RS 504393 inhibits M-MDSCs recruiting in immune microenvironment of bladder cancer after gemcitabine treatment.

Bladder cancer (BC) is a malignant tumor of urinary epithelium. Gemcitabine is an introduced treatment for BC and also has immunomodulatory function, but the immunoregulation mechanism is not clear. In this study, we found that gemcitabine-treated BC cell recruited more monocyte-myeloid-derived suppressed cells (M-MDSCs), which played a significant role in immune suppression and contributed to cancer progression. We found that this phenomenon was induced by Chemokine (C-C motif) ligand 2 (CCL2), an M-MDSCs recruitment related monomeric polypeptide. Gemcitabine treatment promotes the generation of CCL2 and CCL2 could attach to C-C chemokine receptor type 2 (CCR2) to recruit M-MDSCs. We used RS 504393, a selective CCR2 antagonist, to inhibit the recruitment of M-MDSCs. RS 504393 improved the prognosis by blocking chemotaxis of M-MDSCs, and this finding sheds lights on how to prevent and alleviate the side effects occurred on the gemcitabine-treated BC patients.