Jose Ordovas PhD Professor/Senior Scientist

1. Apo E and pharmacogenetics: tailoring cures to the patient Jose Ordovas PhD Professor/Senior Scientist JM-USDA-Human Nutrition Research Center on Aging, Tufts University Boston, MA

2. Pharmacogenetics If genetic make-up can be used to predict a patient's susceptibility to disease or their likely response to treatment, care could be tailored to individual patients. A major gene involved in cardiovascular disease and a focus of much study is the one coding for apolipoprotein  (apo E). Apo E is one of the first genes being used to predict risk and response to treatment.

3. Apolipoprotein E Marker for cardiovascular risk • Carriers of the e4 allele (~12%–13% of the white population) have risk factors associated with cardiovascular disease • higher cholesterol levels • higher LDL cholesterol levels • in some instances higher triglyceride levels • Carriers of the e4 allele are at higher risk for cardiovascular disease.

4. 4S study e4 carriers: risk and response • Scandinavian Simvastatin Survival Study • The original 4Sstudy convinced people of the importance of cholesterol as a risk factor and the fact that real benefit is achieved by decreasing cholesterol. • 4S showed that carriers of the e4 allele are at greater risk for cardiovascular disease. • However, carriers of the e4 allele also get more benefit in terms of cardiovascular events from statin treatment than those who are not carriers. Lancet 1994;344(8934):1383-1389

5. 4S substudy e4 allele carriers • Carriers of the e4 allele of the apo E gene are at a higher risk of coronary heart disease than people with other genotypes. • The 4S substudy examined whether the risk of death or major coronary event in survivors of myocardial infarction depended on apo E genotype and whether response to simvastatin treatment differed between genotypes. • 5.5 years of follow-up data from 966 Danish and Finnish myocardial infarction survivors enrolled in the Scandinavian Simvastatin Survival Study were analyzed. Gerdes LU, et al. Circulation 2000;101(12):1366-1371

6. 4S substudy Results: 5.5 year follow-up • Apo E genotype did not predict the risk of a major coronary event. • Myocardial infarction survivors with the e4 allele were at nearly twice the risk of dying than non-carriers, and the excess mortality can be abolished by treatment with simvastatin. • e4 is a common genetic marker that identifies a subgroup of coronary patients that is simultaneously at a higher risk of death and particularly prone to benefit from preventive treatment. Gerdes LU, et al. Circulation 2000;101(12):1366-1371

7. CETP and atherosclerosis Study design • This study was designed to determine if the presence of a common DNA variant predicts whether treatment with pravastatin will delay the progression of coronary atherosclerosis inmen with coronary artery disease (the presence of this DNA variation was referred to as B1, and its absence as B2). • The DNA of 807 men with angiographically documented coronary atherosclerosis was analyzed for the presence of a polymorphism in the gene coding for CETP. • All patients participated in a cholesterol-lowering trial designed to induce the regression of coronary atherosclerosis and were randomly assigned to either pravastatin or placebo for 2 years. Kuivenhoven JA, et al. N Engl J Med 1998; 338(2): 86-93

8. CETP and atherosclerosis Polymorphism in the CETP gene Kuivenhoven JA, et al. N Engl J Med 1998; 338(2): 86-93

9. CETP and atherosclerosis Results • The significant association observed between the B1 allele and the progression of coronary atherosclerosis was abolished by pravastatin. • Pravastatin therapy slowed the progression of coronary atherosclerosis in B1B1 carriers but not in B2B2 carriers. • There is a significant relation between variation at the CETP gene locus and the progression of coronary atherosclerosis that is independent of plasma HDL cholesterol levels and the activities of lipolytic plasma enzymes. • This common DNA variant appears to predict whether treatment with pravastatin will delay the progression of coronary atherosclerosis in men with coronary artery disease. Kuivenhoven JA, et al. N Engl J Med 1998; 338(2):86-93

10. Gene chips Chip technology can be used to identify DNA polymorphisms in the human genome, which may prove useful for large-scale linkage analysis. • Small synthetic pieces of DNA are annealed in arrays on a silicon chip or another matrix. • Human template DNA is hybridized to the chip, indicating the presence or absence of a DNA sequence polymorphism. • Chips may prove useful for studies of the genetic factors that contribute to complex multifactorial disease. The intensity and color of each spot encode information on a specific gene from the tested sample. Courtesy of DOE Human Genome Program(http://www.ornl.gov/hgmis)

11. Gene–gene interaction Practical application • Gene chips will be used to determine • genetic predisposition • response to treatment • In some cases the same gene that predispose to risk will also be a determinant of response. • If you know you are at high risk for cardiovascular disease because of lifestyle or genetics primary or secondary preventive measures can be taken.

12. Genetic screening • The same gene variant that predisposes people to higher risk of cardiovascular disease also predispose them to Alzheimer's disease. • Some commercial ventures are already testing people for apo E in relation to dementia and Alzheimer's, but not yet in relation to cardiovascular disease. • Cardiovascular disease is multifactorial — with both the genetic and the environmental components. • Assessing risk on the basis of a genetic test alone may be misleading. • Clinical application of genetic screening will probably become more routine within 5 years.

13. Human genome project A first step • A coordinated effort is being made to characterize all human genetic material by determining the complete sequence of the DNA in the human genome. The ultimate goal is to discover all of the more than 100000 human genes. Once the genome sequence is known, the meaningful mutations must then be separated from the hundreds of thousands of mutations that are not meaningful. Then identification can begin of the ~500 genes with different mutations involved in cardiovascular disease. The problem that will arise is bio-informatics — how to analyze so much complex information.

14. Gene mapping • More than 250 genes have already been mapped to chromosome 19. • The positions of the genes listed on the lower half of this illustration are known with far greater accuracy than shown here. • The genes listed above the chromosome have been mapped to larger regions of the chromosome -- or merely localized to chromosome 19 generally. apo E Courtesy of DOE Human Genome Program(http://www.ornl.gov/hgmis)

15. Unraveling the complexity • Gene chips with bio-informatics databases will help overcome the complexity of gene variability. • With current work, a statistically significant (2% and 10%) component of gene variability may be explained. • In the future, up to 50% of the variability may be explained. • We will never explain 100% of the variability. • With 50% of the variability explained, therapy will become more individualized and, in the long term, more economical.

16. Risk scales Complementary information • Genetic information and risk scales provide complementary information. • Even relatively good scales are based on probability; they cannot assess every aspect of risk. • The genetic information will increase the utility of algorithms to individuals, not just certain populations or groups. • Genetics information will add the individuality to those equations.