Publications by authors named "Thomas J Kornecook"

6 Publications

  • Page 1 of 1

Engineering Na1.7 Inhibitory JzTx-V Peptides with a Potency and Basicity Profile Suitable for Antibody Conjugation To Enhance Pharmacokinetics.

ACS Chem Biol 2019 04 27;14(4):806-818. Epub 2019 Mar 27.

Drug discovery research on new pain targets with human genetic validation, including the voltage-gated sodium channel Na1.7, is being pursued to address the unmet medical need with respect to chronic pain and the rising opioid epidemic. As part of early research efforts on this front, we have previously developed Na1.7 inhibitory peptide-antibody conjugates with tarantula venom-derived GpTx-1 toxin peptides with an extended half-life (80 h) in rodents but only moderate in vitro activity (hNa1.7 IC = 250 nM) and without in vivo activity. We identified the more potent peptide JzTx-V from our natural peptide collection and improved its selectivity against other sodium channel isoforms through positional analogueing. Here we report utilization of the JzTx-V scaffold in a peptide-antibody conjugate and architectural variations in the linker, peptide loading, and antibody attachment site. We found conjugates with 100-fold improved in vitro potency relative to those of complementary GpTx-1 analogues, but pharmacokinetic and bioimaging analyses of these JzTx-V conjugates revealed a shorter than expected plasma half-life in vivo with accumulation in the liver. In an attempt to increase circulatory serum levels, we sought the reduction of the net +6 charge of the JzTx-V scaffold while retaining a desirable Na in vitro activity profile. The conjugate of a JzTx-V peptide analogue with a +2 formal charge maintained Na1.7 potency with 18-fold improved plasma exposure in rodents. Balancing the loss of peptide and conjugate potency associated with the reduction of net charge necessary for improved target exposure resulted in a compound with moderate activity in a Na1.7-dependent pharmacodynamic model but requires further optimization to identify a conjugate that can fully engage Na1.7 in vivo.
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http://dx.doi.org/10.1021/acschembio.9b00183DOI Listing
April 2019

Discovery of Tarantula Venom-Derived Na1.7-Inhibitory JzTx-V Peptide 5-Br-Trp24 Analogue AM-6120 with Systemic Block of Histamine-Induced Pruritis.

J Med Chem 2018 11 22;61(21):9500-9512. Epub 2018 Oct 22.

Therapeutic Discovery, Amgen Research , Amgen Inc. , 1120 Veterans Blvd , South San Francisco , California 94080 , United States.

Inhibitors of the voltage-gated sodium channel Na1.7 are being investigated as pain therapeutics due to compelling human genetics. We previously identified Na1.7-inhibitory peptides GpTx-1 and JzTx-V from tarantula venom screens. Potency and selectivity were modulated through attribute-based positional scans of native residues via chemical synthesis. Herein, we report JzTx-V lead optimization to identify a pharmacodynamically active peptide variant. Molecular docking of peptide ensembles from NMR into a homology model-derived Na1.7 structure supported prioritization of key residues clustered on a hydrophobic face of the disulfide-rich folded peptide for derivatization. Replacing Trp24 with 5-Br-Trp24 identified lead peptides with activity in electrophysiology assays in engineered and neuronal cells. 5-Br-Trp24 containing peptide AM-6120 was characterized in X-ray crystallography and pharmacokinetic studies and blocked histamine-induced pruritis in mice after subcutaneous administration, demonstrating systemic Na1.7-dependent pharmacodynamics. Our data suggests a need for high target coverage based on plasma exposure for impacting in vivo end points with selectivity-optimized peptidic Na1.7 inhibitors.
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http://dx.doi.org/10.1021/acs.jmedchem.8b00736DOI Listing
November 2018

The discovery of benzoxazine sulfonamide inhibitors of Na1.7: Tools that bridge efficacy and target engagement.

Bioorg Med Chem Lett 2017 08 1;27(15):3477-3485. Epub 2017 Jun 1.

Department of Medicinal Chemistry, Amgen Inc., 360 Binney Street, Cambridge, MA 02142, United States.

The voltage-gated sodium channel Na1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of Na1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat Na1.7 versus human Na1.7 was observed, rendering in vivo rat pharmacology studies challenging. Herein, we report the discovery and optimization of novel benzoxazine sulfonamide inhibitors of human, rat and mouse Na1.7 which enabled pharmacological assessment in traditional behavioral rodent models of pain and in turn, established a connection between formalin-induced pain and histamine-induced pruritus in mice. The latter represents a simple and efficient means of measuring target engagement.
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http://dx.doi.org/10.1016/j.bmcl.2017.05.070DOI Listing
August 2017

Pharmacologic Characterization of AMG8379, a Potent and Selective Small Molecule Sulfonamide Antagonist of the Voltage-Gated Sodium Channel Na1.7.

J Pharmacol Exp Ther 2017 07 4;362(1):146-160. Epub 2017 May 4.

Department of Neuroscience (T.J.K., R.Y., S.A, C.P.I., M.J., D.J., J.H.L., S.G.L., J.Li., D.L., J.Lu., D.M., D.O., K.T., J.W., V.Y., D.X.D.Z., R.T.F., B.D.M.), Department of Medicinal Chemistry (M.M.W.), and Department of Pharmacokinetics and Drug Metabolism (X.B., V.B., J.R.), Amgen Inc., Cambridge, Massachusetts and Thousand Oaks, California

Potent and selective antagonists of the voltage-gated sodium channel Na1.7 represent a promising avenue for the development of new chronic pain therapies. We generated a small molecule atropisomer quinolone sulfonamide antagonist AMG8379 and a less active enantiomer AMG8380. Here we show that AMG8379 potently blocks human Na1.7 channels with an IC of 8.5 nM and endogenous tetrodotoxin (TTX)-sensitive sodium channels in dorsal root ganglion (DRG) neurons with an IC of 3.1 nM in whole-cell patch clamp electrophysiology assays using a voltage protocol that interrogates channels in a partially inactivated state. AMG8379 was 100- to 1000-fold selective over other Na family members, including Na1.4 expressed in muscle and Na1.5 expressed in the heart, as well as TTX-resistant Na channels in DRG neurons. Using an ex vivo mouse skin-nerve preparation, AMG8379 blocked mechanically induced action potential firing in C-fibers in both a time-dependent and dose-dependent manner. AMG8379 similarly reduced the frequency of thermally induced C-fiber spiking, whereas AMG8380 affected neither mechanical nor thermal responses. In vivo target engagement of AMG8379 in mice was evaluated in multiple Na1.7-dependent behavioral endpoints. AMG8379 dose-dependently inhibited intradermal histamine-induced scratching and intraplantar capsaicin-induced licking, and reversed UVB radiation skin burn-induced thermal hyperalgesia; notably, behavioral effects were not observed with AMG8380 at similar plasma exposure levels. AMG8379 is a potent and selective Na1.7 inhibitor that blocks sodium current in heterologous cells as well as DRG neurons, inhibits action potential firing in peripheral nerve fibers, and exhibits pharmacodynamic effects in translatable models of both itch and pain.
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http://dx.doi.org/10.1124/jpet.116.239590DOI Listing
July 2017

MK-7128, a novel CB1 receptor inverse agonist, improves scopolamine-induced learning and memory deficits in mice.

Behav Pharmacol 2011 Apr;22(2):91-100

Neuroscience Drug Discovery, Merck Research Laboratories, Boston, MA 02115, USA.

Cannabinoid receptors (CBRs) play an important role in a variety of physiological functions and have been considered drug targets for obesity and psychiatric disorders. In particular, the CB1R is highly expressed in brain regions crucial to learning and memory processes, and several lines of evidence indicate that pharmacological blockade of this receptor could have therapeutic applications in the treatment of cognitive disorders. In this study, we investigated whether MK-7128 (0.1, 0.3, and 1 mg/kg, orally), a novel and selective CB1R inverse agonist, could improve learning and memory deficits induced by scopolamine (1 mg/kg, subcutaneously) in mice. The investigators also assessed CB1R occupancy in the brain to ensure target engagement of MK-7128, and showed that MK-7128 significantly improved both Y-maze spontaneous alternation and object habituation performance in scopolamine-treated mice and inhibits the binding of radioiodinated AM251 in murine cortex and hippocampus. These data indicate that MK-7128 improves cognitive performance in a model of cholinergic hypofunction and suggest that efficacy is achieved at relatively low levels of CB1R occupancy in the brain. Our results extend earlier findings suggesting a role of CB1Rs in the modulation of memory processes and a potential therapeutic application for CB1R inverse agonists in cognitive disorders.
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http://dx.doi.org/10.1097/FBP.0b013e3283423d7eDOI Listing
April 2011

Prefrontal cortex lesions and scopolamine impair attention performance of C57BL/6 mice in a novel 2-choice visual discrimination task.

Behav Brain Res 2009 Dec 4;204(1):67-76. Epub 2009 May 4.

Merck Research Laboratories, CNS Pharmacology, 33 Avenue Louis Pasteur, Boston, MA 02115, USA.

Sustained attention is defined as the ability or capacity to remain focused on the occurrence of rare events over long periods of time. We describe here the development of a novel, operant-based attention task that can be learned by mice in 8-10 days. Mice were trained on a 2-choice visual discrimination task in an operant chamber, wherein the correct response on any given trial was a lever-press cued by a stimulus light. Upon reaching a criterion of greater than 80% correct responses, all subjects were tested in a mixed-trial attention paradigm combining four different stimulus durations within a single session (0.5, 1, 2, or 10 s). During attention testing, the percentage of correct responses decreased as a function of stimulus duration, indicating a performance decrement which parallels increasing attentional demand within the task. Pretreatment with the muscarinic-receptor antagonist scopolamine yielded a reliable, dose-dependent performance deficit whereas nicotine treatment improved the percentage of correct responses during trials with the greatest attentional demand. Moreover, medial prefrontal cortex lesions impaired attention performance without affecting acquisition or retention of the discrimination rule. These results underscore the utility of this task as a novel means of assessing attentional processes in mice in a relatively high-throughput manner.
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http://dx.doi.org/10.1016/j.bbr.2009.04.036DOI Listing
December 2009