What Is Personalised Medicine?

Personalised medicine is a novel and revolutionary topic in the healthcare industry. It has the potential to transform medical interventions by providing tailored therapeutic strategies based on the genomic profile of the individual. The mission of personalised medicine is to provide the right drug, with the right dose at the right time to the right patient.¹

With this in mind, health care professionals have the ability to overcome trial and error prescribing methods and rely on medicines that best suits the individual. Historically, the same medicine would be given to the same person regardless of ethnicity or genomic make-up. This dated model of a trial and error approach leads to poorer outcomes for patients in terms of adverse side effects, drug interactions, and potential disease progression whilst effective treatment is delayed.²

The aim of personalised medicine, according to the Food and Drug Administration (FDA), is to increase the benefits and reduce the risks of medication adverse events to patients by classifying individuals by subpopulations that vary in their response to a therapeutic agent for their specific ailment.

Personalised medicine is expanding extensively in cancer research, and is hopefully the breakthrough we need to fight and outsmart cancer. We used to diagnose and treat cancer through a one treatment approach by taking a biopsy of the tumour and analyzing it under the microscope. However, health care practitioners realized one size does not fit all. Now, scientists are also extracting DNA from the tumour and using more advanced techniques to scan for abnormalities. This is called genomic cancer testing.

Genomic cancer testing

Genomic cancer testing will help advance the use of precision medicine by finding the cancer’s underlying characteristics and not just its locations. To do this, the test will identify a patient’s unique DNA changes within the cancer cells to determine how the tumour behaves and grows.

With these test results, your doctor may be better informed of your unique cancer driver and potentially address the abnormality earlier. For instance, scientists realized that some breast cancer cells express a protein called HER2 on their cancer cells that causes the cancer to grow exponentially.² Scientists were then able to develop a medicine that specifically targets HER2 on breast cancer cells.

However, the medical community realized not all breast cancers expressed HER2; some patients had no expression. Thus, to determine if this drug would work for patients, health care practitioners offer genomic cancer screening to see if the patient’s cancer cells express the HER2 protein to help determine if the patients would get targeted treatments for HER2. Without using genomic cancer testing, patients would be exposed to HER2 treatment using the same trial and error approach, which may lead to unwanted side effects for a therapy that does not suit them.

What Is Genomic Cancer Screening?

What should you expect when you go for genomic cancer screening? The first step is to find out how likely you are to develop a specific disease. The risk is based on your medical and family history. If your physician did not request this test on your behalf, you will then be asked why you want to be tested. This may be to find out if you have a predisposition for a certain disease. For example, a relative was diagnosed with breast cancer at an early age. This conversation will be discussed with a genetic counsellor.

The counsellor will help you decide the pros and cons, costs, and limits of testing. He or she will also explain to you anything you are unfamiliar with such as how genes are passed on to children and how families inherit certain cancers. After the genetic counsellor assesses your risk and provides you with information, you will have to give your informed consent in writing. The informed consent should cover topics like the purpose of the genetic test, the reasons for offering the test, the type of test, and the test’s accuracy.

Once you have signed the consent forms, the lab tests will be done. The type of lab test will depend on what the test is for. Genetic tests can be done through a sample of blood, cheek swab, hair, urine, amniotic fluid, or other bodily tissues. In contrast, if you are coming with preexisting cancer, the genetic counsellor will provide you with a genomic test. Genetic testing and genomic testing sound similar, but they are indeed different procedures. Genetic testing refers to the genes a person is born with and their likelihood of acquiring a gene mutation to develop into cancer.³ In contrast, genomic testing looks at the molecular composition of the tumour ie. if the cancer cells express HER2 protein.

In advanced genomic testing, a biopsy is taken of the patient’s tumour through either a tissue sample or a liquid biopsy similar to a blood test. Sometimes invasive procedures are required depending on the location of the cancer. This may involve extra risks such as anaesthesia or excisions. After a biopsy is taken of your tumour, cancer cells are isolated and extracted. Scientists use the cancer cell’s DNA and sequence this in the lab. Sophisticated equipment is used to scan for abnormalities of the DNA and dictate how the tumour behaves.

If abnormalities are found, scientists explore further if these are known mutations. Mutations are compared to the treatment that is available in the market. If there is a match, your health care team will have a treatment path to guide them. If there is not a match, then you will at least know your genomic abnormality for any future treatments.  Pharmaceutical companies are continually developing treatments for specific mutations and conditions, thus there may be a chance that a cancer may match new therapies in the future.

What Is Next for Personalised Medicine?

Pharmaceutical companies need to continue pursuing personalised medicine to help advance patients’ needs. For instance, health care teams might have identified several genomic mutations for a patient’s cancer, but there is still no treatment on the market. Pharmaceutical companies should be investing money into precision medicine, so personalised therapies are available to patients. Other approaches are also continuously being developed on the scientific end to preemptively assess mutations. Before, tumour biopsies were the only way to assess cancer’s genetic make-up. Now, researchers developed a way to use a simple blood test to detect genomic differences. This is termed a liquid biopsy. One of the first uses of a liquid biopsy was to assess if pregnant mothers were carrying a baby with Down Syndrome.² The blood test detects circulating DNA to determine if the child has Down Syndrome genes. Developing simple procedures will help advance the future for personalised medicine and give patients’ opportunities they never had in the past.

What Are the Disadvantages of Personalised Medicine?

Sometimes individuals do not want to know what the future holds for them, and that is their choice. Personalised medicine and genomic testing may cause more harm than good with added stressors now that the opportunities are readily available. For instance, regarding the same circumstance stated above, pregnant mothers have the opportunity to test for Down Syndrome, but not all mothers want to. Additionally, there are also economic challenges involved when pursuing personalised medicine.

First, the pharmaceutical industry generally uses a blockbuster model, which focuses on developing and marketing drugs for a broad population group.⁴ This allows companies to get the most return on their investments.

Pharmaceutical companies also have to use clinical trials to determine if a medication will go to market. Generally, clinical trials are expensive and require a lot of time and money when enrolling patients. There are specific health standards patients must have such as controlled blood pressure, diabetes, and specific disease markers before enlisting into a clinical trial.

With personalised medicine, clinical trials must have patients with specific genomic markers. Patients are usually unaware if they have this marker since it requires additional testing, so pharmaceutical companies have to increase awareness of their drug trial through promotional and marketing means aka more money.⁵ When patients do enroll into the clinical trial, pharmaceutical companies must also do their own diagnostic testing to determine if the genomic marker is accurate.

This causes additional expenses for an already expensive process. In the scientific community, we hope that the government incentives pharmaceutical industries to help specific subpopulations receive the medication they need. Personalised medicine will revolutionise the health care industry and hopefully hold the future for cancer treatment.

References

1. König, Inke R et al. “What is precision medicine?.” The European respiratory journal 50,4 1700391. 19 Oct. 2017, doi:10.1183/13993003.00391-2017
2. Mathur, Sunil, and Joseph Sutton. “Personalised medicine could transform healthcare.” Biomedical reports 7,1 (2017): 3-5. doi:10.3892/br.2017.922
3. Stanislaw, Christine et al. “Genetic evaluation and testing for hereditary forms of cancer in the era of next-generation sequencing.” Cancer biology & medicine 13,1 (2016): 55-67. doi:10.28092/j.issn.2095-3941.2016.0002
4. Jørgensen, Jan Trøst. “From blockbuster medicine to personalised medicine.” Personalised medicine 5,1 (2008): 55-63. doi:10.2217/17410541.5.1.55
5. Sairamesh J, Rossbach M. An economic perspective on personalised medicine. HUGO J. 2013;7:1. doi: 10.1186/1877-6566-7-1.