2. Pharmacogenomics and Pharmacist Provided Patient Care
Kathryn Momary Pharm.D., BCPS
Associate Professor
Mercer University
College of Pharmacy

3. Financial Disclosure
Investigator Initiated Grant from Merck

4. Objectives
Summarize and use appropriately the nomenclature associated with the area of pharmacogenomics.
Describe the role of pharmacogenetic testing for certain medications in current clinical practice.
Predict how genetic polymorphisms in genes encoding drug metabolism could effect drug response

5. Current Pharmacotherapy Approach
Population
with a
given disease
Same therapy for all patients
Intolerance
Good response
Poor or non-response
↓ dose or different drug
↑ dose or different drug

6. Factors Influencing Drug Response
Age
Race/ ethnicity
Pharmacokinetics
Concomitant diseases
Concomitant medications
GENOTYPE

7. Clinical Application of Pharmacogenomics
Population
with disease
Predicted
response
Genotype
Therapy
 dose or
different drug
Toxicity
Good
response
Traditional therapy
Poor
response
Different drug or alternative therapy

8. Pharmacogenomics
Hereditary basis for inter-individual differences in drug response
Goal: optimize drug therapy and limit drug toxicity based on a person’s DNA

9. How did it begin?
Began with observations of unusual, inherited drug response
Driven by observations variability in drug response
Then researchers sought to find genetic causes of this variation

10. History of Pharmacogenomics
1956: Discovery of glucose-6 phosphate dehydrogenase polymorphism
1957: “Inheritance might explain many
individual differences in the efficacy
of drugs and in the occurrence of
adverse drug reactions.” -Motulsky
1959: “Pharmacogenetics” introduced by Vogel
Human
Genome
Project

11. You may may not care about genes but you care about proteins!
DNA
Nucleotides
mRNA
Proteins
Amino acids
Drug Targets
Metabolizing Enzymes
Transcription
Translation
Proteins and medication response:
Drug receptors
Drug metabolizing enzymes
Proteins involved in disease physiology

12. Genetic Variability

13. Types of Genetic Variation
Polymorphism – Variations occurring at a frequency of at least 1% in the human population
Rare mutations / defects – Occur in < 1% of the population and can cause inherited diseases such as cystic fibrosis, Huntington's disease, or hemophilia

14. Single Nucleotide Polymorphism (SNP)
“Wild-type” allele 
Codon
Nucleotides GCA CCC AAT AGA AGC CAT
Amino acid Ala Pro Asn Arg Ser His  
“Variant” allele 
Codon
Nucleotides GCA CCC AAT GGA AGC CAT
Amino acid Ala Pro Asn Gly Ser His  

15. Types of SNPs
Nonsynonymous – SNP resulting in an amino acid substitution
Arg16Gly or Arg16→Gly
Synonymous – SNP not resulting in an amino acid substitution due to significant redundancy in the genetic code
GGA and GGC both code for glycine
A1166C or A1166→C

16. Nomenclature in Pharmacogenomics
CYP450 and Other Drug Metabolizing Enzymes

17. Star-allele Nomenclature*1
Designated reference sequence with which polymorphic sites are compared
The first sequence described
May not be the most common allele in every ethnic population
Robarge et al. CPT. 2007;82:244-8.

18. Star-allele Nomenclature
A unique number is assigned (i.e. *2,*3) when a novel variant is identified:
That leads to an amino acid substitution
Affects transcription, splicing, translation, or post-transcriptional or post-translational modification
If multiple variant alleles existing on the same chromosome are shown to have a functional effect on the protein, in a context where no single polymorphism has an effect
Robarge et al. CPT. 2007;82:244-8.

19. Star-allele Nomenclature
A unique letter is assigned (*3B vs. *3A)
Nonfunctional nucleotide changes thought to exist on the same chromosome
Inherited with a named star allele
Principle star allele is designated by A
Robarge et al. CPT. 2007;82:244-8.

20. CYP450 Allele Nomenclature Committee
Peer-review process
Maintains allele nomenclature for 25 of 28 known human CYP genes
Function-centric focus (phenotype → genotype data)
Developed prior to the genome explosion
May not sufficiently describe polymorphisms beyond SNPs
Utility in a genotype → phenotype world?
Robarge et al. CPT. 2007;82:244-8.

21. Why do I care?!?!?!?

22. Case Study Gasche et al. NEJM 2004;351:2827-31.
62 yo male with a h/o chronic lymphoma
Chief complaint: 3 day h/o fatigue, dyspnea, fever, and a cough
Objective: a/o, hypoxemic but normocapnic, bilateral infiltrates on X-ray, yeast found on broncheoalveolar lavage
A/P: Bilateral pneumonia with possible fungal infection
Begin ceftriaxone, clarithromycin, and voriconazole
Oral codeine to relieve cough

23. Case Study Gasche et al. NEJM 2004;351:2827-31.
On hospital day 4 the patient was found unresponsive.
In addition, the patient was dehydrated and experiencing renal dysfunction.
Noninvasive ventilation was begun and he was transferred to the ICU.
However, noninvasive ventilation did not improve his level of consciousness.
Administration of naloxone (an opiod receptor antagonist) did improve responsiveness.

24. So…what happened?

25. Kidney – renal elimination
Codeine:
CYP3A4 – Norcodeine
Glucuronidation – Codeine-6 glucuronide
CYP2D6 – MORPHINE
CYP3A4 is inhibited by clarithromycin and voriconazole
This patient had ultra-rapid or extensive CYP2D6 activity
80%
Kidney – renal elimination
Gasche et al. NEJM 2004;351:

26. Clopidogrel as an Example

28. CYP2C19 Gene
Wild Type:
CYP2C19 *1
Variants associated with decreased activity or “loss of function”:
CYP2C19*2
CYP2C19*3
Variant associated with increased activity or “gain of function”:
CYP2C19*17

29. Iverson Genetics - PlaviStat
Metabolic Capacity
Type of polymorphism
Number of Copies
Extensive - EM
None
Intermediate - IM
Loss of function 1
Poor - PM 2
Ultra-Rapid single - UMS
Gain of function
Ultra-Rapid double - UMD

30. Clopidogrel and CYP2C19
Possession of a CYP2C19*2 or *3 allele is associated with:
Decreased formation clopidogrel active metabolite
Less efficient inhibition of platelet aggregation by clopidogrel
Increased risk of adverse cardiovascular events and stent thrombosis with clopidogrel
Geisler et al. Pharmacogenomics. 2008;9:
Kim et al. Clin Pharmacol Ther. 2008;84:
Trenk et al. J Am Coll Cardiol. 2008;51:

31. CYP2C19 Genotype and Clopidogrel Response
HYPER Responders
CYP2C19 *1/*17
Average Responders
CYP2C19 *1/*1
↑ Risk of Cardiovascular Events
HYPO
Responders
CYP2C19 *1/*2
↓ Production of active metabolite
HYPO
Responders
CYP2C19 *2/*2

32. CYP2C19 and Clopidogrel Things to keep in mind…
Other factors effecting response, such as drug interactions
Other causes of variability
Diabetes
Smoking
Adherence
Other genes?

33. CYP2C19 Genotyping Tests Currently available
Test is a “send out” at most insitutions
Turn around time is hours
Standard cost is $300

34. What do you do? Increase the dose? Therapeutic alternative?
Loading dose of 600mg, MD 150mg
The data with this is conflicting
Therapeutic alternative?
Prasugrel – ONLY INDICATED FOR PCI
Ticagrelor – indicated for ACS

35. Clopidogrel Patient Case

36. FD is a 57 year old male who began having crushing substernal chest pain while watching TV at home.
In the emergency department, FD was given aspirin 325mg and sublingual nitroglycerin. Cardiac enzymes were drawn and he had an EKG done that revealed persistent ST-segment elevations, so he was rushed to the catheterization lab for treatment of his STEMI.
Standard medications for the cath lab are given included clopidogrel 600mg po x 1.
He had a Taxus stent (paclitaxel drug eluting stent) placed in his LCx, and blood flow was restored. His drips were discontinued after the intervention in the cath lab and he was transferred to the CICU for observation.

37. They ask you what this means. How would you define FD?
A CYP2C19 genotyping test is performed for FD and the following report is provided to the medical team:
CYP2C19*2/*3
They ask you what this means. How would you define FD?
FD is an ultra-rapid metabolizer
FD is an extensive metabolizer
FD is an intermediate metabolizer
FD is a poor metabolizer

38. What does this CYP2C19 metabolizer status mean for FD?
He is a VERY poor metabolizer
Significant decrease in clopidogrel active metabolite production
Increased risk of cardiovascular events

39. They would also like a recommendation on how to address this information.
Continue clopidogrel 75mg daily
Increase clopidogrel dose to 150mg daily
Change to prasugrel 10mg daily
Change to ticagrelor 90mg q12h
Considerations:
Cost
Compliance

40. How would you counsel FD on his CYP2C19 genotype?
You have a fairly common change in your DNA that causes you to have a decrease in response to clopidogrel
We are going to change your medication to ensure that you get the best possible therapy
Terms to avoid:
Mutant
Dysfunction

41. Warfarin as an Example

42. Activated Clotting Factors Hypofunctional Clotting Factors Carboxylase
Oxidized Vitamin K
Reduced Vitamin K
VKORC1
S-warfarin
R-warfarin
CYP2C9
CYP1A / CYP3A4

43. CYP2C9 Gene Common alleles and their frequencies
CYP2C9*1 - Wild-type
CYP2C9*2 - Arg144Cys
CYP2C9*3 - Ile359Leu
CYP2C9*5 – Asp360Glu
CYP2C9*2 and *3 alleles
About 35% of Caucasians, but only 3% of African Americans and Asians, carry  1 variant allele.
CYP2C9*5
Found only in African Americans
Decreased CYP2C9 activity

44. Activated Clotting Factors Hypofunctional Clotting Factors Carboxylase
Oxidized Vitamin K
Reduced Vitamin K
VKORC1
S-warfarin
R-warfarin
CYP2C9
CYP1A / CYP3A4

45. CYP2C9 Genotype and Warfarin Dose Requirement Higashi et al
CYP2C9 Genotype and Warfarin Dose Requirement Higashi et al. JAMA 2002;287:1690.
p<0.001
Median dose (mg/day)

46. CYP2C9 Genotype and Warfarin Dose Requirement
CYP2C9*2 and *3 alleles
Increased risk of INR above range
Longer time to achieve stable dosing
Higher risk for bleeding during initiation
Higher risk of bleeding during long term therapy
In a study of 368 European Americans, CYP2C9 genotype found to account for 6-10% of the variability in warfarin dose.
Higashi et al. JAMA 2002;287:1690. Limdi et al. CPT 2008;83:312.
Rieder et al. N Engl J Med 2005;352:2285.

47. Activated Clotting Factors Hypofunctional Clotting Factors Carboxylase
Oxidized Vitamin K
Reduced Vitamin K
VKORC1
S-warfarin
R-warfarin
CYP2C9
CYP1A / CYP3A4

48. VKORC1 Gene and Warfarin
p<0.001
VKORC1 genotype accounted for 25% of the variability
in warfarin dose.
Rieder et al. N Engl J Med 2005;352:2285.

49. Contribution to the Variability in Warfarin Dose Requirements
McClain et al. Genet Med. 2008;10:89-98.

50. Updated and Expanded in 2010

51. Warfarin Dosage from the Official Prescribing Information
The dose of COUMADIN must be individualized by monitoring the PT/INR. Not all factors causing warfarin dose variability are known. The maintenance dose needed to achieve a target PT/INR is influenced by:
Clinical factors including age, race, body weight, sex, concomitant medications, and comorbidities and
Genetic factors (CYP2C9 and VKORC1 genotypes).
Select the starting dose based on the expected maintenance dose, taking into account the above factors. … If the patient’s CYP2C9 and VKORC1 genotypes are not known, the initial dose of COUMADIN is usually 2 to 5 mg per day.
The patient’s CYP2C9 and VKORC1 genotype information, when available, can assist in selection of the starting dose. Table 5 describes the range of stable maintenance doses observed in multiple patients having different combinations of CYP2C9 and VKORC1 gene variants. Consider these ranges in choosing the initial dose.
Warfarin Prescribing Information. Bristol-Myers Squibb Company 2010

52. CYP2C9 and VKORC1 Genotypes and Warfarin Dose
CYP2C9 Genotype
VKORC1 genotype
*1/*1
*1/*2
*1/*3
*2/*2
*2/*3
*3/*3
-1639AA
3-4
0.5-2
-1639AG
5-7
-1639GG
Warfarin Prescribing Information. Bristol-Myers Squibb Company 2010

53. Warfarin Dosing Algorithms
>7 algorithms have been published
International Warfarin Pharmacogenomics Consortium
4043 racially diverse subjects
Model includes age, height, weight, VKORC1 AA and AG genotype, 5 different CYP2C9 genotype levels, race, enzyme inducer use, and amiodarone use
Accurately predicts low and high dose requirements
warfarindosing.org

54. Patient Case RG is a 49 yo caucasian male diagnosed with a DVT
5’5” and 145 lbs
SH: smoked 1ppd for ~30 years, EtOH 1 drink/day
PMH: HTN, hyperlipidemia, DVT
Meds: simvastatin 40mg po daily, hydrochlorothiazide 25mg po daily
Labs: INR prior to initiating therapy was 1.1
Rapid genotyping performed: CYP2C9 *1/*3, VKORC A/G
Maintenance warfarin dose:

55. CYP2C9 and VKORC1 Genotypes and Warfarin Dose
CYP2C9 Genotype
VKORC1 genotype
*1/*1
*1/*2
*1/*3
*2/*2
*2/*3
*3/*3
-1639AA
3-4
0.5-2
-1639AG
5-7
-1639GG
Warfarin Prescribing Information. Bristol-Myers Squibb Company 2010

59. Clinical Decision Making To genotype or not to genotype prior to starting warfarin?
It depends…
Are they already receiving warfarin therapy? No
New to therapy?
Ability to follow up in Coumadin clinic
High risk for bleed

60. The Future of Pharmacogenomics
Genotyping patients before the information is necessary.
This requires:
Consent from all patients for genetic testing
Technology to store a lot of information (potentially entire patient genomes)
An electronic medical record that supports the information
A system to effectively communicate the genotype information in a straight forward manner

61. Vanderbilt University as an Example
PREDICT: Pharmacogenomic Resource for Enhanced Decisions in Care and Treatment
ALL patients undergoing cardiac catheterization at Vanderbilt University Medical Center will be genotyped for CYP2C19
The CYP2C19 genotype will be available in the medical record in case clopidogrel is needed in the future

62. Population at risk for disease
Clinical Application of Pharmacogenomics
Population at risk for disease
Predicted
response
Population
with disease
Therapy
Genotype
 dose or
different drug
Toxicity
Good
response
Traditional therapy
Different drug or alternative therapy
Poor
response

63. One More Case…
JM presents to your pharmacy straight from the doctor and is waiting in the store to get his new prescription filled.
Presents with a new prescription for warfarin 5mg PO daily
He also has a genetic report with him today
Patient Profile:
Name: JM
Age: 56 Sex: M Allergies: NKDA
Home Medication List:
Omeprazole 40mg PO daily
Albuterol 2 puffs PO q4h prn
Sertraline 100mg PO daily
Lisinopril 20mg PO daily
Atorvastatin 40mg PO daily
Metformin ER 1000mg PO daily
Last date of fill for all medications was 1 week ago.

64. Which genes do you care about?
Omeprazole – metabolized by CYP2C19
Albuterol – stimulates the β2 receptor
Sertraline – metabolized by CYP2D6, 3A4, 2C9, 2C19
Lisinopril – none
Atorvastatin – CYP3A4, SLCO1B1
Metformin – none
Warfarin – CYP2C9, VKORC1
Patient Profile:
Name: JM
Age: 56 Sex: M Allergies: NKDA
Home Medication List:
Omeprazole 40mg PO daily
Albuterol 2 puffs PO q4h prn
Sertraline 100mg PO daily
Lisinopril 20mg PO daily
Atorvastatin 40mg PO daily
Metformin ER 1000mg PO daily
Last date of fill for all medications was 1 week ago.

65. JM’s genotypes CYP2C19 *1/*1 CYP2C9 *1/*3 CYP2D6 SLCO1B1
Omeprazole – metabolized by CYP2C19
Albuterol – stimulates the β2 receptor
Sertraline – metabolized by CYP2D6, 3A4, 2C9, 2C19
Lisinopril – none
Atorvastatin – CYP3A4, SLCO1B1
Metformin – none
Warfarin – CYP2C9, VKORC1
CYP2C19 *1/*1
Normal
CYP2C9 *1/*3
Intermediate metabolizer
CYP2D6
Ultrarapid metabolizer
SLCO1B1
VKORC A/A
Low warfarin dose

66. JM’s genotypes CYP2C19 *1/*1 CYP2C9 *1/*3 CYP2D6 SLCO1B1
Omeprazole – metabolized by CYP2C19
Albuterol – stimulates the β2 receptor
Sertraline – metabolized by CYP2D6, 3A4, 2C9, 2C19
Lisinopril – none
Atorvastatin – CYP3A4, SLCO1B1
Metformin – none
Warfarin – CYP2C9, VKORC1
CYP2C19 normal metabolizer. No change needed.
CYP2C19 *1/*1
Normal
CYP2C9 *1/*3
Poor metabolizer
CYP2D6
Ultrarapid metabolizer
SLCO1B1
VKORC A/A
Low warfarin dose
CYP2C9 and 2D6 likely counterbalance each other. Plus, if he’s receiving benefit without side effects…leave it alone.
Do you need to change the dose?

67. CYP2C9 and VKORC1 Genotypes and Warfarin Dose
CYP2C9 Genotype
VKORC1 genotype
*1/*1
*1/*2
*1/*3
*2/*2
*2/*3
*3/*3
-1639AA
3-4
0.5-2
-1639AG
5-7
-1639GG
Warfarin Prescribing Information. Bristol-Myers Squibb Company 2010

68. JM’s genotypes CYP2C19 *1/*1 CYP2C9 *1/*3 CYP2D6 SLCO1B1
Omeprazole – metabolized by CYP2C19
Albuterol – stimulates the β2 receptor
Sertraline – metabolized by CYP2D6, 3A4, 2C9, 2C19
Lisinopril – none
Atorvastatin – CYP3A4, SLCO1B1
Metformin – none
Warfarin – CYP2C9, VKORC1
CYP2C19 normal metabolizer. No change needed.
CYP2C19 *1/*1
Normal
CYP2C9 *1/*3
Poor metabolizer
CYP2D6
Ultrarapid metabolizer
SLCO1B1
VKORC A/A
Low warfarin dose
CYP2C9 and 2D6 likely counterbalance each other. Plus, if he’s receiving benefit without side effects…leave it alone.
Do you need to change the dose? Yes, it needs to be decreased to 2-3mg PO daily

69. Clinical Genotyping

70. Clinical Pharmacogenetic Testing
FDA regulated
In vitro diagnostic device (IVD) or test kit
Self contained package with all of the ingredients
“Home-brew” tests
Developed by an individual clinical lab
Accounts for the majority of available tests
Don’t require FDA approval, but are regulated by CLIA (Clinical Laboratory Improvement Amendment)
No proficiency testing is currently required for pharmacogenetic tests
Shin et al. AJHP. 2009;66:

71. FDA Approved Pharmacogenetic Tests
Shin et al. AJHP. 2009;66:

72. Clinical Labs Performing Pharmacogenetic Tests
Shin et al. AJHP. 2009;66:

73. Genetic Non-Discrimination Act
GINA signed into Law by President Bush May 21, 2008
Ensures that no one can be denied coverage or have their premiums increased because of their genetic information
Genetic Information is defined as:
an individual’s genetic tests (including genetic tests done as part of a research study);
genetic tests of the individual’s family members (defined as dependents and up to and including 4th degree relatives);
genetic tests of any fetus of an individual or family member who is a pregnant woman, and genetic tests of any embryo legally held by an individual or family member utilizing assisted reproductive technology;
the manifestation of a disease or disorder in family members (family history);
any request for, or receipt of, genetic services or participation in clinical research that includes genetic services (genetic testing, counseling, or education) by an individual or family member.

74. Genetic Non-Discrimination Act
How will the law be enforced?
Corrective action and monetary penalties.
Individuals may also have the right to pursue private litigation.
What doesn’t GINA do?
Does not extend to life insurance, disability insurance and long-term care insurance.
Employment provisions generally do not apply to employers with fewer than 15 employees.
Does not prohibit the health insurer from determining eligibility or premium rates for an individual based on the manifestation of a disease or disorder in that individual.

75. References with Pharmacogenomic Information
OMIM – Online Mendelian Inheritence in Man
Search engine associated with Pubmed
Has information on genes
PharmGKB – Pharmacogenomics Knowledge Base
Information specifically on genes associated with drug response
Lexi-Comp online
When search online for a drug can get info from pharmacogenomics specific book
Some pharmacogenomic information in standard lexi books also
FDA website
Information from the agency perspective
Includes educational material, table of valid genetic biomarkers, and a link to the respective drug label