Abstract
Cholangiocarcinoma (CCA) is a highly aggressive cancer of the biliary tract, distinguished by significant intratumoral heterogeneity (ITH), which contributes to therapy resistance and unfavorable clinical outcomes. Traditional genome profiling has revealed recurring driver changes in CCA; yet, genomic data alone fails to elucidate functional pathway activation, adaptive signaling, and the diverse treatment responses reported among tumor locations and disease subtypes. This review analyses the use of integrated sequencing technologies, proteogenomics, and phosphoproteomics to systematically characterize intratumoral heterogeneity in cholangiocarcinoma and convert molecular diversity into therapeutically applicable discoveries. We present evidence that the combination of genomic sequencing and mass spectrometry-based proteomics facilitates the direct correlation of genetic mutations with protein expression, post-translational modifications, and signaling system activity. Phosphoproteomic profiling specifically offers functional insights into kinase-driven networks that dictate tumor aggressiveness, therapeutic susceptibility, and adaptive resistance mechanisms, which cannot be anticipated only from DNA-level analysis. We propose that integrating proteogenomic and phosphoproteomic analyses into diagnostic and therapeutic assessments can enhance molecular classification, reveal subtype- and region-specific therapeutic dependencies, and guide rational combination treatment strategies, based on recent extensive proteogenomic studies and functional proteomic investigations in CCA. Pathway-level analysis of intratumoral heterogeneity provides a framework for selecting targeted medicines, predicting resistance, and informing personalized treatment strategies in CCA. The combination of sequencing, proteogenomics, and phosphoproteomics is essential for advancing precision oncology in cholangiocarcinoma. The implementation of this multi-layered analytical approach may better patient classification, refine therapy choices, and eventually improve clinical outcomes for individuals with this particular heterogeneous cancer.