Edging closer to precision medicine
Our genes, lifestyle and environment all play a role in making us unique as individuals.
Taking into account these differences when providing healthcare can make it easier to prevent, diagnose and treat illnesses. This approach to healthcare is now widely known as precision medicine.
The term is used to distinguish it from personalised medicine which implies that treatments are unique to each individual. Instead, precision medicine tailors treatments to particular groups of people who have common traits.
Advances in areas like genetics mean medicine is about to become more precise than ever before. The UK is a pioneer in this area, having launched the 100,000 Genomes Project in 2012. The project reached its half way mark in February this year when it completed sequencing 50,000 genomes. The invaluable data it is producing will help us better understand how the interplay between our genes, lifestyle and environment affects our health.
The right treatment at the right time
Precision medicine aims to make it easier to provide the best treatment or intervention for patients. At the moment, whenever you visit a doctor, you are likely to get the same first-line treatment as anyone else exhibiting the same symptoms. However, the NHS estimates that such treatments are only likely to be effective for about 30 to 60% of patients.
To find the right treatment for any given patient, doctors generally have to rely on trial and error. This can be frustrating for patients and comes at a great cost to the NHS, which prescribes about £16 billion worth of drugs each year.
Precision medicine can help doctors prescribe drugs that have fewer side effects, which is particularly important if these include toxicity. A 2016 study concluded that hospital admissions caused by adverse drug reactions (ADR) are an increasing problem for the NHS.
A previous study, published in 2004, estimated that ADR-related hospital admissions cost the NHS £466m each year. Commonly used drugs like aspirin, diuretics and warfarin were among those most often responsible for ADR-related admissions.
Warfarin is an anticoagulant often prescribed to people who have had a heart attack or stroke. Figures from 2014 estimate that over 11 million people in the UK are prescribed the drug annually. Getting too little can lead to a stroke and too much can cause life-threatening bleeding. But finding the right dose is tricky because it can vary by up to 40-fold between individuals.
One reason why people react differently to the drug is their genetic makeup. Variations in the CYP2C9, VKORC1, CYP4F2 and GGCX genes affect how the body responds to warfarin and can cause sensitivity to it.
Giving doctors access to people’s genetic information could therefore help bring down the rate of adverse drug reactions.
Better diagnosis and prevention
Precision medicine may also make diagnosis faster and simpler.
The 100,000 Genome Project is focussing on sequencing the genes of people with common cancers and rare diseases because they both have a strong link to the genome.
Collectively, rare diseases affect 7% of the UK population (roughly 3.5 million people) but diagnosis is often a protracted and costly process. Understanding our DNA better could therefore make a marked difference to people with rare diseases.
In cases where someone’s genetic make up predisposes them to a condition like cancer or heart disease, doctors may be able to suggest early interventions to prevent or delay its onset. This could save the NHS money too because patients are less likely to need acute care early on.
According to the British Heart Foundation, more than 620,000 people in the UK have a faulty gene that puts them at risk of developing Cardiovascular Disease.
We are already seeing certain cancers being categorised and treated according to genetic markers. For example, the single gene mutation in the human epidermal growth factor receptor 2 (HER2) gene in breast cancer cells can be targeted with the monoclonal antibody Trastuzumab. Melanomas can also be subtyped according to the mutations BRAF, RAS, and NF.
Before precision medicine can become the norm, several hurdles need to be overcome.
For genetics to play a more central role in healthcare, gene-related technology needs to get even faster and cheaper. Better IT infrastructure will also be needed for healthcare.
Sequencing more people’s genes is also likely to generate a huge amount of data which all needs to be stored securely. The raw data from one genome alone is about 200GB which would fill the average laptop’s hard drive.
Interpreting the data also presents a challenge. To begin with, it will need to be standardised and presented in a format that doctors can easily understand. More healthcare professionals will also need training in genetics. Health Education England has already set up the Genomics Education Programme to help with this.
According to the Chief Medical Officer Dame Sally C Davies’ latest annual report, titled Generation Genome, assembling, processing and assessing the data, to advise on diagnosis and treatment, will require a broad range of specialists all working together. This includes diagnostic staff in laboratories and imaging, computer scientists, statisticians, bioinformaticians and data scientists.
In the report, she said: “Adopting genomic technologies into routine practice will require changes in the design, operation and workforce of healthcare organisations. The skill sets that are needed are mostly unfamiliar to the current workforce, and experts are in short supply both nationally and internationally.”
Better knowledge is also needed because we have still only scratched the surface when it comes to understanding our genome. There are numerous potential markers and mechanistic pathways that need to be understood and are necessary to help stratify the data being collected. The Medical Research Council has put together stratification guidance to help with analysing the large data sets associated with precision medicine.
There are also concerns about privacy and the ethical implications of collecting people’s data. The 100,000 Genomes Project is likely to help inform regulation in this area, since they have an Ethics Advisory Committee which advises Genomics England.
They have been following the principle of informed consent.
The Chief Medical Officer Prof Dame Sally C Davies has warned that whatever data protection rules are in place, they mustn't impede progress from being made. In her annual report, she warns against “exceptionalism” - the idea that our genetic information is unlike any other data about us because it holds information that makes us who we are. She argues that medical professionals already handle sensitive data about people, such as details on their sexual history or mental wellbeing, and that genetic data should be treated in the same way.
Embedding precision medicine into everyday healthcare still requires a lot of work but initiatives like the 100,000 Genomes Project means the UK is likely to be one of the first countries to do so. This is likely to strengthen the NHS and is an exciting prospect for patients.
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