Inhibitor of ubiquitin-specific protease (USP) 7 activity (IC50 = 424 nM). Displays uncompetitive inhibition. Also inhibits USP7-mediated p53 deubiquitination (IC50 = 0.8 μM). Stabilizes p53 and inhibits cancer cell growth; induces p53-dependent apoptosis in p53 wild type and null isogenic cancer cell lines.