4 research outputs found
Structure–Efficiency Relationship of [1,2,4]Triazol-3-ylamines as Novel Nicotinamide Isosteres that Inhibit Tankyrases
Tankyrases 1 and 2 are members of
the poly(ADP-ribose) polymerase
(PARP) family of enzymes that modulate Wnt pathway signaling. While
amide- and lactam-based nicotinamide mimetics that inhibit tankyrase
activity, such as XAV939, are well-known, herein we report the discovery
and evaluation of a novel nicotinamide isostere that demonstrates
selectivity over other PARP family members. We demonstrate the utilization
of lipophilic efficiency-based structure–efficiency relationships
(SER) to rapidly drive the evaluation of this series. These efforts
led to a series of selective, cell-active compounds with solubility,
physicochemical, and in vitro properties suitable for further optimization
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 sitea 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
Identification of NVP-TNKS656: The Use of Structure–Efficiency Relationships To Generate a Highly Potent, Selective, and Orally Active Tankyrase Inhibitor
Tankyrase
1 and 2 have been shown to be redundant, druggable nodes
in the Wnt pathway. As such, there has been intense interest in developing
agents suitable for modulating the Wnt pathway in vivo by targeting
this enzyme pair. By utilizing a combination of structure-based design
and LipE-based structure efficiency relationships, the core of XAV939
was optimized into a more stable, more efficient, but less potent
dihydropyran motif <b>7</b>. This core was combined with elements
of screening hits <b>2</b>, <b>19</b>, and <b>33</b> and resulted in highly potent, selective tankyrase inhibitors that
are novel three pocket binders. NVP-TNKS656 (<b>43</b>) was
identified as an orally active antagonist of Wnt pathway activity
in the MMTV-Wnt1 mouse xenograft model. With an enthalpy-driven thermodynamic
signature of binding, highly favorable physicochemical properties,
and high lipophilic efficiency, NVP-TNKS656 is a novel tankyrase inhibitor
that is well suited for further in vivo validation studies
Allosteric Inhibition of SHP2: Identification of a Potent, Selective, and Orally Efficacious Phosphatase Inhibitor
SHP2
is a nonreceptor protein tyrosine phosphatase (PTP) encoded by the <i>PTPN11</i> gene involved in cell growth and differentiation
via the MAPK signaling pathway. SHP2 also purportedly plays an important
role in the programmed cell death pathway (PD-1/PD-L1). Because it
is an oncoprotein associated with multiple cancer-related diseases,
as well as a potential immunomodulator, controlling SHP2 activity
is of significant therapeutic interest. Recently in our laboratories,
a small molecule inhibitor of SHP2 was identified as an allosteric
modulator that stabilizes the autoinhibited conformation of SHP2.
A high throughput screen was performed to identify progressable chemical
matter, and X-ray crystallography revealed the location of binding
in a previously undisclosed allosteric binding pocket. Structure-based
drug design was employed to optimize for SHP2 inhibition, and several
new protein–ligand interactions were characterized. These studies
culminated in the discovery of 6-(4-amino-4-methylpiperidin-1-yl)-3-(2,3-dichlorophenyl)pyrazin-2-amine
(SHP099, <b>1</b>), a potent, selective, orally bioavailable,
and efficacious SHP2 inhibitor