Cancer Vaccines Immunotherapy Explained (How Do Provenge Vaccines Cure Prostate Cancer?)
Cancer vaccines work by stimulating the immune system to recognize and attack cancer cells. Unlike traditional vaccines that prevent infectious diseases, cancer vaccines are designed to treat existing cancer or prevent its recurrence. The basic mechanism of cancer vaccines involves presenting cancer-specific antigens to the immune system and triggering an immune response.
Cancer cells often express specific proteins or antigens that are not present or are present in lower amounts in normal cells. These antigens can serve as targets for the immune system. Cancer vaccines present these antigens to the immune system in various ways. This can involve using tumor cells, tumor-associated antigens, or synthesized peptides that mimic the cancer antigens. Once the antigens are presented, the immune system recognizes them as foreign or abnormal. This recognition activates immune cells, particularly T cells, which are key players in the immune response. Then, activated T cells can recognize and target cancer cells expressing the specific antigens, and they can do an attack to destroy the cancer cells.
One example of a cancer vaccine that has been used in the real world is the Provenge (Sipuleucel-T) vaccine for advanced prostate cancer. Provenge is a personalized cancer vaccine that involves collecting a patient's own immune cells, specifically antigen-presenting cells (APCs) called dendritic cells. These collected dendritic cells are then exposed to a protein called prostatic acid phosphatase (PAP), which is found on most prostate cancer cells. This process allows the dendritic cells to "learn" to recognize PAP as a foreign or abnormal substance. The activated dendritic cells, now trained to recognize the prostate cancer antigen, are then reintroduced into the patient's bloodstream. Once in the body, these activated dendritic cells stimulate an immune response. T cells, a type of immune cell, are activated and directed to target and attack prostate cancer cells expressing PAP.
Provenge represents a specific approach to cancer vaccination. Other cancer vaccines, targeting different types of cancers and using diverse strategies, are also in various stages of development and clinical trials.