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Purpose: More than 15 years have passed since the first description of the unbound brain-to-plasma partition coefficient (Kp,uu,brain) by Prof. Margareta Hammarlund-Udenaes, which was enabled by advancements in experimental methodologies including cerebral microdialysis. Since then, growing knowledge and data continue to support the notion that the unbound (free) concentration of a drug at the site of action, such as the brain, is the driving force for pharmacological responses. Towards this end, Kp,uu,brain is the key parameter to obtain unbound brain concentrations from unbound plasma concentrations. Methods: To understand the importance and impact of the Kp,uu,brain concept in contemporary drug discovery and development, a survey has been conducted amongst major pharmaceutical companies based in Europe and the USA. Here, we present the results from this survey which consisted of 47 questions addressing: 1) Background information of the companies, 2) Implementation, 3) Application areas, 4) Methodology, 5) Impact and 6) Future perspectives. Results and conclusions: From the responses, it is clear that the majority of the companies (93%) has established a common understanding across disciplines of the concept and utility of Kp,uu,brain as compared to other parameters related to brain exposure. Adoption of the Kp,uu,brain concept has been mainly driven by individual scientists advocating its application in the various companies rather than by a top-down approach. Remarkably, 79% of all responders describe the portfolio impact of Kp,uu,brain implementation in their companies as 'game-changing'. Although most companies (74%) consider the current toolbox for Kp,uu,brain assessment and its validation satisfactory for drug discovery and early development, areas of improvement and future research to better understand human brain pharmacokinetics/pharmacodynamics translation have been identified. [ABSTRACT FROM AUTHOR]

• Target deconvolution can enhance pharmaceutical R&D productivity. • A combination of approaches is usually required for successful target deconvolution. • Target validation should include direct binding, target engagement and functional studies. • Target ID methods usually focus on proteins, overlooking RNA, DNA, lipid and metal ion targets. Investment in phenotypic drug discovery has led to increased demand for rapid and robust target deconvolution to aid successful drug development. Although methods for target identification and mechanism of action (MoA) discovery are flourishing, they typically lead to lists of putative targets. Validating which target(s) are involved in the therapeutic mechanism of a compound poses a significant challenge, requiring direct binding, target engagement, and functional studies in relevant physiological contexts. A combination of orthogonal approaches can allow target identification beyond the proteome as well as aid prioritisation for resource-intensive target validation studies. [ABSTRACT FROM AUTHOR]

A drug discovery startup company or academic lab entering the screening arena faces numerous challenges as it tries to manage the large quantity of data generated by a typical drug discovery screening campaign. Although there are sophisticated off-the-shelf software solutions available, their use requires substantial forethought and attention to detail if the data they capture are to be of sufficient quality to serve the various purposes to which it will be put. For newcomers to the field of screening data management in particular, the problem is compounded by a lack of literature covering the practical aspects of managing screening data. The authors provide some practical advice based on their experience of using a commercially available software suite. They discuss issues ranging from the organizational aspects to examples of how the form and content of metadata can have a big impact on whether results can be easily queried, pivoted, and reported. It is also hoped that their experiences might provide an opportunity for reflection to data management practitioners operating in established environments. [ABSTRACT FROM AUTHOR]

Recognition of some of the limitations of target-based drug discovery has recently led to the renaissance of a more holistic approach in which complex biological systems are investigated for phenotypic changes upon exposure to small molecules. The subsequent identification of the molecular targets that underlie an observed phenotypic response — termed target deconvolution — is an important aspect of current drug discovery, as knowledge of the molecular targets will greatly aid drug development. Here, the broad panel of experimental strategies that can be applied to target deconvolution is critically reviewed. [ABSTRACT FROM AUTHOR]

Deals with the areas wherein silico approaches are already operating in early pharmaceutical research and contribute significantly to drug discovery. Aim of target discovery; Process of target validation; Details on the lead identification phase; Conclusion. INSETS: Box 1. Prediction of gene function exemplified by the...;Box 2. Future directions.

Recent years have seen a paradigm shift away from optimizing the brain:blood concentration ratio toward the more relevant brain:blood unbound concentration ratio (K p,uu,br ) in CNS drug discovery. Here, we review the recent developments in the in silico and in vitro model systems to predict the K p,uu,br of discovery compounds with special emphasis on the in-vitro – in-vivo correlation. We also discuss clinical ‘translation’ of rodent K p,uu,br and highlight the future directions for improvement in brain penetration prediction. Important in this regard are in silico K p,uu,br models built on larger datasets of high quality, calibration and deeper understanding of experimental in vitro transporter systems, and better understanding of blood–brain barrier transporters and their in vivo relevance aside from P-gp and BCRP. [ABSTRACT FROM AUTHOR]

Evaluation of drug–target interaction kinetics is becoming increasingly important during the drug-discovery process to investigate selectivity of a drug and predict in vivo target occupancy. To date, it remains challenging to obtain kinetic information for interactions between G-protein-coupled receptors (GPCRs) and small-molecule ligands in a label-free manner. Often GPCRs need to be solubilized or even stabilized by mutations which can be difficult and is time consuming. In addition, it is often unclear if the native conformation of the receptors is sustained. In this study, surface plasmon resonance (SPR) and surface acoustic wave (SAW) technologies have been used to detect ligand binding to the GPCR chemokine (C-X-C motif) receptor 4 (CXCR4) expressed in lipoparticles. We first evaluated different strategies to immobilize CXCR4-expressing lipoparticles. The highest small-molecule binding signal in SPR and SAW was achieved with a matrix-free carboxymethylated sensor chip coated with wheat germ agglutinin for lipoparticle capturing. Next, the binding kinetics of the anti-CXCR4 antibody 12G5 raised against a conformational epitope (k on = 1.83 × 10 6 M − 1 s − 1 , k off = 2.79 × 10 − 4 s − 1 ) and the small molecule AMD3100 (k on = 5.46 × 10 5 M − 1 s − 1 , k off = 1.01 × 10 − 2 s − 1 ) were assessed by SAW. Our kinetic and affinity data are consistent with previously published radioligand-binding experiments using cells and label-free experiments with solubilized CXCR4. This is the first study demonstrating label-free kinetic characterization of small-molecule binding to a GPCR in the membrane environment. The presented method holds the potential to greatly facilitate label-free assay development for GPRCs that can be expressed at high levels in lipoparticles. [ABSTRACT FROM AUTHOR]

Huntington''s disease (HD) is a progressive and fatal neurodegenerative disease, and the most common inherited CAG repeat disorder. A polyglutamine expansion in the N-terminus of the huntingtin protein (HTT) leads to protein misfolding and downstream pathogenic processes culminating in widespread functional impairment and neurodegeneration in the striatum, cortex and other brain areas. To date, only symptomatic treatments are available that address motor, psychiatric and cognitive deficits. Here we review recent strategies for developing disease-modifying therapies designed to limit or abolish the pathogenic activities of the primary molecular target in HD, the mutant HTT protein itself. [Copyright &y& Elsevier]

Huntington''s Disease (HD) is a rare neurodegenerative disease caused by mutation of the huntingtin gene that results in a protein with an expanded stretch of glutamine repeats (polyQ). Knowledge of validated targets is in its infancy, and thus, traditional target-based drug discovery strategies are of limited use. Alternative approaches are needed, and early attempts were aimed at identifying molecules that inhibited the aggregation of polyQ huntingtin fragments. More recently, phenotypic assays were used to find molecules able to reverse some of the pathogenic mechanisms of HD. Such discovery strategies have an impact on the configuration of screening cascades for effective translation of drug candidates toward clinical trials. [Copyright &y& Elsevier]