Soon: a vaccine against prostate cancer?

What does the small pox virus has to do with prostate cancer? Well, scientists are using relatives of the deadly virus to develop a vaccine that holds lots of promise for patients with advanced prostate cancer. The vaccine Prostvac-VF is still in the testing stage and is a ground-breaking project of BN ImmunoTherapeutics, a division of Danish biotech firm Bavarian Nordic.

In the clinical trial development program of Prostvac-VF, the vaccine the vaccine was tested in 125 male patients with advanced prostate cancer that was resistant to most cancer drugs. The study conducted with the help of researchers at the Dana-Farber Cancer Institute and Harvard Medical School in Boston.

The results of the trial was very promising, with patients treated with the vaccine having extended survival of 8 months or more compared to those who did not receive the vaccine. According to researcher Dr. Philip Kantoff:

“The average survival for these men is two years…At three years, 30 percent of the men who got the vaccine were still alive.”

Prostvac is one of therapeutic vaccines currently in the development stage Therapeutic vaccines are used to treat diseases that have been diagnosed and are therefore different from prophylactic vaccines which prevent diseases.

Prostvac was developed from genetically-engineered cowpox virus and fowlpox viruses which are related to the small pox virus. The viruses were weakened and genetically engineered to carry irregular versions of the prostate specific antigen (PSA), which are produced only by prostate cells. In addition, the vaccine also induces the production of “three costimulatory molecules that spur the immune system to a more vigorous attack on tumor cells.”

The results of the study have been published in the Journal of Clinical Oncology. The authors concluded that immunotherapy with Prostvac-VF was well tolerated and associated with a 44% reduction in the death rate and an 8.5-month improvement in median overall survival rate in patients with metastatic castration-resistant prostate cancer. However, larger studies needed to confirm these findings.

Dr. Kantoff continues:

“Although this study is relatively small, it offers encouraging evidence of a clinically meaningful benefit from this vaccine approach.”

A trial that intends to include about 600 patients is in the planning.

There is a large economic potential for an effective prostate vaccine. Prostate cancer is a leading cause of mortality among American men, ranking second only to lung cancer as cancer killer. 2009 statistics from the American Cancer Society give 192,000 diagnosed cases 27,000 deaths. Financial analysts foresee a billion-dollar market for such a vaccine.