As my regular readers probably have noted from prior posts, I am a strong advocate for research and the development of a prostate cancer vaccine. A cancer vaccine is different from the more “common” types of vaccines that are familiar to us. The “common” vaccines (i.e. tetanus or polio) are administered prior to having an illness. They are designed to expose a person to either dead or living antibodies to encourage an individual’s own body to make its own antibodies. These antibodies will then fight off the disease if there is an exposure in the future. A cancer vaccine is given after the cancer has developed, and is designed to “teach” the immune system how to recognize cancer cells as foreign bodies and then fight them.
Sadly, today, cell Genesys, Inc. (CEGE) announced that it has terminated VITAL-2, the second of two Phase 3 clinical trials of GVAX immunotherapy for prostate cancer. This trial compared GVAX immunotherapy combined with Taxotere (docetaxel) to Taxotere plus prednisone in survivors with advanced-stage prostate cancer.
The Independent Data Monitoring Committee (IDMC) recommended that the trial be terminated. The committee’s recommendation stemmed from its observation of an imbalance in deaths between the two arms of the study.
Out of the 408 enrolled survivors, the IDMC noted 114 deaths had occurred of which 67 occurred in the GVAX plus Taxotere combination treatment arm (experimental arm) and 47 deaths occurred in the Taxotere control arm. Neither the IDMC nor Cell Genesys have been able to account for imbalance in deaths.
Cell Genesys has said that it plans to analyze the clinical data to attempt to understand the cause of the higher death rate in the experimental arm.
Cell Genesys has requested that the IDMC perform a previously unscheduled futility analysis of VITAL-1, the other Phase 3 clinical trial of GVAX immunotherapy. It is hoped that the results of the VITAL-1 analysis will become available in one month.
GVAX immunotherapy for prostate cancer is comprised of two prostate tumor cell lines that have been modified to secrete GM-CSF (granulocyte-macrophage colony-stimulating factor), an immune stimulatory cytokine that plays a key role in stimulating the body’s immune response, and then irradiated for safety. GVAX is designed to be administered through intradermal injections on an outpatient basis.
These results are an unfortunate loss for our community.
Joel T Nowak MA, MSW