CD19+ tumor-infiltrating B-cells prime CD4+ T-cell immunity and predict platinum-based chemotherapy efficacy in muscle-invasive bladder cancer.

ABSTRACT

PURPOSE: CD19+ tumor-infiltrating B-cells (CD19+ TIB) play a crucial role in tumorigenesis, but their clinical relevance in muscle-invasive bladder cancer (MIBC) remains unknown. This study aimed to investigate the prognostic value of CD19+ TIB for post-surgery survival and adjuvant chemotherapy response in MIBC. EXPERIMENTAL DESIGN: We assessed TIB by immunohistochemical staining of CD19 in 246 MIBC patients from Zhongshan Hospital and Shanghai Cancer Center. We evaluated the survival benefit of platinum-based chemotherapy according to CD19+ TIB. The mechanism underlying CD19+ TIB antitumor immunity was explored through the Cancer Genome Atlas (TCGA) dataset analysis and an in vitro Ag presentation assay. RESULTS: CD19+ TIB extensively infiltrated into the tumor stroma of MIBC. Adjuvant chemotherapy (ACT) led to a significantly increased benefit in the high CD19+ TIB MIBC patients (P = 0.003). In multivariate analysis, high CD19+ TIB MIBC patients had significantly longer OS with ACT in the discovery set (HR = 0.487, P = 0.038). TCGA gene expression analyses showed enrichment of adaptive immunity, T-cell-mediated immunity, and antigen-presentation signaling pathways in high CD19+ TIB MIBC patients. Moreover, CD19+ TIB co-localized with activated CD4+ TIT and expressed surface markers characteristic of antigen-presenting cells. Finally, an antigen-presentation assay demonstrated the antigen-presentation function of CD19+ TIB. CONCLUSION: CD19+ TIB was identified as an independent prognostic factor, which could predict for post-surgery survival and platinum-based ACT benefits in MIBC. CD19+ TIB serve as antigen-presenting cells (APCs) to activate CD4+ TIT in the tumor environment of MIBC.