EGFR and neoplasm: Previous studies reported that regorafenib targets multiple tumor pathways involved in BTC progression, including epidermal growth factor receptor (EGFR), rat sarcoma (RAS), rapidly accelerated fibrosarcoma (RAF), vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), and platelet-derived growth factor receptor (PDGFR) signaling pathways (7–10).