Study: Immunotherapy helped prostate cancer patients live longer

Metastatic prostate cancer patients who received a vaccine of poxviruses engineered to spur an immune system attack on prostate tumor cells lived more than eight months longer those receiving a placebo, according to researchers at the Dana-Farber Cancer Institute.

A randomized, 125-patient Phase II study studied the PROSTVAC-VF vaccine, a combination of two weakened poxviruses that have been genetically programmed to produce slightly irregular versions of prostate specific antigen, and three co-stimulatory molecules. The vaccine is produced by Bavarian Nordic ImmunoTherapeutics.

At the three-year point after the study, 30 percent of the PROSTVAC-VF patients were alive, versus 17 percent of the control group, according to a Dana Farber statement. The median survival of the vaccine group was 24.5 months, compared with 16 months for the control group--an 8.5-month increase.

"Although this study is relatively small, it offers encouraging evidence of a clinically meaningful benefit from this vaccine approach," says principal investigator and lead author Philip Kantoff. Investigators are planning a Phase III trial that will enroll about 600 patients to further evaluate the vaccine's effectiveness.

The most common side effect was irritation at the spot where men had the injection, the U.K.'s Guardian reports. One man developed a problem with blood clots and had a heart attack, which the researchers say was "possibly related to treatment." Study findings will appear in the Journal of Clinical Oncology.

- read the Dana Farber press release
- check out the Guardian's coverage