Finding a cancer vaccine is the Holy Grail of oncology, but has remained largely an unrealized dream — until now. This week, the Food and Drug Administration approved a drug that actually trains the body's immune system to fight off advanced prostate cancer.
That's a big deal. Prostate cancer is the second leading cause of cancer death in American men (after lung cancer,) according to the American Cancer Society, and about one in six men will be diagnosed with it during his lifetime.
The drug, called Provenge, is the first drug to be developed by the Dendreon Corporation, which was founded in 1992 by a pair of Stanford professors. Provenge is not exactly a new drug. In fact, according to The New York Times, three years ago it failed to meet the FDA's standards for approval.
But while the drug's unique capabilities are a huge step forward, it's hardly a panacea. In clinical trials, the treatment only extended the lives of patients about four months compared with a placebo. After three years, 32 percent treated with Provenge were alive, compared with 23 percent of those who got the placebo.
"The big story here is that this is the first proof of principle and proof that immunotherapy works in general in cancer, which I think is a huge observation," Dr. Philip Kantoff, chief of solid tumor oncology at the Dana-Farber Cancer Institute in Boston and the lead investigator in Dendreon’s largest clinical trial for the drug told the Times.
Provenge is not a preventive vaccine like those for the measles, hepatitis or the newer vaccine developed to block the virus that can lead to cervical cancer. It's a therapeutic vaccine, used only after prostate cancer has already developed and approved by the FDA specifically for more advanced stages.
The way the drug works is a marvel of modern science: first, the patient's white blood cells are extracted from their blood, the same way they would be during blood donation, and certain immune cells are separated out. Those cells are then injected with a combination of a protein often found on prostate tumors and an immune booster. The treated cells are then re-introduced to the patient's blood supply three times over the course of a month. The main side effects of Provenge in clinical trials were fever, chills, fatigue and pain.
Typically, men with prostate cancer have to undergo surgery to remove the prostate gland (which can have undesirable side effects, such as difficulty achieving erection) along with radiation and/or chemotherapy, both of which have a host of uncomfortable side effects, followed by treatment with drugs that reduce the levels of testosterone (which contributes to tumor growth.)
According to the Times, Dendreon hopes to develop other similar cancer vaccines, including one for bladder cancer. In fact, treatment vaccines could be the wave of the future in the world of oncology: dozens of other vaccines are in development with other companies.
By Darragh Worland
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