Long-term outcomes in corticosteroid-refractory Graves' orbitopathy treated with tocilizumab.

Background: Up to 20% of patients with moderate to severe Graves' orbitopathy (GO) do not respond to high-dose glucocorticoids (GC). A few studies, including a randomized trial, have demonstrated the efficacy of interleukin-6 (IL-6) blockade with tocilizumab (TCZ) in GC-refractory GO. However, data on predictors of response to TCZ and long-term outcomes are lacking.

Methods: Observational single-center study on ten consecutive patients treated with TCZ for GC-refractory GO, between 2016 and 2020. Median (interquartile range) follow-up was 24 (12-36) months.

Results: Inflammation and exophthalmos improved dramatically in all patients within months after starting TCZ. Mean Clinical Activity Score decreased from 4.80 ±  1.13 to 0.70 ± 0.82 points at 6 months (mean change: -4.10 ± 1.52; p < .0001). Proptosis improved from 23.2 ± 2.1 to 20.6 ± 2.0 mm at 6 months (mean change: -2.9 ± 1.4 mm; p < .0001). Diplopia resolved in 7 patients. Thyroid receptor antibodies decreased markedly during TCZ treatment. Baseline serum IL-6 levels did not predict clinical response. TCZ was well-tolerated. During follow-up, 3 patients were diagnosed with cancer (breast cancer in 2 and urothelial cancer in 1).

Conclusions: TCZ was rapidly effective and well-tolerated in our patients with GC-refractory GO. Four patients experienced mild/moderate adverse events as neutropenia, hyperlipidemia, and infections; nearly a third developed cancer during the follow-up. The increased incidence observed could be explained by the high prevalence of smokers, that are at higher risk for Graves' orbitopathy and solid malignancies as breast cancer. Thus, regular cancer screening could be proposed to this vulnerable population receiving high doses of immunosuppressants.