Case report: identification of ERC1-RET fusion in a patient with pancreatic ductal adenocarcinoma

Fusion genes in pancreatic tumors

Gene fusions and rearrangements play a crucial role in tumor biology. They are rare events typically detected in KRAS wild-type (WT) pancreatic tumors. Their identification can inform clinical management by enabling precision oncology, as fusions involving BRAF, FGFR2, RET, NTRK, NRG1, and ALK represent actionable targets in KRAS-WT cancers, and serve diagnostic purposes since fusions involving PRKACA/B represent the diagnostic hallmark of intraductal oncocytic papillary neoplasms (IOPNs). Although they are rare, the therapeutic and diagnostic importance of these genomic events should not be underestimated, highlighting the need for quality-ensured molecular diagnostics in the management of cancer. Herein we review the existing literature on the role of fusion genes in pancreatic tumors and their clinical potential as effective biomarkers and therapeutic targets.

RET signaling pathway and RET inhibitors in human cancer

Rearranged during transfection (RET) receptor tyrosine kinase was first identified over thirty years ago as a novel transforming gene. Since its discovery and subsequent pathway characterization, RET alterations have been identified in numerous cancer types and are most prevalent in thyroid carcinomas and non-small cell lung cancer (NSCLC). In other tumor types such as breast cancer and salivary gland carcinomas, RET alterations can be found at lower frequencies. Aberrant RET activity is associated with poor prognosis of thyroid and lung carcinoma patients, and is strongly correlated with increased risk of distant metastases. RET aberrations encompass a variety of genomic or proteomic alterations, most of which confer constitutive activation of RET. Activating RET alterations, such as point mutations or gene fusions, enhance activity of signaling pathways downstream of RET, namely PI3K/AKT, RAS/RAF, MAPK, and PLCγ pathways, to promote cell proliferation, growth, and survival. Given the important role that mutant RET plays in metastatic cancers, significant efforts have been made in developing inhibitors against RET kinase activity. These efforts have led to FDA approval of Selpercatinib and Pralsetinib for NSCLC, as well as, additional selective RET inhibitors in preclinical and clinical testing. This review covers the current biological understanding of RET signaling, the impact of RET hyperactivity on tumor progression in multiple tumor types, and RET inhibitors with promising preclinical and clinical efficacy.

FGFR2-ERC1: A Subtype of FGFR2 Oncogenic Fusion Variant in Lung Adenocarcinoma and the Response to Anlotinib

Background

Fibroblast growth factor receptor (FGFR) fusions in non-small cell lung cancer (NSCLC) are small genomic events. At present, there is no standard treatment strategy for patients with NSCLC carrying an FGFR fusion.

Case Presentation

We report the case of a 45-year-old female patient who was diagnosed with lung adenocarcinoma and underwent right upper lobectomy and postoperative adjuvant chemotherapy. After 13 months, the patient’s lung lesions progressed. Next-generation sequencing of venous blood and lung tissues confirmed an FGFR2-ERC1 fusion, and she received chemotherapy and immunotherapy. Two months later, the patient’s lung lesions progressed again. Based on the target effect of anlotinib on FGFR, the patient was subsequently treated with anlotinib, and the progression-free survival interval exceeded 8.0 months.

Conclusion

These findings showed that patients with lung adenocarcinoma carrying an FGFR2-ERC1 fusion gene may benefit from anlotinib. This case provided evidence to support the use of anlotinib in the treatment of NSCLC patients with FGFR fusion gene subtypes.