Immunotherapy / Cancer Vaccine
Cancer immunotherapy is the use of the immune system to reject cancer. The main premise is stimulating the patient's immune system to attack the malignant cells in an effort to destroy them. Vaccines are medicines that boost the immune system’s natural ability to protect the body against disease.
The immune system is a complex network of organs, tissues and specialized cells that act collectively to defend the body. When an infectious microbe invades the body, the immune system recognizes it as foreign, destroys it and “remembers” it to prevent against another infection. Vaccines take advantage of this body response action.
Provenge (sipuleucel-T), produced by Dendreon Corporation, was approved by the Food and Drug Administration in April 2010 as the first autologous cellular immunotherapy for metastatic prostate cancer. Provenge is designed to stimulate a patient’s immune response to target prostate cancer cells. It is not a preventive vaccine like for measles; instead, it is a therapeutic (treatment) vaccine used to treat men who already have prostate cancer. Provenge was approved for men for whom hormone deprivation drugs no longer work, but who still have few if any symptoms.
Provenge is personalized for each patient as a one-time treatment. This immunotherapy vaccine is made from a patient’s own immune cells. A patient’s own blood is extracted and the white blood cells, which make up the immune system, are processed and “trained” to target a protein called PAP that is found primarily on prostate tumor cells and on normal prostate cells. The patient receives three infusions of these immune cells, typically two weeks apart. The most common side effects were chills, fever, fatigue, nausea, joint ache, headache, and back pain.
Clinical trial research shows that Provenge extends patient survival by an average of four months, although many men treated with Provenge have survived three years or more. Provenge does not appear to shrink tumors significantly or cause a drop in PSA levels.
Initially, Provenge will be available at 50 centers that participated in the clinical trial research. Dendreon Corporation is expanding its manufacturing capacity so the product will be more widely available by mid-2011.
