Aficamten is a small-molecule cardiac myosin inhibitor designed to treat hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere resulting in excessive cardiac contractility. The first-in-class cardiac myosin inhibitor, mavacamten, improves symptoms in obstructive HCM. Here we present aficamten, a selective small-molecule inhibitor of cardiac myosin that diminishes ATPase activity by strongly slowing phosphate release, stabilizing a weak actin-binding state.

In vitro and in vivo preclinical pharmacokinetic characterization of aficamten, a small molecule cardiac myosin inhibitor.

Aficamten, a small molecule selective inhibitor of cardiac myosin, was characterised in preclinical and studies.Protein binding in human plasma was 10.4% unbound and ranged from 1.

Pharmacokinetics, mass balance, tissue distribution, metabolism, and excretion of [C]aficamten following single oral dose administration to rats.

The pharmacokinetics, metabolism, excretion, mass balance, and tissue distribution of [C]aficamten were evaluated following oral administration of an 8 mg/kg dose in Sprague Dawley rats and in a quantitative whole-body autoradiography study in Long Evans rats.[C]Aficamten accounted for ∼80% and a hydroxylated metabolite (M1) accounted for ∼12% of total radioactivity in plasma over 48-h (AUC). Plasma was 4-h and the of total plasma radioactivity was 5.

Cardiac myosin inhibitor, CK-586, minimally reduces systolic function and ameliorates obstruction in feline hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) remains the most common cardiomyopathy in humans and cats with few preclinical pharmacologic interventional studies. Small-molecule sarcomere inhibitors are promising novel therapeutics for the management of obstructive HCM (oHCM) patients and have shown efficacy in left ventricular outflow tract obstruction (LVOTO) relief. The objective of this study was to explore the 6-, 24-, and 48-hour (h) pharmacodynamic effects of the cardiac myosin inhibitor, CK-586, in six purpose-bred cats with naturally occurring oHCM.

Discovery of Nelutroctiv (CK-136), a Selective Cardiac Troponin Activator for the Treatment of Cardiovascular Diseases Associated with Reduced Cardiac Contractility.

Cardiac myosin activation has been shown to be a viable approach for the treatment of heart failure with reduced ejection fraction. Here, we report the discovery of nelutroctiv (), a selective cardiac troponin activator intended for patients with cardiovascular conditions where cardiac contractility is reduced. Discovery of nelutroctiv began with a high-throughput screen that identified compound , a muscle selective cardiac sarcomere activator devoid of phosphodiesterase-3 activity.

Cardiac Troponin Activator Increases Cardiac Contractility in Rats.

Novel cardiac troponin activators were identified using a high throughput cardiac myofibril ATPase assay and confirmed using a series of biochemical and biophysical assays. HTS hit increased rat cardiomyocyte fractional shortening without increasing intracellular calcium concentrations, and the biological target of and was determined to be the cardiac thin filament. Subsequent optimization to increase solubility and remove PDE-3 inhibition led to the discovery of and enabled pharmacological evaluation of cardiac troponin activation without the competing effects of PDE-3 inhibition.

Effects of Aficamten on cardiac contractility in a feline translational model of hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease in humans and cats and lacks efficacious pharmacologic interventions in the preclinical phase of disease. LV outflow tract obstruction (LVOTO) is commonly observed in HCM-affected patients and is a primary driver of heart failure symptoms and reduced quality of life. Novel small-molecule cardiac myosin inhibitors target actin-myosin interactions to alleviate overactive protein interactions.

Pharmacokinetics of a single dose of Aficamten (CK-274) on cardiac contractility in a A31P MYBPC3 hypertrophic cardiomyopathy cat model.

Hypertrophic cardiomyopathy (HCM) is the most prevalent cardiac disease in cats and lacks efficacious preclinical pharmacologic intervention, prompting investigation of novel therapies. Genetic mutations encoding sarcomeric proteins are implicated in the development of HCM and small molecule myosin inhibitors are an emerging class of therapeutics designed to target the interaction of actin and myosin to alleviate the detrimental effects of inappropriate contractile protein interactions. The purpose of this study was to characterize the pharmacodynamic effects of a single oral dose of the novel cardiac myosin inhibitor aficamten (CK-274) on cardiac function in purpose bred cats with naturally occurring A31P MYBPC3 mutation and a clinical diagnosis of HCM with left ventricular outflow tract obstruction (LVOTO).

Discovery of Reldesemtiv, a Fast Skeletal Muscle Troponin Activator for the Treatment of Impaired Muscle Function.

The discovery of reldesemtiv, a second-generation fast skeletal muscle troponin activator (FSTA) that increases force production at submaximal stimulation frequencies, is reported. Property-based optimization of high throughput screening hit led to compounds with improved free exposure and muscle activation potency compared to the first-generation FSTA, tirasemtiv. Reldesemtiv demonstrated increased muscle force generation in a phase 1 clinical trial and is currently being evaluated in clinical trials for the treatment of amyotrophic lateral sclerosis.

Discovery of Aficamten (CK-274), a Next-Generation Cardiac Myosin Inhibitor for the Treatment of Hypertrophic Cardiomyopathy.

Hypercontractility of the cardiac sarcomere may be essential for the underlying pathological hypertrophy and fibrosis in genetic hypertrophic cardiomyopathies. Aficamten (CK-274) is a novel cardiac myosin inhibitor that was discovered from the optimization of indoline compound . The important advancement of the optimization was discovery of an Indane analogue () with a less restrictive structure-activity relationship that allowed for the rapid improvement of drug-like properties.

Discovery of , the First Direct Fast Skeletal Muscle Troponin Activator.

The identification and optimization of the first activators of fast skeletal muscle are reported. Compound was identified from high-throughput screening (HTS) and subsequently found to improve muscle function via interaction with the troponin complex. Optimization of for potency, metabolic stability, and physical properties led to the discovery of tirasemtiv (), which has been extensively characterized in clinical trials for the treatment of amyotrophic lateral sclerosis.

Discovery of GBT440, an Orally Bioavailable R-State Stabilizer of Sickle Cell Hemoglobin.

We report the discovery of a new potent allosteric effector of sickle cell hemoglobin, GBT440 (), that increases the affinity of hemoglobin for oxygen and consequently inhibits its polymerization when subjected to hypoxic conditions. Unlike earlier allosteric activators that bind covalently to hemoglobin in a 2:1 stoichiometry, binds with a 1:1 stoichiometry. Compound is orally bioavailable and partitions highly and favorably into the red blood cell with a RBC/plasma ratio of ∼150.

Highly selective inhibition of myosin motors provides the basis of potential therapeutic application.

Direct inhibition of smooth muscle myosin (SMM) is a potential means to treat hypercontractile smooth muscle diseases. The selective inhibitor CK-2018571 prevents strong binding to actin and promotes muscle relaxation in vitro and in vivo. The crystal structure of the SMM/drug complex reveals that CK-2018571 binds to a novel allosteric pocket that opens up during the "recovery stroke" transition necessary to reprime the motor.

Activation of fast skeletal muscle troponin as a potential therapeutic approach for treating neuromuscular diseases.

Limited neural input results in muscle weakness in neuromuscular disease because of a reduction in the density of muscle innervation, the rate of neuromuscular junction activation or the efficiency of synaptic transmission. We developed a small-molecule fast-skeletal-troponin activator, CK-2017357, as a means to increase muscle strength by amplifying the response of muscle when neural input is otherwise diminished secondary to neuromuscular disease. Binding selectively to the fast-skeletal-troponin complex, CK-2017357 slows the rate of calcium release from troponin C and sensitizes muscle to calcium.

Cardiac myosin activation part 1: from concept to clinic.

Decreased cardiac contractility is a central feature of systolic heart failure and yet we have no effective drugs to improve cardiac contractility. Existing drugs that increase cardiac contractility do so indirectly through signaling cascades and their use is limited by their mechanism-related adverse effects. Direct activation of the cardiac sarcomere to increase cardiac contractility may provide a means to avoid these limitations.

Cardiac myosin activation: a potential therapeutic approach for systolic heart failure.

Decreased cardiac contractility is a central feature of systolic heart failure. Existing drugs increase cardiac contractility indirectly through signaling cascades but are limited by their mechanism-related adverse effects. To avoid these limitations, we previously developed omecamtiv mecarbil, a small-molecule, direct activator of cardiac myosin.

Discovery of omecamtiv mecarbil the first, selective, small molecule activator of cardiac Myosin.

We report the design, synthesis, and optimization of the first, selective activators of cardiac myosin. Starting with a poorly soluble, nitro-aromatic hit compound (1), potent, selective, and soluble myosin activators were designed culminating in the discovery of omecamtiv mecarbil (24). Compound 24 is currently in clinical trials for the treatment of systolic heart failure.

Discovery of the First Potent and Selective Inhibitor of Centromere-Associated Protein E: GSK923295.

Inhibition of mitotic kinesins represents a novel approach for the discovery of a new generation of anti-mitotic cancer chemotherapeutics. We report here the discovery of the first potent and selective inhibitor of centromere-associated protein E (CENP-E) 3-chloro-N-{(1S)-2-[(N,N-dimethylglycyl)amino]-1-[(4-{8-[(1S)-1-hydroxyethyl]imidazo[1,2-a]pyridin-2-yl}phenyl)methyl]ethyl}-4-[(1-methylethyl)oxy]benzamide (GSK923295; 1), starting from a high-throughput screening hit, 3-chloro-4-isopropoxybenzoic acid 2. Compound 1 has demonstrated broad antitumor activity in vivo and is currently in human clinical trials.

Octahydrophenanthrene-2,7-diol analogues as dissociated glucocorticoid receptor agonists: discovery and lead exploration.

As exemplified by the lead compound 2, octahydrophenanthrene-2,7-diol analogues exhibit the profile of a pathway-selective or "dissociated" agonist of the glucocorticoid receptor (GR), retaining the potent activity that glucocorticoids have for transrepression (as measured by inhibition of IL-1 induced MMP-13 expression) but showing an attenuated capacity for transactivation (as measured in an MMTV luciferase reporter assay). With the guidance of a homology model of the GR ligand binding domain, structural modifications to 2 were carried out that were successful in replacing the allyl and propynyl side chains with groups likely to be more chemically stable and less likely to produce toxic metabolites. Key to success was the introduction of an additional hydroxyl group onto the tricyclic carbon framework of the series.

In vitro and in vivo characterization of 3-[2-[6-(2-tert-butoxyethoxy)pyridin-3-yl]-1H-imidazol-4-yl]benzonitrile hydrochloride salt, a potent and selective NPY5 receptor antagonist.

To investigate the anorectic potential of NPY5 receptor antagonists, we have profiled the in vitro and in vivo properties of 3-[2-[6-(2-tert-butoxyethoxy)pyridin-3-yl]-1H-imidazol-4-yl]benzonitrile hydrochloride salt (1). This compound was found to have excellent NPY5 receptor affinity and selectivity, potent functional antagonism, and good peripheral and central nervous system exposure in rats. This compound attenuated bovine pancreatic polypeptide induced food intake in rats but failed to demonstrate anorectic activity in rodent natural feeding models.

Discovery of potent, nonsteroidal, and highly selective glucocorticoid receptor antagonists.

An approach to the computer-assisted, pharmacophore design of nonsteroidal templates for the glucocorticoid receptor (GR) that contained an element of pseudo-C2 symmetry was developed. The enatiomer of the initial design, 1Ra, and not the designed molecule, 1S, showed the desired ligand binding to the GR. The pseudo-C2 symmetry of the template allowed for rapid improvements in GR activity resulting in potent, selective, nonsteroidal GR antagonists, CP-394531 and CP-409069.