How Medicines Are Discovered – Past & Present (PDF)

How Medicines Are Discovered – Past & Present David E. Thurston [email protected] Advanced Clinical Pharmacology 2024-2025 Day 1, Session 1.1, Discovery Chemistry & Biology Monday 11th November 2024, 09.30-10.30, FWB G79 ...

How Medicines Are Discovered – Past & Present David E. Thurston [email protected] Advanced Clinical Pharmacology 2024-2025 Day 1, Session 1.1, Discovery Chemistry & Biology Monday 11th November 2024, 09.30-10.30, FWB G79  Learning Objectives To understand:  The economics and risks of drug discovery  The meaning of a “lead” compound  How drugs are discovered by both non-rational and rational approaches  The process of drug discovery and development  The impact of Precision Medicine on drug discovery 2  Why are Drugs Important? 1. Health of the Nation Devastation caused by Malaria, Aids, Cholera, Ebola etc in Africa, and recently Covid-19, across the world.  Developed countries are not so concerned simply with survival.  Even less serious diseases such as influenza can cause chaos in the developed world. 2. Economy In 2023, the expenditure on pharmaceutical research performed by UK businesses was £9.0 billion (UK Government figures).  This amount represented 18% of all research and development (R&D) performed by businesses in the UK (UK Government figures).  AZ in Macclesfield exports account for 2% of all UK exports (BBC4 30/1/24).  The next highest product group was motor vehicles and parts (10.8%). 3. International Prestige  e.g., Companies such as GSK, AZ.  A thriving biotech sector. “Healthy Nation is a Prosperous Nation” 3 Success of Drug Discovery Varies Across Different Therapeutic Areas Number of Pipeline Drugs in the US by Therapy Area 4 Global Growth of Biopharmaceuticals + Biosimilars and Bioequivalents 5 End of the “One Size Fits All” Approach to Drug Therapy  At present most drug therapies still follow the “One Size Fits All” approach. This means that:  A patient may not receive the optimal drug and/or dosing for their disease.  The drug prescribed may lead to ADRs which can be life-threatening.  Even worse: Drug may not work at all wasting time and causing further distress to patient! The Future Personalised Medicine & Pharmacogenomics 6  Pharmacogenomic Sciences: Biomarkers  To use pharmacogenetics, biomarkers and/or metabonomics to: Predict risk of disease occurrence and re- occurrence to allow early/best intervention (e.g., using biomarkers and metabonomics). To discover safer more-effective therapeutic agents Indicate best drug therapy for individual patients. Monitor and optimise drug therapy for individual patients or groups of patients by maximising efficacy (e.g., evaluating metabolism) and minimising side effects. “– the right medicine at the right dose for the right patient.” 7  Vemurafenib (ZelborafTM) Discovered by Plexxikon (now part of the Daiichi Sankyo group and Hoffmann–La Roche) H F O N O S N N CH3 H F H 3C O N Vemurafenib received FDA approval for the treatment of late-stage melanoma on August 17, 2011. 8 Source: New Engl. J Med 363, 9: 876-878 (2010). 26/32 = 81% 10 The Three Main Phases of the Creation of a New Drug: Discovery, Development and Commercialisation 11  Economics  UK’s most successful R&D industry  Requires very high investment in R&D  ~18% of total UK R&D budget (Greater than for any other Industrial Sector)  It is a very high cost and high risk Industry Can NHS afford the cost of new drugs ? 12  Reasons for High Costs of Drugs Three major reasons:  Expense of investment and research  Relatively short period of exclusivity (e.g., Patents approximately 20 years only)  High risk (e.g., attrition rate, litigation) (e.g., Thalidomide still best example)  Current cost of producing a new drug can be intimidating even to a large company. e.g., The current cost of producing a new drug is quite substantial. On average, it costs around $2.3 billion to develop a new drug, from discovery through clinical trials to market approval. This figure can vary depending on the complexity of the drug and the length of the development process, which typically spans over a decade.  New consideration of “Block-Buster” versus Pharmacogenomic-based Drugs 13 Daily Telegraph Wednesday 23rd October 2024  Patent Life  Major problem is that patent life is usually approx 20 years. If 12 years development at a cost of $2.3 billion, then only (20-12) = 8 years to recover costs and make a profit.  Problem is that development time tends to increase due to:  Increased sophistication of research  Increased requirement for more-sophisticated evaluation Therefore, Effective Patent Life (EPL) is reducing  Ongoing arguments between governments and industry to add years to patents, “extended patents,” etc. (Incentives for orphan drugs etc)  Companies try to reduce length of discovery/development cycle. NB: increasing number of generic manufacturers avoid discovery/development costs, by starting to work on patented products as early as possible. 15 Relatively Short Patent Lives Lead to Pressures on Drug Companies e.g.,  “Explosive Marketing” – which can be dangerous for patients.  Competition from “Me Too” products where original patent is “broken”.  Companies are forced to devise clever new strategies to extend patents which may not necessarily benefit the patient or organisations such as the NHS from a financial standpoint (e.g., omeprazole). 16  Risk  Very high risk in drug discovery/development cycle: Attrition (Success rate is about 1 in 10,000 of NCEs) Risk of delayed toxicity and legal action  Companies try to minimize risks by staying in research areas in which they have built up an expertise. These are called “Strategic Intents” eg., Anticancer drugs, Anti-inflammatories, Cardiovascular, Anti-infectives, Oncology.  If drug is withdrawn from market: very expensive, lawyers etc. Often “Class Action”. Some lawyers & patients “try it on”. “Wealthy” pharmaceutical companies seen as fair targets.  e.g., NORPLANT: In USA, all 900,000 women fitted with Norplant were contacted by lawyers acting for a few for possible “Class Action” against Wyeth in USA.  “Yellow Card” reporting scheme to MHRA in UK. 17  Discovery of Lead Compounds  “Lead Compound” – First compound or structural motif of a new family of therapeutic agents to be discovered.  Rarely the actual drug structure that will be marketed or even that will go to clinical trial.  Very precious entity (although “targets” are now considered precious as well – but not always patented).  A “Lead Compound” is a potentially highly valuable financial asset (Therefore - Protect IP). 18  Where Do New “Lead” Compounds Come From? Screening (Phenotypic) (Synthetic, Natural Products, Side Effects Existing drugs for Re- (Clinical Observation) Metabolism Positioning) Studies Natural Products Re-Positioning Rational Drug Design (e.g., Molecular Pruning, Conformational Restriction, Bioisosteres, Conjugation, Prodrugs, Biochemical/Physiological Studies, Structure- Based Approaches/Molecular Modeling Serendipity (Chance Observation) Small Molecules Biologics  How Are New Drugs Discovered? Non-Rational Approaches Rational Approaches 1. Screening 7. Molecular Pruning 2. Natural Products 8. Conformationally Restricted Analogues 3. Side Effects of Existing Drugs 9. Bioisosteric Changes (Functional Group Manipulation) 4. Drug Repositioning 10. Chemical Conjugation 5. Metabolic Studies 11. Prodrug Approach 6. Chance Observation (Serendipity) 12. Biochemical/Physiological Studies 13. Structural Biology Based Approach 14. Genomics 15. Biologics 20 1. Screening for “Hits” (that may provide “Leads”) 1. First choose therapeutic area and “target” 2. Usually target is a macromolecule such as: Protein (e.g., enzyme, signalling protein, protein-protein pair) Glycoprotein (e.g., internal or cell surface receptor) Nucleic acid (e.g., DNA or RNA) 3. Then choose and develop assay: Manual Semi-High-Throughput High-Throughput (HTS) 4. Choose molecules, libraries or extracts to screen 5. Carry out screen and analyse data for “hits” 6. Develop “hit” to “lead” (medicinal chemistry/synthesis) 21  Types of Primary Screens 1. Enzyme-based 2. Receptor-based 3. Biochemical-type (e.g., Protein, DNA, RNA, sugars etc) 4. Cell-based (i.e., In Vitro) 5. In Vivo (e.g., Xenopus or Zebra Fish embryos) Note:  Can be “Manual”, Semi-High-Throughput, or High-Throughput (HTS)  Mostly Light or Fluorescence Based (Radioactive labelling rarely used now) 22  Low Through-Put Screening was used in the discovery of Imatinib (GleevecTM) Imatinib (red) bound to the ATP-binding pocket of BCR-ABL Protein (green) 23  2. Natural Products Plants and Trees Bacteria/Fungi (e.g., Streptomyces) Marine Organisms Animals  Plants and Trees  Plants and trees are prodigious “organic chemists”.  They produce large numbers of organic molecules ranging in complexity and often rich in stereochemical centres.  Reason for production often unknown, but could be “attack/defence weapons” (e.g., Dicoumarols/Clover, Phytoestrogens/Soy) Clover Soy  Isolation of active ingredient can be challenging.  Can be used for commercial production of drugs.  Some Examples of Useful Drugs From Plants Cardiac Glycosides Foxglove (Digitalis lanata) Atrial fibrillation or flutter and other heart disorders Snowdrop Galantamine (Galanthus spp.) Early-stage Alzheimer’s disease Khella (Toothpick plant) Cromoglicic acid (Ammi visnaga) Eye allergies Snow Drop Chilli Peppers Capsaicin (e.g., Capsicum annuum) Localised neuropathic pain Cassia senna L. (C. acutifolia Delile) or Sennosides A to D Alexandria senna) Constipation Tea Plant Green Tea (Camellia sinensis) Leaf Extract Warts (external genital and perianal)  Pacific Yew Tree (Taxus brevifolia) Paclitaxel (Taxol )  Paclitaxel (Taxol ) is a highly complex tetracyclic diterpene found in the bark and needles of the Pacific yew tree Taxus brevifolia.  The cytotoxic nature of extracts of Taxus brevifolia was first demonstrated in 1964.  Pure paclitaxel was isolated in 1966 and its structure published in 1971. Synthetic Ester Fragment Baccatin  However, it did not OH R1O O appear in the clinic until R CH3 NH O H3C >30 years after its discovery. CH3 O CH3  Docetaxel (Taxotere ) H O is a more recently OH AcO introduced semi- HO O.CO.Ph synthetic analogue with similar therapeutic and R1 toxicological properties. R Paclitaxel (TaxolTM) CO.CH3 Docetaxel (TaxotereTM) CO.Ph CO.O.C(CH3)3 H 27 Some terms used to study the presence of drugs in plants/trees: “Pharmacognosy” “Natural Products Research” “Ethnobotany” “Ethnopharmacology” “Bioprospecting” Rain Forests and other special plant/tree habitats are disappearing – Should we be worried? 29  Drugs Produced by Bacteria and Fungi Microorganism Drug Penicillium notatum Penicillin Streptomyces venezuelace Chloramphenicol Penicillium griseofulvum Griseofulvin Streptomyces griseus Streptomycin Streptomyces fradiae Neomycin O H H O N S CH3 H N CH3 O COOH Chloramphenicol Penicillin V Penicillium notatum Streptomyces venezuelace 30 Marine Organisms: Trabectidin (YondelisTM) [ET-743] OCH3 O HO CH3 H3C O A H3C N B CH3 N O S O HO O H3CO O Sea Squirt NH C (Ecteinascidia HO turbinata) Ecteinascidin-743 (ET-743) ET-743 is a DNA-binding agent derived from the marine tunicate Ecteinascidia turbinata Rather than methylating DNA in the major groove as is the case with dacarbazine and temozolomide, ET-743 alkylates the N2 of guanine in the minor groove thus forming a bulky adduct which blocks DNA processing. It is particularly active against soft tissue sarcomas (STS) which are one of the most difficult forms of cancer to treat. 31  Drugs From Animals: Premarin (Conjugated Estrogens, Wyeth) Sodium estrone sulfate Conjugated Estrogenic Hormones Trademarks: Conestron (Wyeth); Genisis (Organon); Premarin (Ayerst) Literature References: An amorphous preparation contg water-soluble, conjugated forms of mixed estrogens obtained from urine of pregnant mares. The principal estrogen present is sodium estrone sulfate. The total estrogenic potency of the preparation is expressed in terms of an equiv quantity of sodium estrone sulfate. Prepn: Bates, Cohen, US 2565115 (1951 to Squibb); Stiller, O'Keefe, US 2720483 (1955 to Olin Mathieson). CAUTION: These substances are listed as known human carcinogens: Report on Carcinogens, Tenth Edition (DHHS/PHS/NTP, 2002) p III- 116. Therap-Cat: Estrogen. 3. “Lead” Molecules Discovered Through Side Effects (Accidental Clinical Observations) e.g., Phenytoin Isoniazid  One study in the late 1990s suggested Tolbutamide that 106,000 deaths and 2.2 million Acetazolomide (DiamoxTM) serious drug events were caused by Nitrogen Mustards ADRs in the US each year. Viagra (Sildenafil) x 2!  Another study suggested that ADRs are Flibanserin (AddyiTM) responsible for 5-7% of hospital Aminoglutethimide admissions in the US and Europe, and m-TOR Inhibitors (Rapamycin) lead to the withdrawal of 4% of new D-Cycloserine medicines. Zolpidem Dramamine  Sometimes the “side effect” or ADR may Lonaten (Minoxidil) be a “welcome” or “positive” one that can Seroxat lead to a new therapeutic indication for OsphenaTM the drug or a subsequently optimised DianetteTM analogue. LyricaTM 33 Minoxidil (Loniten , RegaineTM) N N NH2 N O NH2 34  Sildenefil (Viagra , Pfizer) O CH3 N O O HN N S N N N H3C O CH3 CH3  Sildenafil (ViagraTM) was originally developed as an antihypertensive agent but an observed side effect during the clinical trials led to the present indication for Erectile Dysfunction (ED).  Follow-on phosphodiesterase (PDE) inhibitors now marketed by rival companies (e.g., Tadalafil, CialisTM) 35  Vorapaxar (ZontivityTM) Vorapaxar (SCH 530348) is a thrombin receptor (Protease- Activated Receptor, PAR-1) antagonist based on the natural product himbacine, discovered by Schering- Plough and developed by Merck & Co. Himbacine is an alkaloid isolated from the bark of Antiplatelet Agent Protease-Activated Receptor (PAR-1) Australian magnolias. Its Antagonist) activity as a muscarinic receptor antagonist, with specificity for the muscarinic acetylcholine receptor M2, made it a promising starting point in Alzheimer's disease research. Although this drug development program failed, the analogue vorapaxar was developed as a thrombin receptor antagonist and is now approved by the FDA in the USA. Himbacine (from the bark of Australian magnolias)  4. Drug Repositioning: Purposeful Search for New Type of Activity in Existing Drug Drug Repositioning (also known as Drug Re-purposing, Drug Re-profiling, Therapeutic Switching, or Drug Re-tasking) is a purposeful search to see whether an existing drug may have an application in a different therapeutic area and/or for a new indication.  Drug repositioning has been growing in importance in the last few years as an increasing number of drug development and pharmaceutical companies see their drug pipelines drying up and realize that many previously promising technologies have failed to deliver ‘as advertised’.  A significant advantage of drug repositioning over traditional drug development is that since the repositioned drug has already passed a significant number of toxicity and other tests, its safety is known and the risk of failure for reasons of adverse toxicology are reduced.  More than 90% of drugs fail during development, and this is the most significant reason for the high costs of pharmaceutical R&D. In addition, re-purposed drugs can bypass much of the early cost and time needed to bring a drug to market.  On the other hand, drug repositioning faces some challenges itself since the intellectual property issues surrounding the original drug may be complex and from a commercial point of view it may not always make sense to take such a drug to market. Examples: Pregabalin (LyricaTM) and Ropinirole (RequipTM) 37  Pregabalin (LyricaTM) Second Patent: Neuropathic First Patent: 1993-2013 Pain 2003-2017 First Approval in EU and USA in 2004: In 2014 Pfizer have been For Generalised Anxiety Disorder claiming breach of second (GAD) and Epilepsy patent by generic manufacturers Actavis and Mylan 38 Compound Libraries for Repositioning Studies 39  5. Metabolism Studies e.g., Desipramine (Pertofran ) from Imipramine (Tofranil ) Temazepam from Diazepam Exisulind (AptosynTM) from Sulindac (ClinorilTM) Paliperidone (InvegaTM) from Risperidone 40  Discovery of Oxazepam and Temazepam Through Metabolism Studies on Diazepam O HN OH N Cl H3C O N Oxazepam N Cl H3C O N Diazepam OH N Cl Note: (a) Liver cell culture techniques and/or mice, (b) HPLC-type techniques followed by (c) synthesis, and (d) evaluation. Temazepam 41 6. Chance Observations (“Serendipity”) e.g., Diazepam Nitrogen Mustards Cisplatin Penicillin Isoniazid LSD Vorinostat? The Three Princes of Serendip 42  Discovery of Cisplatin  In the 1960s Barnett Rosenberg, a biophysicist working at the University of Michigan, observed that passing an alternating electric current through platinum electrodes in an electric cell containing E. coli led to arrest of cell division without killing the cells.  Continued growth without division led to unusually elongated cells with a spindle-like appearance.  The cause of the cytostatic effect was eventually traced to platinum complexes formed electrolytically at concentrations of only 10 parts per million in the presence of ammonium salts and light. 43  Ammonium Salts + Light + - Pt Pt H3N Cl Pt H3N Cl Platinum complexes formed electrolytically at concentrations of only 10 parts per million 44  H3N Cl H3N Pt + H3N Pt H3N Cl Cisplatin DNA DNA Adduct Newer Generations of Cisplatins O H2 H3N O N O O Pt Pt H3N O N O O H2 O Carboplatin (ParaplatinTM) Oxaliplatin (EloxatinTM) 45 Rational Drug Design Often Quoted First Example of “Rational Drug Design” H + N C N O H CH3 Pralidoxime 46  Mechanism of Action of Pralidoxime O O CH3 O O P O F P H3C O F F N HO OH CH3 Cl CH3 Cl NH2 Sarin Novichok Serine Electrostatic Interaction Nucleophilic Attack Phosphorylated (“Poisoned”) Regenerated Acetylcholine Acetylcholine Esterase Enzyme Esterase Enzyme Cholinesterase Reactivator; Antidote for nerve gases and organophosphate insecticide poisoning; US Patent 2816113 to U.S. Army (1957); A. A. Kondritzer et al., J. Pharm. Sci. 50, 109 (1961). 47  7. Molecular Pruning Try to obtain a new “lead” molecule or change the “activity profile” of an existing one (could be a complex natural product, or complex “hit” molecule from a high through-put screen) by chopping away portions of a biologically-active molecule to try to evaluate the “pharmacophore”. 1. Non-interactive part of drug may interfere with fit at receptor through steric interaction 2. Non-pharmacophore may be important for ADME characteristics 3. Therefore, chop molecule down systematically 4. Discover which parts are essential vs superfluous 48 - Very precise interaction of drug/receptor – Agonist or Antagonist  Example: Morphine The morphine family of analgesics is a classic example of how a molecule can be trimmed (or “pruned”) to give rise to novel drugs with similar or enhanced potency and/or a modified type of activity: HO O H NCH3 HO 49  First Pruning CH3 N CH3 N R MORPHINAN 0 OR1 OH Analogs OR OH MORPHINE (R = R1 = H) MORPHINAN H CODEINE (R = CH3, R1 = H) NH HEROIN (R = R1 = CO.CH3) HO LEVORPHANOL H DromoranTM (Roche) NCH3 50  MORPHINE CODEINE HEROIN Through noting which MORPHINAN parts of the molecule are crucial, or conversely not LEVORPHANOL important, the structure of the Increased BENZOMORPHAN “minimum pruning pharmacophore” can CYCLAZOCINE be worked out. PENTAZOCINE MEREPIDINE (DemerolTM) DEXTROPROPOXYPHENE (DistalgesicTM, DarvonTM) METHADONE (PhyseptoneTM) TRAMADOL 51  Conclusion – the Pharmacophore is: CH3 Tertiary N Nitrogen CH3 CH3 O Quaternary Carbon Aromatic Ring Methadone 52  8. Conformationally-Restricted Analogs Buprenorphine HO HO (TemgesicTM) O N Morphine O H H3CO NCH3 H HO CH3 C(CH3)3 An “Oripavine” HO  In some cases an increase in structural complexity and/or rigidity can lead to increased potency (and a new drug product)  Increased rigidity of molecule decreases degrees of freedom for rotation, enhancing interaction with receptor(s)  Buprenorphine is 10-20 x more potent than morphine but with a lower level of dependence liability (i.e., receptor selectivity)  So potent and lipophilic it can be administered sublingually  May be ADME effects as well Also: Etorphine is ~10,000–30,000 times more potent than morphine. It is used in a 53 dart by vets to immobilize large animals  9. Bioisosteres/Functional Group Manipulation Substitution of atoms and ring systems with different ones of similar shape, volume and electron distribution/charge Idea developed during early work on antihistamines Can change inhibitor to agonist and vice versa Can change ADME or ADMET characteristics significantly Used to create “Me Too” and “Follow-On” products 54  Examples of Bioisosteric Changes Atoms & Functional Groups Ionising Systems S CH CH N CH O C , NH, CH2 CH3 -H, -F, -OH, -NH2 Smaller Ring Systems Larger Ring Systems N N S N O H S N N N N N S O N O N N N 55  Bioisosteric Approach to Make “Me Too” Drugs to “Break” the Patents of Other Pharmaceutical Companies H H N N CH3 S CH3 Ranatidine (ZantacΤΜ) Glaxo N CH H3C O O2N First Patents: 1978 to Allen & Hanburys H3C H H N N S CH3 Cimetidine (TagametΤΜ) SKB HN N N NC First Patents: 1974-1976 to SKF Histamine H2-receptor antagonists 56 10. Conjugates (Targeting Strategies) Joining two entities together to obtain a synergistic therapeutic effect, a formulation/delivery benefit, or for targeting purposes:  Drug-Drug  Antibody-Drug  Two Component Systems (e.g., ADEPT) 57  Example: Drug-Drug - Analgesics COOH HO O CH3 O N CH3 O H Aspirin Paracetamol 58  Benorylate Ester Linkage O H N CH 3 H 3C O O O O BenoralTM (Sanofi Winthrop) Analgesic; Anti-inflammatory; Antipyretic.  First Reported in 1965  Discontinued in UK in 2004  Still available in other countries (e.g., USA) 59  Zynlonta® (Loncastuximab tesirine, Lonca-T, ADCT-402) CD19-Targeted Antibody Chemical Linker Approved by FDA in 2021 Cytotoxic Payload CD19-Expressing Diffuse Large B-Cell Lymphoma (DLBCL) Cells 60  11. Prodrug Approach  Chemical modification of an active therapeutic agent to improve bioavailability or reduce toxicity upon administration.  A prodrug is converted back to the biologically-active therapeutic agent via chemical (e.g., hydrolysis) or enzymic (e.g., peptidase) reactions. Example: Enzymic Conversion Reductive cleavage Prodrug Targeting by bacterial flora of Inflammatory Diseases of the lower bowel Bowel COOH COOH H N H N N N S NH2 + H2N OH S N N OH O O O O Sulfapyridine 5-Aminosalicylic Sulfasalazine acid SalazopyrinTM (Pfizer) 61  12. Biochemical/Physiological Studies Many drugs in common use today have their origin in basic biochemical/physiological studies on transmitters (i.e., Exogenous Mediators) HO e.g. CH2CH2NH2R CH2CH2NH HN N N H Histamine Serotonin OH HO CH2CH2NH HO CHCH2NH2R HO HO Noradrenaline Dopamine CH3CO.O.CH2CH2NMe3 O2CCH2CH2CH3NH3 62 e.g., Salbutamol, L-Dopa, Sumatriptan) Example of a drug discovered through biochemical studies on Noradrenaline OH OH H N HO CHCH2NH2 HO C(CH3)3 HO HO Noradrenaline Salbutamol (VentolinTM) Bronchodilator Selective beta2 agonists Produce bronchodilation Short acting, salbutamol or terbutaline 63 Long acting: formoterol and salmeterol  13. Structural Biology- Based Approaches First elucidate structure of protein, receptor etc, then: (a) Physical Screen or (b) Virtual Screen Nelfinavir, a protease inhibitor used for HIV treatment, is often quoted as an example of a drug Neidle, S. and Thurston, D.E., “Chemical Approaches to discovered by “Structure-Based” approach. the Discovery and Development of Cancer Therapies”, Nature Reviews Cancer, 5, 285-296 (2005). Use of Computational Methods (a) Molecular modeling (b) Virtual screening e.g., The STAT3 Dimer Bound to DNA  14. Genomics  The DNA (deoxyribonucleic acid) molecule is the genetic blueprint for each cell and ultimately the blueprint that determines most aspects of a living organism. Human Genome Project (1990-2003) Lots of genome sequence information now available for humans and several other animal species (e.g., mice, monkeys, dogs), and plants, trees crops etc. Questions: How to exploit it? What tools are available?  Potential Applications Therapeutics – Cancers – Antitumour Agents – Antifungals – Antibacterials – Antivirals – Anti-parasitic – Other diseases? Tools for Functional Genomics and Target Validation 67  How to use genomic information: Associate gene with particular disease and then try to switch gene off, perhaps up-regulate if protein missing, or even insert healthy version of gene: e.g., Upregulated oncogene in cancer Faulty gene in Cystic Fibrosis and Muscular Dystrophy Examples of tools available: Antisense Oligonucleotides, RNAi, Small Molecules DNA Arrays (AffymetrixTM Chips) Proteomics/Protein Arrays Transcription Factor Arrays etc CRISPR-Cas9 Gene knockout Point mutation insertion or correction Large gene knock-in (specific genetic locus or safe harbour locus) Reporter gene knock-in Inducible gene expression Gene over-expression Custom heterozygous or homozygous mutations Approval of Lumasiran (OxlumoTM) in 2020 for oxalate metabolism disorders Moderna  15. Biologics (or Biopharmaceuticals)  Any medicinal product manufactured in, or extracted from, biological sources (as distinct from chemically synthesized pharmaceutical products).  Can be composed of sugars, proteins or nucleic acids (combinations of these), or may be living entities such as cells and tissues.  Isolated from a variety of natural sources (i.e., human, animal or microorganism), and are usually produced using biotechnology-based methods.  In many geographical regions, biologics are regulated through different pathways compared to small molecule drugs and medical devices (e.g., BLA [Biological Licence Application] versus NDA [New Drug Application] in USA). Examples: 1. Vaccines 2. Recombinant Therapeutic Proteins (e.g., insulin, growth hormone) 3. Glycoproteins (e.g., Interferons [cytokines]) 4. Enzymes (e.g., Asparaginase) 5. Antibody Therapies (e.g., ADCs) 6. Blood or Blood Components It can be argued that most 7. Allergenics Biologics are discovered 8. Cells (e.g., CAR-T) through a “Rational” drug 9. Gene Therapies discovery approach. 10. Tissues 11. Interferon 71 Biologics: Monoclonal Antibodies (mAbs) THERAPEUTIC USE EXAMPLES Haematological Cancers Rituximab Solid Cancers Trastuzumab Kidney Transplant rejection Muromonab-CD3 Blood Clot Prevention in angioplasty Abciximab Antiviral (e.g., HIV) Ibalizumab Antibacterial (e.g. Anthrax) Raxibacumab Crohn’s Disease & Ulcerative Colitis Infliximab Rheumatoid Arthritis Adilimumab Asthma Omalzumab Multiple Sclerosis Natalizumab Macular Degeneration Ranibizumab Paroxysmal Nocturnal Hemoglobinuria Eculizumab Psoriasis Ustekinumab Ankylosing Spondylitis Golimumab Muckle-Wells Syndrome Canakinumab Bone Loss (Osteoporosis) Denosumab Systemic Lupus Erythematosus Belimumab Hypercholesterolemia Alirocumab Atopic Dermatitis Dupilumab Hemophilia A Emicizumab X-Linked Hypophosphatemia Burosumab Hereditary Angioedema Lanadelumab Migraine Erenumab Thrombocytopenic Purpura Caplacizumab Sickle Cell Disease Crizanlizumab Neurodegeneration Diseases (e.g., Alzheimer’s Disease) Aducanumab 73  Conclusions The best was to discover a new “lead” molecule (is probably): 1. Core team of scientists with expertise in pathophysiology of a disease discover new “target” (e.g., transmitter, enzyme, receptor and/or signalling pathway) relevant to the disease. 2. Obtain molecular structure of protein, enzyme or receptor associated with signalling pathway (e.g., X-Ray, NMR etc). 3. Establish a physical assay. Then agonists or antagonists can be identified by screening diverse “Full Deck” libraries followed by a medicinal programme for “hit to lead”. 4. Once a good quality structure of the target macromolecule exists, consider in silico screening to produce further “hits” or fine-tune existing ones. 75 END 76 Examples of Useful Drug Discovery Books and Journals 77  78 2021 Publication Date: 30 March 2021 Book Series on the Drug Discovery Process and Individual Drug Families: Royal Society of Chemistry (RSC) Drug Discovery Series (see http://pubs.rsc.org/bookshop/collections/series?issn=2041-3203 for complete listing of over 80 books in the series)