CD274 and chordoma: There were no statistically significant differences between clival and sacral chordoma cell lines in expression of HLA-A, B, C (% positivity P = 0.18, MFI P = 0.67), PD-L1 (% positivity P = 0.89, MFI P = 0.89), or EGFR (% positivity P = 0.55, MFI P = 0.77).