Palbociclib (PD 0332991), a selective inhibitor of CDK4/6, approved for the treatment of hormone-receptor positive breast cancer (43), has been recently tested in in vitro cell-line chordoma models harboring the loss of CDKN2A (41), suggesting a potential in vivo action of anti-CDK4/6 in chordomas harboring this genomic alteration. This evidence concerns the gene CDK4 and chordoma.