Gene expression analysis of patient-derived melanoma biopsies after 14 days of domatinostat treatment (ongoing phase I/II trial NCT03278665) demonstrated increased expression of IFNG, the 10-gene IFN-γ signature, the pembrolizumab response signature, and APM/MHC genes and increased immune cytolytic activity scores in individual samples compared with baseline. This evidence concerns the gene ANPEP and melanoma.