Cholangiocarcinogenesis and targeted therapy for cholangiocarcinoma

Abstract

Cholangiocarcinoma includes a highly heterogeneous group of malignant tumors of the biliary tract, developing from the epithelium of the intra- and extrahepatic bile ducts. The incidence of cholangiocarcinoma is growing worldwide and currently accounts for about 15% of all primary neoplastic diseases of the liver and up to 3% of malignant neoplasms of the gastrointestinal tract. The asymptomatic course of these tumors in combination with a very aggressive course and low sensitivity to cytotoxic therapy contributes to a fairly high mortality rate from this disease, amounting to up to 2% in the structure of cancer mortality in the world. The high heterogeneity of cholangiocarcinoma at the genomic, epigenetic and molecular levels significantly reduces the effectiveness of the available treatments. In recent decades, new diagnostic tools and treatment methods have been developed to improve the results of treatment of patients with cholangiocarcinoma. The prevalence of BRAF gene mutations is associated with the occurrence of various tumors, including cholangiocarcinoma. Currently, more than 30 mutations in the BRAF gene with oncogenic potential have been registered. Basically, the V600 codon is affected, an amino acid change occurs, which ultimately leads to the fact that the BRAF protein becomes constantly active, even in the absence of growth factors. Dabrafenib is an inhibitor of the BRAF protein, which is permanently overactive in mutated cells. The use of dabrafenib as monotherapy leads to the development of resistance after 6–7 months. Dabrafenib is used with trametinib, a MEK inhibitor that also blocks the Ras-Raf-MEK-MAPK kinase pathway, to prevent the resistance.