INSR and chordoma: Indeed, a series of tyrosine kinase inhibitors (TKIs) have been used in the pre-clinical trials of chordoma (12), including the inhibitors against the epidermal growth factor receptor (EGFR) like afatinib, erlotinib, and lapatinib (13), the inhibitors against tyrosine-protein kinase Met (c-MET) like crizotinib, the inhibitors against Platelet-derived growth factor receptor (PDGFR) such as imatinib (14), and the inhibitors of the type I IGF receptor/insulin receptor (IGF1R/INSR) inhibitor linsitinib together with erlotinib (15).