Molecular classification of cholangiocarcinoma

Cholangiocarcinoma (CCA) are heterogeneous tumors that arise from the malignant transformation of cholangiocytes along the biliary tree. CCA heterogeneity occurs at multiple levels and results in resistance to therapy and poor prognosis. Here, we review the molecular classification of CCA by focusing on the latest progresses based on genetic, epigenetic, transcriptomic and proteomic profiles. In addition, we introduce the emerging field of radiogenomics.

Genome-wide integrative omics approaches have been widely reported by using large cohorts of CCA patients. Morphomolecular correlations have been established, including enrichment of FGFR2 gene fusions and IDH1/2 mutations in iCCA. A specific IDH mutant iCCA subtype displays high mitochondrial and low chromatin modifier expression linked to ARID1A promoter hypermethylation. Examples of translation of these classifications for the management of CCA have also been reported, with prediction of drug efficacy based on genetic alterations.

Although there is currently no international consensus on CCA morphomolecular classification, the recent initiatives developed under the umbrella of The European Network for the Study of Cholangiocarcinoma (ENSCCA) should favor new collaborative research. Identifying distinct molecular subgroups and developing appropriate targeted therapies will improve the clinical outcome of patients with CCA.