A cross-species assessment of in silico prediction methods of steady-state volume of distribution using Simcyp simulators.

Predicting steady-state volume of distribution (V) is a key component of pharmacokinetic predictions and often guided using preclinical data. However, when bottom-up prediction from physiologically-based pharmacokinetic (PBPK) models and observed V misalign in preclinical species, or predicted V from different models varies significantly, no consensus exists for selecting models or preclinical species to improve the prediction. Through systematic analysis of V prediction across rat, dog, monkey, and human, using common methods, a practical strategy for predicting human V, with or without integration of preclinical PK information is warranted.

KT-253, A Novel MDM2 Degrader and p53 Stabilizer, Has Superior Potency and Efficacy Than MDM2 Small Molecule Inhibitors.

Murine double minute 2 (MDM2) is an E3 ligase that inhibits the tumor suppressor protein p53. Clinical trials employing small-molecule MDM2/p53 interaction inhibitors (SMIs) have demonstrated limited activity, underscoring an unmet need for a better approach to target MDM2. KT 253 is a highly potent and selective heterobifunctional degrader that overcomes the MDM2 feedback loop seen with SMIs and induces apoptosis in a range of hematologic and solid tumor lines.

Pharmacologic Activation of STING in the Bladder Induces Potent Antitumor Immunity in Non-Muscle Invasive Murine Bladder Cancer.

Stimulator of interferon genes (STING) is an innate immune receptor activated by natural or synthetic agonists to elicit antitumoral immune response via type I IFNs and other inflammatory cytokines. Bacillus Calmette-Guerin (BCG) is the standard of care as intravesical therapy for patients with high-risk non-muscle invasive bladder cancer (NMIBC). There are limited options available for patients with NMIBC who developed BCG unresponsiveness.

Prediction of Transporter-Mediated Drug-Drug Interactions and Phenotyping of Hepatobiliary Transporters Involved in the Clearance of E7766, a Novel Macrocycle-Bridged Dinucleotide.

E7766 represents a novel class of macrocycle-bridged dinucleotides and is under clinical development for immuno-oncology. In this report, we identified mechanism of systemic clearance E7766 and investigated the hepatobiliary transporters involved in the disposition of E7766 and potential drug interactions of E7766 as a victim of organic anion-transporting polypeptide (OATP) inhibitors. In bile-duct cannulated rats and dogs, E7766 was mainly excreted unchanged in bile (>80%) and to a lesser extent in urine (<20%).

Physiologically-Based Pharmacokinetic Modeling in Renal and Hepatic Impairment Populations: A Pharmaceutical Industry Perspective.

The predictive performance of physiologically-based pharmacokinetics (PBPK) models for pharmacokinetics (PK) in renal impairment (RI) and hepatic impairment (HI) populations was evaluated using clinical data from 29 compounds with 106 organ impairment study arms were collected from 19 member companies of the International Consortium for Innovation and Quality in Pharmaceutical Development. Fifty RI and 56 HI study arms with varying degrees of organ insufficiency along with control populations were evaluated. For RI, the area under the curve (AUC) ratios of RI to healthy control were predicted within twofold of the observed ratios for > 90% (N = 47/50 arms).

First-in-human study of the PARP/tankyrase inhibitor E7449 in patients with advanced solid tumours and evaluation of a novel drug-response predictor.

Background: This phase 1 study examined the safety, maximum-tolerated dose (MTD) and antitumour activity of E7449, a novel PARP 1/2 and tankyrase 1/2 inhibitor.

Methods: E7449 was orally administered once daily in 28-day cycles to patients with advanced solid tumours (50-800-mg doses). Archival tumour samples from consenting patients were evaluated for the expression of 414 genes in a biomarker panel (2X-121 drug-response predictor [DRP]) found to be predictive of the response to E7449 in cell lines.

Physiologically-Based Pharmacokinetic Models for Evaluating Membrane Transporter Mediated Drug-Drug Interactions: Current Capabilities, Case Studies, Future Opportunities, and Recommendations.

Physiologically-based pharmacokinetic (PBPK) modeling has been extensively used to quantitatively translate in vitro data and evaluate temporal effects from drug-drug interactions (DDIs), arising due to reversible enzyme and transporter inhibition, irreversible time-dependent inhibition, enzyme induction, and/or suppression. PBPK modeling has now gained reasonable acceptance with the regulatory authorities for the cytochrome-P450-mediated DDIs and is routinely used. However, the application of PBPK for transporter-mediated DDIs (tDDI) in drug development is relatively uncommon.

Celecoxib is a substrate of CYP2D6: Impact on celecoxib metabolism in individuals with CYP2C9*3 variants.

Celecoxib was characterized as a substrate of human cytochrome P450 (CYP) 2D6 in vitro. In recombinant CYP2D6, celecoxib hydroxylation showed atypical substrate inhibition kinetics with apparent K, K, and V of 67.2 μM, 12.

Application of Micropatterned Cocultured Hepatocytes to Evaluate the Inductive Potential and Degradation Rate of Major Xenobiotic Metabolizing Enzymes.

Long-term coculture models of hepatocytes are promising tools to study drug transport, clearance, and hepatoxicity. In this report we compare the basal expression of drug disposition genes and the inductive response of prototypical inducers (rifampin, phenobarbital, phenytoin) in hepatocyte two-dimensional monocultures and the long-term coculture model (HepatoPac). All the inducers used in the study increased the expression and activity of CYP3A4, CYP2B6 and CYP2C enzymes in the HepatoPac cultures.

Discovery and Characterization of a Water-Soluble Prodrug of a Dual Inhibitor of Bacterial DNA Gyrase and Topoisomerase IV.

Benzimidazole 1 is the lead compound resulting from an antibacterial program targeting dual inhibitors of bacterial DNA gyrase and topoisomerase IV. With the goal of improving key drug-like properties, namely, the solubility and the formulability of 1, an effort to identify prodrugs was undertaken. This has led to the discovery of a phosphate ester prodrug 2.

Single B-cell deconvolution of peanut-specific antibody responses in allergic patients.

Background: The frequencies, cellular phenotypes, epitope specificity, and clonal diversity of allergen-specific B cells in patients with food allergy are not fully understood but are of major pathogenic and therapeutic significance.

Objective: We sought to characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy.

Methods: B cells binding fluorescently labeled Ara h 1 or Ara h 2 were phenotyped and isolated by means of flow cytometric sorting from 18 patients at baseline and 13 patients during therapy.

B-cell repertoire responses to varicella-zoster vaccination in human identical twins.

Adaptive immune responses in humans rely on somatic genetic rearrangements of Ig and T-cell receptor loci to generate diverse antigen receptors. It is unclear to what extent an individual's genetic background affects the characteristics of the antibody repertoire used in responding to vaccination or infection. We studied the B-cell repertoires and clonal expansions in response to attenuated varicella-zoster vaccination in four pairs of adult identical twins and found that the global antibody repertoires of twin pair members showed high similarity in antibody heavy chain V, D, and J gene segment use, and in the length and features of the complementarity-determining region 3, a major determinant of antigen binding.

Second-generation antibacterial benzimidazole ureas: discovery of a preclinical candidate with reduced metabolic liability.

Compound 3 is a potent aminobenzimidazole urea with broad-spectrum Gram-positive antibacterial activity resulting from dual inhibition of bacterial gyrase (GyrB) and topoisomerase IV (ParE), and it demonstrates efficacy in rodent models of bacterial infection. Preclinical in vitro and in vivo studies showed that compound 3 covalently labels liver proteins, presumably via formation of a reactive metabolite, and hence presented a potential safety liability. The urea moiety in compound 3 was identified as being potentially responsible for reactive metabolite formation, but its replacement resulted in loss of antibacterial activity and/or oral exposure due to poor physicochemical parameters.

Convergent antibody signatures in human dengue.

Dengue is the most prevalent mosquito-borne viral disease in humans, and the lack of early prognostics, vaccines, and therapeutics contributes to immense disease burden. To identify patterns that could be used for sequence-based monitoring of the antibody response to dengue, we examined antibody heavy-chain gene rearrangements in longitudinal peripheral blood samples from 60 dengue patients. Comparing signatures between acute dengue, postrecovery, and healthy samples, we found increased expansion of B cell clones in acute dengue patients, with higher overall clonality in secondary infection.

Polyproline fold-In imparting kinetic stability to an alkaline serine endopeptidase.

Polyproline II (PPII) fold, an unusual structural element was detected in the serine protease from Nocardiopsis sp. NCIM 5124 (NprotI) based on far UV circular dichroism spectrum, structural transitions of the enzyme in presence of GdnHCl and a distinct isodichroic point in chemical and thermal denaturation. The functional activity and conformational transitions of the enzyme were studied under various denaturing conditions.

Complex drug interactions of HIV protease inhibitors 2: in vivo induction and in vitro to in vivo correlation of induction of cytochrome P450 1A2, 2B6, and 2C9 by ritonavir or nelfinavir.

Drug-drug interactions (DDIs) with the HIV protease inhibitors (PIs) are complex, paradoxical (e.g., ritonavir/alprazolam), and involve multiple mechanisms.

A comparison of the roles of peroxisome proliferator-activated receptor and retinoic acid receptor on CYP26 regulation.

The cytochrome P450 26 family is believed to be responsible for all-trans-retinoic acid (atRA) metabolism and elimination in the human fetus and adults. CYP26A1 and CYP26B1 mRNA is expressed in a tissue-specific manner, and mice in which the CPY26 isoform has been knocked out show distinct malformations and lethality. The aim of this study was to determine differences in CYP26A1 and CYP26B1 regulation and expression.

Expression and functional characterization of cytochrome P450 26A1, a retinoic acid hydroxylase.

Retinoic acid (RA) is a critical signaling molecule that performs multiple functions required to maintain cellular viability. It is also used in the treatment of some cancers. Enzymes in the CYP26 family are thought to be responsible for the elimination of RA, and CYP26A1 appears to serve the most critical functions in this family.

Age-dependent kinetics and metabolism of dichloroacetate: possible relevance to toxicity.

Dichloroacetate (DCA) is an investigational drug for certain metabolic diseases. It is biotransformed principally by the zeta-1 family isoform of glutathione transferase (GSTz1), also known as maleylacetoacetate isomerase (MAAI), which catalyzes the penultimate step in tyrosine catabolism. DCA causes a reversible peripheral neuropathy in several species, including humans.

Cytochrome P450 enzymes and transporters induced by anti-human immunodeficiency virus protease inhibitors in human hepatocytes: implications for predicting clinical drug interactions.

Although many of the clinically significant drug interactions of the anti-human immunodeficiency virus (HIV) protease inhibitors (PIs) can be explained by their propensity to inactivate CYP3A enzymes, paradoxically these drugs cause (or lack) interactions with CYP3A substrates that cannot be explained by this mechanism (e.g., alprazolam).

In vitro LC-MS cocktail assays to simultaneously determine human cytochrome P450 activities.

Using liquid chromatography-mass spectrometry (LC-MS), two sensitive cocktail assays were developed, one to simultaneously determine activities of the cytochrome P450 enzymes, CYP1A2 (phenacitin), 2B6 (bupropion), 2C8 (amodiaquine) and 2C19 (omperazole), and the other to determine simultaneously activities of CYP3A4/5 (testosterone), 2C9 (tolbutamide) and 2D6 (dextromethorphan). These cocktail assays are sensitive, require only a small amount of microsomal protein, employ selective and high turnover CYP substrates and do not require post-incubation extraction. In each of these cocktails, no interactions were observed between the substrates.

Comparative analysis of two classes of quorum-sensing signaling systems that control production of extracellular proteins and secondary metabolites in Erwinia carotovora subspecies.

In Erwinia carotovora subspecies, N-acyl homoserine lactone (AHL) controls the expression of various traits, including extracellular enzyme/protein production and pathogenicity. We report here that E. carotovora subspecies possess two classes of quorum-sensing signaling systems defined by the nature of the major AHL analog produced as well as structural and functional characteristics of AHL synthase (AhlI) and AHL receptor (ExpR).

Inhibition and recovery of rat hepatic glutathione S-transferase zeta and alteration of tyrosine metabolism following dichloroacetate exposure and withdrawal.

Dichloroacetate (DCA) is an investigational drug for certain metabolic disorders, a by-product of water chlorination and a metabolite of certain industrial solvents and drugs. DCA is biotransformed to glyoxylate by glutathione S-transferase zeta (GSTz1-1), which is identical to maleylacetoacetate isomerase, an enzyme of tyrosine catabolism. Clinically relevant doses of DCA (mg/kg/day) decrease the activity and expression of GSTz1-1, which alters tyrosine metabolism and may cause hepatic and neurological toxicity.

ExpR, a LuxR homolog of Erwinia carotovora subsp. carotovora, activates transcription of rsmA, which specifies a global regulatory RNA-binding protein.

N-acyl homoserine lactone (AHL) is required by Erwinia carotovora subspecies for the expression of various traits, including extracellular enzyme and protein production and pathogenicity. Previous studies with E. carotovora subsp.