Endocrine-related Adverse Events Caused by Immune Checkpoint Inhibitors

Immune checkpoint inhibitor (ICI) includes agents that block cytotoxic T-cell-associated antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), and programmed cell death protein ligand 1 (PD-L1). Since the FDA-approval of the CTLA-4 inhibitor ipilimumab in 2011, ICI drugs have emerged as a powerful new tool in the treatment for several advanced cancers. Now indications for ICI have expanded dramatically due to their efficacy and include a wide array of cancer types. However, the administration of ICI, whereas, carry the risk of developing immune-related adverse events (irAEs) and may lead to serious and even fatal events. Endocrine dysfunctions are among the most common irAEs that have been reported in clinical trials with ICI, including thyroid dysfunction, hypopituitarism, primary adrenal insufficiency (PAI) and insulin-deficient diabetes (ICI-DM). However, it is difficult to acquire a complete picture of irAEs from randomized controlled trials (RCTs) due to limitations in the study design and realistic practicalities.