ORLANDOIn patients with hormone-refractory, metastatic prostate cancer, an allogeneic vaccine delays progression of disease and prolongs survival, according to data presented at the 38th Annual Meeting of the American Society of Clinical Oncology (abstract 729).
In this phase II study of 34 patients, the vaccine (GVAX, Cell Genesys, Inc., Foster City, California) showed evidence of a dose-response relationship in prostate-specific antigen (PSA) progression, time to progression, and survival, setting the stage for a phase III trial scheduled to be launched in the first half of 2003.
"The more important work is up ahead," said lead investigator Jon-athan Simons, MD, director, Winship Cancer Institute, Atlanta. "Now that a safe range of doses has been defined, larger clinical trials can be done."
The vaccine is composed of PC-3 and LNCaP tumor cells irradiated and genetically modified to secrete granulocyte macophage colony-simulating factor (GM-CSF).
In this study, there were no dose-limiting or autoimmune toxicities in 24 patients given a lower vaccine dose (prime dose of 500 million cells, followed by 12 booster doses of 100 million cells each) or in 10 patients given a higher dose (same prime dose, but with booster doses of 300 million cells each).
Toxicities primarily consisted of nonserious injection site reactions, along with fatigue, fever, and flu-like symptoms.
Trend Toward Increased Survival