Multiregional Immune Profiling Reveals Prognostic Patterns in Bladder Cancer
Background and objective
Muscle-invasive bladder cancer (MIBC) is a biologically heterogeneous disease with variable prognosis after radical cystectomy. While conventional clinicopathological parameters offer limited prognostic value, growing evidence highlights the role of the tumor immune microenvironment (TIME)—including immune cell composition and spatial architecture—as robust biomarkers for disease progression and outcomes.
Methods
The study included 251 consecutive patients with MIBC who underwent cystectomy (2004–2014, LMU Munich). Three 1-mm-diameter cores were sampled from the tumor invasive front and center in the cystectomy specimen. Six immune checkpoint proteins (ICPs; IDO, PD-L1, PD-1, LAG-3, TIM-3, and VISTA) were quantified digitally following immunohistochemical (IHC) staining. ICP-positive immune and tumor cells were stratified and densities were hierarchically clustered. Multivariable Cox models were then used to assess the association with overall (OS) and disease-free survival. The minimum tumor sample count needed to detect the maximum ICP expression per patient was estimated via a 1000-fold bootstrap resampling simulation.
Key findings and limitations
IDO+ and VISTA+ immune cells dominated the TIME, while PD-L1+ tumor cells exhibited a dichotomous expression pattern. Analysis of three spatially distinct cores was sufficient to recover maximal expression of low-abundance TIM-3+ and VISTA+ immune cells, while four cores were required for all other markers. ICP-based clustering revealed three TIME subtypes (CID1–3), of which CID3 was associated with markedly worse prognosis (median OS 18.5 vs 100.5 mo; p = 0.0007). This classification outperformed Union for International Cancer Control staging and improved patient stratification in late-stage MIBC.
Conclusions and clinical implications
A six-marker, multiregional ICP panel delivers a robust, stage-independent, actionable risk stratification in MIBC. At least four biopsies are advised for routine immune profiling; further longitudinal external validation is warranted.
