Dayglo

Written by Abi Bown / Produced by Theatre of Debate

Research

What is Pharmacogenetics?

Pharmacogenetics is made up of the words pharmacology and genetics. Pharmacology is the branch of medicine concerned with the uses and effects of drugs. Pharmacogenetics is concerned with patient variation in drug response caused by a patients’ genetic profile. Pharmacogenetics is underpinned by the idea of giving patients the right drug, at the right dose, in order to maximise benefits and minimise side effects.

Links

www.ucel.ac.uk/rlos/genetics/Pharmacogenetics/

The University of Cambridge e-learning collaboration website resources at this link offer clear accessible definitions supported by short audio/visual presentations – ideal for a student research project.

The Science

Here you need to understand the difference between genotype and phenotype.

  • Genotype is concerned with the genetic make-up of an organism- in this case, human beings.
  • Phenotype is how this genetic make-up translates into observable characteristics.

The human genome is made up of around 25,000 genes and 3 billion base pairs, or nucleotides.A change on one of these base pairs is called a single nucleotide polymorphism (or SNP, pronounced ‘snip’). Such changes in a persons’ genotype can significantly affect their observable phenotype.

Examples

  • A SNP on the ABCC11 gene determines whether a person produces wet or dry earwax.
  • A SNP on the OCA2 gene determines green eye colour in Caucasian people.

Changes in the genotype of a person can have significant effects on their phenotype in terms of their reactions to medicines. So, while one person may find that the dose they take cures their ailment and causes them no side effects, another person might become very ill at the same dose of the same medicine because a SNP in their genome means they cannot metabolise the drug properly.

Adverse Drug Reactions

Bad reactions to medicine are more of a problem than a bit of sickness and a few days off school.Adverse drug reactions are estimated to cost the NHS around £2 billion annually.

They are estimated to be responsible for 6.5% of UK hospital admissions and are the fourth leading cause of death in the USA.

It is also estimated that in the UK, at any one time, the equivalent of three 800-bed hospitals are full of patients experiencing adverse drug reactions. Some adverse drug reactions are caused by other factors, like other medications, drinking alcohol or taking too high a dosage. However, a significant number have a genetic factor underlying them and these genetic factors are what lie at the heart of some pharmacogenetic research.

Pharmacogenetics in Medical Practice

At the moment, most medicines prescribed with a ‘companion’ diagnostic test (the pharmacogenetic test) are prescribed by doctors in hospitals rather than coming from your GP. In future, it is likely that a number of medicines prescribed by your GP will be accompanied by a pharmacogenetic test to ensure your safety (avoiding adverse drug reactions) and the effectiveness of the medicine (curing the disease or easing the symptoms). The pharmacogenetic test needs to be performed on a sample of DNA, which can be obtained from a blood test or saliva swab.

Using genetics to target medicines: two approaches

Genetic information can be used in two main ways to target medicines. One approach looks for genetic variation in, say, a tumour, and then a medicine is prescribed that only works on this particular genetic tumour type. Herceptin is one such drug: it controls the symptoms of advanced stage breast cancer and only works in the 25-35% of patients who have a SNP on the HER2 gene of their tumours.This means that patients are routinely given a genetic test, and their oncologist (a doctor specialising in cancer treatment) prescribes Herceptin only if they have been shown able to respond to it.

Another approach is to look for genetic variation in enzymes involved in metabolizing medicines once they have entered the body.The effectiveness of certain enzymes has been linked to variation in selected genes and this effectiveness can affect the safety of the medicine if, for example, an enzyme that metabolises a medicine does not work properly, resulting in the drug building up in the body and causing toxic side effects.

Challenges of Pharmacogenetic Medicine

Pharmacogenetics has many potential benefits, and great advances are being made in human genetic research.This has tempted some enthusiastic supporters to predict a new era of healthcare – personalised medicine. An excellent review from the Royal Society, “Personalised Medicines: Hopes and realities” sets out cautions, challenges and potential”

http://royalsociety.org/uploadedFiles/Royal_Society_Content/policy/publications2005/9631.pdf

There are some examples of pharmacogenetic tests and medicines being used in clinical practice, mainly in the area of cancer treatment as outlined earlier. In reality, there are many hurdles to overcome before we are all being regularly given treatment based on our genes, and the introduction of pharmacogenetics is likely to be slow and gradual.This might be appropriate because it will allow scientists time to generate evidence to support whether the tests and medicines are working as predicted to benefit patients.

Some of the many challenges are:

  • A large number of interacting genetic patient characteristics (eg. age, kidney and liver function) and environmental factors cause variation in response to a drug, and the role of genetic variation has to be viewed alongside these other factors.
  • It is difficult to link a genetic variant unambiguously with a particular drug response.
  • An association between a particular genetic variant and a response to a drug in one population may not be present in another, hence broadly speaking, a test may be useful in one location (country) but not another.
  • Even when associations between a genetic variant and drug response have been clearly demonstrated, suitable tests still have to be developed and proved to be effective in clinical trials.
  • There are challenges to designing and funding trials.
  • A test that has succeeded in a clinical trial still has to be shown to be useful in a healthcare setting and its economic consequences studied. Pharmacogenetic tests have to be financially worthwhile for the NHS. Licensing committees have the difficult job of judging whether buying and running pharmacogenetic tests will make drug treatment more effective and reduce the cost of adverse drug reactions.
  • Regulatory agencies will have to consider how they assess and license pharmacogenetic products and set their price. In addition, reimbursement agencies will need to assess whether the pharmacogenetic test and medicine shows ‘added value’ compared with existing treatments.This means understanding the costs and benefits of the new test and medicine compared with existing treatments.
  • Health services will have to adjust to cope with new ways that involve using genetic information to select and target medicines.
  • The behaviour of individual doctors, pharmacists and other health care professionals will need to adapt to learn how best to prescribe medicines using genetic data.

Family implications

Some genetic tests may reveal more than just your potential reaction to a medication.These are called ‘incidental’ findings. Some SNPs are also linked with increased risks of particular diseases, such as type-2 diabetes and Alzheimer’s disease. You may not want to know this information, and/or it may have implications for others in your family.

More generally, should patients be obliged to take a genetic test? It might be in their best interests, but should they have the freedom to decline? Would a doctor then prescribe an expensive medicine that might have no value? Or damaging side-effects?

As well as individuals, pharmacogenetics has the potential to impact on groups, because the tests can be used to identify sub-groups of the population by identifying, for example, safe- responders or non-responders.What will happen to people who cannot respond to any drug treatment for a given condition? Will drug companies invest in developing drugs for small groups of patients, or healthcare providers be willing or able to afford to buy them?

Global justice

Pharmacogenetics is a particularly Western concept in medicine. Worldwide, 884 million people, which equates to 1⁄8 of the world’s total population, do not have access to clean water, let alone advanced medical techniques. As the wealthy Western world continuously advances medicine, a large gap is created based on access to health and medical products.

Colour-coded medicine

Related to the above point, there is also a risk that pharmaceutical companies who produce pharmacogenetic drugs will target them at majority populations in wealthy Western countries who are most likely to be able to pay for them. In doing this, people from other ethnic backgrounds living in wealthy Western countries may be disadvantaged by lacking access to pharmacogenetic medicine.

Glossary

Breast cancer (malignant breast neoplasm)

Breast cancer is the collective term for all the cancers that originate in breast tissue. Most of these begin in the glandular tissue, though the most common of all breast cancers starts in the breast ducts. Most cases of breast cancer are not familial – they occur when there is either no family history or only one case in an older relative, which would be expected to occur by chance.

About 300 men develop breast cancer in the UK every year. Of all women who develop breast cancer, about 1 in 5 has a significant family history of the disease. Of these, around a quarter – or 2,400 patients each year – have inherited faults in known breast cancer genes, e.g. BRCA1 and BRCA2.

A further 4,800 – 7,200 people each year are believed to be affected by other genetic factors linked to breast cancer, but the specific genes involved are not yet known in many cases.

If there is a history of breast cancer, or some other cancers (especially ovarian cancer) in your family, this may increase your risk of developing the disease, and possibly developing it at a younger age. It doesn’t, however, mean that you’ll definitely get breast cancer.We can’t always say what causes breast cancer or predict who will develop it, but a combination of inherited, lifestyle and environmental factors can play a role.

The size, stage, rate of growth, and other characteristics of the tumour determine the kinds of treatment.Treatment may include surgery, drugs (hormonal therapy and chemotherapy), radiation and/or immunotherapy.

Chemotherapy

Chemotherapy is a treatment for cancer, in which “cytotoxic” drugs are used to kill cancerous cells. “Cyto” means cell, “toxic”, to kill, and these drugs prevent cancer cells from dividing and growing.They are used to treat solid tumours (cancerous lumps) affecting organs such as the breast or bowel, as well as blood cancers such as leukaemia.

www.nhs.uk/Conditions/Chemotherapy/Pages/Definition.aspx

www.bupa.co.uk/individuals/health-information/directory/c/chemotherapy

DNA

Deoxyribonucleic acid – DNA – is the complex chemical that carries genetic information. DNA is contained in chromosomes, which are found in the nuclei of most cells.The gene is the unit of inheritance and different forms of the same gene are called alleles.The Human Genome Project has worked out the human DNA sequence, and its data are useful for forensic science and medical research.

www.bbc.co.uk/schools/gcsebitesize/science/edexcel/genes/dnarev1.shtml

Licensing medicines and pharmacogenetic tests

Since 1968, after the thalidomide disaster in the early 1960s, all medicines have to be licensed before they can be prescribed in a particular country. In Europe, this licensing process is overseen by the European Medicines Agency and each EU member state has particular licensing processes in place for their country. Before a medicine is licensed, it can only be prescribed as part of a clinical trial, overseen by another regulatory body. By contrast, pharmacogenetic tests are not as highly controlled and do not have to go through clinical trials before they are used in practice, although this may change in future as regulatory bodies are realising that these tests have a key role to play in affecting subsequent treatment options.

www.cen.eu/cen/AboutUs/Pages/default.aspx

Genetic Testing (also called DNA-based tests)

Sophisticated techniques to test for genetic disorders involve an examination of the DNA itself. Genetic testing is done by analysing small samples of DNA collected from blood, saliva or body tissues. In the case of disease, samples can also be taken from e.g. tumours.

Genetic tests are used for several reasons, including:

  • Carrier screening, which involves identifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to be expressed;
  • Pre-implantation genetic diagnosis, screening IVF embryos for disease;
  • Pre-natal diagnostic testing; where an early-stage foetus is tested;
  • Newborn screening;
  • Genealogical DNA testing (for tracing ancestry);
  • Presymptomatic testing for predicting adult-onset disorders such as Huntington’s disease;
  • Presymptomatic testing for estimating the risk of developing, for example, adult-onset cancers and Alzheimer’s disease;
  • Confirmational diagnosis of a condition identified by its symptoms;

See for example: http://kidshealth.org/parent/system/medical/genetics.html

Geneticists

These are the many types of expert who specialise in genetics, ranging from medical doctors who go on to specialise in this area to biologists – pure scientists who work in labs.

Hereditary condition

Parents pass on one copy of each gene to their children. If one or both of those copies is mutated, the child is at risk of inheriting a genetic disorder.

According to the Human Genome Project, both environmental and genetic factors can influence the development of any disease, including hereditary diseases.A hereditary disease or genetic disorder is caused by abnormalities in a person’s genetic material or genome, which can therefore be passed on to their children.

www.livestrong.com/article/161925-types-of-hereditary-diseases/#ixzz1WiV8vjPT

www.tree.com/health/genetic-health-inherited-conditions.aspx

Hospice

Hospices specialise in the control of pain and other symptoms.They are smaller and quieter than hospitals and often work at a much gentler pace. Many have kitchens, sitting rooms and accommodation for relatives, and maybe even a bar. Accommodation and care in a hospice are free of charge, some set up as part of the health service and others funded by charities. Many hospices also have home care teams and day centres for people living at home.

Macmillan

Macmillan Cancer Support improves the lives of people affected by cancer. One in three of us will get cancer.As treatments improve, more and more people are living with cancer in their daily lives.This means they need more than medical help, they also need practical, emotional and financial support.

http://www.macmillan.org.uk/Aboutus/AboutUsHome.aspx

Mammogram/Breast Screening

The NHS Breast Screening Programme screens around 1.6 million women a year.Women aged 50 to 70 who are registered with a GP are automatically invited for screening every three years. Screening takes place at a special clinic or mobile breast screening unit. A mammogram (X-ray of the breast) is taken by a health professional and then studied to look for any abnormalities.The aim is to find breast cancer at an early stage, when any changes in the breast would be too small to feel and when there is a good chance of successful treatment and full recovery. It is estimated that breast screening saves 1,400 lives a year.

https://www.nhs.uk/conditions/breast-cancer-screening/

It should be noted that currently the evidence for breast cancer screening in the UK is being reviewed amid controversy about the measure’s effectiveness.

The NHS says screening saves lives, but other researchers have argued that it may cause more harm than good.

https://www.bbc.co.uk/news/health-15444879

Mastectomy

A mastectomy is an operation to remove a breast, usually because it has been affected by breast cancer. It is also used to remove non-cancerous breasts in order to reduce the risk of breast cancer developing in people who are at high risk.

www.nhs.uk/conditions/Mastectomy/Pages/Introduction.aspx

Oncologist

A doctor who specialises in the diagnosis and treatment of cancer. Once a cancer diagnosis is made, it is the oncologist’s role to explain the cancer diagnosis and meaning of the disease stage to the patient.They will discuss various treatment options; recommend the best course of treatment; deliver optimal care; and improve quality of life through both curative therapy and care to help ease pain and symptom management.

www.medterms.com/script/main/art.asp?articlekey=4637

Opportunity Cost

In the UK, healthcare is provided by the NHS.The government draws money from taxes and national insurance and then decides how much to spend on healthcare.This means that each year there is a fixed healthcare budget and, because not everyone can be treated, a decision has to be made about which treatments to offer.These decisions can be made by a doctor treating a patient or at a broader population level. Economics provides a useful way of thinking about the impact of making decisions to treat one person, or group of people, rather than another.This is called ‘opportunity cost’. If you treat someone then you can hopefully help them, but this means there will be a person or group of people who cannot be treated.These hard choices must be made and ideally informed by evidence that shows the potential benefits of medicines weighed up against the cost.The aim is to maximise value for money.

Punk

In July 1975, Britain was in recession. Unemployment figures were the worst since World War II, with school leavers least likely to find work. Margaret Thatcher had become leader of the Conservative Party in February 1975 and had begun formulating her own brand of Tory policy.

Many of the young people who became punks in the next few years were from impoverished working-class inner-city backgrounds.The social and political climate in which they had been growing up resulted in a feeling that was a mixture of frustration, boredom and poorly focused anger. Coupled with the increasing disillusionment with the complacency of established rock bands, it is not surprising that what emerged became what is now known as ‘punk’. Punk music was, for its audience, a refreshing, much needed break from the progressive rock of the early and mid-1970s.

Consequently, many punk songs had angry lyrics that criticised the government, the media and Western society in general; for example, ‘I’m so bored with the USA’ by The Clash and ‘God Save the Queen’ by the Sex Pistols.The subjects of many other punk lyrics were boredom, teenage rebellion and independence and cynical parodies of love songs – recurring themes in the songs of such bands as X Ray Spex and the Buzzcocks.

Piercings, tattoos and multicoloured Mohawks were soon to become a signature look for the fan. Most fans would describe themselves as outcasts due to their political beliefs and disenchantment with society and through the music and fashion they had found a way to express their individuality and find a niche for themselves.

The ideological culture of punk held some very worthy beliefs such as anti-rascism, anti- sexism, anti-homophobia, vegetarianism and environmental protection.

www.caughtoffguard.co.uk/punk_culture.html

www.bbc.co.uk/dna/h2g2/A791336

Radiotherapy

Many people with cancer will have radiotherapy as part of their cancer treatment. It can be given either as:

  • External radiotherapy from outside the body using high energy x-rays.
  • Internal radiotherapy from a radioactive material placed inside the body.

Radiotherapy works by destroying cancer cells in the area that’s treated.Although normal
cells can also be damaged by radiotherapy, they can usually repair themselves.

Radiotherapy can cure some cancers and also reduce the chance of a cancer coming back after surgery. It may also be used to control a cancer or to help reduce its symptoms.

https://www.macmillan.org.uk/cancer-information-and-support/treatment/types-of-treatment/radiotherapy

https://www.nhs.uk/conditions/radiotherapy/

Secondary metastasis

The original cancer is known as a primary tumour or primary cancer. If cells break away and spread to another part of the body, forming a new tumour, this is called a metastasis or secondary cancer. So, a secondary breast cancer is when the cancer that started in the breast has spread to another part of the body.

Sickle Cell Anaemia

Sickle Cell Anaemia is an inherited genetic condition which affects the red blood cells which contain a special protein called haemoglobin (Hb for short).The function of haemoglobin is to carry oxygen from the lungs to all parts of the body.

People with sickle cell anaemia have sickle haemoglobin (HbS) which is different from the normal haemoglobin (HbA). Normal red blood cells can bend and flex easily, and so travel around the blood vessels easily.When sickle haemoglobin gives up its oxygen to the tissues, it sticks together to form long rods inside the red blood cells, making these cells rigid and sickle-shaped.

These cells are then less able to squeeze through small blood vessels, which easily become blocked, preventing oxygen from getting through and causing severe pain and organ damage.

The majority of people with sickle cell disease are of African or Caribbean descent, although it also affects those from Asia, the Middle East and the eastern Mediterranean. Everyone has two copies of the haemoglobin gene, one from each parent.Those with Sickle Cell Anaemia have two HbS genes.Those who have one HbA gene and one HbS gene have sickle cell trait and are referred to as carriers.There are 240,000 carriers of sickle cell anaemia and they’re only at risk of problems under extreme conditions, such as during major surgery.

Teenage Cancer Trust

Every day in the UK, six young people are told they have cancer. These young people often receive hospital treatment in inappropriate facilities catering for children or the elderly.Teenage Cancer Trust focuses on the needs of teenagers and young adults with cancer by providing specialist units in NHS hospitals designed to give young people the very best chance of a positive outcome.As well as state-of-the-art facilities to keep patients occupied during long stays in hospital, the units provide an environment where young people can meet others in a similar situation.Teenage Cancer Trust has built 17 units and plans to build a further 16 so that all young people needing hospital treatment for cancer across the UK have access to the dedicated, specialist support they provide. For further information visit www.teenagecancertrust.org

XRay Spex

X-Ray Spex were an English punk band from London, formed in 1976. Poly Styrene was the stage name of Marianne Joan Elliott-Said, a British musician, songwriter and singer, who was lead vocalist in the band. Despite her relatively short stint with X-Ray Spex, Styrene’s overt feminism and mixed-race heritage marked her out among her punk contemporaries and won her legions of fans for generations to come. Poly Styrene was receiving treatment for an advanced form of breast cancer when she passed away in 2011.

www.guardian.co.uk/music/2011/apr/26/poly-styrene-dies-aged-53

http://en.wikipedia.org/wiki/X-Ray_Spex