Targeting Sialylation Enhances the Therapeutic Efficacy of the Nectin-4–Targeted Antibody–Drug Conjugate Enfortumab Vedotin in Bladder Cancer

More than half of patients with advanced or metastatic bladder cancer are ineligible for cisplatin chemotherapy or have poor response to cisplatin. Recently, the combination therapy of enfortumab vedotin (EV), a Nectin-4-targeted antibody-drug conjugate (ADC), with the anti-PD-1 antibody pembrolizumab (EV + pembrolizumab) has shown high and durable response rates, as well as survival benefits, for these patients with bladder cancer. Identifying factors that affect the response to single-agent EV or EV + pembrolizumab therapy could help to further improve response rates. In this study, we showed that Nectin-4 expression is negatively correlated with sialylation and complex type N-glycans levels and positively correlated with high-mannose type N-glycans levels in bladder cancer. Pharmacologic inhibition of sialylation sensitized bladder cancer to EV monotherapy and its combination with immunotherapy both in vitro and in vivo. Mechanistically, α-2,6-sialylation mediated the downregulation of Nectin-4. Furthermore, the removal of sialylation increased the endocytosis of EV by bladder cancer cells and enhanced EV-mediated immunogenic cell death. Collectively, these findings suggest that sialylation is a promising therapeutic target to improve EV sensitivity and provide a rational basis for clinical application of sialylation inhibitors in bladder cancer. SIGNIFICANCE: Suppressed enfortumab vedotin endocytosis and elevated degradation of its target Nectin-4 is mediated by sialylation, which can be targeted to improve the therapeutic efficacy of the antibody-drug conjugate in bladder cancer.