Discovery of MK-8189, a Highly Potent and Selective PDE10A Inhibitor for the Treatment of Schizophrenia

Seven-membered N-heterocycles as approved drugs and promising leads in medicinal chemistry as well as the metal-free domino access to their scaffolds

Azepanes or azepines are structural motifs of many drugs, drug candidates and evaluated lead compounds. Even though compounds having N-heterocyclic 7-membered rings are often found in nature (e.g. alkaloids), the natural compounds of this group are rather rare as approved therapeutics. Thus, recently studied and approved azepane or azepine-congeners predominantly consist of semi-synthetically or synthetically-obtained scaffolds. In this review a comparison of approved drugs and recently investigated leads was proposed taking into regard their structural aspects (stereochemistry), biological activities, pharmacokinetic properties and confirmed molecular targets. The 7-membered N-heterocycles reveal a wide range of biological activities, not only against CNS diseases, but also as e.g. antibacterial, anticancer, antiviral, antiparasitic and against allergy agents. As most of the approved or investigated potential drugs or lead structures, belonging to 7-membered N-heterocycles, are synthetic scaffolds, this report also reveals different and efficient metal-free cascade approaches useful to synthesize both simple azepane or azepine-containing congeners and those of oligocyclic structures. Stereochemistry of azepane/azepine fused systems, in view of biological data and binding with the targets, is discussed. Apart from the approved drugs, we compare advances in SAR studies of 7-membered N-heterocycles (mainly from 2018 to 2023), whereas the related synthetic part concerning various domino strategies is focused on the last ten years.

Imidazopyrimidine: from a relatively exotic scaffold to an evolving structural motif in drug discovery

Nitrogen-fused heterocycles are of immense importance in modern drug discovery and development. Among them, imidazopyrimidine is a highly versatile scaffold with vast pharmacological utility. These compounds demonstrate a broad spectrum of pharmacological actions, including antiviral, antifungal, anti-inflammatory, and anticancer. Their adaptable structure allows for extensive structural modifications, which can be utilized for optimizing pharmacological effects via structure-activity relationship (SAR) studies. Additionally, imidazopyrimidine derivatives are particularly noteworthy for their ability to target specific molecular entities, such as protein kinases, which are crucial components of various cellular signaling pathways associated with multiple diseases. Despite the evident importance of imidazopyrimidines in drug discovery, there is a notable lack of a comprehensive review that outlines their role in this field. This review highlights the ongoing interest and investment in exploring the therapeutic potential of imidazopyrimidine compounds, underscoring their pivotal role in shaping the future of drug discovery and clinical medicine.

Fragment-based drug discovery for disorders of the central nervous system: designing better drugs piece by piece

Fragment-based drug discovery (FBDD) has emerged as a powerful strategy to confront the challenges faced by conventional drug development approaches, particularly in the context of central nervous system (CNS) disorders. FBDD involves the screening of libraries that comprise thousands of small molecular fragments, each no greater than 300 Da in size. Unlike the generally larger molecules from high-throughput screening that limit customisation, fragments offer a more strategic starting point. These fragments are inherently compact, providing a strong foundation with good binding affinity for the development of drug candidates. The minimal elaboration required to transition the hit into a drug-like molecule is not only accelerated, but also it allows for precise modifications to enhance both their activity and pharmacokinetic properties. This shift towards a fragment-centric approach has seen commercial success and holds considerable promise in the continued streamlining of the drug discovery and development process. In this review, we highlight how FBDD can be integrated into the CNS drug discovery process to enhance the exploration of a target. Furthermore, we provide recent examples where FBDD has been an integral component in CNS drug discovery programs, enabling the improvement of pharmacokinetic properties that have previously proven challenging. The FBDD optimisation process provides a systematic approach to explore this vast chemical space, facilitating the discovery and design of compounds piece by piece that are capable of modulating crucial CNS targets.

Fragment-to-Lead Medicinal Chemistry Publications in 2022

This Perspective is the eighth in an annual series that summarizes successful fragment-to-lead (F2L) case studies published each year. A tabulated summary of relevant articles published in 2022 is provided, and features such as target class, screening methods, and ligand efficiency are discussed both for the 2022 examples and for the combined examples over the years 2015-2022. In addition, trends and new developments in the field are summarized. In 2022, 18 publications described successful fragment-to-lead studies, including the development of three clinical compounds (MTRX1719, MK-8189, and BI-823911).

Is Target-Based Drug Discovery Efficient? Discovery and "Off-Target" Mechanisms of All Drugs

Target-based drug discovery is the dominant paradigm of drug discovery; however, a comprehensive evaluation of its real-world efficiency is lacking. Here, a manual systematic review of about 32000 articles and patents dating back to 150 years ago demonstrates its apparent inefficiency. Analyzing the origins of all approved drugs reveals that, despite several decades of dominance, only 9.4% of small-molecule drugs have been discovered through "target-based" assays. Moreover, the therapeutic effects of even this minimal share cannot be solely attributed and reduced to their purported targets, as they depend on numerous off-target mechanisms unconsciously incorporated by phenotypic observations. The data suggest that reductionist target-based drug discovery may be a cause of the productivity crisis in drug discovery. An evidence-based approach to enhance efficiency seems to be prioritizing, in selecting and optimizing molecules, higher-level phenotypic observations that are closer to the sought-after therapeutic effects using tools like artificial intelligence and machine learning.

Towards Novel Potential Molecular Targets for Antidepressant and Antipsychotic Pharmacotherapies

Depression and schizophrenia are two highly prevalent and severely debilitating neuropsychiatric disorders. Both conventional antidepressant and antipsychotic pharmacotherapies are often inefficient clinically, causing multiple side effects and serious patient compliance problems. Collectively, this calls for the development of novel drug targets for treating depressed and schizophrenic patients. Here, we discuss recent translational advances, research tools and approaches, aiming to facilitate innovative drug discovery in this field. Providing a comprehensive overview of current antidepressants and antipsychotic drugs, we also outline potential novel molecular targets for treating depression and schizophrenia. We also critically evaluate multiple translational challenges and summarize various open questions, in order to foster further integrative cross-discipline research into antidepressant and antipsychotic drug development.