Polypharmacology of epacadostat: a potent and selective inhibitor of the tumor associated carbonic anhydrases IX and XII.

Epacadostat (EPA), a selective indoleamine-2,3-dioxygenase 1 (IDO1) inhibitor, has been investigated in vitro as a human (h) Carbonic Anhydrase Inhibitor (CAI). The kinetic data clearly show, for the first time, EPA to be a highly effective and selective inhibitor for the tumor-associated isoforms hCA IX/XII. We report the high resolution X-ray crystal structure of the EPA-hCA II adduct, and assessed its binding mode to CA IX/XII by means of computational techniques. EPA may exert antitumor effects also due to the potent inhibition of the tumor-associated CAs.