Systemic treatment of advanced or recurrent biliary tract cancer

Biliary tract cancer (BTC) is a disease entity comprising diverse epithelial tumors with features of cholangiocyte differentiation, and it includes cholangiocarcinoma (CCA) and gallbladder cancer (GBC). Depending on its anatomical location, cholangiocarcinoma is categorized as intrahepatic (iCCA), perihilar (pCCA), or distal (dCCA). Nearly two-thirds of patients with biliary tract cancer present with advanced disease at diagnosis and in 68-86% of resections the cancer eventually recurs either locoregionally or at a distance. Chemotherapy is the first-line therapy for advanced or recurrent BTC. With the development of next-generation sequencing (NGS)-guided molecular targeted therapy, more options are available for treatment of advanced BTC. Chemotherapy, and especially a triplet regimen based on gemcitabine/cisplatin/nab-paclitaxel, has had the most significant effect, and fluorouracil, leucovorin, irinotecan plus oxaliplatin (FOLFIRINOX) combined with bevacizumab is promising. Molecular targeted therapy should be based on genome sequencing and appears essential to precision medicine. Fibroblast growth factor receptor (FGFR) inhibitors and isocitrate dehydrogenase (IDH) inhibitors are promising emerging targeted therapies mainly for iCCA. Other targeted therapies such as anti-human epidermal growth factor receptor-2 (HER2) therapies, MEK inhibitors, BRAF inhibitors, and poly ADP ribose polymerase (PARP) inhibitors had tentatively displayed efficacy. Further evaluations of combination strategies in particular are needed. An immune checkpoint inhibitor (ICI) alone is less efficacious, but an ICI in addition to chemotherapy or radiotherapy has resulted in a response according to many case series. However, ICIs are still being evaluated in several ongoing studies. Combination therapies have garnered attention because of interactions between signaling pathways of carcinogenesis in BTC.