Dendreon's Provenge: Moment of Truth

If Dendreon(DNDN Quote) is now king of all cancer vaccines, the company's coronation may come Tuesday inside a Chicago convention hall.

That's where a large crowd of urologists (and perhaps an equal number of investors) are gathering to witness the presentation of data from a pivotal clinical trial of Provenge, Dendreon's cancer therapeutic vaccine.

Dendreon shares are up markedly ever since the company announced April 14 that the phase III Provenge study was successful in extending the lives of men with advanced prostate cancer. Missing from Dendreon's triumphant announcement, however, were any details from the study, including the specifics about Provenge's survival benefit.

Which is why the annual meeting of the American Urological Association at Chicago's McCormick Place convention center is suddenly so important. The Provenge data, culled from the phase III study known as IMPACT, will be presented at 2:20 p.m. Central Daylight Time.

The continued rally in Dendreon's stock price depends on the actual Provenge data matching, or exceeding, expectations set by the company's April 14 announcement.

What exactly are those Provenge expectations? They're hard to pinpoint precisely, but Dendreon CEO Mitch Gold stated that the survival benefit seen in the IMPACT trial was "consistent" with results in the previous Provenge studies. That suggests a survival benefit favoring Provenge in the range of four to four-and-a-half months compared to patients in the control arm.

The IMPACT study was designed to succeed if Provenge could reduce the risk of death by 22%. Stated statistically, that equates to a "hazard ratio" of 0.78. Again, Dendreon hasn't provided any hard numbers yet, but the company did state that Provenge hit its pre-specified level of statistical significance, which implies at least a 22% reduction in the risk of death.