Tumor-Associated Mast Cells in Urothelial Bladder Cancer: Optimizing Immuno-Oncology

Urothelial bladder cancer (UBC) is one of the most prevalent and aggressive malignancies. Recent evidence indicates that the tumor microenvironment (TME), including a variety of immune cells, is a critical modulator of tumor initiation, progression, evolution, and treatment resistance. Mast cells (MCs) in UBC are possibly involved in tumor angiogenesis, tissue remodeling, and immunomodulation. Moreover, tumor-infiltration by MCs has been reported in early-stage UBC patients. This infiltration is linked with a favorable or unfavorable prognosis depending on the tumor type and location. Despite the discrepancy of MC function in tumor progression, MCs can modify the TME to regulate the immunity and infiltration of tumors by producing an array of mediators. Nonetheless, the precise role of MCs in UBC tumor progression and evolution remains unknown. Thus, this review discusses some critical roles of MCs in UBC. Patients with UBC are treated at both early and late stages by immunotherapeutic methods, including intravenous bacillus Calmette-Guerin instillation and immune checkpoint blockade. An understanding of the patient response and resistance mechanisms in UBC is required to unlock the complete potential of immunotherapy. Since MCs are pivotal to understand the underlying processes and predictors of therapeutic responses in UBC, our review also focuses on possible immunotherapeutic treatments that involve MCs.

Automated summary

Urothelial bladder cancer (UBC) is a common and aggressive malignancy, with the tumor microenvironment (TME) and mast cells (MCs) playing potential key roles in tumor progression and treatment. Early-stage UBC patients may have infiltration of MCs, which could impact prognosis based on tumor type and location. Immunotherapeutic methods are common in treating UBC, and understanding MC involvement may be crucial in unlocking the full potential of immunotherapy.