Immune Checkpoint Inhibitors-induced Thyroid Dysfunction in Patients with Advanced Malignancies

Background: Immune checkpoint inhibitors (ICIs), including antiprogrammed cell death receptor-1, antiprogrammed cell death ligand-1, and anticytotoxic T-lymphocyte-antigen 4, have improved patients’ outcome in advanced malignancies. These agents are associated with immune-related adverse events, including skin toxicity, gastrointestinal toxicity, hepatotoxicity, renal toxicities, and endocrinopathies.Method: We retrospectively reviewed the electronic medical records of patients treated with ICIs for advanced malignancies from two tertiary cancer care centers in the Emirate of Dubai, United Arab Emirates (UAE), including Dubai Hospital and American Hospital from November 2015 to January 2019. The patients were identified through the hospital cancer registry. We retrospectively collected data regarding the subjects’ demographics, cancer type, type of ICIs, thyroid-related adverse events, and duration of treatment.Results: In the present paper, 43 patients received ICI and 19 (44%) developed thyroid dysfunctions. The median age of ICI-receiving subjects was 60 (27-80) years; 26 of them were male and 17 were female. Pembrolizumab was the most used agent (42%). Pretreatment thyroid functions were normal for all the patients. Following treatment initiation, 19 (44%) patients developed thyroid abnormalities, including overt hypothyroidism (n = 11, 57%), overt hyperthyroidism (n = 2, 11%), subclinical hypothyroidism (n = 4, 21%), and subclinical hyperthyroidism (n = 2, 11%). Thyroid abnormalities developed in 56% of them treated with Pembrolizumab and 37% treated with Nivolumab.Conclusion: Hypothyroidism was the most prevalent thyroid adverse event in the patients treated with ICIs in our study and the majority of thyroid dysfunction encounters took place in the first 6 weeks after ICI initiation. The treatment was well tolerated and there were no treatment-related discontinuations or deaths.