Immune inactivation by neuropilin-1 predicts clinical outcome and therapeutic benefit in muscle-invasive bladder cancer

Background Immune checkpoint blockade (ICB) and adjuvant chemotherapy (ACT) have shown clinical benefit in muscle-invasive bladder cancer (MIBC) with only a few predictive biomarkers identified so far. Neuropilin-1 (NRP1) has been identified as a key immune checkpoint and a novel immunotherapeutic target but the clinical significance of NRP1 remains unclear in MIBC. Methods Three independent cohorts were involved in our study: IMvigor210 Cohort (n = 348), The Cancer Genome Atlas Cohort (TCGA, n = 391), and Zhongshan Hospital Cohort (ZSHS, n = 130). Parallel detection and validation of risk stratification based on NRP1 expression were executed in patients treated with anti-PD-L1 agent and adjuvant chemotherapy (ACT). Results NRP1 expression conferred poor survival and predicted response to both PD-L1 blockade and cisplatin-based ACT in MIBC. Further exploration revealed high-level NRP1 was extremely associated with infiltration of exhausted CD8(+) T cells, immature NK cells and M2 polarized tumor-associated macrophages in MIBC patients. Moreover, elevated NRP1 expression was also correlated with low mutation burden and reduced mutation in cell cycle pathway. Conclusions Our study firstly identified and validated the clinical implications of NRP1 expression for prognosis and systematic therapeutic responses (PD-L1 blockade and ACT) in MIBC. NRP1 expression was associated with an immunosuppressive microenvironment with dysfunctional effector immune cells. Prospective investigations of its roles in the therapeutic landscape of MIBC warrant more consideration.