GNE-6776 non-covalently targets USP7 12 Å distant from the catalytic cysteine. GNE-6776 attenuates ubiquitin binding and thus inhibits USP7 deubiquitinase activity. GNE-6776 interacts with acidic residues that mediate hydrogen-bond interactions with the ubiquitin Lys48 side chain. GNE-6776 targets cellular USP7, MDM2, and p53 signalling pathways.GNE-6776 selectively inhibits recombinant USP7 relative to 36 other deubiquitinases. GNE-6776 remains selective even at 100 μM, a more than sixfold higher concentration than used in cellular assays. GNE-6776 significantly inhibits USP7 while remaining selective against 44-47 other detected deubiquitinases.