AbstractBackgroundCholangiocarcinomas (CCAs) are highly desmoplastic neoplasms with a tumour microenvironment plentiful in myofibroblasts (MFBs).MFB‐derivedPDGF‐BBsurvival signalling is a mediator ofCCAcell resistance to apoptotic stimuli. This raises the concept that targetingPDGFR‐β, a cognate receptor ofPDGF‐BB, represents a potential strategy for the treatment of humanCCA.AimsHerein, we examine a role for inhibitingPDGFR‐β in restoringCCAcell sensitivity to apoptotic stimuliin vitroandin vivo.MethodsWe employed humanCCAsamples from 41 patients (19 intrahepatic and 22 extrahepaticCCAsamples), the humanCCAcell linesKMCH‐1 andHUCCT‐1 as well as shPDGFR‐β‐KMCH‐1 and human myofibroblasticLX‐2 cells for these studies.In vivo‐experiments were conducted using a syngeneic rat orthotopicCCAmodel.ResultsOf severalMFB‐derived growth factors profiled,PDGF‐BBandCTGFwere most abundantly expressed; however, onlyPDGF‐BBattenuated tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) cytotoxicity. Co‐culturingCCAcells withPDGF‐BB‐secretingMFBs significantly decreasedTRAIL‐inducedCCAcell apoptosis when compared with monoculture conditions; this cytoprotective effect was abrogated in the presence of the tyrosine kinase inhibitors imatinib mesylate or linifanib, which inhibitPDGFR‐β. Consistent with these findings,MFB‐imparted cytoprotection also was abolished whenPDGFR‐β was knocked down as demonstrated in shPDGFR‐β‐KMCH‐1 cells. Finally, administration of imatinib mesylate increasedCCAcell apoptosis and reduced tumour growth in a rodentin vivo‐CCAmodel that mimics the human disease.ConclusionsTargetingPDGFR‐β sensitizesCCAcells to apoptotic stimuli and appears to be therapeuticin vivo.