Avastin approval raises hopes - and eyebrows



The US Food & Drug Administration (FDA) has approved the Genentech/Roche medicine Avastin for treatment of late-stage breast cancer, used in combination with the established anti-cancer medicine paclitaxel. 

Avastin (bevacizumab) is a monoclonal antibody which inhibits the formation of new blood vessels around a tumour. Its advantages over other cancer drugs include a highly specific action; a long half-life in the body; a lower chance that drug resistance will develop; and reduced risk of metastasis (cancer spreading).  

The drug is already licensed in the US as a combination therapy for some bowel and lung cancers, though other countries' regulators - including the UK's National Institute of Clinical Excellence (Nice) - have rejected it for both diseases. Nice decided Avastin was not effective enough to justify its high cost, a decision criticised by the industry and patients. 

The FDA's acceptance of Avastin in late February went against the recommendation made by its own oncology drugs advisory committee (ODAC) two months earlier. ODAC's main objection was that clinical trial data showed that Avastin only delayed tumour progression, rather than extending survival, which is the usual criterion for late-stage cancer therapies.  

Share movements indicated the unexpected nature of the approval: Genentech's price jumped by an immediate 11 per cent, while Roche (Genentech's majority shareholder) was up 4.1 per cent.  

'The approval should not be interpreted as a change in policy regarding cancer drug approvals,' says Richard Pazdur, Director of the FDA's Office of Oncology Drug Products. 'We still believe that overall survival remains the gold standard for cancer drug approval, but delaying the progression of a tumour may in itself be a clinical benefit.' He adds that the FDA has already approved three other breast cancer drugs (taxol, lapatinib, and ixabetilone) because of their effect on tumour progression. 

The FDA seems to have been persuaded to approve Avastin on the basis of preliminary results of five as yet unfinished trials, which Genentech presented to the agency after ODAC had made its decision based on published trial data. The controversial approval is, however, only provisional, and may be revoked once the results of these later trials are fully available.  

Karol Sikora, professor of cancer medicine at Imperial College London, said it was 'puzzling' why Avastin showed no significant survival benefit, after it had exhibited a clear six-month survival advantage in colorectal cancer. He said Avastin's true value would only be known after the many trials in progress in the UK and elsewhere had been completed.  
Peter Mitchell