Prediction and early diagnosis of immune-checkpoint inhibitor-induced inflammatory arthritis from molecular biomarkers – Where are we now?

ABSTRACT Introduction Immune-checkpoint inhibitors (ICI) works by blocking inhibitory signals of T cells. This produces an effective anti-tumor response but can also cause immune-related adverse events (irAEs). Most irAEs are transient, but ICI-induced inflammatory arthritis (ICI-IIA) might become chronic and affect the quality-of-life, or even necessitate treatment discontinuation. However, there exist no tools to identify patients that are susceptible to develop ICI-IIA. Areas covered This non-systematic review briefly presents a sparse number of studies, that have tried to identify circulating biomarkers for early prediction of ICI-IIA. Challenges, recommendations, and possibilities related to biomarker discovery in the context of ICI-IIA are then covered. Expert opinion Improved diagnosis adapted from rheumatological settings is needed for future studies to avoid a major pitfall of bad endpoints. Synovial tissue biopsies, omics technologies and particularly integration of multiple omics data is useful when searching for biomarkers of ICI-IIA and can also help unravel underlying biological mechanisms. Future biomarkers could ultimately aid clinical decision-making and facilitate early prophylaxis, pave the way for new treatment or even translational models to study autoimmune arthritis.