FDA cites vandetanib toxicity ahead of AZ panel review

FDA staffers today unveiled their concerns about the risk of high levels of toxicity of AstraZeneca's ($AZN) experimental thyroid cancer drug vandetanib.

With a panel of experts gathering on Thursday to review AstraZeneca's ($AZN) experimental thyroid cancer drug vandetanib, FDA staffers today unveiled their concerns about the risk of high levels of toxicity faced by prospective patients. The agency highlighted that "a substantial number of patients receiving vandetanib required a dose reduction and/or interruption" during a critical trial of the therapy. Close to a third of the patients taking the drug experienced significant side effects, compared to only 13 percent of the patients taking a placebo.

Once tapped as a top potential blockbuster in the AstraZeneca pipeline, investigators have significantly narrowed their work on the drug since it failed to extend the survival rate of lung cancer victims. The therapy may need to be restricted for now to advanced, inoperable cancer cases, which analysts say could cut its peak sales to $100 million.

"Given the substantial toxicity seen with vandetanib, should its indicatio