New Cancer Vaccine Explored as Potential Treatment for Prostate Cancer Patients with Rising PSA

The gist: A new vaccine treatment  called Prostvac might help treat advanced prostate cancer patients whose tumors are resistant to hormone therapy and who have had either surgery or radiation. Prostvac boosts a patient’s own immune system to fight cancer.  A small clinical trial showed that Prostvac is safe and can be given to patients earlier. More research is needed to see just how well the vaccine works.

“Aiming to increase treatment options for prostate cancer patients who have an early relapse, investigators from a multi-institutional cooperative group — including Rutgers Cancer Institute of New Jersey — have demonstrated that a vaccine therapy that stimulates the body’s own immune defenses can be given safely and earlier in the course of prostate cancer progression.

“As part of a Phase II clinical trial, adult patients with advanced prostate cancer (as evidenced by two rising prostate-specific antigen or PSA values and no visible metastasis) whose cancer is resistant to hormone therapy and had either surgery or radiation were recruited from member institutions in the ECOG-ACRIN Cancer Research Group. In their work, published in the current online edition of European Urology, ECOG-ACRIN investigators examined two different experimental treatment options.

“In step one, patients were treated with PROSTVAC-V/TRICOM and PROSTVAC-F/TRICOM. PROSTVAC-V is derived from a vaccinia virus that was used for many years to vaccinate against smallpox. This virus is modified to produce a PSA protein that helps focus the body’s immune response to the PSA in the prostate tumor. In addition, it is modified to produce three other proteins that help increase an immune cell’s ability to destroy its target (TRICOM). PROSTVAC-F is made from the fowlpox virus, which is found in birds and not known to cause any human disease. It contains the same genetic material as PROSTAC-V, but is given multiple times to further boost the body’s immune system.”