Multiregional Immune Profiling Reveals Prognostic Patterns in Bladder Cancer

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Muscle-invasive bladder cancer (MIBC) is a heterogeneous disease with variable prognosis.
• Conventional prognostic markers for MIBC are limited.
• The tumor immune microenvironment (TIME) is increasingly recognized as a crucial factor in disease progression and patient outcomes.

Purpose of the Study:

• To investigate the prognostic value of immune checkpoint proteins (ICPs) in the TIME of MIBC patients.
• To develop a robust risk stratification model for MIBC based on ICP expression.
• To determine the optimal number of tumor biopsies for comprehensive immune profiling.

Main Methods:

• Analysis of 251 MIBC patients undergoing cystectomy.
• Quantification of six ICPs (IDO, PD-L1, PD-1, LAG-3, TIM-3, VISTA) using immunohistochemistry on tumor cores.
• Hierarchical clustering of ICP-positive immune and tumor cells to define TIME subtypes.
• Multivariable Cox models to assess association with overall survival (OS) and disease-free survival (DFS).
• Bootstrap resampling to estimate minimum tumor sample count for maximal ICP expression.

Main Results:

• IDO+ and VISTA+ immune cells were dominant; PD-L1+ tumor cells showed dichotomous expression.
• Three spatially distinct cores were sufficient for most ICPs, while four were needed for others.
• Three TIME subtypes (CID1-3) were identified, with CID3 showing significantly worse prognosis (median OS 18.5 vs 100.5 months, p=0.0007).
• The ICP-based classification improved patient stratification compared to Union for International Cancer Control staging, especially in late-stage MIBC.

Conclusions:

• A six-marker, multiregional ICP panel provides robust, stage-independent risk stratification for MIBC.
• At least four biopsies are recommended for routine immune profiling in MIBC.
• Further longitudinal external validation of this ICP-based stratification model is warranted.