Among patients with castration-resistant prostate cancer, the addition of hormone therapy following vaccine treatment improved overall survival compared with either treatment alone or when the vaccine followed hormone treatment, according to recent data published in the July 15 Clinical Cancer Research, a journal of the American Association for Cancer Research.
Philip M. Arlen, M.D., director of the Clinical Research Group for the Laboratory of Tumor Immunology and Biology, Center for Cancer Research, at the National Cancer Institute, said the findings have important implications for guiding treatment decisions for prostate cancer patients.
"Vaccines, if and when they are approved, can be safely and effectively combined with other therapies, including hormones," said Arlen. "There appears to be an advantage in overall survival."
Arlen and colleagues enrolled 42 patients who had castration-resistant prostate cancer. These patients were randomly assigned to receive either a poxvirus-based prostate-specific antigen vaccine or hormone therapy with nilutamide. At progression, patients received the other therapy and continued to receive their original therapy.
For all the patients enrolled in the study, the three-year survival probability was 71 percent and the median overall survival was 4.4 years. Patients randomized to the vaccine had a three-year survival probability of 81 percent and an overall survival of 5.1 years, while patients taking nilutamide had a three-year survival probability of 62 percent and an overall survival of 3.4 years.