Drug Metabolism And Pharmacokinetics Research Articles

Recent Developments in ADC Technology: Preclinical Studies Signal Future Clinical Trends.

The antibody–drug conjugate (ADC) field is in a transitional period. Older approaches to conjugate composition and dosing regimens still dominate the ADC clinical pipeline, but preclinical work is driving a rapid evolution in how we strategize to improve efficacy and reduce toxicity towards better therapeutic outcomes. These advances are largely based upon a body of investigational studies that together offer a deeper understanding of the absorption, distribution, metabolism, and excretion (ADME) and drug metabolism and pharmacokinetics (DMPK) fates of both the intact conjugate and its small-molecule component. Knowing where the drug goes and how it is processed allows mechanistic connections to be drawn with commonly observed clinical toxicities. The field is also starting to consider ADC interactions with the immune system and potential synergistic therapeutic opportunities therein. In an indication of future directions for the field, antibody conjugates bearing non-cytotoxic small-molecule payloads are being developed to reduce side effects associated with treatment of chronic diseases. ADCs are not a magic bullet to cure disease. However, they will increasingly become valuable therapeutic tools to improve patient outcomes across a variety of indications.

Discovery of N-(4-(2,4-Difluorophenoxy)-3-(6-methyl-7-oxo-6,7-dihydro-1H-pyrrolo[2,3-c]pyridin-4-yl)phenyl)ethanesulfonamide (ABBV-075/Mivebresib), a Potent and Orally Available Bromodomain and Extraterminal Domain (BET) Family Bromodomain Inhibitor.

The development of bromodomain and extraterminal domain (BET) bromodomain inhibitors and their examination in clinical studies, particularly in oncology settings, has garnered substantial recent interest. An effort to generate novel BET bromodomain inhibitors with excellent potency and drug metabolism and pharmacokinetics (DMPK) properties was initiated based upon elaboration of a simple pyridone core. Efforts to develop a bidentate interaction with a critical asparagine residue resulted in the incorporation of a pyrrolopyridone core, which improved potency by 9-19-fold. Additional structure-activity relationship (SAR) efforts aimed both at increasing potency and improving pharmacokinetic properties led to the discovery of the clinical candidate 63 (ABBV-075/mivebresib), which demonstrates excellent potency in biochemical and cellular assays, advantageous exposures and half-life both in animal models and in humans, and in vivo efficacy in mouse models of cancer progression and inflammation.

Electrochemical bromination of late stage intermediates and drug molecules

Abstract Aromatic C H bromination is one of the applications of late stage functionalization that provides precursors for generation of radio-labelled compounds to support drug metabolism and pharmacokinetic (DMPK) studies or provide a “handle” for further functionalization to expand SAR studies without having to resort to de novo synthesis. Electrochemical aromatic bromination was attempted on late stage intermediates and drug molecules such as cytidine, uridine, Tenofovir, MK-4618, Sch48973 and MK-8457. The reactions were conducted under mild galvanostatic electrolysis condition in aqueous NaBr solution. The brominated products were obtained and converted to the corresponding tritium labelled products. Electrochemical methodology provides an alternative way to quickly generate aryl bromides of late stage intermediates or drug molecules that are very useful in drug discovery.

Antiparasitic Sesquiterpenes from the Cameroonian Spice Scleria striatinux and Preliminary In Vitro and In Silico DMPK Assessment

The antiparasitic activity and preliminary in vitro and in silico drug metabolism and pharmacokinetic (DMPK) assessment of six isomeric sesquiterpenes (1–6), isolated from the Cameroonian spice Scleria striatinux De Wild (Cyperaceae) is reported. The study was prompted by the observation that two of the compounds (1 and 2) exhibited varying levels of antiparasitic activity on Plasmodium falciparum, Trypanosoma brucei rhodesiense, Trypanosoma cruzi and Leishmania donovani. The in silico method employed a total of 46 descriptors, calculated using Schrödinger QikProp software. 18 of these molecular descriptors that are often used to predict DMPK profiles of drug-like molecules have been selected for discussion. In vitro experimental assessment of metabolic stability made use of human liver microsomes, which was used to correlate theoretical predictions with experimental findings. Overall, the test compounds have been found to have acceptable physicochemical properties and fall within the ranges associated with “drug-like” molecules. Moreover, the compounds exhibited minimal degradation in incubations with human liver microsomes. Although some of these compounds have been reported previously (1, 2, 4 and 5), this is the first report on their antiparasitic activities, as well as assessment of their DMPK profiles. These results have therefore provided a window for further development of this novel class of sesquiterpene molecules as potential antiparasitic drugs.Graphical

Classics in Chemical Neuroscience: Xanomeline.

Xanomeline (1) is an orthosteric muscarinic acetylcholine receptor (mAChR) agonist, often referred to as M1/M4-preferring, that received widespread attention for its clinical efficacy in schizophrenia and Alzheimer's disease (AD) patients. Despite the compound's promising initial clinical results, dose-limiting side effects limited further clinical development. While xanomeline, and related orthosteric muscarinic agonists, have yet to receive approval from the FDA for the treatment of these CNS disorders, interest in the compound's unique M1/M4-preferring mechanism of action is ongoing in the field of chemical neuroscience. Specifically, the promising cognitive and behavioral effects of xanomeline in both schizophrenia and AD have spurred a renewed interest in the development of safer muscarinic ligands with improved subtype selectivity for either M1 or M4. This Review will address xanomeline's overall importance in the field of neuroscience, with a specific focus on its chemical structure and synthesis, pharmacology, drug metabolism and pharmacokinetics (DMPK), and adverse effects.

In Vivo and In Vitro Optimization of Screening Antimalarial Hits toward Lead Molecules for Preclinical Development

In order to overcome one of the greatest challenges in malaria treatment, drug resistance, new drug candidates are urgently needed, which should preferably act via novel mechanisms. Successful optimization of a phenotypic screening hit based on a quinoline-4-carboxamide derivative resulted in the highly promising lead structure 4, which according to the Medicines for Malaria Venture (MMV) met the efficacy and drug metabolism and pharmacokinetics (DMPK) requirements for a malaria drug target candidate and consequently was selected for preclinical development.

Discovery and Characterization of ACT-451840: an Antimalarial Drug with a Novel Mechanism of Action.

More than 40 % of the world's population is at risk of being infected with malaria. Most malaria cases occur in the countries of sub-Saharan Africa, Central and South America, and Asia. Resistance to standard therapy, including artemisinin combinations, is increasing. There is an urgent need for novel antimalarials with new mechanisms of action. In a phenotypic screen, we identified a series of phenylalanine-based compounds that exhibit antimalarial activity via a new and yet unknown mechanism of action. Our optimization efforts culminated in the selection of ACT-451840 [(S,E)-N-(4-(4-acetylpiperazin-1-yl)benzyl)-3-(4-(tert-butyl)phenyl)-N-(1-(4-(4-cyanobenzyl)piperazin-1-yl)-1-oxo-3-phenylpropan-2-yl)acrylamide] for clinical development. Herein we describe our optimization efforts from the screening hit to the potential drug candidate with respect to antiparasitic activity, drug metabolism and pharmacokinetics (DMPK) properties, and in vivo pharmacological efficacy.

Is there a paradigm shift in use of microsomes and hepatocytes in drug discovery and development?

Opinion

In vivo Real-Time Mass Spectrometry for Guided Surgery Application

Here we describe a new instrument (SpiderMass) designed for in vivo and real-time analysis. In this instrument ion production is performed remotely from the MS instrument and the generated ions are transported in real-time to the MS analyzer. Ion production is promoted by Resonant Infrared Laser Ablation (RIR-LA) based on the highly effective excitation of O-H bonds in water molecules naturally present in most biological samples. The retrieved molecular patterns are specific to the cell phenotypes and benign versus cancer regions of patient biopsies can be easily differentiated. We also demonstrate by analysis of human skin that SpiderMass can be used under in vivo conditions with minimal damage and pain. Furthermore SpiderMass can also be used for real-time drug metabolism and pharmacokinetic (DMPK) analysis or food safety topics. SpiderMass is thus the first MS based system designed for in vivo real-time analysis under minimally invasive conditions.

An Overall Comparison of Small Molecules and Large Biologics in ADME Testing

<p class="ADMETabstracttext">Biologics mainly monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) as new therapeutics are becoming increasingly important biotherapeutics. This review is intended to provide an overall comparison between small molecules (SMs) and biologics or large molecules (LMs) concerning drug metabolism and pharmacokinetic (DMPK) or associated with absorption, distribution, metabolism and elimination (ADME) testing from pharmaceutical industry drug discovery and development points of view, which will help design and conduct relevant ADME testing for biologics such as mAbs and ADCs. Recent advancements in the ADME for testing biologics and related bioanalytical methods are discussed with an emphasis on ADC drug development as an example to understand its complexity and challenges from extensive in vitro characterization to in vivo animal PK studies. General non-clinical safety evaluations of biologics in particular for ADC drugs are outlined including drug-drug interaction (DDI) and metabolite/catabolite assessments. Regulatory guidance on the ADME testing and safety evaluations including immunogenicity as well as bioanalytical considerations are addressed for LMs. In addition, the preclinical and human PK data of two marked ADC drugs (ADCETRIS, SGN-35 and KADCYLA, T-DM1) as examples are briefly discussed with regard to PK considerations and PK/PD perspectives.</p>

Optimizing DMPK Properties: Experiences from a Big Pharma DMPK Department

The disposition of a drug is dependent on interactions between the body and the drug, its molecular properties and the physical and biological barriers presented in the body. In order for a drug to have a desired pharmacological effect it has to have the right properties to be able to reach the target site in sufficient concentration. This review details how drug metabolism and pharmacokinetics (DMPK) and physicochemical deliveries played an important role in data interpretation and compound optimization at AstraZeneca R&D in Södertälje, Sweden. A selection of assays central in the evaluation of the DMPK properties of new chemical entities is presented, with guidance and consideration on assay outcome interpretation. Early in projects, solubility, LogD, permeability and metabolic stability were measured to support effective optimization of DMPK properties. Changes made to facilitate high throughput, efficient bioanalysis and the handling of large amounts of samples are described. Already early in drug discovery, we used an integrated approach for the prediction of the fate of drugs in human (early dose to man) based on data obtained from in vitro experiments. The early dose to man was refined with project progression, which triggered more intricate assays and experiments. At later stages, preclinical in vivo pharmacokinetic (PK) data was integrated with pharmacodynamics (PD) to allow predictions of required dose, dose intervals and exposure profile to achieve the desired effect in man. A well-defined work flow of DMPK activities from early lead identification up to the selection of a candidate drug was developed. This resulted in a cost effective and efficient optimization of chemical series, and facilitated informed decision making throughout project progress.

Evaluation of hepatic metabolism and pharmacokinetics of ibuprofen in rats under chronic hypobaric hypoxia for targeted therapy at high altitude

With studies indicative of altered drug metabolism and pharmacokinetics (DMPK) under high altitude (HA)-induced hypobaric hypoxia, consideration of better therapeutic approaches has continuously been aimed in research for HA related illness management. DMPK of drugs like ibuprofen may get affected under hypoxia which establishes the requirement of different therapeutic dose regimen to ensure safe and effective therapy at HA. This study examined the effects of the chronic hypobaric hypoxia (CHH) on hepatic DMPK of ibuprofen in rats. Experimental animals were exposed to simulated altitude of 7620m (∼25,000ft) for CHH exposure (7 or 14 days) in decompression chamber and administered with ibuprofen (80mg/kg, body weight, p.o.). Results demonstrated that CHH significantly altered PK variables of ibuprofen and activities of both phase-I and II hepatic metabolic enzymes as compared to the animals under normoxic conditions. Hepatic histopathological observations also revealed marked alterations. Increase in pro-inflammatory cytokines/chemokines viz. IL-1β, IL-2, IFN-γ, TNF-α exhibited close relevance with diminished CYP2C9 expression under CHH. Moreover, the down-regulated CYP2C9 level further supported the underlying mechanism for reduced metabolism of ibuprofen and as a result, increased retention of parent drug in the system. Increased mean retention time, Vd, T½ of ibuprofen, and decreased AUC, Cmax and clearance during CHH further strengthened the present findings. In conclusion, CHH exposure significantly affects hepatic DMPK of ibuprofen, which may further influence the usual therapeutic dose-regimen. Further, there is requirement of human studies to evaluate their susceptibility toward hypobaric hypoxia.

Discovery of a Novel HDAC3 Selective Inhibitor and its Evaluation in Lymphoma Model

Histone deacetylase (HDAC) inhibition is a potentially attractive approach to cancer therapy. A number of HDAC inhibitors are in clinical development stages for the treatment of cancer as well as immune and inflammatory disorders. Although there are several approved HDAC inhibitors by the US FDA, they show a broad inhibitory spectrum against HDAC subfamily. Herein, we synthesized a series of novel hydroxamate analogs, and evaluated them with lymphoma cancer cell. Conclusively, we identified an HDAC3 selective inhibitor which shows good anticancer activity for the lymphoma model, as well as a good drug metabolism and pharmacokinetics (DMPK) profile.

Discovery of Inhibitors of Trypanosoma brucei by Phenotypic Screening of a Focused Protein Kinase Library.

A screen of a focused kinase inhibitor library against Trypanosoma brucei rhodesiense led to the identification of seven series, totaling 121 compounds, which showed >50 % inhibition at 5 μm. Screening of these hits in a T. b. brucei proliferation assay highlighted three compounds with a 1H-imidazo[4,5-b]pyrazin-2(3H)-one scaffold that showed sub-micromolar activity and excellent selectivity against the MRC5 cell line. Subsequent rounds of optimisation led to the identification of compounds that exhibited good in vitro drug metabolism and pharmacokinetics (DMPK) properties, although in general this series suffered from poor solubility. A scaffold-hopping exercise led to the identification of a 1H-pyrazolo[3,4-b]pyridine scaffold, which retained potency. A number of examples were assessed in a T. b. brucei growth assay, which could differentiate static and cidal action. Compounds from the 1H-imidazo[4,5-b]pyrazin-2(3H)-one series were found to be either static or growth-slowing and not cidal. Compounds with the 1H-pyrazolo[3,4-b]pyridine scaffold were found to be cidal and showed an unusual biphasic nature in this assay, suggesting they act by at least two mechanisms.

Drug metabolism and pharmacokinetic diversity of ranunculaceae medicinal compounds.

The wide-reaching distributed angiosperm family Ranunculaceae has approximately 2200 species in around 60 genera. Chemical components of this family include several representative groups: benzylisoquinoline alkaloid (BIA), ranunculin, triterpenoid saponin and diterpene alkaloid, etc. Their extensive clinical utility has been validated by traditional uses of thousands of years and current evidence-based medicine studies. Drug metabolism and pharmacokinetic (DMPK) studies of plant-based natural products are an indispensable part of comprehensive medicinal plant exploration, which could facilitate conservation and sustainable utilization of Ranunculaceae pharmaceutical resources, as well as new chemical entity development with improved DMPK parameters. However, DMPK characteristics of Ranunculaceaederived medicinal compounds have not been summarized. Black cohosh (Cimicifuga) and goldenseal (Hydrastis) raise concerns of herbdrug interaction. DMPK studies of other Ranunculaceae genera, e.g., Nigella, Delphinium, Aconitum, Trollius, and Coptis, are also rapidly increasing and becoming more and more clinically relevant. In this contribution, we highlight the up-to-date awareness, as well as the challenges around the DMPK-related issues in optimization of drug development and clinical practice of Ranunculaceae compounds. Herb-herb interaction of Ranunculaceae herb-containing traditional Chinese medicine (TCM) formula could significantly influence the in vivo pharmacokinetic behavior of compounds thereof, which may partially explain the complicated therapeutic mechanism of TCM formula. Although progress has been made on revealing the absorption, distribution, metabolism, excretion and toxicity (ADME/T) of Ranunculaceae compounds, there is a lack of DMPK studies of traditional medicinal genera Aquilegia, Thalictrum and Clematis. Fluorescent probe compounds could be promising substrate, inhibitor and/or inducer in future DMPK studies of Ranunculaceae compounds. A better understanding of the important herb-drug/herb-herb interactions, bioavailability and metabolomics aspects of Ranunculaceae compounds will bolster future natural product-based drug design and the comprehensive investigation of inter-individual inconsistency of drug metabolism.

Pyridopyrimidinone Derivatives as Potent and Selective c-Jun N-Terminal Kinase (JNK) Inhibitors.

A novel series of 2-aminopyridopyrimidinone based JNK (c-jun N-terminal kinase) inhibitors were discovered and developed. Structure-activity relationships (SARs) were systematically developed utilizing biochemical and cell based assays and in vitro and in vivo drug metabolism and pharmacokinetic (DMPK) studies. Through the optimization of lead compound 1, several potent and selective JNK inhibitors with high oral bioavailability were developed. Inhibitor 13 was a potent JNK3 inhibitor (IC50 = 15 nM), had high selectivity against p38 (IC50 > 10 μM), had high potency in functional cell based assays, and had high stability in human liver microsome (t 1/2 = 76 min), a clean CYP-450 inhibition profile, and excellent oral bioavailability (%F = 87). Moreover, cocrystal structures of compounds 13 and 22 in JNK3 were solved at 2.0 Å. These structures elucidated the binding mode (Type-I binding) and can pave the way for further inhibitor design of this pyridopyrimidinone scaffold for JNK inhibition.

Synthesis, SAR, and series evolution of novel oxadiazole-containing 5-lipoxygenase activating protein inhibitors: discovery of 2-[4-(3-{(r)-1-[4-(2-amino-pyrimidin-5-yl)-phenyl]-1-cyclopropyl-ethyl}-[1,2,4]oxadiazol-5-yl)-pyrazol-1-yl]-N,N-dimethyl-acetamide (BI 665915).

The synthesis, structure-activity relationship (SAR), and evolution of a novel series of oxadiazole-containing 5-lipoxygenase-activating protein (FLAP) inhibitors are described. The use of structure-guided drug design techniques provided compounds that demonstrated excellent FLAP binding potency (IC50 < 10 nM) and potent inhibition of LTB4 synthesis in human whole blood (IC50 < 100 nM). Optimization of binding and functional potencies, as well as physicochemical properties resulted in the identification of compound 69 (BI 665915) that demonstrated an excellent cross-species drug metabolism and pharmacokinetics (DMPK) profile and was predicted to have low human clearance. In addition, 69 was predicted to have a low risk for potential drug-drug interactions due to its cytochrome P450 3A4 profile. In a murine ex vivo whole blood study, 69 demonstrated a linear dose-exposure relationship and a dose-dependent inhibition of LTB4 production.

Discovery and SAR of novel series of imidazopyrimidinones and dihydroimidazopyrimidinones as positive allosteric modulators of the metabotropic glutamate receptor 5 (mGlu5).

We report the discovery and SAR of two novel series of imidazopyrimidinones and dihydroimidazopyrimidinones as metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulators (PAMs). Exploration of several structural features in the western and eastern part of the imidazopyrimidinone core and combinations thereof, revealed compound 4a as a mGlu5 PAM with good in vitro potency and efficacy, acceptable drug metabolism and pharmacokinetic (DMPK) properties and in vivo efficacy in an amphetamine-based model of psychosis. However, the presence of CNS-mediated adverse effects in preclinical species precluded any further in vivo evaluation.

Pharmacokinetics in Drug Discovery: An Exposure-Centred Approach to Optimising and Predicting Drug Efficacy and Safety.

The role of pharmacokinetics (PK) in drug discovery is to support the optimisation of the absorption, distribution, metabolism and excretion (ADME) properties of lead compounds with the ultimate goal to attain a clinical candidate which achieves a concentration-time profile in the body that is adequate for the desired efficacy and safety profile. A thorough characterisation of the lead compounds aiming at the identification of the inherent PK liabilities also includes an early generation of PK/PD relationships linking in vitro potency and target exposure/engagement with expression of pharmacological activity (mode-of-action) and efficacy in animal studies. The chapter describes an exposure-centred approach to lead generation, lead optimisation and candidate selection and profiling that focuses on a stepwise generation of an understanding between PK/exposure and PD/efficacy relationships by capturing target exposure or surrogates thereof and cellular mode-of-action readouts in vivo. Once robust PK/PD relationship in animal PD models has been constructed, it is translated to anticipate the pharmacologically active plasma concentrations in patients and the human therapeutic dose and dosing schedule which is also based on the prediction of the PK behaviour in human as described herein. The chapter outlines how the level of confidence in the predictions increases with the level of understanding of both the PK and the PK/PD of the new chemical entities (NCE) in relation to the disease hypothesis and the ability to propose safe and efficacious doses and dosing schedules in responsive patient populations. A sound identification of potential drug metabolism and pharmacokinetics (DMPK)-related development risks allows proposing of an effective de-risking strategy for the progression of the project that is able to reduce uncertainties and to increase the probability of success during preclinical and clinical development.

Design and synthesis of highly potent and isoform selective JNK3 inhibitors: SAR studies on aminopyrazole derivatives.

The c-jun N-terminal kinase 3 (JNK3) is expressed primarily in the brain. Numerous reports have shown that inhibition of JNK3 is a promising strategy for treatment of neurodegeneration. The optimization of aminopyrazole-based JNK3 inhibitors with improved potency, isoform selectivity, and pharmacological properties by structure–activity relationship (SAR) studies utilizing biochemical and cell-based assays, and structure-based drug design is reported. These inhibitors had high selectivity over JNK1 and p38α, minimal cytotoxicity, potent inhibition of 6-OHDA-induced mitochondrial membrane potential dissipation and ROS generation, and good drug metabolism and pharmacokinetic (DMPK) properties for iv dosing. 26n was profiled against 464 kinases and was found to be highly selective hitting only seven kinases with >80% inhibition at 10 μM. Moreover, 26n showed good solubility, good brain penetration, and good DMPK properties. Finally, the crystal structure of 26k in complex with JNK3 was solved at 1.8 Å to explore the binding mode of aminopyrazole based JNK3 inhibitors.