2.38 g, half the dose recommended by EUGOGO for patients with moderate to severe active TED. In all patients (n=11) with TRAbs recorded pre and post treatment, all showed significant reduction (7.64 to 3.98 international units per litre, P=0.01).

Conclusion: Low dose rituximab suppresses B-cells, is clinically efficacious, is associated with reduced requirement for systemic steroids, and results in significant reduction of TRAbs. Data is now being prospectively collected on TRAbs in patients treated with steroids and steroid-sparing agents alone.