Exelixis drops after FDA study deal falls through

SOUTH SAN FRANCISCO, Calif. (AP) -- Shares of biotech drugmaker Exelixis Inc. plummeted Tuesday after the company said it did not reached an agreement with federal health regulators on a study of its experimental prostate cancer drug, cabozantinib.

The company is pursuing a small, pivotal study of its drug in late-stage prostate cancer patients suffering from bone pain. The company said it plans to make reduction in pain the primary measure of the trial and begin testing by year-end.

The company was seeking a binding agreement with the Food and Drug Administration that would sign off on the study, but said it "did not reach a timely agreement," with regulators. Such agreements are seen as a federal endorsement of a study's design and can usually increase the chances of approval.

The company said it would move ahead with the study despite the lack of an agreement with the FDA.

"Based on advice from leading investigators and regulatory consultants, we believe it is in the best interests of both patients and Exelixis to initiate the trial as soon as possible," said Exelixis in a statement.

Company shares plunged $3.12, or 40 percent, to $4.61 in midday trading. Over the past year, shares have traded between $12.82 and $4.09.