A Consensus Molecular Classification of Muscle-invasive Bladder Cancer

Area of Science:

• Oncology
• Genomics
• Bioinformatics

Background:

• Muscle-invasive bladder cancer (MIBC) is a complex disease with varied molecular profiles and clinical outcomes.
• Existing molecular classifications for MIBC lack standardization, hindering clinical application.

Purpose of the Study:

• To establish an international consensus on MIBC molecular subtypes by reconciling diverse classification schemes.
• To develop a unified classification system for improved clinical utility in bladder cancer research.

Main Methods:

• Analysis of 1750 MIBC transcriptomic profiles from multiple datasets and cohorts.
• Network-based analysis of six independent MIBC classification systems to identify consensus molecular classes.
• Assessment of survival associations using multivariable Cox models.

Main Results:

• Identification of a consensus set of six molecular classes: luminal papillary (24%), luminal nonspecified (8%), luminal unstable (15%), stroma-rich (15%), basal/squamous (35%), and neuroendocrine-like (3%).
• Demonstrated differences in oncogenic mechanisms, immune/stromal cell infiltration, and clinical characteristics among consensus classes.
• Development of a single-sample classifier for assigning consensus class labels based on tumor transcriptome.

Conclusions:

• The consensus classification provides a robust framework for MIBC molecular subtyping.
• Enables standardized testing and validation of predictive biomarkers in future clinical trials for bladder cancer.
• Facilitates clinical application of molecular subtyping for patient stratification and treatment response prediction.