Prostate cancer immunotherapy shows favorable patient survival

New data analyses from a phase III clinical trial suggest favorable results using an investigational form of immunotherapy in men with prostate cancer.

The analyses examined results from VITAL-1, Cell Genesys, Inc.’s recently terminated phase III clinical trial that compared GVAX immunotherapy for prostate cancer with docetaxel (Taxotere) chemotherapy plus prednisone. VITAL-1, which included 626 advanced prostate cancer patients with asymptomatic castrate-resistant metastatic disease, was terminated in October 2008 based on the results of a futility analysis conducted at the company’s request that indicated the trial had less than a 30% chance of meeting its predefined primary endpoint of an improvement in overall survival.

However, the final Kaplan-Meier survival curves for the two treatment arms suggest a late favorable effect of GVAX immunotherapy on patient survival compared with chemotherapy, with the curve for GVAX patients crossing above the chemotherapy curve at approximately the same time median survival was reached in both treatment arms (21 months). Additionally, the data suggest that patients with Halabi predicted survival greater than or equal to 18 months may have a more favorable response to the immunotherapy, according to the study authors, led by Celestia S. Higano, MD, of the University of Washington, Seattle.

Treatment with GVAX immunotherapy was generally well tolerated and had a very favorable side effect profile, Cell Genesys reported at the 2009 Genitourinary Cancers Symposium in Orlando, FL.

“We believe that the further analyses of the VITAL-1 trial presented today indicate that GVAX immunotherapy for prostate cancer has clinical activity and a favorable safety profile compared to Taxotere chemotherapy, the standard of care for men with advanced prostate cancer,” said Stephen A. Sherwin, MD, of Cell Genesys.