The widely used generic anticoagulant warfarin illustrates many of the ways in which pharmacogenetics can add value in the biopharmaceutical industry. For this drug, metabolism is affected by genetic variation among other factors. Getting dosing right is difficult and risks are high, since underdose can lead to strokes and overdose to bleeding, for example in the gut or brain. It estimates that genetic testing could prevent 85,000 serious bleeds and 17,000 strokes a year, leading to healthcare savings of $1bn per annum.
As a response to this, tests for warfarin-metabolising genes are being developed. The drug label, which was first modified in 2007, was updated for a third time in January 2010 to provide information on how specific genetic variants may influence a patient?s response. In Europe, the EU-PACT study is looking at the effect of gene-based dosing on 2000 patients. This study is taking place across eight centres, including some of the academic founding partners of London Genetics. Following work by the International Warfarin Pharmacogenetics Consortium, which developed an algorithm with the potential to help doctors prescribe the optimal warfarin dose, the NIH has started a large clinical trial to test whether gene-based dosing leads to optimal outcomes. It will involve 1200 patients and report in 2012. Backing up these trials, in March it was announced that a Medco Research Institute/Mayo Clinic real-world study had shown that when genetic data was available to warfarin-prescribing doctors, hospitalisations due to bleeding fell by nearly a third.
For
this well-established generic, pharmacogenetics is enabling it to be
prescribed in a more cost-effective and safe way, with significant
impact on the product?s lifecycle expectations. The point to note here
is that not only do these studies show how pharmacogenetics can inform
increasingly safe treatment of patients, but also effective patient
treatment. The other upside for the pharma companies involved may well
be increased revenues from a boost in confidence about warfarin
prescription.