Stevens A | Volume 3; Issue 1 (2022) | Mapsci-JIMER-3(1)-035 | Review Article Citation: Stevens A, Gupta S, Aleman M, Cleves A, Ocen J, Frazer R. Endocrine Toxicities of Checkpoint Inhibitor Immunotherapy: Diagnostic Challenge and Management. J Intern Med Emerg Res. 2021;3(1):1-5. DOI: https://doi.org/10.37191/Mapsci-2582-7367-3(1)-035 Journal of Internal Medicine and Emergency Research ISSN: 2582-7367 Stevens A, et al., 2022-Intern Med Emerg Res Review Article Endocrine Toxicities of Checkpoint Inhibitor Immunotherapy: Diagnostic Challenge and Management Alys Stevens 1* , Senjuti Gupta 1 , Menna Aleman 2 , Anne Cleves 1 , Joanita Ocen 1 and Ricky Frazer 1 Abstract Immune Checkpoint Inhibitors (ICIs) have transformed the landscape of oncology and are now utilized across many tumor sites. A significant proportion of patients receiving ICIs will develop endocrine toxicity, the majority of which are irreversible and potentially fatal. Toxicities can affect more than one endocrine organ at a time, occur even following discontinuation of therapy, and often present with non-specific symptoms. A low threshold to consider these toxicities within the differential diagnosis is therefore of paramount importance. Once detected many of the hormone deficiencies associated with ICIs can be effectively replaced exogenously; following which most ICIs can be safely continued. This is of particular importance as there is emerging evidence to suggest that patients who develop toxicity may ultimately have overall improved outcomes from a cancer perspective in some tumor sites. Keywords: Endocrine toxicities; Immunotherapy; Diagnosis; Immune checkpoint inhibitors; Oncology; Hormone deficiencies. Introduction Immune Checkpoint Inhibitors (ICIs) have transformed the landscape of oncology, demonstrated improved survival outcomes are now utilized across many tumor sites. Checkpoint proteins on cell surfaces, including those on malignant cells, bind to T cells causing them to remain inactive and thus downregulate the immune system. ICIs are monoclonal antibodies which inhibit this interaction and thus stimulate an immune response. Given this mechanism of action of checkpoint inhibitor immunotherapy in cancer, it is perhaps not surprising that the side effects of ICI therapy are autoimmune in nature and can affect any organ. Endocrinopathies have emerged as one of the most common side effects of ICIs, particularly with combination anti-CTLA-4 anti-PD1 therapy. Whilst most side effects of ICIs are reversible, the majority of 1 Velindre Cancer Centre, Velindre Rd, Cardiff, UK 2 Cardiff University, Cardiff, UK * Corresponding Author: Alys Stevens, Velindre Cancer Centre, Velindre Rd, Cardiff, UK. Accepted Date: 01-10-2022 Published Date: 02-10-2022 Copyright© 2022 by Stevens A, et al., all rights reserved. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.