Unveiling resistance mechanisms to EGFR inhibitors in cholangiocarcinoma

Advances in pharmacotherapy for cholangiocarcinoma: from conventional therapies to targeted drugs

INTRODUCTION

Cholangiocarcinomas (CCA) are rare, highly invasive tumors often diagnosed at an advanced disease stage with an associated poor prognosis. Surgery represents the only chance for curative-intent treatment, but recurrence rates remain high. Neoadjuvant or adjuvant chemotherapy are options for patients with resectable CCA to increase recurrence-free survival and overall survival, while palliative chemotherapy represents the treatment for unresectable disease. Global efforts are currently focused on the development of novel more effective therapies.

AREAS COVERED

A review was conducted in August 2021 using the PubMed database with the following keywords: 'cholangiocarcinoma,' 'chemotherapy,' and 'therapy.' Manuscripts reporting on first- and second-line chemotherapy, neoadjuvant and adjuvant treatment regimens, and targeted therapies currently being tested or employed in the management of CCA were examined.

EXPERT OPINION

The prognosis of CCA is negatively affected by several factors including a lack of reliable biomarkers leading to delayed diagnoses, high inter- and intra-tumoral heterogeneity, and few effective chemotherapy regimens. In pursuit of more effective therapies, ongoing trials are testing both conventional and targeted drugs.

Will advanced cholangiocarcinoma become a targetable malignancy?

Cholangiocarcinoma and biliary tract cancers are rare but aggressive tumors that are characterized by an heterogenous molecular and genetic footprint. Genetic aberrations such as FGFR2 fusion and ErBb2 amplification are common in those cancers. Recent studies aimed at exploring the efficacy and benefit of targeted therapy in the treatment of advanced cholangiocarcinoma. Many promising drugs exist and warrant additional investigations. This review will summarize available results and highlight therapeutic strategies incorporated in clinical trials.

Testing for ROS1, ALK, MET, and HER2 rearrangements and amplifications in a large series of biliary tract adenocarcinomas

Biliary tract carcinomas are divided into intrahepatic, perihilar, distal extrahepatic cholangiocarcinomas, and gallbladder adenocarcinomas. Therapies targeting ROS1, ALK, MET, and HER2 alterations are currently evaluated in clinical trials. We assessed ROS1 and ALK translocations/amplifications as well as MET and HER2 amplifications for each tumor subtype by fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC) in 73 intrahepatic, 40 perihilar bile duct, 36 distal extrahepatic cholangiocarcinomas, and 45 gallbladder adenocarcinomas (n = 194). By FISH, we detected targetable alterations in 5.2% of cases (n = 10): HER2 and MET amplifications were found in 4.1% (n = 8) and 1.0% (n = 2), respectively. The HER2-amplified cases were mostly gallbladder adenocarcinomas (n = 5). The MET- and HER2-amplified cases were all positive by IHC. Fourteen cases without MET amplification were positive by IHC, whereas HER2 over-expression was detected by IHC only in HER2-amplified cases. We detected no ALK or ROS1 translocation or amplification. Several alterations were consistent with aneuploidy: 24 cases showed only one copy of ROS1 gene, 4 cases displayed a profile of chromosomal instability, and an over-representation of centromeric alpha-satellite sequences was found in five cases. We confirm a relatively high rate of HER2 amplifications in gallbladder adenocarcinomas and the efficacy of IHC to screen these cases. Our results also suggest the value of IHC to screen MET amplification. Contrary to initial publications, ROS1 rearrangements seem to be very rare in biliary tract adenocarcinomas. We confirm a relatively high frequency of aneuploidy and chromosomal instability and reveal the over-representation of centromeric alpha-satellite sequences in intrahepatic cholangiocarcinomas.

Neuroendocrine Changes in Cholangiocarcinoma Growth

Cholangiocarcinoma (CCA) is a highly aggressive malignancy that emerges from the biliary tree. There are three major classes of CCA-intrahepatic, hilar (perihilar), or distal (extrahepatic)-according to the location of tumor development. Although CCA tumors are mainly derived from biliary epithelia (i.e., cholangiocytes), CCA can be originated from other cells, such as hepatic progenitor cells and hepatocytes. This heterogeneity of CCA may be responsible for poor survival rates of patients, limited effects of chemotherapy and radiotherapy, and the lack of treatment options and novel therapies. Previous studies have identified a number of neuroendocrine mediators, such as hormones, neuropeptides, and neurotransmitters, as well as corresponding receptors. The mediator/receptor signaling pathways play a vital role in cholangiocyte proliferation, as well as CCA progression and metastases. Agonists or antagonists for candidate pathways may lead to the development of novel therapies for CCA patients. However, effects of mediators may differ between healthy or cancerous cholangiocytes, or between different subtypes of receptors. This review summarizes current understandings of neuroendocrine mediators and their functional roles in CCA.