Molecular Pathogenesis and Targeted Therapies for Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is a molecularly heterogeneous hepatobiliary neoplasm with poor prognosis and limited therapeutic options. The incidence of this neoplasm is growing globally. One third of iCCA tumors are amenable to surgical resection, but most cases are diagnosed at advanced stages with chemotherapy as the only established standard of practice. No molecular therapies are currently available for the treatment of this neoplasm. The poor understanding of the biology of iCCA and the lack of known oncogenic addiction loops has hindered the development of effective targeted therapies. Studies with sophisticated animal models defined IDH mutation as the first gatekeeper in the carcinogenic process and led to the discovery of striking alternative cellular origins. RNA- and exome-sequencing technologies revealed the presence of recurrent novel fusion events (FGFR2 and ROS1 fusions) and somatic mutations in metabolic (IDH1/2) and chromatinremodeling genes (ARID1A, BAP1). These latest advancements along with known mutations in KRAS/BRAF/EGFR and 11q13 high-level amplification have contributed to a better understanding of the landscape of molecular alterations in iCCA. More than 100 clinical trials testing molecular therapies alone or in combination with chemotherapy including iCCA patients have not reported conclusive clinical benefits. Recent discoveries have shown that up to 70% of iCCA patients harbor potential actionable alterations that are amenable to therapeutic targeting in early clinical trials. Thus, the first biomarkerdriven trials are currently underway.