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Personalised medicine based on pharmacogenetics: a critical approach is called for

As of early 2013, real therapeutic advances in the field of pharmacogenetics are still few and generally modest.

The aim of pharmacogenetics (or pharmacogenomics) is to provide personalised medicine, offering a drug only to patients on whom it has a good chance of being effective, or avoiding giving a drug to patients with an increased risk of suffering adverse effects.

Pharmacogenetics requires genetic testing, the power of discrimination of which must be carefully evaluated as for any diagnostic test. Evaluation is difficult, sometimes biased.

The genetic tests used are not sophisticated enough to select the patients likely to derive great benefit from the treatment. And while the target of personalised treatment is the tumour, it also targets healthy organs, and this can result in specific adverse effects.

The existence of a genetic test, even with a strong power of discrimination, is not sufficient to establish the benefit of personalised treatment. For this, clinical trials must have shown that the therapy is genuinely more effective (or less toxic) in patients with a particular genetic trait than in those who do not have it.

Pharmacogenetics has raised great hopes for the treatment of cancers. But, more often than not, the initial encouraging results have not been confirmed by large-scale clinical trials with stringent clinical evaluation criteria.

As at the beginning of 2013, advances associated with pharmacogenetics are still few and generally modest.

It is better not to confuse research hypotheses and evidence of improved treatment.

©Prescrire 1 June 2013

"Pharmacogenetics and personalised medicine: maintain a critical approach" Prescrire Int 2013; 22 (139): 161-163. (Pdf, subscribers only).
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See also:

Mirage or reality?
Prescrire Int 2013;
22 (139):144.
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