An inhibitor of USP7 (IC50 = 424 nM); dose-dependently inhibits USP7-mediated p53 deubiquitination in a cell-free assay (IC50 = ~0.8 μM) and in vitro; selective for USP7 over a panel of proteases including aspartic, serine, and metalloproteases (IC50s = >10 μM), several cysteine proteases (IC50s = >1 and >10 μM), and the deubiquitinating enzymes UCH-L1 (IC50 = >1 μM) and SENP1 (IC50 = >10 μM; increases p53 levels; inhibits proliferation of HCT116 cells (IC50 = ~1 μM); induces apoptosis in HCT116 cells