What is Personalised Medicine?

Medicine has always aspired to treat the individual. What is new is the ability to do it with data — matching treatments to a person's biology rather than to population averages.

The concept

Clinicians have always tried to match patients with the right treatment. Until recently, though, there was no practical way to know in advance how a particular individual would respond to a particular drug. Advances in genetics changed that, making it possible to identify inherited traits that influence both disease risk and drug response.

Personalised medicine — also called precision medicine — uses that information, alongside clinical and lifestyle factors, to target treatment more accurately.

The limits of the current model

Standard prescribing is built on what works best across a population. Two people presenting with the same symptoms generally receive the same first-line treatment, and adjustments are made afterwards based on how they respond.

This works reasonably well much of the time, but it means a meaningful proportion of people spend weeks or months on a treatment that was never likely to suit them, sometimes accumulating side effects along the way. Response rates to first-line treatments vary considerably between conditions and drug classes, and in several areas a substantial minority of patients see little benefit.

Pharmacogenomics offers a way to shorten that trial-and-error period where the evidence supports it.

Where it is already in use

• Cancer treatment — the most advanced application. Tumours are routinely tested for specific mutations, and targeted therapies are selected accordingly. HER2 testing in breast cancer and EGFR testing in lung cancer are standard practice.
• Clopidogrel — CYP2C19 variants affect whether this antiplatelet drug is activated properly. Some cardiology services now test after stenting.
• Abacavir — HLA-B*5701 testing before prescribing this HIV medication prevents a potentially fatal hypersensitivity reaction. Testing is mandatory.
• DPYD testing — now routine in the NHS before certain chemotherapy drugs, to identify people at risk of severe toxicity.
• Warfarin — CYP2C9 and VKORC1 variants influence dose requirements.

NHS involvement

The NHS has invested substantially in genomic medicine, including the 100,000 Genomes Project and the subsequent NHS Genomic Medicine Service, which brought whole genome sequencing into routine care for certain rare diseases and cancers. NHS England has also signalled intent to expand pharmacogenomic testing more broadly.

Realistic expectations

Personalised medicine is genuinely transforming some areas of care — oncology most of all. It is not yet a general replacement for conventional prescribing, and it is worth being clear about why:

• The evidence is strong for certain drug–gene pairs and thin for many others
• Genetics is one factor among many — kidney and liver function, age, other medications, adherence and lifestyle often matter more
• Testing has to demonstrably improve outcomes to justify routine use

The direction of travel is clear, but the honest picture is selective adoption where evidence supports it, rather than wholesale transformation.

Where consumer testing fits

Consumer genetic testing can provide useful context about metabolism and inherited risk, and for some people it prompts changes that general advice did not. It is a starting point for conversations with a clinician — not a substitute for clinical genetic testing, and never a basis for changing prescribed medication.

Never stop, start or adjust a prescribed medicine on the basis of a genetic result alone. Take it to the clinician who prescribes it.

Testing with Rightangled

Rightangled's DNA tests assess markers relating to health risk and medication response, with results reviewed by our clinical team, which includes GPhC-registered independent prescribers, and medical oversight from our doctor, Dr Abdullah.

Verify us with the General Pharmaceutical Council (registration 9011933), see our LegitScript certification, and read reviews on Trustpilot.

Related reading: no more one size fits all.

This article is for general information and does not replace personalised medical advice.