No abstract

Genomic alterations targeting the Epidermal Growth Factor Receptor (EGFR) gene have been strongly associated with cancer pathogenesis. The clinical effectiveness of EGFR targeted therapies, including small molecules directed against the kinase domain such as gefitinib, erlotinib and afatinib, have been proven successful in treating non-small cell lung cancer patients with tumors harboring EGFR kinase domain mutations. Recent large-scale genomic studies in glioblastoma and lung cancer have identified an additional class of oncogenic mutations caused by the intragenic deletion of carboxy-terminal coding regions. Here, we report that combinations of exonic deletions of exon 25 to 28 lead to the oncogenic activation of EGF receptor in the absence of ligand and consequent cellular transformation, indicating a significant role of C-terminal domain in modulating EGFR activation. Furthermore, we show that the oncogenic activity of the resulting C-terminal deletion mutants are efficiently inhibited by EGFR-targeted drugs including erlotinib, afatinib, dacomitinib as well as cetuximab, expanding the therapeutic rationale of cancer genome-based EGFR targeted approaches. Finally, in vivo and in vitro preclinical studies demonstrate that constitutive asymmetric dimerization in mutant EGFR is a key mechanism for oncogenic activation and tumorigenesis by C-terminal deletion mutants. Therefore, our data provide compelling evidence for oncogenic activation of C-terminal deletion mutants at the molecular level and we propose that C-terminal deletion status of EGFR can be considered as a potential genomic marker for EGFR-targeted therapy.

Biliary tract cancers (BTCs) are a group of aggressive malignancies that arise from the bile duct and gallbladder. BTCs include intrahepatic cholangiocarcinoma (IH-CCA), extrahepatic cholangiocarcinoma (EH-CCA), and gallbladder cancer (GBCA). BTCs are highly heterogeneous cancers in terms of anatomical, clinical, and pathological characteristics. Until recently, the treatment of resectable BTC, including surgery, adjuvant chemotherapy, and radiation therapy, has largely been based on institutional practice guidelines and evidence from small retrospective studies. Recently, several large randomized prospective trials have been published, and there are ongoing randomized trials for resectable BTC. In this article, we review prior and recently updated evidence regarding surgery, adjuvant and neoadjuvant chemotherapy, and adjuvant radiation therapy for patients with resectable BTC.