The trial showed the approach was feasible, with minimal toxicity and evidence of activation of the immune system following the therapy. Preclinical data have demonstrated that a response can be triggered against cancer cells, both in vitro and in vivo, following incubation of antigen-presenting cells with Biomira's BLP25 vaccine. In the study being presented, dendritic cells extracted from six patients with relapsed metastatic breast cancer were pulsed with liposomal BLP25, and then returned to the patients by injection. Biomira's lead product, a metastatic breast cancer vaccine called Theratope, is in Phase III trials. Three of eight patients receiving the two highest doses of the vaccine are alive and free of disease more than two years following treatment, while the six patients receiving the two lowest doses have relapsed.
Longer survival correlates with vaccine-induced antitumor immunity.
Based on the results, Cell Genesys plans this year to move GVAX into a 60-patient Phase II trial in the same indication. Up to four vaccine treatments were given. The new findings indicate a strong correlation between antitumor effects and immune response. The product has moved into two multicenter Phase II trials, which are employing higher doses and longer vaccination schedules. Results are expected late this year.