Avastin, the top drug of Swiss pharmaceutical company Roche, may lose its approval for treating breast cancer in the United States.
As the world’s best-selling cancer medicine, Avastin has been approved for treating a variety of cancers. However, it failed to extend lives in four trials involving breast cancer patients.
"Given the number of serious and life-threatening side effects, the FDA does not believe there is a favourable risk-to-benefit ratio," Dr Richard Pazdur, the US Food and Drug Administration's head of cancer drugs, told reporters on Thursday.
Some side effects include holes in the stomach and intestines plus bleeding and blood clots.
Roche says that these problems occurred in less than four per cent of patients in the trials. The Basel-based company plans to request a hearing to contest the US decision. In the meantime, Avastin will retain its FDA approval.
In the wake of the news, analysts estimate that the Roche Group could lose as much as $1 billion (SFr0.97 billion) of its $6 billion in annual sales.
swissinfo.ch and agencies