Data from the trial, which enrolled 19 patients, indicate that Gvax immunotherapy results in a statistically significant increase in median PSA (prostate-specific antigen) doubling time as well as the formation of prostate cancer-associated antibodies in 79% of patients who received Gvax immunotherapy. In addition, 16 patients (84%) experienced a decline in PSA slope, a potential measure of the rate of disease progression, after receiving Gvax immunotherapy (p=0.018). PSA levels in eight of 19 patients (42%) remained stable during the six-month treatment period, with a median time to PSA progression of 9.7 months.
Analysis of patient sera taken before and after receiving Gvax immunotherapy showed that 15 of the 19 patients (79%) developed new or enhanced antibody responses against either PC-3 or LNCaP, the two prostate cancer cell lines that comprise Gvax immunotherapy. The product was generally well tolerated in the trial.
Robert Dow, senior vice president of medical affairs and chief medical officer of Cell Genesys, said: “These data suggest that Gvax immunotherapy may have clinical activity for men with early stage, recurrent prostate cancer. We are now planning a larger randomized trial to further examine the potential application of Gvax immunotherapy in this patient population and also look forward to learning more from a study currently under way that is evaluating the product in combination with docetaxel as a preoperative therapy in men with high-risk prostate cancer.”