Bavarian Nordic (B/N) is in the process of testing what might be the next prostate cancer vaccine to become available. They have successfully completed a phase II trial of 125 men with metastatic prostate cancer. The good news, the survival advantage experienced by the trial’s subjects had a statistically significantly longer median overall survival of 8.5 months. Provenge’s survival advantage based on their phase III data was four months.

According to the company, B/N, Prostvac , a therapeutic cancer vaccine, has received fast track status from the FDA. Additionally, the company has received Scientific Advice from the European Medicines Agency and has successfully concluded the required “end of Phase II meeting” with the US Food and Drug Administration (FDA). Both European Medicines Agency and the FDA have indicated a preliminary agreement to conduct a phase III clinical trial.

At this juncture, B/N is planning to propose an international clinical trial protocol which will be submitted to both the Special Protocol Assessment (SPA) and to the FDA. Their goal is to have these submissions completed within a few months. The final design of the clinical protocol will be based on the outcome of this process.

The intention of B/N is to conduct a single global, strongly powered clinical trial that is expected to enroll around 1,200 men. Like the Provenge trial, the study will be placebo-controlled using men with minimally symptomatic, castration-resistant metastatic prostate cancer after failure of surgery or radiotherapy.

One major difference between Provenge and Prostvac is the treatment protocol. Provenge is a personalized treatment that requires that a man’s white blood cells first be removed and be shipped to a manufacturing plant where the cells are treated. After treatment the processed cells are infused back into the man. Prostvac is an “off the shelf” product that is administered subcutaneously to induce a specific, targeted immune response that attacks prostate cancer cells. Like Provenge, the morbidity issues seem to be mild.

Results from the Prostvac phase II trial indicated the investigational group had a significantly longer median overall survival by 8.5 months compared to the control group (p=0.006). The hazard ratio estimate for overall survival from the study is 0.56 (95% CI 0.37-0.85). The study was published in Journal of Clinical Oncology in January 2010.

Prostvac is being developed in collaboration with the National Cancer Institute under a Cooperative Research and Development Agreement with Bavarian Nordic’s U.S.-based subsidiary, BN ImmunoTherapeutics.

Joel T Nowak, MA, MSW