Discovery of Small-Molecule Inhibitors of Ubiquitin Specific Protease 7 (USP7) Using Integrated NMR and in Silico Techniques

USP7
is a deubiquitinase implicated in destabilizing the tumor
suppressor p53, and for this reason it has gained increasing attention
as a potential oncology target for small molecule inhibitors. Herein
we describe the biophysical, biochemical, and computational approaches
that led to the identification of 4-(2-aminopyridin-3-yl)­phenol compounds
described by Kategaya (Nature 2017, 550, 534–538) as specific inhibitors of
USP7. Fragment based lead discovery (FBLD) by NMR combined with virtual
screening and re-mining of biochemical high-throughput screening (HTS)
hits led to the discovery of a series of ligands that bind in the
“palm” region of the catalytic domain of USP7 and inhibit
its catalytic activity. These ligands were then optimized by structure-based
design to yield cell-active molecules with reasonable physical properties.
This discovery process not only involved multiple techniques working
in concert but also illustrated a unique way in which hits from orthogonal
screening approaches complemented each other for lead identification.