3 research outputs found
Optimization of Fused Bicyclic Allosteric SHP2 Inhibitors
SHP2 is a nonreceptor protein tyrosine phosphatase within the mitogen-activated protein kinase (MAPK) pathway controlling cell growth, differentiation, and oncogenic transformation. SHP2 also participates in the programed cell death pathway (PD-1/PD-L1) governing immune surveillance. Small-molecule inhibition of SHP2 has been widely investigated, including in our previous reports describing SHP099 (2), which binds to a tunnel-like allosteric binding site. To broaden our approach to allosteric inhibition of SHP2, we conducted additional hit finding, evaluation, and structure-based scaffold morphing. These studies, reported here in the first of two papers, led to the identification of multiple 5,6-fused bicyclic scaffolds that bind to the same allosteric tunnel as 2. We demonstrate the structural diversity permitted by the tunnel pharmacophore and culminated in the identification of pyrazolopyrimidinones (e.g., SHP389, 1) that modulate MAPK signaling in vivo. These studies also served as the basis for further scaffold morphing and optimization, detailed in the following manuscript
6-Amino-3-methylpyrimidinones as Potent, Selective, and Orally Efficacious SHP2 Inhibitors
Protein tyrosine phosphatase SHP2 is an oncoprotein associated with cancer as well as a potential immune modulator because of its role in the programmed cell death PD-L1/PD-1 pathway. In the preceding manuscript, we described the optimization of a fused, bicyclic screening hit for potency, selectivity, and physicochemical properties in order to further expand the chemical diversity of allosteric SHP2 inhibitors. In this manuscript, we describe the further expansion of our approach, morphing the fused, bicyclic system into a novel monocyclic pyrimidinone scaffold through our understanding of SAR and use of structure-based design. These studies led to the identification of SHP394 (1), an orally efficacious inhibitor of SHP2, with high lipophilic efficiency, improved potency, and enhanced pharmacokinetic properties. We also report other pyrimidinone analogues with favorable pharmacokinetic and potency profiles. Overall, this work improves upon our previously described allosteric inhibitors and exemplifies and extends the range of permissible chemical templates that inhibit SHP2 via the allosteric mechanism
Dual Allosteric Inhibition of SHP2 Phosphatase
SHP2 is a cytoplasmic protein tyrosine
phosphatase encoded by the <i>PTPN11</i> gene and is involved
in cell proliferation, differentiation, and survival. Recently, we
reported an allosteric mechanism of inhibition that stabilizes the
auto-inhibited conformation of SHP2. SHP099 (<b>1</b>) was identified
and characterized as a moderately potent, orally bioavailable, allosteric
small molecule inhibitor, which binds to a tunnel-like pocket formed
by the confluence of three domains of SHP2. In this report, we describe
further screening strategies that enabled the identification of a
second, distinct small molecule allosteric site. SHP244 (<b>2</b>) was identified as a weak inhibitor of SHP2 with modest thermal
stabilization of the enzyme. X-ray crystallography revealed that <b>2</b> binds and stabilizes the inactive, closed conformation of
SHP2, at a distinct, previously unexplored binding siteî—¸a cleft
formed at the interface of the <i>N</i>-terminal SH2 and
PTP domains. Derivatization of <b>2</b> using structure-based
design resulted in an increase in SHP2 thermal stabilization, biochemical
inhibition, and subsequent MAPK pathway modulation. Downregulation
of DUSP6 mRNA, a downstream MAPK pathway marker, was observed in KYSE-520
cancer cells. Remarkably, simultaneous occupation of both allosteric
sites by <b>1</b> and <b>2</b> was possible, as characterized
by cooperative biochemical inhibition experiments and X-ray crystallography.
Combining an allosteric site 1 inhibitor with an allosteric site 2
inhibitor led to enhanced pharmacological pathway inhibition in cells.
This work illustrates a rare example of dual allosteric targeted protein
inhibition, demonstrates screening methodology and tactics to identify
allosteric inhibitors, and enables further interrogation of SHP2 in
cancer and related pathologies