Prostate Cancer Vaccine

Prostate cancer vaccine appears to extend lives by 4.1 months.
Bloomberg News (7/28, Randall) reported, "Dendreon Corp.'s prostate cancer vaccine, Provenge, extended lives by 4.1 months," a discovery that "led to the drug's US approval in April." Even though the scientific community still doesn't "know precisely how the vaccine works or who is most likely to benefit," Harvard researchers explained that "Provenge is the first drug designed to train the body's immune system to fight cancer and is the most effective treatment for certain patients with advanced prostate tumors."
The "active cellular immunotherapy," also known as sipuleucel-T, "consists of the patient's own peripheral-blood mononuclear cells, including antigen-presenting cells, that have been activated outside the body using an engineered protein called PA2024," MedPage Today (7/28, Smith) reported. The "protein is a fusion of prostatic acid phosphatase, a prostate antigen, and granulocyte-macrophage colony-stimulating factor, which activates immune cells." Scientists tested its efficacy by randomizing 512 men to either sipuleucel-T or a placebo, which "consisted of peripheral-blood mononuclear cells that were not activated."
Investigators eventually noted that the "average survival was 25.8 months for men in the Provenge group, compared with 21.7 months for men in the placebo group, meaning that Provenge extended survival by 22 to 25 percent," HealthDay (7/28, Reinberg) reported. "If the vaccine was used by men with less severe disease survival, it might be extended for even longer," and "compared with other treatments, such as chemotherapy, radiation and hormone therapy, Provenge has been touted as having fewer and less severe side effects," according to the study published in the New England Journal of Medicine. "However, the availability and cost of Provenge are issues that need to be resolved