Fears that the cancer drug Avastin may not perform as well as makers Genentech has advertised have been voiced by the US Food and Drug Administration (FDA).
The company claims that Avastin significantly shrinks the deadliest type of glioblastoma multiforme brain tumour, which generally proves fatal within six months.
However, the FDA has questioned response rate as an accurate measurement of effectiveness, particularly since Avastin is known to decrease swelling caused by excess fluid in the brain.
In any event, it says, a drug would need to have a rate above 30% – higher than in Genentech studies – to outweigh the uncertainties connected with brain-tumour imaging.
The FDA is to ask its assessment panel to decide whether Avastin should be granted accelerated approval. The agency usually accepts the panel`s advice, although it is not required to.
Avastin is already approved to treat colon and breast cancer, and generated $2.69 billion (£1.9 billion) of revenues last year. It is marketed in Europe by Roche after its $48.6 billion (£ 34.4 billion) takeover of Genentech.
The drug works by restricting the blood flow to tumours, which is regarded as being a significant advance over older chemotherapy drugs.
Copyright Press Association 2009