US biotech Aveo Oncology saw its shares in a downward spiral yesterday, trading 50% lower in late-afternoon trading after advisors to the US Food and Drug Administration (FDA) rejected its experimental kidney cancer drug tivozanib.

The FDA's Oncologic Drugs Advisory Committee (ODAC) voted 13 to one against approving the drug, after concluding that it failed to demonstrate a favourable benefit-to-risk evaluation for the treatment of advanced renal cell carcinoma in a Phase III trial.

Experts seem concerned that, while matching progression-free survival, there may be a reduction in overall survival with tivozanib when compared with Bayer's Nexavar (sorafenib).

“I cannot picture how I would talk with a patient about putting him or her on tivozanib, allowing them to live without progression longer but possibly to die faster,” said Mikkael Sekeres, panel chairman and associate professor of medicine staff at the Cleveland Clinic’s Taussig Cancer Institute, said during the meeting, as reported by Bloomberg.

If the FDA follows the recommendation, as it usually does, the drug's launch could be set back substantially, particularly as it is looking likely that there will have to be a further clinical trial.

Naturally, the firm is disappointed with the decision, but will now work closely with regulators to address the panel's concerns while the agency continues its review of the marketing application, said Tuan Ha-Ngoc, Aveo's president and chief executive.

Tivozanib is an oral, once-daily, investigational vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor being assessed in kidney cancer and other tumours in a development pact with Astellas.

In February 2011, Aveo and Astellas signed a deal to develop and commercialise tivozanib outside of Asia for the treatment of a broad range of cancers. Subject to regulatory approval, Aveo will lead commercialisation of the drug in North America, while Astellas will take the reins in Europe.