Vaccine Application Extends Life of Metastatic Prostate Cancer Patients

The randomized phase II study was performed by researchers from the Dana-Farber Cancer Institute (Boston, MA, USA) and affiliated organizations. The study involved the PROSTVAC-VF vaccine, a combination of two weakened poxviruses that have been genetically programmed to produce slightly irregular versions of prostate specific antigen (PSA)--a protein on the surface of prostate cells that is abnormal in many prostate cancers--and three costimulatory molecules that spur the immune system to a more vigorous attack on tumor cells.

The double-blinded trial included 125 patients with metastatic prostate cancer who did not respond to standard, hormone-lowering therapy. Eighty-two of the participants received the vaccine, produced by BN ImmunoTherapeutics, Inc. (Mountain View, CA, USA), and 40 received a placebo.

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

Patients tolerated the vaccine well; only a small number experienced side effects such as fatigue, fevers, and nausea. "Although this study is relatively small, it offers encouraging evidence of a clinically meaningful benefit from this vaccine approach,” said lead investigator and lead author Philip Kantoff, M.D., of Dana-Farber, who helped design the trial.

Investigators are now planning a phase III trial that will enroll about 600 patients to evaluate further the vaccine's effectiveness.

Related Links:
Dana-Farber Cancer Institute
BN ImmunoTherapeutics