Discovery of Selective Pituitary Adenylate Cyclase 1 Receptor (PAC1R) Antagonist Peptides Potent in a Maxadilan/PACAP38-Induced Increase in Blood Flow Pharmacodynamic Model.

Inhibition of the pituitary adenylate cyclase 1 receptor (PAC1R) is a novel mechanism that could be used for abortive treatment of acute migraine. Our research began with comparative analysis of known PAC1R ligand scaffolds, PACAP38 and Maxadilan, which resulted in the selection of des(24-42) Maxadilan, , as a starting point. C-terminal modifications of improved the peptide metabolic stability and .

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

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.

Discovery of ( R)-8-(6-Methyl-4-oxo-1,4,5,6-tetrahydropyrrolo[3,4- b]pyrrol-2-yl)-3-(1-methylcyclopropyl)-2-((1-methylcyclopropyl)amino)quinazolin-4(3 H)-one, a Potent and Selective Pim-1/2 Kinase Inhibitor for Hematological Malignancies.

Pim kinases are a family of constitutively active serine/threonine kinases that are partially redundant and regulate multiple pathways important for cell growth and survival. In human disease, high expression of the three Pim isoforms has been implicated in the progression of hematopoietic and solid tumor cancers, which suggests that Pim kinase inhibitors could provide patients with therapeutic benefit. Herein, we describe the structure-guided optimization of a series of quinazolinone-pyrrolodihydropyrrolone analogs leading to the identification of potent pan-Pim inhibitor 28 with improved potency, solubility, and drug-like properties.

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

Inhibitors of the voltage-gated sodium channel Na1.7 are being investigated as pain therapeutics due to compelling human genetics. We previously identified Na1.

Applications of parallel synthetic lead hopping and pharmacophore-based virtual screening in the discovery of efficient glycine receptor potentiators.

Glycine receptors (GlyRs) are pentameric glycine-gated chloride ion channels that are enriched in the brainstem and spinal cord where they have been demonstrated to play a role in central nervous system (CNS) inhibition. Herein we describe two novel classes of glycine receptor potentiators that have been developed using similarity- and property-guided scaffold hopping enabled by parallel synthesis and pharmacophore-based virtual screening strategies. This effort resulted in the identification of novel, efficient and modular leads having favorable in vitro ADME profiles and high CNS multi-parameter optimization (MPO) scores, exemplified by azetidine sulfonamide 19 and aminothiazole sulfone (ent2)-20.

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.

Discovery of imidazopyridazines as potent Pim-1/2 kinase inhibitors.

High levels of Pim expression have been implicated in several hematopoietic and solid tumor cancers, suggesting that inhibition of Pim signaling could provide patients with therapeutic benefit. Herein, we describe our progress towards this goal using a screening hit (rac-1) as a starting point. Modification of the indazole ring resulted in the discovery of a series of imidazopyridazine-based Pim inhibitors exemplified by compound 22m, which was found to be a subnanomolar inhibitor of the Pim-1 and Pim-2 isoforms (IC values of 0.

Discovery and Optimization of Quinazolinone-pyrrolopyrrolones as Potent and Orally Bioavailable Pan-Pim Kinase Inhibitors.

The high expression of proviral insertion site of Moloney murine leukemia virus kinases (Pim-1, -2, and -3) in cancers, particularly the hematopoietic malignancies, is believed to play a role in promoting cell survival and proliferation while suppressing apoptosis. The three isoforms of Pim protein appear largely redundant in their oncogenic functions. Thus, a pan-Pim kinase inhibitor is highly desirable.

Discovery and Optimization of Macrocyclic Quinoxaline-pyrrolo-dihydropiperidinones as Potent Pim-1/2 Kinase Inhibitors.

The identification of Pim-1/2 kinase overexpression in B-cell malignancies suggests that Pim kinase inhibitors will have utility in the treatment of lymphoma, leukemia, and multiple myeloma. Starting from a moderately potent quinoxaline-dihydropyrrolopiperidinone lead, we recognized the potential for macrocyclization and developed a series of 13-membered macrocycles. The structure-activity relationships of the macrocyclic linker were systematically explored, leading to the identification of 9c as a potent, subnanomolar inhibitor of Pim-1 and -2.

Single Residue Substitutions That Confer Voltage-Gated Sodium Ion Channel Subtype Selectivity in the NaV1.7 Inhibitory Peptide GpTx-1.

There is interest in the identification and optimization of new molecular entities selectively targeting ion channels of therapeutic relevance. Peptide toxins represent a rich source of pharmacology for ion channels, and we recently reported GpTx-1 analogs that inhibit NaV1.7, a voltage-gated sodium ion channel that is a compelling target for improved treatment of pain.

Discovery and Structure-Guided Optimization of Diarylmethanesulfonamide Disrupters of Glucokinase-Glucokinase Regulatory Protein (GK-GKRP) Binding: Strategic Use of a N → S (nN → σ*S-X) Interaction for Conformational Constraint.

The HTS-based discovery and structure-guided optimization of a novel series of GKRP-selective GK-GKRP disrupters are revealed. Diarylmethanesulfonamide hit 6 (hGK-hGKRP IC50 = 1.2 μM) was optimized to lead compound 32 (AMG-0696; hGK-hGKRP IC50 = 0.

Oxopyrido[2,3-d]pyrimidines as Covalent L858R/T790M Mutant Selective Epidermal Growth Factor Receptor (EGFR) Inhibitors.

In nonsmall cell lung cancer (NSCLC), the threonine(790)-methionine(790) (T790M) point mutation of EGFR kinase is one of the leading causes of acquired resistance to the first generation tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. Herein, we describe the optimization of a series of 7-oxopyrido[2,3-d]pyrimidinyl-derived irreversible inhibitors of EGFR kinase. This led to the discovery of compound 24 which potently inhibits gefitinib-resistant EGFR(L858R,T790M) with 100-fold selectivity over wild-type EGFR.

The imidazo[1,2-a]pyridine ring system as a scaffold for potent dual phosphoinositide-3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitors.

Based on lead compound 1, which was discovered from a high-throughput screen, a series of PI3Kα/mTOR inhibitors were evaluated that contained an imidazo[1,2-a]pyridine as a core replacement for the benzimidazole contained in 1. By exploring various ring systems that occupy the affinity pocket, two fragments containing a methoxypyridine were identified that gave <100 nM potency toward PI3Kα in enzyme and cellular assays with moderate stability in rat and human liver microsomes. With the two methoxypyridine groups selected to occupy the affinity pocket, analogs were prepared with various fragments intended to occupy the ribose pocket of PI3Kα and mTOR.

Pharmaceutical Optimization of Peptide Toxins for Ion Channel Targets: Potent, Selective, and Long-Lived Antagonists of Kv1.3.

To realize the medicinal potential of peptide toxins, naturally occurring disulfide-rich peptides, as ion channel antagonists, more efficient pharmaceutical optimization technologies must be developed. Here, we show that the therapeutic properties of multiple cysteine toxin peptides can be rapidly and substantially improved by combining direct chemical strategies with high-throughput electrophysiology. We applied whole-molecule, brute-force, structure-activity analoging to ShK, a peptide toxin from the sea anemone Stichodactyla helianthus that inhibits the voltage-gated potassium ion channel Kv1.

Sustained inhibition of the NaV1.7 sodium channel by engineered dimers of the domain II binding peptide GpTx-1.

Many efforts are underway to develop selective inhibitors of the voltage-gated sodium channel NaV1.7 as new analgesics. Thus far, however, in vitro selectivity has proved difficult for small molecules, and peptides generally lack appropriate pharmacokinetic properties.

Engineering potent and selective analogues of GpTx-1, a tarantula venom peptide antagonist of the Na(V)1.7 sodium channel.

NaV1.7 is a voltage-gated sodium ion channel implicated by human genetic evidence as a therapeutic target for the treatment of pain. Screening fractionated venom from the tarantula Grammostola porteri led to the identification of a 34-residue peptide, termed GpTx-1, with potent activity on NaV1.

Discovery of 5-(1H-indol-5-yl)-1,3,4-thiadiazol-2-amines as potent PIM inhibitors.

PIM kinases are a family of Ser/Thr kinases that are implicated in tumorigenesis. The discovery of a new class of PIM inhibitors, 5-(1H-indol-5-yl)-1,3,4-thiadiazol-2-amines, is discussed with optimized compounds showing excellent potency against all three PIM isoforms.

The discovery and optimization of aminooxadiazoles as potent Pim kinase inhibitors.

High levels of Pim expression have been implicated in several hematopoietic and solid tumor cancers. These findings suggest that inhibition of Pim signaling by a small molecule Pim-1,2 inhibitor could provide patients with therapeutic benefit. Herein, we describe our progress towards this goal starting from the highly Pim-selective indole-thiadiazole compound (1), which was derived from a nonselective hit identified in a high throughput screening campaign.

The discovery of novel 3-(pyrazin-2-yl)-1H-indazoles as potent pan-Pim kinase inhibitors.

The three Pim kinases are a small family of serine/threonine kinases regulating several signaling pathways that are fundamental to tumorigenesis. As such, the Pim kinases are a very attractive target for pharmacological inhibition in cancer therapy. Herein, we describe our efforts toward the development of a potent, pan-Pim inhibitor.

Unfolded Protein Response in Cancer: IRE1α Inhibition by Selective Kinase Ligands Does Not Impair Tumor Cell Viability.

The kinase/endonuclease inositol requiring enzyme 1 (IRE1α), one of the sensors of unfolded protein accumulation in the endoplasmic reticulum that triggers the unfolded protein response (UPR), has been investigated as an anticancer target. We identified potent allosteric inhibitors of IRE1α endonuclease activity that bound to the kinase site on the enzyme. Structure-activity relationship (SAR) studies led to 16 and 18, which were selective in kinase screens and were potent against recombinant IRE1α endonuclease as well as cellular IRE1α.

Discovery of 1H-pyrazol-3(2H)-ones as potent and selective inhibitors of protein kinase R-like endoplasmic reticulum kinase (PERK).

The structure-based design and optimization of a novel series of selective PERK inhibitors are described resulting in the identification of 44 as a potent, highly selective, and orally active tool compound suitable for PERK pathway biology exploration both in vitro and in vivo.

Phosphoinositide-3-kinase inhibitors: evaluation of substituted alcohols as replacements for the piperazine sulfonamide portion of AMG 511.

Replacement of the piperazine sulfonamide portion of the PI3Kα inhibitor AMG 511 (1) with a range of aliphatic alcohols led to the identification of a truncated gem-dimethylbenzylic alcohol analog, 2-(5-(4-amino-6-methyl-1,3,5-triazin-2-yl)-6-((5-fluoro-6-methoxypyridin-3-yl)amino)pyridin-3-yl)propan-2-ol (7). This compound possessed good in vitro efficacy and pharmacokinetic parameters and demonstrated an EC50 of 239 ng/mL in a mouse liver pharmacodynamic model measuring the inhibition of hepatocyte growth factor (HGF)-induced Akt Ser473 phosphorylation in CD1 nude mice 6 h post-oral dosing.

Synthesis and preliminary biological evaluation of potent and selective 2-(3-alkoxy-1-azetidinyl) quinolines as novel PDE10A inhibitors with improved solubility.

We report the discovery of a novel series of 2-(3-alkoxy-1-azetidinyl) quinolines as potent and selective PDE10A inhibitors. Structure-activity studies improved the solubility (pH 7.4) and maintained high PDE10A activity compared to initial lead compound 3, with select compounds demonstrating good oral bioavailability.

Discovery of clinical candidate 1-(4-(3-(4-(1H-benzo[d]imidazole-2-carbonyl)phenoxy)pyrazin-2-yl)piperidin-1-yl)ethanone (AMG 579), a potent, selective, and efficacious inhibitor of phosphodiesterase 10A (PDE10A).

We report the identification of a PDE10A clinical candidate by optimizing potency and in vivo efficacy of promising keto-benzimidazole leads 1 and 2. Significant increase in biochemical potency was observed when the saturated rings on morpholine 1 and N-acetyl piperazine 2 were changed by a single atom to tetrahydropyran 3 and N-acetyl piperidine 5. A second single atom modification from pyrazines 3 and 5 to pyridines 4 and 6 improved the inhibitory activity of 4 but not 6.

Small molecule disruptors of the glucokinase-glucokinase regulatory protein interaction: 1. Discovery of a novel tool compound for in vivo proof-of-concept.

Small molecule activators of glucokinase have shown robust efficacy in both preclinical models and humans. However, overactivation of glucokinase (GK) can cause excessive glucose turnover, leading to hypoglycemia. To circumvent this adverse side effect, we chose to modulate GK activity by targeting the endogenous inhibitor of GK, glucokinase regulatory protein (GKRP).