1. Pharmacogenomics
Rita Leone, RN, MSN, CMSRN

2. Objectives Define Pharmacogenomics/Pharmacogenetics
Describe how genetics is used to tailor drug therapies
Discuss the RN’s role (r/t pharmacogenomics)
Identify barriers to integrating pharmacogenomics into practice
Explore current pharmacogenetic testing that affects selection/dosing of drug therapies (Warfarin/Coumadin & Trastuzumab/Herceptin)

3. What is Pharmacogenomics?
Pharmacogenomics is a rapidly growing field of research into the ways in which genetic variation affects drug response
Identifying genetic markers for differences in the way people metabolize drugs
Developing genetic tests that predict how individual patients will respond to drugs (i.e. statins, cancer therapies).
Goal…
To develop precisely targeted, optimal drug therapy
Minimizing drug related adverse events

4. Pharmacogenetics: Your Doctors New Genetic Tools

5. Pharmacogenomics: Role of the RN
Explaining rationale for genetic testing
Provide appropriate patient teaching regarding drug selection
Understand drug dosing variances between patients

6. Barriers
Who pays for the genetic testing if not already standard of care?
FDA
Insurers (i.e. KRAS)
Professional Organizations

7. Warfarin (Coumadin): Factors Affecting Dose/Response
Age
Increased age = decreased dose
Height and Weight
taller and/or weight more = higher warfarin dose
Ethnicity
Ancestry plays an important role
Asians: may need lower doses than Caucasians
African Americans: may need higher doses.
Diet
Warfarin works by inhibiting vitamin K.
consuming large amounts of vitamin K (through foods or supplements) = higher warfarin doses.
Other Medications, Herbs, or Supplements
Many prescription and over-the-counter medications interact with warfarin.
Inform prescribing physician of all medications, herbs, & supplements taking
Other Health Conditions
Some diseases affect how our bodies respond to medications

8. 2 more…introducing the CYP2C9 and VKORC1 Genotypes
1) CYP2C9 gene variant
Instructs body how to make an enzyme that metabolizes warfarin—an enzyme converts one chemical to another
Changes in the CYP2C9 gene can your ability to metabolize or clear warfarin from the body
When the body cannot metabolize warfarin at the usual rate, drug level builds up to a potential overdose
People with these CYP2C9 variants generally need warfarin doses.
2) VKORC1 gene variant
Contains instructions for making an enzyme called vitamin K epoxide reductase, (or VKOR) which plays an important part in making blood-clotting factors.
Warfarin stops blood clots by decreasing the effectiveness of VKOR=lowering the amount of VKOR produced
Since people with this gene variant have enzyme levels to start with, taking an average warfarin dose may their blood clotting factors too much--putting them at a higher risk for adverse events (bleeding)

9. HER2 + Breast Cancer: Target Therapies Affecting Tumor Growth
Aggressive form of breast CA
Associated with genetic variation leading to overproduction of protein called HER2
Tumor samples tested for high levels of HER2
If yes…Herceptin (Trastuzumab) is indicated

10. Using Genetics to Tailor Drug Therapy

11. Where are we at?

12. To summarize…

13. Thank you!
Questions?