HDAC9 and melanoma: Same results were reported with the use of class I HDAC inhibitors on melanoma cell lines, inducing a rapid upregulation of histone acetylation of the PD-L1 gene, an enhanced expression of PD-L1, and an increased tumor control in combination with PD-1 blockade in a murine model, highlighting the high potential of epidrugs to sensitize patients to ICI.