Genetic tests may pinpoint who should get Avastin
LONDON, Oct 3 (Reuters) - Genetic tests could in future show who will respond best to Genentech DNA.N and Roche's (ROG.VX) blockbuster cancer drug Avastin -- a positive development for patients but not necessarily for sales.
Scientists writing in the latest issue of the Journal of Clinical Oncology said they had identified two genetic markers that appeared linked to improved survival in women with breast cancer given the medicine.
Patients with genetic variations known as VEGF-2578 AA and VEGF-1154 A showed better overall survival than those with alternative genotypes, according to an analysis of 363 tumour samples from a previous clinical trial.
Two other variants were linked to significantly fewer cases of high blood pressure.
"Our data support an association between VEGF genotype and median overall survival as well as grade 3 or 4 hypertension when using bevacizumab (Avastin) in metastatic breast cancer," Bryan Schneider of the U.S. Indiana University School of Medicine and colleagues reported.
Industry analysts at Morgan Stanley said the work could be an important first step to defining a narrower patient population for Avastin.
However, the finding still needs to be validated across other clinical trials. It is also unclear if genetic tests might identify responders and non-responders in other tumour types.
Avastin, which had sales of 4.1 billion Swiss francs ($3.6 billion) last year, is used primarly in bowel cancer. It is also approved for lung cancer.
Using cancer drugs in a targeted way based on patients' genetic make-up is a growing theme in oncology.
Genentech and Roche's Herceptin and GlaxoSmithKline's (GSK.L) Tykerb, for example, are approved for only the 25-30 percent of breast cancer patients whose tumours generate a protein called HER-2.
And recent research has shown Erbitux, developed by ImClone IMCL.O and sold by Bristol-Myers Squibb (BMY.N) and Merck KGaA (MRCG.DE), only works in tumours containing the normal, or wild-type, version of a gene known as KRAS.
Until now, no biomarkers have been identified to predict the outcome of treatment with drugs like Avastin, which work by starving tumours of blood supply.
Experts have argued about the market impact of the new trend towards using markers.
Drug companies have welcomed the development, arguing it is good for long-term sales, but some analysts say sales are likely to take at least a short-term hit. (Editing by David Cowell)
