GENETIC PROFILING AND HEALTHCARE MANAGEMENT;
ADME (ABSORPTION, DISTRIBUTION, METABOLISM & ELIMINATION) &
TOXICOLOGY PATENT APPLICATION
The invention relates to a method of assessing the most appropriate therapeutic intervention in an individual, patient, group or population suffering from the debilitating consequences of dysfunction, damage or disease of the body and its systems.
People vary enormously in their response to disease and also in their response to therapeutic interventions aimed at ameliorating the disease process and its progression. However, the provision of medical care and medical management is centered around observations and protocols developed in clinical trials on groups or cohorts of patients plan. This group data is used to derive a standardised method of treatment which is subsequently applied on an individual basis (e.g. the comment that drugs are often prescribed on the basis that everyone is an 70kg white male) .
It is standard practice for clinicians to prescribe the same starting dose of a particular drug for a given indication and then adjust the treatment regimen by monitoring the progress of the disease and therapeutic response in individual patients. Observation of actual therapeutic outcome following these adjustments to patients therapy provides, the basis for determining a prognosis for the disease and developing a clinical management plan for patient care. Many algorithms for the treatment of specific disease have been developed in clinical centres of excellence.
The standard practice of clinical management has its disadvantages. In particular it is retro-active in that changes to patient management will occur following the emergence of therapeutic failures, adverse events or other difficulties in undertaking the therapeutic regime.
The toxicological effect of any treatment involves four main pathways, Absorption, Distribution, Metabolism and Elimination, better known as ADME. The most important axiom of toxicology is that the dose makes the poison". Therefore variation in genes affecting the Absorption, Distribution, Metabolism and Elimination (ADME) of 'therapeutic' substances, accounts for much of the difference in individuals risk of toxicity.
Drugs interact with the body in many different ways to produce their effect. Some drugs act as false substrates of inhibitors for transport systems (e.g. calcium channels) or enzymes
(acetylcholinesterase) . Most drugs however, produce their effects by acting on receptors, usually located in the cell membrane, which normally respond to endogenous chemicals in the body (Weatherall, Leadingham and Warrell 1996). Drugs that activate receptors and produce a response are called agonists
(e.g cholinomimetics) . Antagonists combine with receptors but do not activate them, thus reducing the probability of the transmitter substance combining with the receptor and so blocking receptor activation. The ability of the drug to interact with the receptor depends on the specificity of the drug for the receptor or target' (Brody, Larner and Minneman 1998) .
In addition to the main categories of agonist and antagonist drugs also have mechanisms of action which include:
• blockade of uptake or transport sites (e.g selective serotonin reuptake inhibitors)
• enzyme inhibition (e.g. angiotensin convertying enzyme inhibitors, acetylcholinesterase inhibitors)
• blockade of ion channels (calcium channel antagonists, anaesthetics)
Any drug may produce unwanted or unexpected adverse events, these can range from trivial (slight nausea) to fatal (aplastic anaemia) . According to research published in JAMA
( azarou J, Pomeranz BH, Corey PN. 1998. Incidence of adverse drug reactions in hospitalised patients: a meta-analysis of prospective studies. JAMA Apr 15; 279 (15): 1200-5), in 1994, in US, 106,000 deaths were caused by adverse drug reactions, making ADRs the fourth leading cause of death in US. One of the main reasons for adverse events following drug intake is the drug binding to non-specific or non-target receptors in the body (Brody, Larner and Minneman 1998) . Another reason is the interaction of the drug with other drugs given to the patient. This is a particular problem in the elderly who frequently suffer from multiple illnesses requiring many different classes of drugs and providing a real potential for drug interactions (Weatheral, Leadingham and Warrell 1996) . The drug may also produce adverse events over time as the drug is absorbed, distributed, metabolised and excreted e.g. products of metabolising the drug may be reactive themselves and be toxic to the body. Being able to predicting the likelihood of particular individuals suffering from an adverse event and the severity of that event would be important tool for the practitioner.
Another problem the medical practitioner faces, is that certain patients may be particularly susceptible to drug addiction. Examples of drugs with known addictive properties are Amphetamines, Temazepam and Phenobarbitone, although having approved medicinal use e.g. phenobarbitone for epilepsy, they may cause problems of dependency and misuse in individuals. Knowledge of such an individual's susceptibility before .prescribing certain drugs would be an advantage to the medical practitioner.
The core list of genes for the ADME Genostic, would prove of considerable value in aiding decisions concerning the appropriateness and relevance of therapeutic interventions using many drugs . The use of the ADME Genostic would be of considerable utility in determining the likelihood and magnitude of therapeutic response, complications from drug-
drug interactions, the potential for adverse events and the difficulties that might arise due to previous, concurrent or future dysfunction, damage or disease of body systems in an individual, patient, group or population. All of these factors are of considerable importance in enabling the selection and monitoring of therapeutic interventions and effective healthcare management . "
In addition, the core list of genes in the ADME genostic would also be of considerable utility in enhancing the analysis of clinical trial data derived from drugs in development.
A list of drugs currently on the market can be found in standard works of reference, in particular the British National Formulary, 2002, the Dental Practioners' Formulary, 2002, Martindale, 2002, Herbal medicines, 2002. Drugs available in the United States can be found in U.S. Pharmacopeia, 2002, and drugs available in Japan can be found in Iryoyaku Ninon Iyakuhinshu, 2002, Ippanyaku Nihon Iyakuhinshu, 2002 and Hokenyaku Jiten, 2002. Drugs available in other countries can be found in the appropriate National Formularies. A list of drugs currently under development worldwide can be found in current journals and textbooks.
In a review entitled, Drug-metabolism research challenges in the new millenium: individual variability in drug therapy and drug safety', it has been stated that: n with the rapid progress in the understanding of genetic polymorphism and the development of genechip technology, it becomes quite feasible for individuals to be genotyped with respect to critical genes targeted for drug intervention and genes essential for drug transport and metabolism. the
(future) objective is to identify key genetic variations that could impact drug response and drug safety." A.Y.H. Lu, (1998) Drug metabolism and disposition, Vol 26 (12) pl217-1222.
There is a wealth of information available on the genetic polymorphisms of enzymes involved in drug metabolism. Genetic variation in genes coding for proteins which act as drug metabolising enzymes, drug transporters, DNA repair enzymes, or drug targets can lead to the production of defective enzymes or altered receptor binding affinities . This can have profound effects on the drug efficacy, drug safety and optimal drug dosage. The genetic variation in these genes has been identified and is included in our ADME core list of genes .
We had previously concluded that a large number of genes would be of value in looking at gentic profil /phenotype interactions for the purposes of managing healthcare and drug administration. These are exemplified below.
Example 1
Core, Genes Relevant for Genetic Profiling of Drug Metabolism,
Efficacy and Safety activities
These genes are elaborated below:
KEY TO Λ PROTEIN FUNCTION' COLUMN
E ENZYME
T TRANSPORT & STORAGE
S STRUCTURAL
I IMMUNITY
N NERVOUS TRANSMISSION
G GROWTH S DIFFERENTIATION
In a further novel development we have conducted a further analysis and meta-analysis of the literature which has enabled us to select a subset of the Genostic Drug core to allow the development of a screen for individual persons gene variant profiles the results of which will aid in the prescription of appropriate drugs at appropriate doses . In a novel approach the screen is based on both SNPs and haploptypes combined. Gene based haplotypes consist of a combination of individual SNPs that occur within a defined region of a single gene and in some instances they have been found to have a greater influence on patient response than individual SNPs . An example
is the response of asthmatics to albuterol therapy which shows great interindividual variation that is more strongly associated with ADBR2 haplotype than it is with any individual SNP (Drysdale et al . , 2000).
The raw genetic profile datasets are processed by a database driven "rules engine" delivering genotype specific drug use advice in a user friendly format.
The rules engine is capable of delivering advice on several hundred drugs currently on the market including those in EXAMPLE 2.
Gene based haplotypes consist of a combination of individual SNPs that occur within a defined region of the chromosome and in some instances they have been found to have a greater influence on patient response than individual SNPs. An example is the response of asthmatics to albuterol therapy which shows great interindividual variation that is more strongly' associated with ADBR2 haplotype than it is with any individual SMP (Drysdale et al . , 2000).
EXAMPLE 2 LIST OF DRUGS ON WHICH INDIVIDUAL ADVICE CAN BE PROVIDED
5-fluorouracil, Aσelofenac, Acenocoumarol, Acetaminophen, Acrolein, Adrenochrome, Adriamycin, Albuterol, Alfenatil, Alprazolam, Alprenolol, Amiflamine, Aminochrome, Amiodarone, Amitriptyline, Amlodipine, Amonafide, Amphetamine, Alkylating agents, Anticancer, Anti-leukaemia therapy, Anti-tuberculosis, Ap indine, Arte isinin, Ascorbic acid, Atorvastatin, Beta- naphthoflavone, Bilirubin, Budesonide,' Bufuralol, Buproprion, Caffeine, Cannabis, Captopril, Carbamazepine, Carisoprodol, Carvedilol, Celebrex, Celecoxib, Cerivastatin, Chloramphenicol, Chloropropamide, Chloroquine, Chlorpheniramine, Chlorproguanil, Chlorpromazine, Cimetidine, Cinnarizine, Ciprofloxaσin Cisapride; Cisplatin, Citalopram,
Clarithromycin, Cloinidine, Clomipra ine, Clotrimazole, Clozapine, Cocaine, Codeine, Coumarin, Cyclobenzaprine, Cyclophosphamide, .Cyclosporin a, Cytostatic drugs, Dapsone, Debrisoquine, Delavirdine, Deprenyl, Desipramine, Dexamethasone, Dexfenfluramine, Dextromethorphan, Dextroprόpoxyphene, Diazepam, Diclofenac, Diltiazem, Docetal, Dopachrome, Doxorubicin, D-penicillamine, E-3810, Ecstasy (mdma) , Enalapril, Encainide, Encinide, Epirubicin, Erythromycin, Estradiol, Estrone, Ethacrynic acid, Ethanol, Ethoxyresorufin, Etoposide, Felbamate, Felcainide, Flecainide, Fluconazole, Flunarizine, Fluoroquinolones , Fluoxetine, Fluphenazine, Flurbiprof n, Flutamide, Fluvastatin, Fluvoxamine, Furafylline, Gallopamil, Glipizide, Glyburide, Guanoxan, Halofantrine, Haloperidol, Hexobarbital, Hexobarbitone, Hydralazine, Hydrocodone, Ibuprofen, Ifosfa ide, Imipramine, Indomethacin, Indoramin, Insulin, Interferon, Irbesartan, Irinotecan, Isinopril, Isoniazid, Isosafrole, Isotretinoin, Ketamine , Ketoconazole, Labetalol, Lansoprazole, Levadopa, Levomepromazine, Lidocaine , Lisinopril, Lobeline, Loratidine, Lornoxicam, Losartan, Lovastatin, Maprotiline, Mefenamic acid, Meloxicam, Mephenytoin, Met-a-mphetamine, Methadone, Methotrexate, Methoxsalen, Methoxyamphetamine, Methoxyphenamine, Methyl cholanthrene, Metoclopramide, Metoprolol, Mexiletine, Mianserin, Mibefradii, Miconazole, Midazolam, Minaprine, Mirtazapine, Moclobemide, Modafinil, Morphine, Nafcillin, Naproxen, Nelfinavir, Nicardipine, Nicotine, Nilutamide, Noradrenochrome, Norethindrone, Norfloxacin, Norfluoxetine , Nortriptyline, Norverapam.il, -propylamine, Oestrogen / hrt, Olanzapine, Omeprazole, Ondansetron, Oxfloxacin, Oxprenolol, Paclitaxel, Pantoprazole, Paracetamol, Paraxanthine, Paroxetine, Pentamidine, Pentobarbital, Perhexiline, Perphenazine, Phenacetin, Phenelzine, Phenformin, Phenobarbital, Phenobarbitone, Phenothiazines, Phenylbutazone, Phenytoin, Pindolol, Pioglitazone, Piroxicam, Prednisone, Primidone, Probenioid, Procainamide, Progesterone, Proguanil, Propafenone, Propanolol, Propofol, Propranolol,
Propylajamaline, Quanoxan, Quinidine, Quinine, Rabeprazole, Raltitrexed, Ranitidine, Rauhimbine, Red-haloperidol, Remoxiride, Retinoic acid, Rifabutin, Rifampicin , Riluzole, Risperidone, Ritonavir, R-mephobarbital, Rofecoxib, Ropivacaine, Rosiglitazone, R-warfarin, Salmeterol, ■ Secobarbital, Seratrodast, Sertraline, Simvastatin, S-ephenytoin, S-metoprolol, S-naproxen, Sparteine, Succinylcholine, Sulfadiazine, Sulfamethoxazole, Sulfaphenazole, Sulfasalazine , Sulfinpyr zone, , ulphamethizole, Sulphaphenazole, Sulphonamides , Suprofen, S-arfarin, Tacrine, Tamoxifen, Tegafur, Temazepam, Teniposide, Terbinafine, Terfenadine, Testosterone, Theophylline, Thioridazine, Ticlopidine, Tienilic acid, Timolol, Tolbutamide, Tolcapone, To oxetine, Topiramate, Torasemide, Tramadol, Tranylcypromine, Triazolam, Trifluperidol , Trimethadione, Trimethoprim, Trimipramine, Troglitazone, Tropisetron, Valproic acid, Venlafaxine, Verapamil, Warfarin, Zafirlukast, Zidovudine, Zileuton, Zileuton, Zolmitriptan, Zoloft, Zopiclone, Zuclopentixol
The table below shows a selection of the genes comprising the ADME panel together with some examples of common drugs, the effectiveness of which is influenced by the gene variant:
EXAMPLE 3
A SELECTION OF GENES FROH THE PANEL AND THE DRUGS THEY
METABOLIZE
The selected genes and gene variants can be readily detected in a sample of DNA use of a set of specific gene probes and their detection using a number of well known SNP detection
technologies (such as mass tag detection, DNA probe/chip arrays etc) .
EXAMPLE 4
A SELECTION OF GENES FROM THE PANEL WITH RELEVANT PROBE
SEQUENCES
The genes and gene variants chosen can then be analysed in order to generate individual profiles which can be linked to specific advice concerning optimal drug of choice for a particular disease or condition and the most appropriate dosages for that drug in a given patient (described in Example 4) .
The generation of genetic profiling data and its analysis alongside clinical information derived from patients presents considerable challenges for data handling and analysis . The volume of information, number of information categories and the variable nature of the information (e.g. dimensional or categorical) ensure that the operation of a database combining genetic and clinical information to generate a prognostic outcome is a complex task.
However, the complexity can be dealt with using existing analytical approaches. Association analysis between genetic polymorphisms can be dealt with by using standard statistical techniques (analysis of variance, meta-analysis etc) with appropriate corrections for multiple testing. The thresholds for statistical significance will be derived from scientific
convention (e.g. significance at the 5% level following Bonnferoni correction) . The data concerning genotype/phenotype relationships between the core group of genes and clinical signs and symptoms and therapeutic interventions will form a central component of the database.
The creation of a database containing and elaborating on such genotype/phenotype relationships will become an important tool for the practice of molecular medicine and the development of healthcare management. In order to derive benefit from such a database it must be capable (following interrogation using a patients profile of genetic variation derived from the core group of genes) of analysing the profile and providing a meaningful output to the healthcare professional which will provide guidance on the prognosis, healthcare management and therapeutic interventions appropriate to the patient.
The generation of such an output can be achieved using machine learning algorithms.
The genetic algorithm (Goldberg 1989, Fogarty and Ireson 1994) has been shown to provide a general process for achieving good results for search in large noisy domains. Starting from a population of randomly generated points in a search space, and given an .evaluation of each of those points, the genetic algorithm is designed to converge the population to an optimum point in the search space. Processes of data selection, crossover, mutation and replacement of old members of the dataset achieve this with new members of more value. The effective use of the genetic algorithm process is a representation of the search space, -which is responsive to the heuristics, embodied in the genetic operators.
The user must also supply an evaluation function identifying the degree to which the point in space approaches an optimum ( ^weighting' ) such that the selection operator for propagation through the dataset can choose them.
The genetic algorithm can be used to find predictively meaningful categories that is :
intervals of continuous attribute values sets of nominal attribute values combinations of attributes
Together these attributes can create a simple Bayesian classifier for aspects of healthcare management.
Additional techniques (e.g. Bahadur-Lazarsfeld expansion) enable second order approximation of dependencies between predictive attributes . This allows the full complexity of the individual's genetic variation profile and the specifics of their clinical, psychological and social state to be assessed in order to produce an output concerning their prognosis, healthcare management and the possibilities for therapeutic intervention.
The data can them be presented as a series of recommendations to the practitioner based on advice for specific genotype and drug combinations Example 4.
EXAMPLE 5
ANALYSIS OF DATABASE TO ASCERTAIN GENOTYPE/PHENOTYPE
RELATIONSHIPS
The relevant genotypes can be collated and linked to specific recommendations in a systematic way.
CYP2C19
Genotype code ALLELEl ALLELE2 Phenotype
1 *1 *1 EM Extended etaboliser
2 *1 * *22 I IMM Intermediate
3 *1 *3 IM
4 *2 * *22 P PMM Poor
5 *2 *3 PM
6 *3 *3 PM
Drug Indication Phenotype Advice
H.pylori Increased cure with dual
Omeprazole ulcer PM therapy
Increased cure with dual
IM therapy
EM Triple therapy advised
H.pylori Increased cure with dual Rabeprazole ulcer PM therapy
Increased cure with dual
Pantoprazole IM therapy
60% cure with dual, may Lansoprazole EM prefer triple
Try lower dose, observe carefully for adverse
Mephenytoin Epilepsy PM effects
Try lower dose, observe carefully for adverse
IM effects EM Normal dosage conditions
lower dose, 60% of normal, monitor closely for side
Amytryptiline Depression PM effects lower dose, 80% of normal, monitor closely for side
IM effects EM 100% dose
Fluoxetine Depression PM Consider lower dose
IM Consider lower dose EM Normal dosage
Sertraline Depression PM Consider lower dose
IM Consider lower dose EM Normal dosage
The presentation of this data can be further optimised and enhanced for use by the patients healthcare worker by distilling its content into a series of simple text boxes containing the relevant advice.
EXAMPLE 6
PRESENTATION OF ADVICE CAN BE OPTIMISED TO AID THE USE OF IT
BY THE HEALTHCARE WORKER.
Query Results
WARFARIN
Assembly of such data will allow the merging of accepted treatment algorithms with the polymorphic variation underlying specific aspects of genomic functionality. This will produce new algorithms that will provide a prognostic indication for individual patients and, coupled with the expertise of their responsible clinician, allow the appropriate healthcare decisions to be made in a pro-active way.
The identification of genetic variation in the core list of genes and its application to healthcare management will have significant beneficial effects on the way in which clinicians will be able to formulate plans for healthcare management.
This will be seen in at least two ways . The first by enabling the targeting of resources at appropriate individuals and the second by enabling an objective risk assessment of the optimum configuration for different types of therapeutic intervention (e.g drugs, surgery, radiotherapy, occupational therapy) and the identification of those patients at significant risk of suffering adverse events from therapeutic intervention.
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