Orally available nucleoside analog UMM-766 provides protection in a murine model of orthopox disease.

Although smallpox has been eradicated, other orthopoxviruses continue to be a public health concern as exemplified by the ongoing Mpox (formerly monkeypox) global outbreak. While medical countermeasures (MCMs) previously approved by the Food and Drug Administration for the treatment of smallpox have been adopted for Mpox, previously described vulnerabilities coupled with the questionable benefit of at least one of the therapeutics during the 2022 Mpox outbreak reinforce the need for identifying and developing other MCMs against orthopoxviruses. Here, we screened a panel of Merck proprietary small molecules and identified a novel nucleoside inhibitor with potent broad-spectrum antiviral activity against multiple orthopoxviruses. Efficacy testing of a 7-day dosing regimen of the orally administered nucleoside in a murine model of severe orthopoxvirus infection yielded a dose-dependent increase in survival. Treated animals had greatly reduced lesions in the lung and nasal cavity, particularly in the 10 µg/mL dosing group. Viral levels were also markedly lower in the UMM-766-treated animals. This work demonstrates that this nucleoside analog has anti-orthopoxvirus efficacy and can protect against severe disease in a murine orthopox model.IMPORTANCEThe recent monkeypox virus pandemic demonstrates that members of the orthopoxvirus, which also includes variola virus, which causes smallpox, remain a public health issue. While currently FDA-approved treatment options exist, risks that resistant strains of orthopoxviruses may arise are a great concern. Thus, continued exploration of anti-poxvirus treatments is warranted. Here, we developed a template for a high-throughput screening assay to identify anti-poxvirus small-molecule drugs. By screening available drug libraries, we identified a compound that inhibited orthopoxvirus replication in cell culture. We then showed that this drug can protect animals against severe disease. Our findings here support the use of existing drug libraries to identify orthopoxvirus-targeting drugs that may serve as human-safe products to thwart future outbreaks.

Identification, structural, and biophysical characterization of a positive modulator of human Kv3.1 channels.

Voltage-gated potassium channels (Kv) are tetrameric membrane proteins that provide a highly selective pathway for potassium ions (K+) to diffuse across a hydrophobic cell membrane. These unique voltage-gated cation channels detect changes in membrane potential and, upon activation, help to return the depolarized cell to a resting state during the repolarization stage of each action potential. The Kv3 family of potassium channels is characterized by a high activation potential and rapid kinetics, which play a crucial role for the fast-spiking neuronal phenotype. Mutations in the Kv3.1 channel have been shown to have implications in various neurological diseases like epilepsy and Alzheimer's disease. Moreover, disruptions in neuronal circuitry involving Kv3.1 have been correlated with negative symptoms of schizophrenia. Here, we report the discovery of a novel positive modulator of Kv3.1, investigate its biophysical properties, and determine the cryo-EM structure of the compound in complex with Kv3.1. Structural analysis reveals the molecular determinants of positive modulation in Kv3.1 channels by this class of compounds and provides additional opportunities for rational drug design for the treatment of associated neurological disorders.

Lead optimization of cathepsin K inhibitors for the treatment of Osteoarthritis.

Cathepsin K (Cat K) is a cysteine protease involved in bone remodeling. In addition to its role in bone biology, Cat K is upregulated in osteoclasts, chondrocytes and synoviocytes in osteoarthritic (OA) disease states making it a potential therapeutic target for disease-modifying OA. Starting from a prior preclinical compound, MK-1256, lead optimization efforts were carried out in the search for potent Cat K inhibitors with improved selectivity profiles with an emphasis on cathepsin F. Herein, we report the SAR studies which led to the discovery of the highly selective oxazole compound 23, which was subsequently shown to inhibit cathepsin K in vivo as measured by reduced levels of urinary C-telopeptide of collagen type I in dog.

Base-Mediated Oxidative Degradation of Secondary Amides Derived from p-Amino Phenol to Primary Amides in Drug Molecules.

One of the most common functional groups encountered in drug molecules is the amide, and the most common degradation pathway for amides is base-mediated hydrolysis to its constituent amine and carboxylic acid. Herein, we report for the first time, a base-mediated oxidative degradation pathway of secondary amides to primary amides. This transformation also represents a novel synthetic methodology, reported for the first time in this work, in transforming secondary amides to primary amides without using any oxidative reagents. The introduction of this mechanism into the pharmaceutical literature is important given that the mechanism and required reactants are present to carry out the chemistry in dosage forms.

Identification of potent inhibitors of the sortilin-progranulin interaction.

High-throughput screening methods have been used to identify two novel series of inhibitors that disrupt progranulin binding to sortilin. Exploration of structure-activity relationships (SAR) resulted in compounds with sufficient potency and physicochemical properties to enable co-crystallization with sortilin. These co-crystal structures supported observed SAR trends and provided guidance for additional avenues for designing compounds with additional interactions within the binding site.

Structure-Guided Design and Procognitive Assessment of a Potent and Selective Phosphodiesterase 2A Inhibitor.

Herein we describe the development of a series of pyrazolopyrimidinone phosphodiesterase 2A (PDE2) inhibitors using structure-guided lead identification and design. The series was derived from informed chemotype replacement based on previously identified internal leads. The initially designed compound 3, while potent on PDE2, displayed unsatisfactory selectivity against the other PDE2 isoforms. Compound 3 was subsequently optimized for improved PDE2 activity and isoform selectivity. Insights into the origins of PDE2 selectivity are described and verified using cocrystallography. An optimized lead, 4, demonstrated improved performance in both a rodent and a nonhuman primate cognition model.

Identification of second-generation P2X3 antagonists for treatment of pain.

A second-generation small molecule P2X3 receptor antagonist has been developed. The lead optimization strategy to address shortcomings of the first-generation preclinical lead compound is described herein. These studies were directed towards the identification and amelioration of preclinical hepatobiliary findings, reducing potential for drug-drug interactions, and decreasing the projected human dose of the first-generation lead.

Copper-facilitated Suzuki reactions: application to 2-heterocyclic boronates.

The palladium-catalyzed Suzuki-Miyaura reaction has been utilized as one of the most powerful methods for C-C bond formation. However, Suzuki reactions of electron-deficient 2-heterocyclic boronates generally give low conversions and remain challenging. The successful copper(I) facilitated Suzuki coupling of 2-heterocyclic boronates that is broad in scope is reported. Use of this methodology affords greatly enhanced yields of these notoriously difficult couplings. Furthermore, mechanistic investigations suggest a possible role of copper in the catalytic cycle.