Astex Falls Most Since 2004 as FDA Questions Drug: San Francisco Mover

Astex Pharmaceuticals Inc. (ASTX), a drugmaker that specializes in cancer therapies, fell the most in almost eight years after U.S. regulators said the company’s only approved treatment didn’t show a benefit for an expanded use.

Astex, based in Dublin, California, fell 22 percent to $2.19 at the close in New York, the biggest single-day decline since April 2004.

Astex licenses Dacogen, approved for a condition that often leads to leukemia, to Tokyo-based Eisai Co. (4523) The Food and Drug Administration said Dacogen “failed to demonstrate benefit based on statistical interpretation” for patients 65 years old and older who have acute myelogenous leukemia, a form of blood cancer. An agency advisory panel is scheduled to review the drug on Feb. 9.

“The wording in the press release may telegraph to investors a more rigorous interpretation by the FDA,” said George Zavoico, an analyst with McNicoll Lewis & Vlak LLC in New York. “Eisai needs to say, ‘Look, the result is really significant if you give us a little bit of leeway. This will be the first drug available for an unmet clinical need.’’

Eisai reported Dacogen sales of $190 million in the fiscal year ended March 31, 2011.

A recent study of the drug shows more positive results, said Timothy Enns, a spokesman for Astex.

‘‘It appears that the results are clinically meaningful but that’s exactly the question the FDA will put to the panel and we’ll see what happens,” Enns said. “It’s not a slam dunk from a regulatory perspective, you obviously have to go through the process.”

To contact the reporter on this story: Sarah Frier in New York at sfrier1@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net

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