RAPID EVOLUTION of THYROID DYSFUNCTION in PATIENTS TREATED with NIVOLUMAB

Objective: To describe the evolution of thyroid dysfunction in a series of patients with cancer treated with the immune checkpoint inhibitor anti-programmed cell death protein-1 (PD-1) monoclonal antibody, nivolumab. Methods: Cases of thyroid dysfunction after initiation of checkpoint inhibitor treatment were identified from the Division of Endocrinology clinical practice at Mount Sinai Hospital, New York from April 2016 to February 2017. Charts were reviewed to identify patients treated with nivolumab with new onset of thyroid dysfunction. Results: Nine cases of thyroid function in patients who were treated with nivolumab were identified. There were 4 male and 5 female patients, with a mean age of 66 years (range 50-76 years). Seven patients ultimately developed hypothyroidism. Five of the 7 patients developed abnormal thyroid function tests within the first 90 days of starting therapy (range 21-84 days), 3 of whom had transient hyperthyroidism. Transient hyperthyroidism evolved rapidly to hypothyroidism; elevated thyroid-stimulating hormone (TSH) levels were detected within 16 to 32 days of the last documented low TSH. In the 2 patients without a hyperthyroid phase, TSH levels >50 were found 18 to 28 days after the last normal TSH value. Conclusion: As the use of immune checkpoint inhibitor therapy increases, the need for prompt diagnosis and treatment of drug-induced thyroid disease will become more important. As illustrated in this case series, in contrast to other causes of auto-immune thyroiditis, hypothyroidism can develop rapidly within 3 months of treatment. Close monitoring is necessary to detect the development of thyroid dysfunction and avoid preventable morbidity. Abbreviations: Anti-TPO Abs = anti-thyroglobulin antibodies; CT = computed tomography; CTLA-4 = cytotoxic T-lymphocyte-associated protein 4; FDA = U.S. Food & Drug Administration; FDG-PET = fluorodeoxyglucose-positron emission tomography; PD-1 = programmed cell death protein-1; PD-L1 = programmed death-ligand 1; T3 = triiodothyronine; T4 = thyroxine; TG = thyroglobulin; TPO = thyroperoxidase; TSH = thyroid-stimulating hormone.