9252020 Advanced Medicinal Chemistry Lecture 2 Finding a

9/25/2020 Advanced Medicinal Chemistry Lecture 2: Finding a Lead Dr Jeff Stonehouse Astra. Zeneca R&D Charnwood

9/25/2020 The Drug Discovery Process Target Identification 3 months to 2 years! HTS 3 -4 months Active-to-Hit (At. H) 3 months Hit-to-Lead (Ht. L) 6 -9 months New Lead Optimisation Projects (LO) 2 years Candidate Drug (CD)

9/25/2020 Lead Compounds from a Variety of Sources penicillins 1. Chance Discovery 2. Natural Products taxol 3. Clinical Observation 4. Natural Ligands 5. Existing Drugs 6. High Throughput Screening (HTS) Viagra

9/25/2020 Natural Ligands R=H adrenaline R=Me noradrenaline Formoterol Astra. Zeneca Catechol bioisostere (toxicity) Salbutamol Glaxo. Smith. Kline Catechol bioisostere (toxicity) Increased size (selectivity and duration)

Existing Drugs 9/25/2020 Also known as the “Me-Too” or “Me-Better” Approach Pfizer Issues: short duration Viagra Multiple side effects and incompatibility with other drugs BEWARE: Patent Issues!! Eli Lilly Bayer Cialis Levitra Fewer side effects and incompatibility with other drugs 36 h duration (“the weekend pill”)

9/25/2020 High Throughput Screening (HTS) “An industrialised process which brings together validated, tractable targets and chemical diversity to rapidly identify novel lead compounds for early phase drug discovery” 50 -70% of new drug projects originate from a HTS How? • validated, tractable targets • • industrialised process • • target selection for HTS assay technologies and automation chemical diversity • sample selection for HTS

9/25/2020 Establishing a HTS validated/ tractable targets target ID human & pathogen genomes chemical space compound collection compound selection HT Screen Development

9/25/2020 Microtitre Plates – the HTS test tube For 200 K data points: 96 300 -100 ml 9 mm pitch 125 x 1536 well plates 384 100 -25 ml 4. 5 mm pitch 1536 384 LV 25 -5 ml 4. 5 mm pitch 10 -1 ml 2. 25 mm pitch 500 x 384 well plates 9 mm 2000 x 96 well plates

9/25/2020 Charnwood HTS Technologies; 1995 -2001 • Screening can utilise numerous technologies e. g radioactivity, fluorescence, luminescence • None are universally applicable, each with advantages and disadvantages

9/25/2020 High throughput radioligand binding assays Scintillation Proximity Assay – the first true homogeneous HTS screening technology Molecule too far away to activate bead Nothing bound bead not activated, I 125 Bound molecule Molecule binds bead activated I 125 light produced no light Antibody/receptor I 125 Molecule cannot bind Suitable for I 125, 3 H, 33 P I 125

9/25/2020 SPA (Scintillation Proximity Assay) • First true homogeneous HTS technology • Allows throughput of ~30 K compounds/day in 384 format • Easy to automate, no significant volume of aqueous waste BUT: • Radioactive (safety headaches) • Long read times (>30 min/plate) • Susceptible to quench artefacts • Not applicable to all targets

9/25/2020 FLIPR – a high throughput fluorimeter Fluorescent Imaging Plate Reader Real-time simultaneous imaging of 96 - & 384 -well plates Used for HTS Ca 2+ flux assays and ion channel screening

9/25/2020 FLIPR – how it works PC 96/384 -Tip Pipettor Drawer Holding 5 Microplates 6 W Argon Ion Laser Cooled CCD Camera • Cells loaded with fluorescent dye sensitive to Ca 2+ (fluo-3) • CCD camera images base of microtitre plate • Addition of receptor agonist stimulates Ca 2+ release, resulting in fluorescence increase • Whole plate is read simultaneously, allowing kinetic analysis • ‘Functional’ screen (i. e. whole cell) – greater relevance than simpler screening methods • Throughput is 1000 x greater than cuvette-based fluorimeter assay

9/25/2020 Establishing a HTS validated/ tractable targets target ID human & pathogen genomes chemical space compound collection compound selection HT Screen Development

The Astra. Zeneca Compound Collection 9/25/2020 1994 ASTRA ARCUS ASTRA PAIN CONTROL 1993 1999 Ca 9% compound overlap Not a recipe for an optimal screening bank

9/25/2020 Compound Collection Enhancement • AZ global initiative to boost screening collection – Target: ensure viable Hits from 75% of AZ HTS • Five-year initial lifespan. Two concurrent themes… Acquisition 300 K from 107 available Stringent filters Big Medchem input Accept IP risks Synthesis Nominal 500 K over 5 years Target-class focus Aligned to Research Areas Early Bioscience input

9/25/2020 CCE Structure HTS Charnwood GPCR Kinase Charnwood Alderley Park HTS AP ~60 Scientists Med Chem Bioscience Comp Chem Informatics Central Bioscience Cheminformatics Channel Protease HTS Mölndal Compound Management AP Södertälje HTS US • Chemistry deliberately embedded in Research Areas – Not centralised – Benefit of Project exposure – Feeds parallel synthesis skill back into projects

9/25/2020 CCE – Library Chemistry 3 most commonly used reactions. Amide coupling Reductive amination Sulphonamide formation

9/25/2020 CCE – Common Combinatorial Reactions • Amide Coupling HATU • Sulphonamide Formation NMP • Reductive Amination

9/25/2020 Amide Coupling Sulphonamide Formation Reductive Amination Mechanism