Publications by authors named "Scott Summerfield"

33 Publications

Half-Life Extension of BMP1/TLL Metalloproteinase Inhibitors Using Small-Molecule Human Serum Albumin Binders.

Bioconjug Chem 2021 02 1;32(2):279-289. Epub 2021 Feb 1.

GlaxoSmithKline US, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States.

Reducing the required frequence of drug dosing can improve the adherence of patients to chronic treatments. Hence, drugs with longer half-lives are highly desirable. One of the most promising approaches to extend the half-life of drugs is conjugation to human serum albumin (HSA). In this work, we describe the use of , a small-molecule noncovalent HSA binder, to extend the half-life and pharmacology of small-molecule BMP1/TLL inhibitors in humanized mice (HSA KI/KI). A series of conjugates of with BMP1/TLL inhibitors were prepared. In particular, showed good solubility and a half-life extension of >20-fold versus the parent molecule in the HSA KI/KI mice, reaching half-lives of >48 h with maintained maximal inhibition of plasma BMP1/TLL. The same conjugate showed a half-life of only 3 h in the wild-type mice, suggesting that the half-life extension was principally due to specific interactions with HSA. It is envisioned that conjugation to should be applicable to a wide range of small molecule or peptide drugs with short half-lives. In this context, AlbuBinders represent a viable alternative to existing half-life extension technologies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.bioconjchem.0c00662DOI Listing
February 2021

2020 White Paper on Recent Issues in Bioanalysis: BMV of Hybrid Assays, Acoustic MS, HRMS, Data Integrity, Endogenous Compounds, Microsampling and Microbiome ( - Recommendations on Industry/Regulators Consensus on BMV of Biotherapeutics by LCMS, Advanced Application in Hybrid Assays, Regulatory Challenges in Mass Spec, Innovation in Small Molecules, Peptides and Oligos).

Bioanalysis 2021 Feb 20;13(4):203-238. Epub 2021 Jan 20.

Bristol-Myers Squibb, Pennington, NJ, USA.

The 14 edition of the Workshop on Recent Issues in Bioanalysis (14 WRIB) was held virtually on June 15-29, 2020 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations, and regulatory agencies worldwide. The 14 WRIB included three Main Workshops, seven Specialized Workshops that together spanned 11 days in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccine. Moreover, a comprehensive vaccine assays track; an enhanced cytometry track and updated Industry/Regulators consensus on BMV of biotherapeutics by Mass Spectrometry (hybrid assays, LCMS and HRMS) were special features in 2020. As in previous years, this year's WRIB continued to gather a wide diversity of international industry opinion leaders and regulatory authority experts working on both small and large molecules to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance and achieving scientific excellence on bioanalytical issues. This 2020 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the Global Bioanalytical Community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2020 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication covers the recommendations on (Part 1) Hybrid Assays, Innovation in Small Molecules, & Regulated Bioanalysis. Part 2A (BAV, PK LBA, Flow Cytometry Validation and Cytometry Innovation), Part 2B (Regulatory Input) and Part 3 (Vaccine, Gene/Cell Therapy, NAb Harmonization and Immunogenicity) are published in volume 13 of Bioanalysis, issues 5, and 6 (2021), respectively.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2020-0324DOI Listing
February 2021

Perspectives on gender parity in bioanalysis: an interview with Scott Summerfield.

Bioanalysis 2019 Apr 18;11(7):675-676. Epub 2019 Apr 18.

Department of Bioanalysis, Immunogenicity & Biomarkers, GlaxoSmithKline R&D, Park Road, Ware, SG12 0DP, UK.

Biography Having studied for a PhD and postdoctoral fellowship in proteomics Scott moved into the field of regulated Bioanalysis in 1997 when joining SmithKline Beecham. In 2001, Scott moved to Neuroscience Drug Discovery to lead a bioanalytical team supporting PK, DMPK and metabolite id work. In 2009, he returned to the regulated bioanalytical group, initially as a Section Leader and subsequently as Site Head and currently as WW Head of Bioanalysis at GSK. Scott has experience of small and molecule bioanalysis as well as leading both bioanalytical and discovery and development project teams across GSK.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2019-0073DOI Listing
April 2019

2018 White Paper on Recent Issues in Bioanalysis: 'A global bioanalytical community perspective on last decade of incurred samples reanalysis (ISR)' (Part 1 - small molecule regulated bioanalysis, small molecule biomarkers, peptides & oligonucleotide bioanalysis).

Bioanalysis 2018 Nov 29;10(22):1781-1801. Epub 2018 Nov 29.

US FDA, Silver Spring, MD, USA.

The 2018 12 Workshop on Recent Issues in Bioanalysis (12th WRIB) took place in Philadelphia, PA, USA on April 9-13, 2018 with an attendance of over 900 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day full immersion in bioanalysis, biomarkers and immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LC-MS, hybrid ligand binding assay (LBA)/LC-MS and LBA/cell-based assays approaches. This 2018 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2018 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for LC-MS for small molecules, peptides, oligonucleotides and small molecule biomarkers. Part 2 (hybrid LBA/LC-MS for biotherapeutics and regulatory agencies' inputs) and Part 3 (large molecule bioanalysis, biomarkers and immunogenicity using LBA and cell-based assays) are published in volume 10 of Bioanalysis, issues 23 and 24 (2018), respectively.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2018-0268DOI Listing
November 2018

The importance of evaluating the chemical structures and strategies to avoid pitfalls in quantitative bioanalysis.

Bioanalysis 2019 Jan 26;11(2):85-101. Epub 2018 Nov 26.

Bioanalysis, Immunogenicity, & Biomarkers, PTS-In Vivo/In Vitro Translation, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA.

Quantitative bioanalytical data are crucial in pharmaceutical research and development, allowing project teams to make informed scientific decisions on the progression of candidate molecules to medicines. Many challenges are often encountered during the bioanalysis of drugs in biological matrices which require resolution in a timely manner. In this publication, guidance is provided to bioanalytical scientists on how to identify potential problems before they become an obstacle for the drug development and to share our experiences dealing some of most common problems encountered in the bioanalytical laboratory. Relevant topics in bioanalysis such as stabilization approaches for glucuronides (Acyl and N-); prodrugs (phosphate and esters), amides, amines, N-oxides; bioanalysis of light sensitive molecules, halogenated drugs and lactones are discussed in this publication.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2018-0211DOI Listing
January 2019

The business of bioanalysis: new technology integration into bioanalytical workflows.

Bioanalysis 2018 Nov 23;10(22):1775-1779. Epub 2018 Oct 23.

Nominal Mass Platforms, SCIEX, 71 Four Valley Drive, Concord, ON, L4K 4V8, Canada.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2018-0269DOI Listing
November 2018

Incurred sample reanalysis at GSK: what have we learned?

Bioanalysis 2018 Nov 16;10(21):1755-1766. Epub 2018 Oct 16.

Department of Bioanalysis, Immunogenicity & Biomarkers, GlaxoSmithKline R&D, Park Road, Ware, SG12 0DP, UK.

Outcomes of incurred sample reanalysis (ISR) studies have been reviewed from a decade of internally supported bioanalysis. From over 1000 bioanalytical pharmacokinetic end points, 26 bioanalytical studies have failed against predefined ISR acceptance criteria, ultimately resulting in the rejection of three partial and two full datasets (instability or preanalytic contamination). The remaining investigations highlighted methodological root causes including unexpected within-study assay variability, inappropriate assay range and sample homogeneity. However, the data variability remained acceptable for the purposes of decision-making and asset progression. Overall, ISR adds value in early development to characterize the reliability of a nascent assay and then also at the latter stages where pharmacokinetic data are pivotal to submission. However, for the intermediate development studies there is a question whether ISR adds much additional value in understanding assay performance or whether the industry is just too conservative to follow the guidance. This is where the future debate must be.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2018-0204DOI Listing
November 2018

The business of bioanalysis: summary of panel discussions.

Bioanalysis 2018 08 23;10(15):1169-1175. Epub 2018 Jul 23.

Astra Zeneca, Building 623, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2018-0153DOI Listing
August 2018

Rapid Bioavailability and Disposition protocol: A novel higher throughput approach to assess pharmacokinetics and steady-state brain distribution with reduced animal usage.

Eur J Pharm Sci 2018 Sep 29;122:13-21. Epub 2018 May 29.

Platform Technology and Science, GlaxoSmithKline R&D Shanghai, China.

Besides routine pharmacokinetic (PK) parameters, unbound brain-to-blood concentration ratio (K) is an index particularly crucial in drug discovery for central nervous system (CNS) indications. Despite advantages of K from steady state after constant intravenous (i.v.) infusion compared with one- or multiple time points after transient dosing, it is seldom obtained for compound optimization in early phase of CNS drug discovery due to requirement of prerequisite PK data to inform the study design. Here, we designed a novel rat in vivo PK protocol, dubbed as Rapid Bioavailability and Disposition (RBD), which combined oral (p.o.) dosing and i.v. infusion to obtain steady-state brain penetration, along with blood clearance, oral exposure and oral bioavailability for each discovery compound, within a 24 hour in-life experiment and only a few (e.g., 3) animals. Protocol validity was verified through simulations with a range of PK parameters in compartmental models as well as data comparison for nine compounds with distinct PK profiles. PK parameters (K, CL and oral AUC) measured from the RBD protocol for all compounds, were within two-fold and/or statistically similar to those derived from conventional i.v./p.o. crossover PK studies. Our data clearly indicates that the RBD protocol offers reliable and reproducible data over a wide range of PK properties, with reduced turnaround time and animal usage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejps.2018.05.027DOI Listing
September 2018

Prediction of brain:blood unbound concentration ratios in CNS drug discovery employing in silico and in vitro model systems.

Drug Discov Today 2018 07 13;23(7):1357-1372. Epub 2018 Mar 13.

Platform Technology and Science, GlaxoSmithKline R&D Center, Shanghai, China.

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) in CNS drug discovery. Here, we review the recent developments in the in silico and in vitro model systems to predict the K of discovery compounds with special emphasis on the in-vitro-in-vivo correlation. We also discuss clinical 'translation' of rodent K and highlight the future directions for improvement in brain penetration prediction. Important in this regard are in silico K 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.drudis.2018.03.002DOI Listing
July 2018

Drug Distribution into Peripheral Nerve.

J Pharmacol Exp Ther 2018 05 6;365(2):336-345. Epub 2018 Mar 6.

Department of Mechanistic Safety and Disposition (H.L., X.S., T.F., S.W.), Bioanalysis, Immunogenicity and Biomarkers (L.H., X.Z., K.D.), Integrated Biological Platform Sciences (Y.C., We.Z., J.L., J.W.), Brain Delivery Technologies (Wa.Z.), Platform Technology and Science (G.C.T.), and Department of Neuroexcitation Discovery Performance Unit (G.L., W.C., T.Y., X.Y., Z.W.), GlaxoSmithKline R&D, Shanghai, People's Republic of China; and Department of Bioanalysis, Immunogenicity and Biomarkers, Platform Technology and Science, GlaxoSmithKline, Ware, United Kingdom (S.G.S.).

Little is known about the impact of the blood-nerve barrier (BNB) on drug distribution into peripheral nerves. In this study, we examined the peripheral nerve penetration in rats of 11 small-molecule drugs possessing diverse physicochemical and transport properties and ProTx-II, a tarantula venom peptide with molecular mass of 3826 Daltons. Each drug was administered as constant rate intravenous infusion for 6 hours (small molecules) or 24 hours (ProTx-II). Blood and tissues including brain, spinal cord, sciatic nerve, and dorsal root ganglion (DRG) were collected for drug concentration measurements. Unbound fractions of a set of compounds were determined by equilibrium dialysis method in rat blood, brains, spinal cords, sciatic nerves, and DRG. We also investigated the influence of -[4-[2-(6,7-dimethoxy-3,4-dihydro-1-isoquinolin-2-yl)ethyl]phenyl]-5-methoxy-9-oxo-10-acridine-4-carboxamide (GF120918), a P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) inhibitor, on the peripheral nerve and central nervous system (CNS) tissue penetration of imatinib. We found that: 1) the unbound fraction in brain tissue homogenate highly correlates with that in the spinal cord, sciatic nerve, and DRG for a set of compounds and thus provides a good surrogate for spinal cord and peripheral nerve tissues, 2) small-molecule drugs investigated can penetrate the DRG and sciatic nerve, 3) P-gp and BCRP have a limited impact on the distribution of small-molecule drugs into peripheral nerves, and 4) DRG is permeable to ProTx-II, but its distribution into sciatic nerve and CNS tissues is restricted. These results demonstrate that small-molecule drugs investigated can penetrate peripheral nerve tissues, and P-gp/BCRP may not be a limiting factor at the BNB. Biologics as large as ProTx-II can access the DRG but not sciatic nerve and CNS tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1124/jpet.117.245613DOI Listing
May 2018

Toward best practices in data processing and analysis for intact biotherapeutics by MS in quantitative bioanalysis.

Bioanalysis 2017 Dec 24;9(23):1883-1893. Epub 2017 Nov 24.

Bioanalysis, Immunogenicity & Biomarkers, In vitro/In vivo Translation Platform, R&D Platform Technology & Science, GSK, 709 Swedeland Rd. King of Prussia, PA, 19460, USA.

Aim: Typically, quantitation of biotherapeutics from biological matrices by LC-MS is based on a surrogate peptide approach to determine molecule concentration. Recent efforts have focused on quantitation of the intact protein molecules or larger mass subunits of monoclonal antibodies. To date, there has been limited guidance for large or intact protein mass quantitation for quantitative bioanalysis.

Methodology: Intact- and subunit-level analyses of biotherapeutics from biological matrices are performed at 12-25 kDa mass range with quantitation data presented.

Results: Linearity, bias and other metrics are presented along with recommendations made on the viability of existing quantitation approaches.

Conclusion: This communication is intended to start a discussion around intact protein data analysis and processing, recognizing that other published contributions will be required.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2017-0179DOI Listing
December 2017

2017 White Paper on recent issues in bioanalysis: aren't BMV guidance/guidelines 'Scientific'? (Part 1 - LCMS: small molecules, peptides and small molecule biomarkers).

Bioanalysis 2017 Nov 17;9(22):1807-1825. Epub 2017 Nov 17.

Pfizer, Groton, CT, USA.

The 2017 11th Workshop on Recent Issues in Bioanalysis (11th WRIB) took place in Los Angeles/Universal City, California from 3 April 2017 to 7 April 2017 with participation of close to 750 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, weeklong event - A Full Immersion Week of Bioanalysis, Biomarkers and Immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small and large molecule analysis involving LCMS, hybrid LBA/LCMS and ligand-binding assay (LBA) approaches. This 2017 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2017 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for Small Molecules, Peptides and Small Molecule Biomarkers using LCMS. Part 2 (Biotherapeutics, Biomarkers and Immunogenicity Assays using Hybrid LBA/LCMS and Regulatory Agencies' Inputs) and Part 3 (LBA: Immunogenicity, Biomarkers and PK Assays) are published in volume 9 of Bioanalysis, issues 23 and 24 (2017), respectively.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2017-4975DOI Listing
November 2017

Correlation between Membrane Protein Expression Levels and Transcellular Transport Activity for Breast Cancer Resistance Protein.

Drug Metab Dispos 2017 05 16;45(5):449-456. Epub 2017 Feb 16.

Departments of Mechanistic Safety and Disposition (H.L., T.F., X.S.), Bioanalysis, Immunogenicity and Biomarker (L.H., R.G., K.D.), Protein, Cellular and Structural Sciences (Q.C.), Modeling and Computational Sciences (Y.-Y.Z.), Integrated Biological Platform Sciences (W.Z.), and Drug Metabolism and Pharmacokinetics (Y.L., J.S.), Platform Technology and Science, GlaxoSmithKline R&D China; and Department of Bioanalysis, Immunogenicity and Biomarker (S.S.), Platform Technology and Science, GlaxoSmithKline, Ware, United Kingdom.

Emerging evidence indicates an important role for the breast cancer resistance protein (BCRP) in limiting brain penetration of substrate drugs. While in vitro transwell assays can provide an indication of BCRP substrate potential, the predictability of these assays in relation to in vivo brain penetration is still under debate. The present study examined the correlation of BCRP membrane protein expression level and transcellular transport activity across Madin-Darby canine kidney (MDCK) II monolayers. We expressed human BCRP or murine BCRP1 in MDCKII wild-type cells using BacMam2 virus transduction. The selective P-glycoprotein (P-gp) inhibitor LY335979 (1 M) was included in the transport medium to measure BCRP-mediated transcellular transport for P-gp and BCRP cosubstrates. The BCRP levels in membrane extracts from MDCKII-BCRP or MDCKII-Bcrp1 cells were quantified by liquid chromatography-tandem mass spectrometry. The results are summarized as follows: 1) the membrane protein expression levels correlate with the corrected efflux ratios of substrates for human BCRP and murine BCRP1 within the efflux ratios investigated; 2) we demonstrate good concordance in rank order between the BCRP and BCRP1-mediated efflux ratios for 12 drugs; and 3) we propose an approach to contextualize in vitro BCRP transport data of discovery compounds by comparing them to the in vitro and in vivo transport data of the reference drug dantrolene and taking into account interbatch variation in BCRP expression. This approach correctly predicted compromised brain penetration for 25 discovery compounds in rodents, which were BCRP substrates but not P-gp or weak P-gp substrates. These results suggest that BCRP-expressing MDCKII cells are useful in predicting the in vivo role of BCRP in brain penetration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1124/dmd.116.074245DOI Listing
May 2017

From patient to tube: the importance of physiologically relevant quantitative bioanalytical assays.

Bioanalysis 2016 Dec;8(24):2595-2604

GlaxoSmithKline R&D, Park Road, Ware, Herts SG12 0DP, UK.

Circulating drug concentrations (clinical or preclinical) underly many interactions between industry and regulators; expressing safety coverage, pharmacokinetic-pharmacodynamic relationships or defining bioequivalence and dosing regimens. Accurate and precise measurement of these circulating concentrations is pivotal to the evolution and validation of any bioanalytical method that supports regulatory interactions. Since the bioanalyst is presented with a sub-aliquot of sampled biological matrix, how do they ensure this aliquot reflects the concentration in the subject at the time of collection? Here we share experiences from project support (internal and at CROs) that suggests we need to be ever vigilant translating the needs of bioanalysis with those of project teams. The simple mantra is for bioanalytical measurements to be physiologically relevant to the patient.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2016-0214DOI Listing
December 2016

2016 White Paper on recent issues in bioanalysis: focus on biomarker assay validation (BAV) (Part 1 - small molecules, peptides and small molecule biomarkers by LCMS).

Bioanalysis 2016 Nov 7;8(22):2363-2378. Epub 2016 Oct 7.

Novartis, East Hanover, NJ, USA.

The 2016 10 Workshop on Recent Issues in Bioanalysis (10 WRIB) took place in Orlando, Florida with participation of close to 700 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations, and regulatory agencies worldwide. WRIB was once again a 5-day, weeklong event - A Full Immersion Week of Bioanalysis including Biomarkers and Immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small and large molecule analysis involving LCMS, hybrid LBA/LCMS, and LBA approaches, with the focus on biomarkers and immunogenicity. This 2016 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. This white paper is published in 3 parts due to length. This part (Part 1) discusses the recommendations for small molecules, peptides and small molecule biomarkers by LCMS. Part 2 (Hybrid LBA/LCMS and regulatory inputs from major global health authorities) and Part 3 (large molecule bioanalysis using LBA, biomarkers and immunogenicity) will be published in the Bioanalysis journal, issue 23.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2016-4992DOI Listing
November 2016

Issues facing the bioanalytical community: summary of round table discussions.

Bioanalysis 2016 Nov 19;8(21):2189-2193. Epub 2016 Sep 19.

Merck Research Labs, Department of Pharmacokinetics, Pharmacodynamics & Drug Metabolism, West Point, PA 19486, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio-2016-4993DOI Listing
November 2016

Examining the Uptake of Central Nervous System Drugs and Candidates across the Blood-Brain Barrier.

J Pharmacol Exp Ther 2016 08 18;358(2):294-305. Epub 2016 May 18.

GlaxoSmithKline R&D, Platform Technology and Science, Park Road, Ware (S.G.S); and GlaxoSmithKline R&D, Platform Technology and Science, Zhangjiang Hi-Tech Park, Pudong, Shanghai, China (Y.Z., H.L.).

Assessing the equilibration of the unbound drug concentrations across the blood-brain barrier (Kp,uu) has progressively replaced the partition coefficient based on the ratio of the total concentration in brain tissue to blood (Kp). Here, in vivo brain distribution studies were performed on a set of central nervous system (CNS)-targeted compounds in both rats and P-glycoprotein (P-gp) genetic knockout mice. Several CNS drugs are characterized by Kp,uu values greater than unity, inferring facilitated uptake across the rodent blood-brain barrier (BBB). Examples are shown in which Kp,uu also increases above unity on knockout of P-gp, highlighting the composite nature of this parameter with respect to facilitated BBB uptake, efflux, and passive diffusion. Several molecules with high Kp,uu values share common structural elements, whereas uptake across the BBB appears more prevalent in the CNS-targeted drug set than the chemical templates being generated within the current lead optimization paradigm. Challenges for identifying high Kp,uu compounds are discussed in the context of acute versus steady-state data and cross-species differences. Evidently, there is a need for better predictive models of human brain Kp,uu.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1124/jpet.116.232447DOI Listing
August 2016

Integrating in Silico and in Vitro Approaches To Predict Drug Accessibility to the Central Nervous System.

Mol Pharm 2016 05 4;13(5):1540-50. Epub 2016 Apr 4.

Drug Metabolism and Pharmacokinetics, Platform Technology and Science China, GlaxoSmithKline R&D , Shanghai, China.

Estimation of uptake across the blood-brain barrier (BBB) is key to designing central nervous system (CNS) therapeutics. In silico approaches ranging from physicochemical rules to quantitative structure-activity relationship (QSAR) models are utilized to predict potential for CNS penetration of new chemical entities. However, there are still gaps in our knowledge of (1) the relationship between marketed human drug derived CNS-accessible chemical space and preclinical neuropharmacokinetic (neuroPK) data, (2) interpretability of the selected physicochemical descriptors, and (3) correlation of the in vitro human P-glycoprotein (P-gp) efflux ratio (ER) and in vivo rodent unbound brain-to-blood ratio (Kp,uu), as these are assays routinely used to predict clinical CNS exposure, during drug discovery. To close these gaps, we explored the CNS druglike property boundaries of 920 market oral drugs (315 CNS and 605 non-CNS) and 846 compounds (54 CNS drugs and 792 proprietary GlaxoSmithKline compounds) with available rat Kp,uu data. The exact permeability coefficient (Pexact) and P-gp ER were determined for 176 compounds from the rat Kp,uu data set. Receiver operating characteristic curves were performed to evaluate the predictive power of human P-gp ER for rat Kp,uu. Our data demonstrates that simple physicochemical rules (most acidic pKa ≥ 9.5 and TPSA < 100) in combination with P-gp ER < 1.5 provide mechanistic insights for filtering BBB permeable compounds. For comparison, six classification modeling methods were investigated using multiple sets of in silico molecular descriptors. We present a random forest model with excellent predictive power (∼0.75 overall accuracy) using the rat neuroPK data set. We also observed good concordance between the structural interpretation results and physicochemical descriptor importance from the Kp,uu classification QSAR model. In summary, we propose a novel, hybrid in silico/in vitro approach and an in silico screening model for the effective development of chemical series with the potential to achieve optimal CNS exposure.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.molpharmaceut.6b00031DOI Listing
May 2016

The quest for assay robustness across the life cycle of a bioanalytical method.

Bioanalysis 2015 ;7(7):815-24

Bioanalytical Science & Toxicokinetics, Drug Metabolism & Pharmacokinetics, GlaxoSmithKline Research & Development, Ware, UK.

White has been an analytical chemist for 28 years, with a range of knowledge and experience across multiple disciplines including pharmaceuticals, foodstuffs, environmental and forensic analysis. Steve works within the regulated bioanalytical group at GSK supporting both preclinical and clinical bioanalysis. His responsibilities have included leadership of bioanalytical, dose formulation and sample management teams as well as assisting with the set up of the Anti-Doping Testing Laboratory for the London 2012 Olympics. In his current role, Steve is part of the UK bioanalytical leadership team with a focus on regulatory & compliance issues. Steve is the small molecule rep for GSK within the European Bioanalysis Forum (EBF), a member of the EBF Steering Committee and also contributed to the Global Bioanalysis Consortium S2 team. The successful validation or qualification of an assay plus incurred sample reproducibility gives the bioanalyst confidence of assay suitability. However, these elements alone do not give the full picture of how reliable an assay may be during routine production use for analysis of unknown study samples. The robustness of an assay can be understood by applying key performance indicators to monitor assay performance pre- and post-transfer between laboratories, plus a cross-validation step during assay transfer. The measurement of assay robustness (beyond the context of cross-validation) should not be considered as yet another regulatory layer, but more as a means for the bioanalyst to better understand an individual assay within a large portfolio, when used for its intended purpose.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio.15.25DOI Listing
February 2016

Integrating internal and external bioanalytical support to deliver a diversified pharmaceutical portfolio.

Bioanalysis 2014 May;6(10):1311-9

GlaxoSmithKline R&D, Dave Jack Centre for David Jack Centre for R&D, Park Road, Ware, Hertfordshire, SG12 0DP, UK.

The portfolios of pharmaceutical companies have diversified substantially over recent years in recognition that monotherapies and/or small molecules are less suitable for modulating many complex disease etiologies. Furthermore, there has been increased pressure on drug-development budgets over this same period. This has placed new challenges in the path of bioanalytical scientists, both within the industry and with contract research organizations (CROs). Large pharmaceutical, biotechnology and small-medium healthcare enterprises have had to make important decisions on what internal capabilities they wish to retain and where CROs offers a significant strategic benefit to their business model. Our journey has involved asking where we believe an internal bioanalytical facility offers the greatest benefit to progressing drug candidates through the drug-development cycle and where externalization can help free up internal resources, adding flexibility to our organization in order to deal with the inevitable peaks and troughs in workload.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio.14.93DOI Listing
May 2014

Preliminary investigation into the use of a real-time PCR method for the quantification of an oligonucleotide in human plasma and the development of novel acceptance criteria.

Bioanalysis 2014 Jan;6(2):127-36

Bioanalytical Science & Toxicokinetics, Drug Metabolism & Pharmacokinetics, GlaxoSmithKline Research & Development, Ware, UK.

Background: The aim of the work was to evaluate the sensitivity and reproducibility of real-time reverse transcriptase PCR for quantitative analysis of an oligonucleotide in a biological matrix. A novel approach for the identification of outliers when assessing the suitability of calibration standards and QC samples is investigated.

Results: A suitable assay was established for the determination of the oligonucleotide in human plasma over a range of 0.5-100 ng/ml.

Conclusion: In these preliminary investigations, the precision and accuracy of the method was established for the quantification of the oligonucleotide in human plasma. It was established that the method was precise and accurate for quantification of the oligonucleotide in human plasma. The acceptability of the data was assessed using a novel three-step process to identify any outliers, involving the use of the Grubbs' test. The analytical method only requires a small sample volume (<0.01 ml), so would be applicable in analysis of low-volume samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio.13.284DOI Listing
January 2014

In vitro, in vivo and in silico models of drug distribution into the brain.

J Pharmacokinet Pharmacodyn 2013 Jun 13;40(3):301-14. Epub 2013 Feb 13.

GlaxoSmithKine R&D, Sir David Jack Research Centre, Ware, SG12 0DP, Hertfordshire, United Kingdom.

Achieving sufficient brain penetration to elicit efficacy in humans is one of the most challenging tasks for scientists in CNS Drug Discovery. Substantial progress has been made in the past decade in understanding the factors influencing the rate and extent of brain distribution via a variety of in vivo, in vitro and in silico methodologies, and hence, predict their likelihood of success in man. This purpose of this review is to summarize the current approaches with a special focus on parameters related to free drug concentrations in brain which are the most pharmacologically relevant for the majority of CNS disease targets. Due to the dynamic and complex nature of this targeted organ, it is inevitable that these approaches have not been able to provide a fully comprehensive assessment of brain distribution and are expected to evolve further in the years to come.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10928-013-9303-7DOI Listing
June 2013

Combining PET biodistribution and equilibrium dialysis assays to assess the free brain concentration and BBB transport of CNS drugs.

J Cereb Blood Flow Metab 2012 May 25;32(5):874-83. Epub 2012 Jan 25.

GlaxoSmithKline, Clinical Imaging Centre, Hammersmith Hospital, London, UK.

The passage of drugs in and out of the brain is controlled by the blood-brain barrier (BBB), typically, using either passive diffusion across a concentration gradient or active transport via a protein carrier. In-vitro and preclinical measurements of BBB penetration do not always accurately predict the in-vivo situation in humans. Thus, the ability to assay the concentration of novel drug candidates in the human brain in vivo provides valuable information for de-risking of candidate molecules early in drug development. Here, positron emission tomography (PET) measurements are combined with in-vitro equilibrium dialysis assays to enable assessment of transport and estimation of the free brain concentration in vivo. The PET and equilibrium dialysis data were obtained for 36 compounds in the pig. Predicted P-glycoprotein (P-gp) status of the compounds was consistent with the PET/equilibrium dialysis results. In particular, Loperamide, a well-known P-gp substrate, exhibited a significant concentration gradient consistent with active efflux and after inhibition of the P-gp process the gradient was removed. The ability to measure the free brain concentration and assess transport of novel compounds in the human brain with combined PET and equilibrium dialysis assays can be a useful tool in central nervous system (CNS) drug development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/jcbfm.2012.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3345915PMC
May 2012

Assessment of the blood-brain barrier in CNS drug discovery.

Neurobiol Dis 2010 Jan 5;37(1):33-7. Epub 2009 Aug 5.

Immunoinflammation Centre of Excellence for Drug Discovery, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, SG1 2NY, UK.

A wide variety of models have been developed over the years to predict blood-brain barrier (BBB) penetration, most of them have focussed on predicting total concentrations of drug and then expressing this as a brain:blood (or plasma) ratio. This approach is somewhat flawed and fails to address the critical issue of understanding the relationship between access of free drug to the requisite site of action. In this short review, we highlight the need for an integrated approach and whilst blood-brain barrier permeability is an important determinant in achieving efficacious CNS drug concentrations it should not be viewed or measured in isolation. Optimal CNS penetration is achieved through the correct balance of permeability, a low potential for active efflux and the appropriate physicochemical properties that allow for drug partitioning and distribution into brain tissue. Such an approach should enhance and accelerate our understanding and ability to predict CNS efficacy in terms of free drug concentrations and the rate at which they are achieved.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.nbd.2009.07.033DOI Listing
January 2010

Discovery DMPK: changing paradigms in the eighties, nineties and noughties.

Expert Opin Drug Discov 2009 Mar;4(3):207-18

Preclinical Development, DMPK, GlaxoSmithKline R&D, Park Road, Ware, SG12 0DP UK.

Background: The science of drug metabolism and pharmacokinetics (DMPK) plays a critical role in supporting the selection of potent, selective leads that retain the appropriate physicochemical properties to ensure distribution from the site of administration into the tissue or target of interest. Historically, Discovery DMPK has bridged the gap between the disciplines of biology and medicinal chemistry thereby ensuring a clinical focus during the discovery and early development phases.

Objective: Here we discuss the fundamentals of DMPK screening in drug discovery from a historical perspective, highlighting DMPK's part in improving the chances of success for novel drug candidates and suggesting new and exciting areas for future development.

Conclusions: Such a broad remit has resulted in the development of a wide variety of assays, both in vitro and in vivo, focused on assessing the developability risks associated with a molecule's progression into clinical development, such as likely bioavailability in humans, the potential for drug-drug interactions, human metabolism, interactions with transporters and the potential for metabolism-mediated idiosyncratic toxicity. Arguably DMPK has already adopted many of the concepts now of interest in translational medicine and quantitative pharmacology while scientific and regulatory pressures continue to drive the subject towards better and more integrated approaches, such as systems thinking.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1517/17460440902729405DOI Listing
March 2009

Central nervous system drug disposition: the relationship between in situ brain permeability and brain free fraction.

J Pharmacol Exp Ther 2007 Jul 3;322(1):205-13. Epub 2007 Apr 3.

Department of Drug Metabolism and Pharmacokinetics, Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, GlaxoSmithKline R&D, New Frontiers Science Park, Third Ave., Harlow, Essex CM19 5AW, UK.

The dispositions of 50 marketed central nervous system (CNS) drugs into the brain have been examined in terms of their rat in situ (P) and in vitro apparent membrane permeability (P(app)) alongside lipophilicity and free fraction in rat brain tissue. The inter-relationship between these parameters highlights that both permeability and brain tissue binding influence the uptake of drugs into the CNS. Hydrophilic compounds characterized by low brain tissue binding display a strong correlation (R(2) = 0.82) between P and P(app), whereas the uptake of more lipophilic compounds seems to be influenced by both P(app) and brain free fraction. A nonlinear relationship is observed between logP(oct) and P over the 6 orders of magnitude range in lipophilicity studied. These findings corroborate recent reports in the literature that brain penetration is a function of both rate and extent of drug uptake into the CNS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1124/jpet.107.121525DOI Listing
July 2007

In vitro prediction of brain penetration - a case for free thinking?

Expert Opin Drug Discov 2006 Nov;1(6):595-607

Drug Metabolism and Pharmacokinetics, Neurology and Gastrointestinal Centre of Excellence for Drug discovery, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, United Kingdom.

Realising adequate brain penetration is a major obstacle in the design of drugs that target the CNS. Much of the understanding at present is derived from studies in rodents and it is difficult to translate many of these measurements to the clinical setting. The complex nature of the brain means that there are numerous compartments to consider when trying to understand brain penetration; these include regional differences in brain tissue morphology and composition, flow of fluid around the CNS network and the protective barriers between the brain and the periphery. A consequence of this complexity is that several parameters can be measured to assess different aspects of brain penetration and until recently no coherent model of brain penetration had been proposed. This review examines the understanding so far of the factors influencing brain penetration and the progress made as a result of in vitro studies. The shift towards thinking in terms of free brain concentrations and free brain fractions has not only provided a new insight into the nature of brain penetration, but also offers the future prospect of providing a better link between efficacy and a relevant unbound measure of brain penetration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1517/17460441.1.6.595DOI Listing
November 2006