by Alicia M Prater PhD

Created on: May 03, 2010

Provenge is a first in the medical field – a therapeutic vaccine for cancer. Its maker, Dendreon, has been seeking Food and Drug Administration (FDA) approval of Provenge since 2005, and to this aim, they have been conducting clinical trials since at least 2002. In 2007, the company was told that they still lacked data, and the FDA wanted survival statistics. Then, on April 29, 2010, the FDA finally

approved Provenge for the treatment of metastatic castration-resistant (hormone refractory) prostate cancer, an advanced form of the disease.

After the 2007 rejection by the FDA, Dendreon conducted clinical studies on 512 men and found that Provenge increased the life span by approximately 4 months (surviving to roughly 26 months) compared to placebo (surviving to roughly 22 months). Roughly a third of the men treated with Provenge survived to 3 years compared to roughly a fourth of those given placebo. However, one concern among researchers and clinicians is that the drug does not slow the progression of the disease.

The only other option for men who fall into the Provenge treatment group is chemotherapy with Taxotere (docetaxel), which can generally be expected to extend life by two or three months and produces severe, and sometimes debilitating, side effects. The clinical trials have shown that Provenge generally produces few side effects that last only a few days: fever, headache, fatigue, nausea, joint aches, and back pain. Some clinicians see this drug replacing chemotherapy as the first choice for these patients because of the reduced side effects and increased survival.

Provenge requires the patient’s white blood cells to exert its effect, making its administration different from other drugs. First, the patient’s white cells are isolated from a blood sample and sent to a lab where the drug is “made”. The cells are exposed to a protein specific to prostate cancer, priming them for an immune response. In this way, Provenge works by increasing the body’s immune response against the cancer, and because of this immunomodulatory effect, the drug is referred to as a vaccine. However, traditional vaccines are used for preventing illness; Provenge is a therapeutic option for advanced stage disease.

About 3 days after this procedure, the patient is transfused with their primed white blood cells. The procedure is repeated three times, every 2 weeks. The whole treatment is expected to cost $93,000. Currently, Dendreon has one production facility in New Jersey, but they are planning facilities in Los Angeles and Atlanta. They also expect to expand beyond the original 50 centers, but they are predicting being able to treat only 2000 patients in the next year (2010-2011).

Sources:

Prostate Cancer Research Institute

American Cancer Society

New York Times

CNN

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