PDGFRB and chordoma: Most tumors were positive by immunohistochemistry for PDGFR-α (92%), PDGFR-β (85%), c-Kit (77%), c-Met (96%), pAKT (82%), mTOR (56%), HER2 (24%), and EGFR (26%), yet imatinib, an FDA-approved drug that inhibits PDGFR-α, PDGFR-β, and c-Kit, has shown little to no efficacy in chordoma in vivo models9.