IL‑6: A key player in the EGFR‑TKI‑resistant tumor microenvironment and its therapeutic implications (Review)

IL‑6, a pleiotropic inflammatory cytokine predominantly secreted by fibroblasts, myeloid‑derived suppressor cells, tumor‑associated macrophages and tumor cells, is associated with poor prognosis of and therapeutic resistance in non‑small cell lung cancer (NSCLC). The activation of signaling pathways, including the JAK/STAT3, MAPK and PI3K/AKT pathways, promotes tumor survival. Furthermore, the IL‑6/JAK/STAT3 signaling axis has emerged as a key driver of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‑TKI) resistance, orchestrating intricate crosstalk within the tumor microenvironment (TME) to promote cell survival and immunosuppression. The present review synthesized current evidence on the dual role of IL‑6 in mediating EGFR‑TKI resistance and blunting anti‑tumor immunity. The present review highlights the preclinical rationale for combining IL‑6 blockade with EGFR‑TKI or immune checkpoint inhibitors to overcome refractory disease. The present review also highlights the structure, molecular mechanisms and clinical insights of IL‑6 in the TME of EGFR‑mutant NSCLC and may provide optimized therapeutic strategies for EGFR‑TKI‑refractory NSCLC.