Point-of-care genomic testing suggested for stroke patients
NHS stroke patients would benefit from a one-hour genomic test, given at the point of care, to see if clopidogrel should be given, a NICE draft report suggests
The National Institute for Health and Care Excellence (NICE) has published draft guidance recommending point-of-care genomic testing for people who have had a stroke. This test looks for some known variants in the CYP2C19 gene, and aims to minimise or even prevent the adverse reactions sometimes seen in those prescribed the drug clopidogrel. If this guidance is adopted in NHS practice, this could mean better and more precise prescriptions for stroke patients.
What did NICE identify?
NICE estimates that about one-third of people in the UK have a CYP2C19 gene variant that could slow down or even stop clopidogrel metabolism. Currently, to see if a patient has one of these gene variants, a blood sample would have to be taken and sent to and tested in a genomics laboratory; a process that takes days. Efforts have been made to integrate laboratory testing into routine care for stroke, for example see NHS Tayside’s efforts, which we reported on last year.
A standard laboratory test would cost less than £140 per patient, but NICE is recommending that a point-of-care test be used. This is a small increase to just under £200 per patient, but would provide results in a clinically actionable timeframe of just one hour. It can also be done onsite. “This test ensures we’re getting the best care to people quickly, while at the same time ensuring value for money for the taxpayer,” said NICE’s interim director of medical technology and digital evaluation Mark Chapman.
Rethinking clopidogrel as stroke’s go-to drug
Clopidogrel is a commonly prescribed drug for patients following stroke and TIA (transient ischaemic attack), also called a ‘mini-stroke’. Recurrent strokes account for 46% of the 100,000 strokes that take place every year in the UK.
As an antiplatelet drug, clopidogrel lowers the patient’s stroke risk by preventing the blood from clotting. A blood clot can reduce or stop blood flow to areas of the brain, killing off the brain’s neurones through oxygen deprivation. Antiplatelet drugs prevent this by stopping platelets from clumping together, keeping the oxygen-rich blood flowing freely.
Clopidogrel is a pro-drug. This means that it first needs to be metabolised in the body into its active state. The protein that does this is encoded by a gene called CYP2C19. Some people have specific variants in this gene that cause this protein (which is an enzyme) to be less effective. This, in turn, affects their chances of having another stroke.
- Short online course: Genomics 101: From Gene to Protein
“Treatment with clopidogrel is effective in preventing further strokes for the majority of people who don’t have the gene variant. But until now doctors have not known who cannot be treated with clopidogrel until after they’ve had a second stroke or TIA, and that could be too late,” NICE’s Mark Chapman explained.
Genomic point-of-care testing could offer patients with CYP2C19 variants the opportunity to be tested and prescribed an alternative antiplatelet drug on the same day, which would reduce their future stroke risk.
Spotlight on pharmacogenomics
NICE’s draft guidance highlights point-of-care pharmacogenomics, which is the study of how medicines interact with our genome. This can include how quickly the body activates drugs, like clopidogrel, or breaks them down. For prescribing clinicians, knowing this information can influence the effective dose for an individual, or even whether that drug should be prescribed for the patient at all.
The NHS also recognised pharmacogenomic testing as being one of the key priorities outlined in last year’s genomics strategy report, ‘Accelerating genomic medicine in the NHS‘.
- Read more on the report: The NHS’s new strategy for genomics: Five key takeaways
- Funded taught course: Pharmacogenomics and Stratified Healthcare
NICE’s final version of the guidance is due for publication later this year. Until then, why not read the second of this two-part piece, where we will look at pharmacogenomics in more detail and with a focus on how it can be used in predicting the risk of serious side effects from certain drugs.
