Post on 30-Dec-2015
description
Pharmacogenetics&
Pharmacogenomics
Personalized Medicine
Drugs and Genes• Pharmacogenetics:
– Study of the genetic factors that influence an organism's reaction to a drug
• Pharmacogenomics: – Development of drug therapies to compensate for
genetic differences in patients
• Genotype: – The genetic makeup of an
organism
• Phenotype:– An organisms’ observable traits
Review of Genes
Human Genome is Variable
Human Genome is Variable• Contains 3x109 base pairs of DNA
– 3 billion!
• Between 2 people (except identical twins) the rate of genetic variation (individuality) is about 0.1%[0.1% of 3 billion = 3 million base pair differences]
• The most common cause of genetic variation
• SNPs occur on average every 1000 bases
• Understanding SNPs has shown promise for improving disease detection and treatments
Single Nucleotide PolymorphismPolymorphism
“Poly” Many“Morphe” Form
General Population 94%
Single Nucleotide Polymorphism 6%
Examples of SNPs and Disease
SNPs in Beta-globinSickle Cell Anemia
SNPs in BRCA1Predisposed for breast cancer
Protein
Single Nucleotide Polymorphisms
Regulatory Sequence Coding Region
Coding SNP:changes amino acidsequence (function)
Outside gene
Linked SNPs
Non-coding SNP:changes amountof protein
Causative SNPs
SNPs Can Change Drug Response
• Pharmacokinetic: changes in drug metabolism• Pharmacodynamic: changes in drug targets
– enzymes, receptors, or transporters
Genetic Polymorphisms
Pharmacokinetic
Absorption Distribution Metabolism Excretion
Pharmacodynamic
Receptors Ion Channels Enzymes Immune System
SNPs and CYPs
• Cytochrome P450 enzymes are commonly found with SNPs
Drug Metabolism
Polymorphism Substrate
CYP2B6 doxorubicin, nicotine
CYP2C9 warfarin, doxorubicin
CYP2C19 diazepam, proton pump inhibitors
CYP2D6 beta-blockers, anti-depressants, codeine, tamoxifen
CYP3A4 erythromycin, HIV protease inhibitors
Effects of SNP in CYP2D6
1: Normal enzyme activity
2: Decreased enzyme activity
Extensive Metabolizer
Pla
sma
Leve
l of
Dru
g
Time
Poor Metabolizer
Pharmacokinetics of Tamoxifen
Mutations Impact Treatment Outcome
No Polymorphisms on CYP2D6
Polymorphisms on CYP2D6
Clin Pharmacol Ther. 2008 January; 83(1): 160–166.
Extensive n=115
Decreased n=65
Rel
apse
-fre
e S
urv
ival
(%
)
P=0.007
Metabolism of Alcohol… 2 Steps
Genetic Polymorphisms and Differences in Alcohol Metabolism
ADH Polymorphism
Metabolism Rate
Populations with High Prevalence
ADH1B*1 SlowMost populations, including most Caucasians, Mexican Americans, and Native AmericansHeavy drinkers
ADH1B*2 Fast Most Asians, 25% of Jews, and some Hispanics
ADH1B*3 Fast African-Americans and 6% of Mission Indians (S. West California)
Genetic Polymorphisms and Differences in Alcohol Metabolism
23andMe
Better Drug Discovery with Pharmacogenetics & Pharmacogenomics
• Increase drug efficacy
• Eliminate adverse drug reactions
• Ensure success for drug approval in clinical trials
• Increase efficiency of clinical trials
Drug Treatment
Available Drugs
Drug 1
Drug 2
Drug 3
Drug 4
No response
Adverse side effect
Weak response
Strong response
Currently best treatment determined by trial and error.
Future genomics may enable us to pick the right drug the first time.
Yesterday’s Medicine
Tomorrow’s Medicine
Personalized Medicine
The right dose ofthe right drug forthe right indication forthe right patient at the right time.
Personalized Medicine: Cancer
Many factors contribute to tumor formation.
Breast Cancer is a Perfect Model
Pharmacogenomics: Gene Candidate to Drug Treatment
Human epidermal growth factor receptor-2 (HER2) in breast cancer cells
Herceptin in Clinical Trials
Cancer Results from a Combination of Genomic Changes
Drug Discovery
The Clinical Trial Process
Safe in humans?
Does the treatment
work?
Better than current
treatment?
More info on the
approved treatment
File NDAFile IND
Less than 1 in 10 Drugs in Clinical Trials Obtain a NDA
In a study of 14 clinical trials, 20-75% of subjects got no benefit
Streamlining of Clinical Trials is the Future
Pharmacogenetics and Pharmacogenomics Summary
1. SNPs in coding and non-coding regions can alter the function or expression of an enzyme that metabolizes drugs
2. Pharmacogenetics impacts the kinetics and dynamics of drugs.
3. Personalized medicine will help treat patients according to their genetic profile, increase drug efficacy, and reduce side effects
4. Designing clinical trials based on SNP profiles can reduce FDA approval time for drugs
Concept Map PharmacogenomicsPharmacodynamics PharmacokineticsGeneSNPsHaplotypePhenotype GenotypeCYPsDrug