Confusion over pharmacogenetic test regulation

A 'gene chip' that aims to predict how well patients will respond to particular medicines has been withdrawn from sale in the US, after the Food and Drug Administration (FDA) requested more supporting data for its claims. The AmpliChip CYP450, launched earlier this year by Swiss firm Roche Diagnostics, is the first commercial application of pharmacogenomics: the matching of medical treatments to a person's genetic make-up. Originally marketed as a diagnostic tool, the FDA has now told Roche that the chip requires a higher level of review, Science magazine reported last week.

The new chip is designed to detect variations in two genes, called CYP2D6 and CYP2C19, that affect the way the body breaks down certain medicines - including some painkillers, antidepressants, antihistamines, heart and blood pressure medicines and antipsychotics. Genetic differences can affect how quickly these drugs are broken down in the liver: people who are so-called 'poor metabolisers' break them down too slowly, increasing the risk of side effects, whereas 'ultra-rapid metabolisers' break them down too quickly, before the drug has had any effect. Roche's new test, which it says will detect such genetic variations, was launched in June as 'the first wide-scale application of diagnostic microarray technology in the world'.

Roche was apparently 'testing the waters' selling the Amplichip as a diagnostic tool, according to US regulatory analyst Ron Eisenwinter. But in a letter sent to the firm last month, the FDA said the chip requires a higher level of review than that usually applied to genetic testing materials, because it is of 'substantial importance in preventing impairment of human health, and uses 'sophisticated' technology. Roche denies it was trying to avoid more intensive regulation: 'We have always planned to seek FDA approval for in vitro diagnostic use' said spokeswoman Melinda Baker. However, the 'big unknown' is how much extra data the FDA will require from Roche, said Kathy Hudson, director of the Genetics and Public Policy Center in Washington, DC. The FDA is said to be struggling to sort out how to regulate such tests. And in the European Union, Roche will have to seek approval for the Amplichip in each member state, as there is no single agency for evaluating medical devices such as that for drugs, reports New Scientist magazine.