FRI553 ICI-induced Thyroid Ophthalmopathy With De Novo Graves’ Disease

Disclosure: S.I. Moctezuma: None. J. Perlman: None. J.S. Mammen: None. Background: Immune checkpoint inhibitors frequently target the thyroid gland. However, immune checkpoint inhibitor (ICI)-induced Graves’ disease (GD) is rare. To our knowledge, there are no reported cases of thyroid eye disease after immune checkpoint inhibitor therapy in patients with newly positive anti-thyroid antibodies. Clinical Case: An 81-year-old man developed thyroiditis within three weeks of a single dose of ipilimumab/nivolumab for the treatment of metastatic cholangiocarcinoma. ICI therapy was discontinued for cardiotoxicity. He presented one year later with onset of periorbital edema, pain with downgaze, redness, irritation and progressive proptosis with diplopia. He did not have a prior history of thyroid disease. Thyroid function tests before the start of ICI therapy revealed euthyroidism [TSH 2.982 uIU/mL (0.55 - 4.78)]. Symptoms of palpitations, weight loss, and hyper-defecation that characterized his initial presentation with thyroiditis were absent at the time of onset of eye disease. At presentation of thyrotoxicosis his TSH was <0.01 uIU/mL, free T4 3.6 ng/dL (0.89 - 1.76) total T3 190 ng/dL (60-180) Thyroid-peroxidase autoantibodies (TPOAb) and thyroid-stimulating immunoglobulin (TSI) were negative. When his visual symptoms appeared, TPOAb remained negative while a repeat TSI antibody was positive [0.64 IU/L (0.00 - 0.55)]. Thyroid ultrasound at the time of thyroiditis revealed a heterogeneous gland without discrete nodules and a normal vascular flow. Most cases of ICI-induced GD have been reported at the start of therapy, particularly in the first 6 weeks, although thyrotoxicosis has been described to occur as late as 224 days after starting PD-1 inhibitor. GD is more frequently reported with combination anti-CTLA-4 and anti-PD-1 therapy. Patients with thyroid ICI-induced adverse events experience either isolated hypothyroidism or thyroiditis spontaneously evolving towards hypothyroidism. However, ICI-induced GD is more likely to have a relapsing-remitting disease. In 2021, Peiffert et al. described the antibody profile for 243 patients with ICI-induced thyrotoxicosis. In this case series, 5 patients developed thyrotoxicosis with positive thyrotropin-receptor antibodies (TRAb). Only 2 patients had a typical clinical presentation of GD. TSI antibodies were not reported. Furthermore, none of the patients with positive TRAb had Graves’ ophthalmopathy. Conclusion: Our case demonstrates the acquisition of auto-antibodies capable of mediating Graves’ disease, and raises the possibility that thyroid eye disease-like orbital inflammation may occur as a side effect of immune checkpoint inhibitor therapy. These symptoms developed as late as one year after initiation of therapy. As with sporadic cases, this can occur in the absence of clinically significant hyperthyroidism. Presentation: Friday, June 16, 2023