The use of peripheral blood biomarkers for predicting the risk of immune-related adverse events in immune checkpoint inhibitor therapy

Background Immune checkpoint inhibitors (ICIs) have revolutionised oncology care, by enhancing the body’s T cell lymphocyte response against tumour cells. ICIs block the inhibitory signalling between tumour cells and the immune system, but consequently reduce immunological tolerance. Subsequently for some, this leads to immune-related adverse events (irAE), a spectrum term for autoimmune-like toxicities induced by ICIs that affects various tissues and organs. This limited narrative review will give a brief overview of immune checkpoint inhibitors and immune-related adverse events for laboratory professionals and review the current evidence for predictive biomarkers. Methods A limited narrative review was conducted by accessing Pubmed and Google from June 2023 to January 2024 to identify references published from database inception to January 2024. Language was restricted to English. Results/findings Professional guidance does not recommend any biomarkers for irAE prediction. Some studies have found an association between the prediction of irAE and interleukin six (IL-6), C-reactive protein (CRP), thyroid stimulating hormone (TSH), albumin, ferritin, full blood count metrics, and lactate dehydrogenase (LDH). However, these have often been single-centre retrospective studies. While an abundance of societal guidance has been produced, it is unclear what blood tests should be included within a baseline profile. Conclusions Presently, there is no singular biomarker routinely available in clinical laboratories that can predict the onset of irAE. A custom battery of tests may be more predictive, but evidence is currently lacking. In the meantime, due to the clinical significance of these complications, laboratory professionals should proactively support prospective studies.