Phase III results confirm survival improvement with PCa immunotherapy

Sipuleucel-T (Provenge) extends overall survival in men with metastatic, castrate-resistant prostate cancer, investigators in Dendreon Corp.’s phase III IMPACT (IMmunotherapy for Prostate AdenoCarcinoma Treatment) study recently announced at the 2010 Genitourinary Cancers Symposium in San Francisco.

A sensitivity analysis performed with longer-term follow-up (36.5 months) and additional events (349 deaths) collected at the time of study closure demonstrated that sipuleucel-T increased 3-year survival by 40% compared with placebo (32.1% vs. 23%), extended median survival by 4.1 months (25.8 months vs. 21.7 months), and reduced risk of death by 22.5% (HR=0.775; p=.032).

In addition, new analyses demonstrated that the median predicted survival of the two treatment arms using the Halabi model were well balanced (20.3 months for sipuleucel-T vs. 21.2 months for placebo). Furthermore, in an analysis in which patients were censored at the time of docetaxel use, the sipuleucel-T treatment effect remained strong (HR=0.649).

"The results from the IMPACT study corroborate earlier studies with sipuleucel-T in demonstrating an improvement in overall survival for men with metastatic castration-resistant prostate cancer," said principal investigator Philip Kantoff, MD, of the Dana-Farber Cancer Institute and Harvard Medical School, Boston. "This is the first therapeutic vaccine to demonstrate a survival benefit in cancer. Furthermore, the results of this study validate cancer immunotherapy as an entirely new treatment paradigm that can provide patients with a clinically meaningful survival benefit coupled with a well-tolerated safety profile."

Some of the study’s authors report financial interest or other relationship with Dendreon.

Look for more news from the Genitourinary Cancers Symposium in the May 1 issue of Urology Times.