8 research outputs found
Localization and Quantification of Drugs in Animal Tissues by Use of Desorption Electrospray Ionization Mass Spectrometry Imaging
Mass spectrometric imaging (MSI) has emerged as a powerful
technique
to obtain spatial arrangement of individual molecular ions in animal
tissues. Ambient desorption electrospray ionization (DESI) technique
is uniquely suited for such imaging experiments, as it can be performed
on animal tissues in their native environment without prior treatments.
Although MSI has become a rapid growing technique for localization
of proteins, lipids, drugs, and endogenous compounds in different
tissues, quantification of imaged targets has not been explored extensively.
Here we present a novel MSI approach for localization and quantification
of drugs in animal thin tissue sections. DESI-MSI using an Orbitrap
mass analyzer in full scan mode was performed on 6 ÎĽm coronal
brain sections from rats that were administered 2.5 mg/kg clozapine.
Clozapine was localized and quantified in individual brain sections
45 min postdose. External calibration curves were prepared by micropipetting
standards with internal standard (IS) on top of the tissues, and average
response factors were calculated for the scans in which both clozapine
and IS were detected. All response factors were normalized to area
units. Quantifications from DESI-MSI revealed 0.2–1.2 ng of
clozapine in individual brain sections, results that were further
confirmed by extraction and liquid chromatography/tandem mass spectrometry
(LC/MS/MS) analysis
Optimization of a Novel Quinazolinone-Based Series of Transient Receptor Potential A1 (TRPA1) Antagonists Demonstrating Potent in Vivo Activity
There has been significant
interest in developing a transient receptor
potential A1 (TRPA1) antagonist for the treatment of pain due to a
wealth of data implicating its role in pain pathways. Despite this,
identification of a potent small molecule tool possessing pharmacokinetic
properties allowing for robust in vivo target coverage has been challenging.
Here we describe the optimization of a potent, selective series of
quinazolinone-based TRPA1 antagonists. High-throughput screening identified <b>4</b>, which possessed promising potency and selectivity. A strategy
focused on optimizing potency while increasing polarity in order to
improve intrinisic clearance culminated with the discovery of purinone <b>27</b> (AM-0902), which is a potent, selective antagonist of TRPA1
with pharmacokinetic properties allowing for >30-fold coverage
of
the rat TRPA1 IC<sub>50</sub> in vivo. Compound <b>27</b> demonstrated
dose-dependent inhibition of AITC-induced flinching in rats, validating
its utility as a tool for interrogating the role of TRPA1 in in vivo
pain models
Discovery of Novel, Induced-Pocket Binding Oxazolidinones as Potent, Selective, and Orally Bioavailable Tankyrase Inhibitors
Tankyrase
(TNKS) is a poly-ADP-ribosylating protein (PARP) whose
activity suppresses cellular axin protein levels and elevates β-catenin
concentrations, resulting in increased oncogene expression. The inhibition
of tankyrase (TNKS1 and 2) may reduce the levels of β-catenin-mediated
transcription and inhibit tumorigenesis. Compound <b>1</b> is
a previously described moderately potent tankyrase inhibitor that
suffers from poor pharmacokinetic properties. Herein, we describe
the utilization of structure-based design and molecular modeling toward
novel, potent, and selective tankyrase inhibitors with improved pharmacokinetic
properties (<b>39</b>, <b>40</b>)
The Discovery and Optimization of a Novel Class of Potent, Selective, and Orally Bioavailable Anaplastic Lymphoma Kinase (ALK) Inhibitors with Potential Utility for the Treatment of Cancer
A class of 2-acyliminobenzimidazoles has been developed
as potent and selective inhibitors of anaplastic lymphoma kinase (ALK).
Structure based design facilitated the rapid development of structure–activity
relationships (SAR) and the optimization of kinase selectivity. Introduction
of an optimally placed polar substituent was key to solving issues
of metabolic stability and led to the development of potent, selective,
orally bioavailable ALK inhibitors. Compound <b>49</b> achieved
substantial tumor regression in an NPM-ALK driven murine tumor xenograft
model when dosed qd. Compounds <b>36</b> and <b>49</b> show favorable potency and PK characteristics in preclinical species
indicative of suitability for further development
The Discovery and Hit-to-Lead Optimization of Tricyclic Sulfonamides as Potent and Efficacious Potentiators of Glycine Receptors
Current pain therapeutics suffer
from undesirable psychotropic
and sedative side effects, as well as abuse potential. Glycine receptors
(GlyRs) are inhibitory ligand-gated ion channels expressed in nerves
of the spinal dorsal horn, where their activation is believed to reduce
transmission of painful stimuli. Herein, we describe the identification
and hit-to-lead optimization of a novel class of tricyclic sulfonamides
as allosteric GlyR potentiators. Initial optimization of high-throughput
screening (HTS) hit <b>1</b> led to the identification of <b>3</b>, which demonstrated ex vivo potentiation of glycine-activated
current in mouse dorsal horn neurons from spinal cord slices. Further
improvement of potency and pharmacokinetics produced in vivo proof-of-concept
tool molecule <b>20</b> (AM-1488), which reversed tactile allodynia
in a mouse spared-nerve injury (SNI) model. Additional structural
optimization provided highly potent potentiator <b>32</b> (AM-3607),
which was cocrystallized with human GlyRα3<sub>cryst</sub> to
afford the first described potentiator-bound X-ray cocrystal structure
within this class of ligand-gated ion channels (LGICs)
Discovery of Potent and Selective 8‑Fluorotriazolopyridine c‑Met Inhibitors
The overexpression of c-Met and/or
hepatocyte growth factor (HGF),
the amplification of the MET gene, and mutations in the c-Met kinase
domain can activate signaling pathways that contribute to cancer progression
by enabling tumor cell proliferation, survival, invasion, and metastasis.
Herein, we report the discovery of 8-fluorotriazolopyridines as inhibitors
of c-Met activity. Optimization of the 8-fluorotriazolopyridine scaffold
through the combination of structure-based drug design, SAR studies,
and metabolite identification provided potent (cellular IC<sub>50</sub> < 10 nM), selective inhibitors of c-Met with desirable pharmacokinetic
properties that demonstrate potent inhibition of HGF-mediated c-Met
phosphorylation in a mouse liver pharmacodynamic model
Discovery of (<i>R</i>)‑6-(1-(8-Fluoro-6-(1-methyl‑1<i>H</i>‑pyrazol-4-yl)-[1,2,4]triazolo[4,3‑<i>a</i>]pyridin-3-yl)ethyl)-3-(2-methoxyethoxy)-1,6-naphthyridin-5(6<i>H</i>)‑one (AMG 337), a Potent and Selective Inhibitor of MET with High Unbound Target Coverage and Robust In Vivo Antitumor Activity
Deregulation
of the receptor tyrosine kinase mesenchymal epithelial
transition factor (MET) has been implicated in several human cancers
and is an attractive target for small molecule drug discovery. Herein,
we report the discovery of compound <b>23</b> (AMG 337), which
demonstrates nanomolar inhibition of MET kinase activity, desirable
preclinical pharmacokinetics, significant inhibition of MET phosphorylation
in mice, and robust tumor growth inhibition in a MET-dependent mouse
efficacy model
Development of Novel Dual Binders as Potent, Selective, and Orally Bioavailable Tankyrase Inhibitors
Tankyrases
(TNKS1 and TNKS2) are proteins in the poly ADP-ribose polymerase (PARP)
family. They have been shown to directly bind to axin proteins, which
negatively regulate the Wnt pathway by promoting β-catenin degradation.
Inhibition of tankyrases may offer a novel approach to the treatment
of <i>APC</i>-mutant colorectal cancer. Hit compound <b>8</b> was identified as an inhibitor of tankyrases through a combination
of substructure searching of the Amgen compound collection based on
a minimal binding pharmacophore hypothesis and high-throughput screening.
Herein we report the structure- and property-based optimization of
compound <b>8</b> leading to the identification of more potent
and selective tankyrase inhibitors <b>22</b> and <b>49</b> with improved pharmacokinetic properties in rodents, which are well
suited as tool compounds for further in vivo validation studies