Personalised medicine – reality or fantasy?
I’m sure you’ll recognise this scenario – a visit to your doctor, a discussion of your symptoms, generation of a prescription, and then those immortal words, “if you don’t feel better in a few weeks, come back and see me”. This, sometimes imprecise, approach to treatment could be a thing of the past if the current vision for personalised medicine becomes reality.
Personalised medicine aims to deliver therapy with the right drug, at the right dose, in the right patient. It takes into account the differing genetic makeup, lifestyle and environment of each individual patient – the reasons that one treatment rarely works for all patients with the same illness. The benefits to healthcare providers, payers and patients are clear; reducing ineffective treatment maximises the huge drug budget, patients will have improved outcomes and reduced side effects, and then there’s the potential to prevent disease. But it’s by no means a simple task and requires global co-operation, a multidisciplinary approach, massive investment, new tools, updated regulations and a willingness to do things differently.
Taking a predictive approach
It’s now easier to predict how each patient will respond to therapy and who is susceptible to certain illnesses, thanks to advances in DNA sequencing, the availability of huge amounts of healthcare data and increased informatics capabilities. The human genome project has indicated which genes are responsible for what function and, importantly, identified DNA mutations that cause or contribute to disease, helping to predict ‘at-risk’ populations and detect illness earlier.
Breast cancer is a good example of a heterogeneous disease currently benefitting from a personalised medicine approach. It’s now thought to be not one, but 11 separate diseases with different causes and risks of relapse. Patients are grouped according to three main markers in the cancer cells, which determine the optimum treatment in conjunction with surgery and/or chemotherapy: those with receptors for oestrogen (70 % of patients) and progesterone are usually treated with hormone therapy, such as tamoxifen; those with HER2 receptors (around 15 %) generally receive Herceptin, a monoclonal antibody therapy; and ‘triple negative patients’, who have none of these markers (15 %), may just receive chemotherapy (1). The addition of Herceptin to the treatment regime for HER2 patients improved overall survival rates by 37 %, with 10-year survival rates increasing from 75 to 84 % (2).
Finding the faulty gene
The identification of faulty breast cancer genes, for instance, BRCA1/BRCA2, has led to predictive testing in certain ‘at-risk’ population groups. Patient/doctor consultations then enable individual risk management, with potential options including increased screening, complementing mammography with MRI, surgery – Angelina Jolie openly discussed her preventative double mastectomy – drug treatment, and lifestyle changes, paying attention to adopting a healthy diet, the amount of alcohol consumed, and taking regular exercise. This predictive testing can also be used to identify inherited risks for many other cancers with a familial link; the DNA of the person with cancer is tested for any faulty genes associated with the disease, and then close family members considered at risk are tested for the same genetic defect.
In lung cancer, 85 to 90 % of patients have one of two specific mutations. These can be identified and have led to targeted treatments for both groups that are more effective and have reduced side effects (3). Elsewhere, research into a common childhood brain tumour has identified a personalised drug combination that is showing early promise for certain patients: a second drug is administered alongside the main treatment, to inhibit a particular signalling pathway and reduce the chance of tumour regrowth (4).
Tailored cancer vaccines
Another exciting development, now entering human trials, is personalised cancer vaccines. These are not preventative like normal vaccines but are similar in that they provoke a cancer patient’s immune system to attack non-self tumour proteins. Cancer immunotherapy is a great breakthrough in oncology and treats tumours in various ways using a person’s own immune system, but this is truly personal! The vaccines are created by sequencing the patient’s tumour DNA and then using powerful, algorithmic data analysis to locate the best vaccine targets. The potential is huge, but all stakeholders must work together to overcome the logistic, speed and cost challenges involved in such individualised treatment.
Enhancing global healthcare
What about other key global healthcare issues that could benefit from personalised medicine? Diabetes is another heterogeneous disease with many subtypes. Even within the most common type 2 diabetes group, patient characteristics are diverse, so it’s not surprising that frontline treatment doesn’t control blood glucose levels in all these patients; investigation of non-responders’ DNA could lead to the identification of markers and more effective treatments. The success of the Type 2 Diabetes (T2D) Knowledge Portal in combating this disease highlights the importance of collaboration and sharing of information in the scientific community (5). Diabetes is also a disease where significant changes in lifestyle are known to be highly effective in reducing symptoms, regardless of a patient’s genetic profile. Patients could exert more individual control over their disease than healthcare practitioners, another example of the changing paradigm of healthcare.
Cardiovascular disease has a huge impact on global health, but so far there are only a few examples where personalised medicine has been clinically useful. For example, the correct prescribed dose of the anti-clotting agent warfarin is determined by checking a patient’s DNA sequence variations – polymorphisms – in both the drug’s molecular target and an enzyme that can inactivate it. Looking to the future, a number of genotype mutations have been identified that could lead to successful therapies to raise HDLs (high density lipids, or good cholesterol), reduce the incidence of strokes and decrease the risk of – or prevent – heart attacks, potentially benefitting a high number of patients and healthcare budgets worldwide (6).
For rare diseases, where current drug development models are too costly, hope lies in the use of personalised stem cell therapy. Patient cells, usually skin fibroblasts, are removed and reprogrammed in vitro, transforming into stem cells that can become nerve cells, heart muscle cells, etc. – or any other type of cell that is needed. These cultured cells can be used to test how the patient’s diseased cells will respond to drugs, providing a fast, low cost, ethical and safe pathway to therapy (7).
A prosperous future beckons
The importance of personalised medicine cannot be underestimated, and considerable investment is being made to help realise the potential of these novel therapies. NHS England has established 13 NHS Genomic Medicine Centres (GMCs) across the country – including hospitals in Manchester, Newcastle, Southampton and South London – which have a track-record of excellence in genomic services (8). The GMCs also engage in collaborative research with the Scottish Genomes Partnership, a Scotland-wide research programme between the universities of Edinburgh, Glasgow, Aberdeen and Dundee, and NHS Scotland (9).
The Medical Research Council has long supported the development of tailored therapies, starting its Precision Medicine Initiative in 2010. This initiative continues to be a major part of its research strategy, with £75 million of funding committed to a range of research consortia (10) working to improve understanding of how treatments and interventions can be tailored to the individual needs of people living with a wide range of diseases and conditions. These activities are co-ordinated with other charities and funding bodies, including Innovate UK, the National Institute of Health Research, UK Health Departments, the British Heart Foundation, Cancer Research UK, and Arthritis Research UK. Elsewhere, Innovate UK reports investment of £6 million into personalised medicine research (11) – and Children with Cancer UK £3.74 million (12) – while UK Research and Innovation says that up to £210 million is to be made available to industry and researchers to improve how data is used to support earlier diagnoses and the development of precision medicine (13).
Summary
Personalised medicine will meet the current desire for healthcare that is patient-centric, evidence-based, holistic and preventable. More and more approaches to improve the specificity of patient therapies are being identified, funded, researched and advanced towards human trials. The technology exists, the clinical need is ever present, and the increasing power of healthcare payers means it will often be about value for money. So, at some point in the future, when you visit – or video link to – your doctor, your treatment won’t be trial and error but will instead be tailor-made.
References
1. https://www.cancerresearchuk.org/about-cancer/breast-cancer/treatment
2. https://www.webmd.com/breast-cancer/news/20141020/herceptin-boosts-survival-for-breast-cancer-study-reports#1
3. https://www.esmo.org/Patients/Personalised-Medicine-Explained/Lung-Cancer
4. https://www.braintumourresearch.org/media/news/news-item/2019/03/27/personalised-drug-combination-shows-promise-for-paediatric-low-grade-glioma-the-most-common-childhood-brain-tumour
5. http://www.type2diabetesgenetics.org/
6. https://www.nature.com/articles/nm.4495
7. https://www.sciencedaily.com/releases/2012/11/121126151021.htm
8. https://www.genomicsengland.co.uk/about-genomics-england/the-100000-genomes-project/genomic-medicine-centres/#gmcmap
9. https://www.scottishgenomespartnership.org
10. https://mrc.ukri.org/research/initiatives/precision-medicine/background
11. https://www.gov.uk/government/news/developing-personalised-medicine-technologies-apply-for-funding
12. https://www.childrenwithcancer.org.uk/research/projects/1-5m-precision-medicine-funding
13. https://www.ukri.org/innovation/industrial-strategy-challenge-fund/from-data-to-early-diagnosis-and-precision-medicine