Dendreon Shares Catch Fire

Updated from 9:39 a.m.

Dendreon (DNDN Quote) soared 43% after the biotech said regulators spelled out what they'll need to see to approve its Provenge vaccine for prostate cancer.

The Seattle-based company said Thursday morning that it got Food and Drug Administration confirmation that the agency "will accept either a positive interim or final analysis of survival from its ongoing Impact study to amend the Biologics License Application for Provenge."

Dendreon shares plunged earlier this month after the FDA asked for additional clinical data on Provenge before approving it. In March, shares had rallied after an FDA advisory panel backed approval.

The May setback was particularly worrisome for Dendreon investors because it suggested that the drug wouldn't get approved for at least a year or two, if at all. Thursday's comments seem to confirm that view, but the stock has been heavily shorted and so is known to react outlandishly to even the slightest development.

"The FDA indicated that either a positive interim or final analysis of survival, as described in the Impact Special Protocol Assessment Agreement, would address their request for the submission of additional clinical data in support of our efficacy claim," said CEO Mitchell H. Gold. "We anticipate completing enrollment in the Impact study this year and anticipate interim survival results in 2008. We are committed to making Provenge available as rapidly as possible to help the many men with late-stage prostate cancer who currently have few appealing treatment options."

Shares soared $2.96 to $9.70.