UPDATED: FDA panel rejects Aveo's kidney cancer drug tivozanib

After grilling investigators for hours about the efficacy data extracted from a pivotal study of the kidney cancer drug tivozanib, an FDA panel of experts voted against recommending an approval for Aveo Oncology's ($AVEO) lead cancer drug. The committee voted 13 to 1 against Aveo, deciding that the biotech had not produced the needed efficacy data in a single, badly designed pivotal study. And given the harsh assessment of Aveo from the panel, this is one vote that is not likely to be overturned inside the agency.

Aveo's shares were eviscerated by the decision, losing 57% of their value seconds after trading was resumed.

The back and forth between the FDA and the biotech's investigators centered closely on the data, with skeptical questions zeroing in on the fact that investigators found that patients in the Nexavar (sorafenib) arm survived slightly longer than the tivozanib group. Aveo argued, though, that the Nexavar group was allowed to cross over to get tivozanib after their disease progressed, possibly skewing the final overall survivor results. And they added that any additional study could be completed after marketing had begun.

A number of analysts believed strongly that Aveo could persevere and win the vote this morning, noting that tivozanib had hit the primary endpoint in an improvement of progression-free survival. But an internal review by FDA staffers rattled a faithful group of investors earlier in the week, noting that the agency had suggested a follow-up study in the spring of 2012 which could concentrate on U.S. patients. Americans were sorely lacking in the company's pivotal trial, which relied heavily on data from Eastern Europe.

Today, the FDA's leading oncology official, Richard Pazdur, also concentrated heavily on data indicating an increased risk of death in the tivozanib arm. And he clearly believed that the panel vote could set a precedent for other drugs posing the same dilemma.

The bad news for Aveo also affects Astellas, which is partnered on the drug and had expected to help launch the therapy later this year.

The FDA, of course, doesn't have to abide by the panel's vote in making its final decision. The agency generally goes along with a negative vote and only occasionally overturns a positive outcome. 

Aveo has been concentrating almost entirely on tivozanib's fate. The biotech restructured last year after deciding to start ramping up a launch effort ahead of the vote. And for today, it's sticking with Plan A until the FDA makes its formal decision.

"While we are disappointed with the outcome of the ODAC vote, we remain confident in the efficacy, safety and tolerability of tivozanib in RCC patients," said Tuan Ha-Ngoc, president and chief executive officer of AVEO, in a statement. "We are committed to the RCC patient community and will work closely with the FDA to address the issues discussed by the panel today as the Agency continues its ongoing review of the New Drug Application for tivozanib."

- here's the release from Aveo

Special Report: Tivozanib – Top 10 Late-Stage Cancer Drugs – 2012