Endocrine Abstracts

The treatment of orbitopathy in the course of Graves’ disease (GO, Graves’ Orbitopathy) still remains a serious therapeutic challenge. Modification of risk factors is considered to be the most important and the most effective method of treatment of benign GO. Treatment with intravenous glucocorticosteroid preparations remains the first-line therapy for moderate- to severe GO but is insufficient in some patients. Radiotherapy has been used in active GO therapy for decades, but its place in the treatment remains undetermined. High hopes are associated with the administration of low doses of rituximab (RTX) – a monoclonal antibody against CD20 antigens presented by lymphocytes B. The aim of the study is to present our clinical experiences in the use of RTX in a single dose in combination with radiotherapy in patients with active orbitopathy where other available forms of treatment were exhausted. Between 2017 and 2020 a group of 8 subjects aged 35–73 with active, moderate to severe GO, not responding to methylprednisolone therapy, was included in treatment. Patients were euthyroid, L-thyroxine supplementation was used if necessary. All patients denied smoking. The follow-up period ranged from 1 to 34 months. While all of the contraindications were excluded, each patient was given a single dose of 500 mg of RTX in a slow continuous intravenous infusion, strictly according to the therapeutic protocol. There were no side effects seen, both during, and after the drug administration. After the pharmacological treatment, each of the patients was referred to a radiotherapy center, to undergo a cycle of ten fractions of the orbit radiation therapy. As the therapy was finished, a hormonal, ophthalmological and imaging reassessment was carried out. There was a significant improvement seen in patients, concerning the clinical activity score (CAS). That included the total deactivation of the inflammatory process in 62.5% of patients. The massive effect of drug administration on the decrease of TRAb level was observed. (mean 23.08 IU/l before and 18.36 IU/l after therapy). MR imaging showed a decrease in eye muscles’ thickness. Our experiences with the use of single dose of RTX combined with radiotherapy indicate an efficacy of this new form of second-line treatment of GO. The reduction of activity of orbitopathy in all patients undergoing the treatment and, in some cases, its complete deactivation is very promising. Moreover, the lack of complications during the drug administration as well as the lack of infusion-related complications indicate the safety of the therapy.