Discovery of TAK-041: a Potent and Selective GPR139 Agonist Explored for the Treatment of Negative Symptoms Associated with Schizophrenia.

The orphan G-protein-coupled receptor GPR139 is highly expressed in the habenula, a small brain nucleus that has been linked to depression, schizophrenia (SCZ), and substance-use disorder. High-throughput screening and a medicinal chemistry structure-activity relationship strategy identified a novel series of potent and selective benzotriazinone-based GPR139 agonists. Herein, we describe the chemistry optimization that led to the discovery and validation of multiple potent and selective in vivo GPR139 agonist tool compounds, including our clinical candidate TAK-041, also known as NBI-1065846 (compound 56). The pharmacological characterization of these GPR139 agonists in vivo demonstrated GPR139-agonist-dependent modulation of habenula cell activity and revealed consistent in vivo efficacy to rescue social interaction deficits in the BALB/c mouse strain. The clinical GPR139 agonist TAK-041 is being explored as a novel drug to treat negative symptoms in SCZ.

First-Time Disclosure of CVN424, a Potent and Selective GPR6 Inverse Agonist for the Treatment of Parkinson's Disease: Discovery, Pharmacological Validation, and Identification of a Clinical Candidate.

Parkinson's disease (PD) is a chronic and progressive movement disorder with the urgent unmet need for efficient symptomatic therapies with fewer side effects. GPR6 is an orphan G-protein coupled receptor (GPCR) with highly restricted expression in dopamine receptor D2-type medium spiny neurons (MSNs) of the indirect pathway, a striatal brain circuit which shows aberrant hyperactivity in PD patients. Potent and selective GPR6 inverse agonists (IAG) were developed starting from a low-potency screening hit (EC50 = 43 µM). Herein, we describe the multiple parameter optimization that led to the discovery of multiple nanomolar potent and selective GPR6 IAG, including our clinical compound CVN424. GPR6 IAG reversed haloperidol-induced catalepsy in rats and restored mobility in the bilateral 6-OHDA-lesioned rat PD model demonstrating that inhibition of GPR6 activity in vivo normalizes activity in basal ganglia circuitry and motor behavior. CVN424 is currently in clinical development to treat motor symptoms in Parkinson's disease.

Improved Scalability of Neuron-Based Phenotypic Screening Assays for Therapeutic Discovery in Neuropsychiatric Disorders.

There is a pressing need to improve approaches for drug discovery related to neuropsychiatric disorders (NSDs). Therapeutic discovery in neuropsychiatric disorders would benefit from screening assays that can measure changes in complex phenotypes linked to disease mechanisms. However, traditional assays that track complex neuronal phenotypes, such as neuronal connectivity, exhibit poor scalability and are not compatible with high-throughput screening (HTS) procedures. Therefore, we created a neuronal phenotypic assay platform that focused on improving the scalability and affordability of neuron-based assays capable of tracking disease-relevant phenotypes. First, using inexpensive laboratory-level automation, we industrialized primary neuronal culture production, which enabled the creation of scalable assays within functioning neural networks. We then developed a panel of phenotypic assays based on culturing of primary neurons from genetically modified mice expressing HTS-compatible reporters that capture disease-relevant phenotypes. We demonstrated that a library of 1,280 compounds was quickly screened against both assays using only a few litters of mice in a typical academic laboratory setting. Finally, we implemented one assay in a fully automated high-throughput academic screening facility, illustrating the scalability of assays designed using this platform. These methodological improvements simplify the creation of highly scalable neuron-based phenotypic assays designed to improve drug discovery in CNS disorders.

A Rapid Phenotypic Whole-Cell Screening Approach for the Identification of Small-Molecule Inhibitors That Counter ß-Lactamase Resistance in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic human pathogen that is prevalent in hospitals and continues to develop resistance to multiple classes of antibiotics. Historically, ß-lactam antibiotics have been the first line of therapeutic defense. However, the emergence of multidrug-resistant (MDR) strains of P. aeruginosa, such as AmpC ß-lactamase overproducing mutants, limits the effectiveness of current antibiotics. Among AmpC hyperproducing clinical isolates, inactivation of AmpG, which is essential for the expression of AmpC, increases bacterial sensitivity to ß-lactam antibiotics. We hypothesize that inhibition of AmpG activity will enhance the efficacy of ß-lactams against P. aeruginosa. Here, using a highly drug-resistant AmpC-inducible laboratory strain PAO1, we describe an ultra-high-throughput whole-cell turbidity assay designed to identify small-molecule inhibitors of the AmpG. We screened 645,000 compounds to identify compounds with the ability to inhibit bacterial growth in the presence of cefoxitin, an AmpC inducer, and identified 2663 inhibitors that were also tested in the absence of cefoxitin to determine AmpG specificity. The Z' and signal-to-background ratio were robust at 0.87 ± 0.05 and 2.2 ± 0.2, respectively. Through a series of secondary and tertiary studies, including a novel luciferase-based counterscreen, we ultimately identified eight potential AmpG-specific inhibitors.

Total skeletal muscle PGC-1 deficiency uncouples mitochondrial derangements from fiber type determination and insulin sensitivity.

Evidence is emerging that the PGC-1 coactivators serve a critical role in skeletal muscle metabolism, function, and disease. Mice with total PGC-1 deficiency in skeletal muscle (PGC-1α(-/-)ß(f/f/MLC-Cre) mice) were generated and characterized. PGC-1α(-/-)ß(f/f/MLC-Cre) mice exhibit a dramatic reduction in exercise performance compared to single PGC-1α- or PGC-1ß-deficient mice and wild-type controls. The exercise phenotype of the PGC-1α(-/-)ß(f/f/MLC-Cre) mice was associated with a marked diminution in muscle oxidative capacity, together with rapid depletion of muscle glycogen stores. In addition, the PGC-1α/ß-deficient muscle exhibited mitochondrial structural derangements consistent with fusion/fission and biogenic defects. Surprisingly, the proportion of oxidative muscle fiber types (I, IIa) was not reduced in the PGC-1α(-/-)ß(f/f/MLC-Cre) mice. Moreover, insulin sensitivity and glucose tolerance were not altered in the PGC-1α(-/-)ß(f/f/MLC-Cre) mice. Taken together, we conclude that PGC-1 coactivators are necessary for the oxidative and mitochondrial programs of skeletal muscle but are dispensable for fundamental fiber type determination and insulin sensitivity.