Ethical Problems in Pharmacogenomic Research

Dr. Fred Lombardo Howard University

Basic Bioethics

 Two predominate philosophies governing ethics in the Western world: – Deontological view-I. Kant (1724-1804) – Utilitarianism-John Locke (1632-1704) and John Stuart Mill (1806-1873)

Deontology/Utilitarianism

 Deontology – The study of duties that persons have toward one another.

– The categorical imperative of Immanuel Kant  Utilitarianism – The view that actions or policies are to be morally evaluated according to the extent to which they promote happiness or well being

Clinical Bioethics

 Principles: – Beneficence (To do Good) – Nonmaleficence (

Primum non nocere)

– Justice (Fairness) – Autonomy (Self-determination) – Veracity (Truth telling) – Utility (The greatest good for the greatest number)

Pharmacogenomics

 Pharmacogenomics: Social, Ethical, and Clinical Dimensions, ed. Mark A. Rothstein, 2003, John Wiley& Sons.

– Challenges  Informed Consent  Control over Research Materials and Data  Confidentiality  Return of Relevant Information to Individual  Commercialism

Definition

 Pharmacogenetics: The role of genetic variation in differential response to pharmaceuticals.

 Pharmacogenomics: The use of genomic technologies in assessing differential response to pharmaceuticals.

II. Genetic polymorphisms in drug metabolizing enzymes From: Evans WE, Relling MV. Pharmacogenomics: Translating functional genomics into rational therapeutics. Science 286:487-491, 1999.

II. CLASSIFICATION

Phase I

•

Asynthetic

•

Introduce or expose a functional group increasing polarity

•

Includes oxidation, reduction and hydrolysis

Phase II

•

Synthetic (conjugation reaction)

•

Couples drug with an endogenous substrate

•

Conjugation with glucuronic acid, sulfate, acetic acid or an amino acid

II. CLASSIFICATION

Phase I (Functionalization):

Oxidation Cytochrome P450 Alcohol Dehydrogenase Monoamine Oxidase Phase II (Conjugation) : Glucuronosyltransferases Acetyltransferases Sulfotransferases Methyltransferases Glutathione Transferases Amino Acid Transferases Reduction Cytochrome P450 Hydrolysis Esterases Amidases

CYP450 NOMENCLATURE

Based upon Nelson et al. DNA & Cell Biology 12:1-51, 1993.

CYP3A4

CYP – abbreviation for cytochrome P450 3 – designates family (> 40% sequence identity) A – designates sub-family (> 55% sequence identity) 4 – designates specific gene/enzyme CYP – designates mRNA or protein

CYP

– designates gene

CYP1A1

– gene that codes for cytochrome P450 1A1 CYP1A1 – mRNA or protein product of CYP1A1 gene

From: Evans WE, Relling MV. Pharmacogenomics: Translating functional genomics into rational therapeutics. Science 286:487-491, 1999.

V. GLUCURONOSYLTRANSFERASES

From: Evans WE, Relling MV. Pharmacogenomics: Translating functional genomics into rational therapeutics. Science 286:487-491, 1999.

Why are some gliomas resistant to nitrosourea alkylating agents?

Evidence suggests this may be the result of an epigenetic phenomenon – one that does not involve a change in DNA sequence. MGMT – methylguanine-DNA methyltransferase Methylation of the promoter region of MGMT may silence the gene From: Esteller M, et al. Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents. NEJM 243:1350-1354, 2000.

From: Esteller M, et al. Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents. NEJM 243:1350-1354, 2000.

From: Esteller M, et al. Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents. NEJM 243:1350-1354, 2000.

Problems Seen

 Inability to form 5-deoxyuridine monophosphate from 5-fluorouracil because of deficiency in dipyrimidine dehydrogenase has led to prolonged pancytopenia and severe mucositis in 2 patients at Howard University.

 Test is now available to measure DPD activity.

F. THIOPURINE METHYLTRANSFERASE (TPMT) 6-mercaptopurine

SH N N

TPMT

N N H SAM SAH

6-methylmercaptopurine

SCH 3 N N N N H

TPMT Activity Distribution of Thiopurine Methyl-transferase Activity

. Reproduced from: Weinshelboum RM, Sladek SL.

Am J Hum Genet

32:651-662, 1980.

From: Yates CR, et al. Molecular diagnosis of thiopurine S methyltransferase deficiency: genetic basis for azathioprine and mercaptopurine intolerance. Ann Intern Med 126:608-614, 1997.

Half-lives and Synthesis Rates of Wild-type and Mutant TPMT Proteins in Yeast.

Parameter

Deg t 1/2 (hr) Form rate (fmole/mg/hr)

TPMT*1

18 335

TPMT*2

0.2



14.8



409

TPMT*3A

0.25

268

TPMT*3C

18 220 From: Tai H-L, et al. Enhanced proteolysis of thiopurine S-methyltransferase (TPMT) encoded by mutant alleles in humans (TPMT*3A, TPMT*2): Mechanisms for the genetic polymorphism of TPMT activity. Proc Natl Acad Sci USA 94:6444, 1997.

G. ALCOHOL DEHYDROGENASE Three forms of class I alcohol dehydrogenase: ADH1 - no functional polymorphisms

ADH2

– variant alleles in 10% caucasians

ADH3

g

1 – variant alleles in 40-50% caucasians allele and

g

2 allele differ by two amino acids (positions 271 and 349)

g

1

g

1 genotype – fast metabolism (in vitro)

g

2

g

2 genotype – slow metabolism (in vitro)

Figure 1: Multivariate Relative Risk of Myocardial Infarction According to the ADH3 Genotype and the Level of Daily Alcohol Consumption. The P values are for the comparison with the values in men who consumed less than one drink per day and who were homozygous for the (gamma)1 allele (the reference group); the lowest relative risk of myocardial infarction (0.14; 95 percent confidence interval, 0.04 to 0.42) was for the group of men who drank daily and who were homozygous for the (gamma)2 allele (P=0.02 for the interaction between the genotype and the level of alcohol consumption). Reproduced from: Hines LM, et al. Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction. NEJM 344:549, 2001.

Figure 2: Adjusted High-Density Lipoprotein Levels According to the Level of Alcohol Consumption and the ADH3 Genotype in 385 Patients with Myocardial Infarction and 385 Controls in the Physicians' Health Study (Panel A) and 325 Postmenopausal Women in the Nurses' Health Study Who Were Not Receiving Hormone-Replacement Therapy (Panel B). Reproduced from: Hines LM, et al. Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction. NEJM 344:549, 2001.

The Genome in Black and White (and Gray) October 10, 2004 (New York Times) By ROBIN MARANTZ HENIG African American Heart Failure Trial (A-HeFT)



In the not-too-distant future, if you're black and have heart failure, drug-company researchers predict you'll be able to go to the doctor and walk out with a prescription tailor made for you.



Well, not tailor-made, exactly, but something that seems to work in people a lot like you. Well, not a lot like you, exactly, except that they're black, too.



In this not-too-distant future, if you're black, your doctor will be able to prescribe BiDil, the first drug in America that's being niche marketed to people of a particular race -- our first ethnic medicine.

The question is – “Who is Black?” Some African Americans may have as much as 40% or 70% Caucasian alleles, while others may have 5% or 10% Australian Aboriginals Surma bribe from Ethiopia Masi, Kenya Confusion: Group identity is confused with group ancestry. For example, the group identity “African Americans” does not reflect a single path of ancestry.

All Black Populations Are Equal



Problem: leads to group characterization without adequate justification.

•

“The more frequent occurrence of hypertension in black (Afro Caribbean) subsamples throughout the Caribbean has been traced to ancestral populations in West Africa and is thus at least partially attributable to gene flow from an originally high prevalence area…” Halberstein RA. Human Biology 1999.

In the review by Kaufman JS and Hall SA. Epidemiology January 2003 Prevalence of Hypertension by Mean Body Mass Index Among Populations of the African Diaspora 0.35

0.30

0.25

0.20

0.15

Nigeria Cameroon St. Lucia Jamaica Barbados Maywood

West Africa 0.10

22 23 24 25 26 27 Body Mass Index 28 29 30 North America Caribbean Cooper RS, Rotimi CN, et al. AJPH. 1997

N=85,000

Study Design Issues and Data Interpretation Blood pressure response to ACE inhibitors

4.6 mm Hg African American SD=14 mm Hg European American SD=12 mm Hg

Similar drug-associated changes in diastolic BP was 90% (95% CI: 92 to 98) for Calcium blockers. 81% (95% CI: 76 to 86) for ACE (Sehgal, Hypertension 2004) Conclusion: the majority of whites and blacks have similar responses to commonly used antihypertensive drugs. Clinical decisions to use a specific drug should be based on other considerations such as efficacy in individual patients, compelling indications, and cost.

We Advocate For 1. Labeling with language indicating the fact that BiDil does not replace existing drugs for the treatment of heart failure and that although it was tested only among African Americans, it may indeed be an effective treatment for heart failure patients who may not self identify (or be identified) as African Americans.

2.

BiDil should not be approved as an African American ONLY drug (and by extension – all “black” people).

The history of drug development and approval does not support ethnic labeling. Due to political, social and economic forces, biomedical research was almost exclusively conducted in people, especially men, of European descent. Results of such studies were extrapolated to other groups without such labels as “White Drug”. In the end, the BiDil story will have similar outcome; if the drug continues to be effective in the treatment of heart failure, the global subset of individuals with heart failure who will benefit from the drug will not be accurately described by the label 'African American'.

3.

We Advocate For Strategies that promote overall health not simply the absence of disease (e.g, heart failure). What good is a drug that reduces mortality from heart failure by 43% if: a.

Because of patent, an otherwise cheap generically available therapeutics becomes unaffordable; b.

It exacerbates racism with resulting increased hypertension and associated complications, including heart failure) due to increased psychosocial stressors; c.

It leads biomedical research down a wrong path by suggesting, without proper scientific justification, that the so-called racial categories are biological?

Actuarial Incidence of Breast Cancer among Women with a BRCA1 or BRCA2 Mutation after Prophylactic Mastectomy or during Surveillance Meijers-Heijboer, H. et al. N Engl J Med 2001;345:159-164

Characteristics of the Women Meijers-Heijboer, H. et al. N Engl J Med 2001;345:159-164

Characteristics of the Tumors in the Eight Women in the Surveillance Group in Whom Breast Cancer Developed Meijers-Heijboer, H. et al. N Engl J Med 2001;345:159-164

Characteristics of the Eight Women in the Surveillance Group in Whom Breast Cancer Developed Meijers-Heijboer, H. et al. N Engl J Med 2001;345:159-164

Dr.Woo Suk Hwang

 Dr. Hwang, veterinary scientist from Seoul National University cloned an Afghan hound named Snuppy (Seoul National University puppy).

 Named Director, Stem-Cell Center, Seoul, Korea.

 Branch labs planned for U.S. and U.K.

Dr. Hwang Aftermath

 Resigned as Director when it was reported that a member of his team had purchased human eggs from as many as 27 women for use in human stem cell experiments.

 Two female members of his team had donated eggs to the cause.

 Egg selling illegal in Korea  Violation of scientific ethics for subordinates to provide ova, even if free of charge.

Elements of Informed Consent

 Threshold requirement: competence  Information requirements – Information – Understanding  Consent requirements – Consent – Authorization

Tuskegee Study (1932-1972)

 Reasons given for continuing study – Long-term benefits for African-Americans – Contribution to scientific knowledge – Benefits for subjects (would receive other medical treatment) – Subjects were not harmed – Treatment might harm (Jarisch-Herxheimer) – Should not waste data collected

Tuskegee Study (1932-1972)

 Reasons given for not telling subjects the truth: – Subjects incapable of understanding – Scientists better equipped to determine what would benefit the subjects (paternalism) – Better to sacrifice a few for the greater good of the whole (utilitarianism)

Tuskegee Study (1932-1972)

 Reasons for breach of veracity tenet continued: – Subjects in the study were better off than those not selected to participate.

– Long-term scientific goals were of greater importance than rights of an individual (Kant’s Categorical Imperative is breached)

Egregious Examples of Unethical Research

 Tuskegee Syphilis Study (1932-1972)  Nazi Experiments on Prisoners-WW II  Willow Brook Study-1960’s  Human Radiation Experiments 1950-1970  LSD Experiments 1930s 

Serratia marcescens

experiments 

Bacillus subtilis

experiments

Belmont Report

 Principles: – Respect for persons’ consent, privacy, confidentiality – Beneficience (Benefits versus Risks) – Justice/Equality

45 Code of Federal Regulations 46.111

 Risks to subjects minimized  Risks reasonable in relation to anticipated benefits.

 Selection of subjects equitable  Provision for safety monitoring  Informed consent documented

45 CFR Part 46.111

 There is adequate provisions to protect the privacy of subjects and to maintain confidentiality of data  Where any of the subjects are likely to be vulnerable to coercion (“susceptible to kindness”) or undue influence, additional safeguards are incorporated to protect the subjects.

Informed Consent

 Benefits  Risks  Alternatives

The Nuremberg Code

 The voluntary consent of the human subject is absolutely essential.

 The experiment should be such as to yield fruitful results for the good of society.

 Experiment based on results of animal experiments and knowledge of the natural history of the disease or problem

The Nuremberg Code

 The experiment should be conducted as to avoid all unnecessary physical and mental suffering and injury.

 No experiment should be conducted where there is an

a priori

reason to believe that death or disabling injury will occur;except in those experiments where the investigators serve as subjects.

The Nuremberg Code

 The degree of risk to be taken should never exceed that determined by the humanitarian importance of the problem to be solved by the experiment.

 Proper preparations should be made and adequate facilities provided to protect the experimental subject against even remote possibilities of injury, disability, or death.

The Nuremberg Code

 The experiment should be conducted only by scientifically qualified persons.

 During the course of the experiment the human subject should be at liberty to bring the experiment to an end (Intention to Treat Precepts)

The Nuremberg Code

 During the course of the experiment the scientist in charge must be prepared to terminate the experiment at any stage, if he/she has probable cause to believe, in the exercise of good faith, superior skill, and careful judgment that the continuation of the experiment is likely to cause injury, disability or death (Stopping Rules)