8 research outputs found
Antibiotic Optimization and Chemical Structure Stabilization of Thiomuracin A
Synthetic studies of the antimicrobial secondary metabolite
thiomuracin
A (<b>1</b>) were initiated to improve chemical stability and
physicochemical properties. Functional group modifications of <b>1</b> included removing the C2–C7 side chain, derivatizing
the C84 epoxide region, and altering the C44 hydroxyphenylalanine
motif. The resulting derivatives simplified and stabilized the chemical
structure and were evaluated for antibacterial activity relative to <b>1</b>. The simplified structure and improved organic solubility
of the derivatives facilitated isolation yields from fermentation
broths and simplified the procedures involved for the process. These
advancements increased material supply for continued medicinal chemistry
optimization and culminated in the identification of <b>2</b>, a structurally simplified and chemically stable analogue of <b>1</b> which retained potent antibiotic activity
Antibacterial and Solubility Optimization of Thiomuracin A
Synthetic
studies of the antimicrobial secondary metabolite thiomuracin
A (<b>1</b>) provided access to analogues in the Northern region
(C2–C10). Selective hydrolysis of the C10 amide of lead compound <b>2</b> and subsequent derivatization led to novel carbon- and nitrogen-linked
analogues (e.g., <b>3</b>) which improved antibacterial potency
across a panel of Gram-positive organisms. In addition, congeners
with improved physicochemical properties were identified which proved
efficacious in murine sepsis and hamster <i>C. difficile</i> models of disease. Optimal efficacy in the hamster model of <i>C. difficile</i> was achieved with compounds that possessed
both potent antibacterial activity and high aqueous solubility
Discovery of Darovasertib (NVP-LXS196), a Pan-PKC Inhibitor for the Treatment of Metastatic Uveal Melanoma
Uveal
melanoma (UM) is the most common primary intraocular malignancy
in the adult eye. Despite the aggressive local management of primary
UM, the development of metastases is common with no effective treatment
options for metastatic disease. Genetic analysis of UM samples reveals
the presence of mutually exclusive activating mutations in the Gq
alpha subunits GNAQ and GNA11. One of the key downstream targets of
the constitutively active Gq alpha subunits is the protein kinase
C (PKC) signaling pathway. Herein, we describe the discovery of darovasertib
(NVP-LXS196), a potent pan-PKC inhibitor with high whole kinome selectivity.
The lead series was optimized for kinase and off target selectivity
to afford a compound that is rapidly absorbed and well tolerated in
preclinical species. LXS196 is being investigated in the clinic as
a monotherapy and in combination with other agents for the treatment
of uveal melanoma (UM), including primary UM and metastatic uveal
melanoma (MUM)
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
Discovery of Darovasertib (NVP-LXS196), a Pan-PKC Inhibitor for the Treatment of Metastatic Uveal Melanoma
Uveal
melanoma (UM) is the most common primary intraocular malignancy
in the adult eye. Despite the aggressive local management of primary
UM, the development of metastases is common with no effective treatment
options for metastatic disease. Genetic analysis of UM samples reveals
the presence of mutually exclusive activating mutations in the Gq
alpha subunits GNAQ and GNA11. One of the key downstream targets of
the constitutively active Gq alpha subunits is the protein kinase
C (PKC) signaling pathway. Herein, we describe the discovery of darovasertib
(NVP-LXS196), a potent pan-PKC inhibitor with high whole kinome selectivity.
The lead series was optimized for kinase and off target selectivity
to afford a compound that is rapidly absorbed and well tolerated in
preclinical species. LXS196 is being investigated in the clinic as
a monotherapy and in combination with other agents for the treatment
of uveal melanoma (UM), including primary UM and metastatic uveal
melanoma (MUM)
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
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)Âpyrazin-2-amine
(SHP099, <b>1</b>), a potent, selective, orally bioavailable,
and efficacious SHP2 inhibitor