AXL drives immunotherapy resistance by modulating IL-17 in bladder cancer.

Given the persistently poor five-year survival rate (<10 %) in metastatic bladder cancer (BLCA) and the limited efficacy of conventional chemotherapy and programmed cell death protein 1 (PD-1) inhibitor monotherapy, there is an urgent need to identify novel immune targets and rational combination strategies. Therefore, we investigated the prognostic association and interplay between AXL receptor tyrosine kinase (AXL) and interleukin 17 (IL-17) in BLCA using multiplex immunofluorescence and immunohistochemistry on tissue microarrays, which revealed their co-upregulation as a biomarker of poor outcome. We further established spontaneous and subcutaneous BLCA mouse models to demonstrate that combining an AXL inhibitor with an anti-PD-1 antibody significantly reduced tumor burden. Proteomic profiling and enrichment analyses in AXL-knockdown cells showed that AXL modulates key immunosuppressive pathways, including IL-17 signaling, negative regulation of type I interferon response, and positive regulation of transforming growth factor-beta (TGF-β) production. These findings were consistent with observations in clinical cohorts, including the cancer genome atlas (TCGA), gene expression omnibus (GEO), and IMvigor210, where high AXL expression correlated with an immunosuppressive tumor microenvironment characterized by increased M2 macrophages, exhausted CD8+ T cells, and elevated PD-L1. In conclusion, AXL/IL-17 co-expression defines a high-risk BLCA subgroup, and targeting AXL represents a promising strategy to overcome resistance to PD-1-based immunotherapy in advanced disease.