Milademetan is a potent and selective MDM2 inhibitor. MDM2 inhibitor DS-3032b binds to and prevents the binding of MDM2 protein to the transcriptional activation domain of the tumor suppressor protein p53 upon oral administration. By preventing this MDM2-p53 interaction, the proteosome-mediated enzymatic degradation of p53 is inhibited and the transcriptional activity of p53 is restored. This results in the restoration of p53 signaling and leads to the p53-mediated induction of tumor cell apoptosis.