Dendreon’s Provenge vaccine is the first autologous cellular immunotherapy to be approved by the FDA. This latest prostate cancer treatment will provide a new option for many men who stop responding to mainstay hormone prostate cancer treatment, when limited treatment options are available.
How Does the Latest Prostate Cancer Treatment Option, Provenge, Work?
Dendreon’s Provenge vaccine is an autologous cellular immunotherapy. It does not prevent a person from developing prostate cancer, but helps the person who has prostate cancer stimulate an immune response against the disease. Provenge is also known as Sipuleucel-T.
The Provenge vaccine works by extracting the patient’s dendritic cells, which are part of the immune system, and then modifying them with genetically engineered material. This allows the cells to express a recombinant protein, which acts as a prostate-cancer associated antigen. The antigen helps the vaccine to target prostate cancer cells by recognising prostatic acid phosphatase (PAP) antigen, which is present in over 95% of all prostate cancers. As such, when the modified cells are infused back into the patient, they act to stimulate the immune system to fight against the prostate cancer.
The Provenge vaccine is the first autologous cellular immunotherapy to be approved by the FDA.
Provenge Prostate Cancer Vaccine Clinical Trial Results - the IMPACT study
The Provenge vaccine has been studied in numerous clinical trials for the treatment of prostate cancer. Three phase III trials were used as part of the marketing application submitted to the FDA in order to gain approval for this latest prostate cancer treatment option. Of these trials, the major trial Dendreon used in the application was the IMPACT study (IMmunotherapy for Prostate AdenoCarcinoma Treatment), which involved over 500 patients with asymptomatic or minimally symptomatic, metastatic, hormone-refractory prostate cancer (HRPC). This study showed that when the Provenge vaccine was used to treat these patients, they lived 4.1 months longer than patients in the group who received placebo. In addition, Provenge-treated patients had their risk of death reduced by 22.5% compared to patients who received the placebo vaccine.
Another major phase III study showed that patients who suffered from asymptomatic metastatic hormone-refractory prostate cancer experienced a similar survival benefit.
What are the Side Effects of Provenge Prostate Cancer Vaccine?
Dendreon has indicated that the most common adverse reactions that have been experienced by patients treated with Provenge include chills, fatigue, fever, back pain, nausea, joint ache, and headache. Other side effects may include breathing problems, dizziness, high blood pressure, nausea and vomiting. The company maintains that these side effects are as a result of the infusion, and usually occur within one day of having the procedure carried out. In clinical trials, nearly all the patients who received Provenge experienced at least one adverse event, while the majority of patients who received the placebo vaccine also experienced at least one adverse event.
Who can This Latest Prostate Cancer Treatment be Used For?
Dendreon received FDA approval in April 2010, for the use of the Provenge vaccine in the treatment of asymptomatic or minimally symptomatic metastatic, hormone-refractory prostate cancer. Metastatic prostate cancer is when the cancer cells have spread from the prostate glands to other parts of the body, and is also known as advanced-stage prostate cancer.
Hormone therapy is the mainstay prostate cancer treatment for patients who have advanced disease. In these patients, hormone therapy helps to prevent the tumour from growing, and therefore extends survival for these patients. However, eventually the patient will develop resistance to hormone therapy and the prostate cancer will continue to grow and spread within the body. Men with advanced-stage metastatic disease have very few other prostate cancer treatment options available once this happens. Some patients chose to go on to be treated with chemotherapy as a last resort in order to help extend survival; however chemotherapy is toxic and often has unwanted side effects.
Advanced-stage prostate cancer is not curable, with patients having a median survival rate of 18-20 months once they reach this stage of the disease if not treated. As such, the latest prostate cancer treatment option, the Provenge vaccine, will provide these patients with another option at this stage of the disease to help prolong their survival.
Readers may also be interest in the following articles:
Prostate Cancer Screening - the Debate Continues
Prostate Cancer Symptoms and Warning Signs in Men
What is Benign Prostatic Hyperplasia (BPH) - Symptoms and Signs
Sources:
Dendreon 2010, ‘PROVENGE® (sipuleucel-T) Is Now FDA Approved’, April 2010
Dendreon 2010, ‘PROVENGE® (sipuleucel-T) Suspension for Intravenous Infusion, Prescribing Information’
Patel andKockler 2008, “Sipuleucel-T: a vaccine for metastatic, asymptomatic, androgen-independent prostate cancer.” Ann Pharmacother. Vol. 42: pp91-98
Christine Redmond - My interest in science and healthcare has seen me working in the laboratory with tiny cells and DNA to helping set up a cancer clinical ...
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