Unlocking the potential of microRNA as predictive biomarkers for efficacy and adverse events in immune checkpoint inhibitor therapy (Review)

Immune checkpoint inhibitors (ICIs) have shown promise in cancer therapy by enhancing antitumor immune responses, but patient responses are variable, with some experiencing limited efficacy and others suffering from severe immune‑related adverse events (irAEs). Identifying predictive biomarkers for ICI efficacy and toxicity is required for optimizing patient selection and treatment outcomes. MicroRNAs (miRNAs), small non‑coding RNA molecules that regulate gene expression, have emerged as potential biomarkers due to their role in immune regulation and tumor biology. Studies have shown that miRNA profiles in tumor tissues and blood can predict ICI responses. Specific miRNAs, such as miR‑155, miR‑21 and miR‑146a, are associated with enhanced antitumor responses, whereas others, such as miR‑34a and miR‑200c, are linked to resistance by modulating immune evasion. Additionally, altered miRNA expression reflects immune activation or dysregulation, playing a role in irAEs. The present review discussed the potential of miRNAs as predictive biomarkers for ICI therapy, their challenges in clinical integration and their promise for improving ICI treatment precision and safety, although further research is required for clinical application.