By Karen Keeler Rogers
Provenge® (sipuleucel-T) is an innovative, autologous immunotherapy vaccine developed by Dendreon Corporation. It was approved by the US Food and Drug Administration just two years ago and, more recently, by Medicare, which now covers its use. It’s called a vaccine because it stimulates the patient’s immune system to fight prostate cancer cells, and it’s called autologous because it’s made from the patient’s own immune cells. Provenge is not a prostate cancer preventive nor does it shrink existing tumors, but research has shown that a full course of Provenge can slow the progression of advanced prostate cancer.
“How well Provenge therapy works varies by patient,” says Evan Pisick, MD, a medical oncologist at Cancer Treatment Centers of America® in Zion, Illinois. “It works best in metastatic cancer patients who have few or no symptoms from the disease and for whom hormone therapy has failed.”
Provenge Reinforces the Body’s Immune Arsenal
In effect, Provenge trains the body’s immune cells to seek out and attack prostate cancer cells wherever they may be hiding. Because each dose of Provenge is manufactured from a patient’s own immune cells, each dose is customized for that patient only.
To make a dose of Provenge, blood is drawn and some of the patient’s immune cells are collected from the sample in a process called leukophoresis. Then, in the manufacturer’s laboratory, the immune cells are exposed to a specially designed antigen that contains a protein called PAP, which is naturally produced by 95 percent of all prostate cancer cells. Antigens are substances in the blood that the immune system recognizes as foreign. The antigen also contains an immune-stimulating factor, called GMCSF, which has been shown to slow the metastasis of tumor cells.1 When the immune cells collected from a patient’s blood sample are exposed to this antigen mixture in the lab, the cells digest the antigen and display pieces of it on their surface.
Next the treated immune cells—which are now a dose of Provenge—are returned to the patient intravenously. Once in the bloodstream, the antigen pieces on the surface of the Provenge cells activate certain other immune cells. Then, like tiny, guided missiles, these other immune cells are able to seek out, recognize, and attack prostate cancer cells anywhere they may be located.
Treatment with Provenge requires three infusions scheduled two weeks apart. Because each dose must be individually made for each patient, blood will be drawn about three days before each infusion. All in all a full course of Provenge takes four to six weeks.
Provenge Has Helped Some Patients Live Longer
Clinical trials with Provenge showed that the treatment “significantly improved survival” in the study populations.2 One was a phase III trial with 512 metastatic prostate cancer patients who were symptom- free and whose cancer was hormone resistant. Two-thirds of the patients received a full course of Provenge infusions while one-third received a placebo. The median survival rate of the patients who received Provenge was 4.5 months longer than the survival rate of the patients who received the placebo. “What we’ve seen,” said Dr. Pisick, “is that the additional months Provenge may provide usually occur when patients are asymptomatic. In other words, the extra months occur when the patients’ quality of life is higher.”
In addition, 34 percent of the Provenge patients were alive at 36 months after treatment compared with only 11 percent of the patients who received the placebo. The study also showed that patients who received the placebo had a 70 percent higher relative risk of dying than the Provenge patients.
Careful Screening of Candidates is Required
If you have been diagnosed with advanced prostate cancer and you wish to be treated with Provenge, you must first meet a number of screening qualifications: you cannot be taking narcotics for pain; you cannot have brain, lung, or liver involvement from the cancer; you must be able to delay or suspend chemotherapy treatment for three months prior to and during treatment with Provenge; and you must be asymptomatic except for rising prostate-specific antigen (PSA) levels in your blood.
It’s also important to remember that Provenge doesn’t work for everyone, and it can have side effects: chills, fever, fatigue, back pain, nausea, joint ache, and headaches are the most common. In one study 1.5 percent of patients in the Provenge group stopped treatment due to side effects.3
“We can’t predict who will have side effects and who won’t or how severe they will be,” said Dr. Pisick. “How well Provenge works for a particular patient also depends on how quickly the cancer is progressing.”
Dr. Pisick offers Provenge therapy to patients who qualify medically as part of a comprehensive individualized treatment protocol. Helping patients proactively manage side effects is critical to maintaining quality of life throughout treatment.
References
1. Eubank TD, Roberts RD, Kahn M, et al. Granulocyte macrophage colony-stimulating factor inhibits breast cancer growth and metastasis by invoking an anti-angiogenic program in tumor-educated macrophages. Cancer Research. 2009;69;2133.
2. Provenge Vaccine “Significantly Improves” Survival in Men with Advanced Prostate Cancer. PSA Rising website. Available at: http://www.psarising.com/med/immun/ provenge-0.5.htm. Accessed February 20, 2012.
3. Provenge Benefits. Dendreon Corporation website. Available at: http://www.provenge.com/provenge-benefits. aspx. Accessed February 20, 2012.