Intra-arterial infusion chemotherapy utilizing cisplatin inhibits bladder cancer by decreasing the fibrocytic myeloid-derived suppressor cells in an m6A-dependent manner

•Intra-arterial infusion chemotherapy (IAIC) utilizing cisplatin could benefit patients with bladder cancer.•Following IAIC, fibrocytic-MDSCs (f-MDSCs) were the immune cell type that were most significantly reduced in number.•The f-MDSCs were found to promote tumor proliferation and metastasis in the BC immune environment.•Cisplatin mediates the immunomodulatory effects of G-CSF by decreasing methylation.•Cisplatin decreased the number of f-MDSCs during IAIC, by blocking G-CSF methylation via targeting METTL3.