Written by: Rob Levy
Medically Reviewed By: Xiao Wei, MD, MAS
Like all vaccines, prostate cancer vaccines work by stimulating the body’s immune system. Unlike vaccines for the flu, COVID-19 and other infections, which protect against disease, prostate cancer vaccines are a form of treatment.
Treatment vaccines activate the immune response against cancer cells by targeting antigens – cancer-related proteins produced in greater abundance in tumor cells than in normal cells.
Researchers are exploring a variety of vaccine approaches that are showing promise in prostate cancer, which has historically been a difficult malignancy to target with vaccines and other immunotherapies.
Types of prostate cancer vaccines
Cancer vaccines, including those for prostate cancer, work by stimulating immune system cells (shown in blue) to attack cancer cells in the body.
Sipuleucel-T (Provenge) is the first, and so far the only, vaccine for prostate cancer to be approved by the U.S. Food and Drug Administration. It is a standard therapy for patients with metastatic prostate cancer that no longer responds to hormone therapy.
Provenge is made by removing immune cells from the patient’s blood and modifying them in the laboratory to target PAP, an antigen, or marker, expressed in most prostate cancer cells. They are then returned to the patient in an infusion to teach the immune system how to detect and destroy prostate cancer cells. In patients with metastatic hormone-resistant prostate cancer, it can slow cancer growth and help patients live longer.
The ongoing phase 3 ProVent trial is evaluating whether Provenge can slow the advance of disease among men on “active surveillance” with non-metastatic prostate cancer at low risk of growing and spreading. Active surveillance involves monitoring the disease rather than treating it right away.
VTP-850: VTP-850 is a vaccine under development that targets four specific prostate cancer antigens, rather than one. A clinical trial is assessing VTP-850 in men with rising levels of prostate-specific antigen (or PSA, a protein used to gauge prostate cancer risk or recurrence) who have had radiation therapy to the prostate or had it surgically removed.
Advantages, and challenges, of cancer treatment vaccines
By targeting specific antigens on tumor cells, cancer treatment vaccines essentially train the immune system to protect itself against cancer. They tend to work best against cancers with large numbers of uniquely cancer-related antigens. Cancers like prostate cancer, which often carry fewer such antigens, tend to be more difficult for the immune system to distinguish from normal cells – and represent more of a challenge for scientists working on treatment vaccines.
At Dana-Farber, researchers are working to better understand why some cancers are more elusive to the immune system than others. They’re also exploring novel ways of enhancing the effectiveness of treatment vaccines.
About the Medical Reviewer
Dr. Xiao Wei, MD, MAS is the Deputy Director of Clinical Research at the Lank Center for Genitourinary Oncology at Dana-Farber Cancer Institute. In addition to caring for patients with genitourinary cancers, Dr. Wei collaborates with academic, industry and laboratory partners to conduct clinical and translational research focused on improving immunotherapy and radioligand treatments for patients with advanced prostate cancer.
Dr. Wei obtained her medical degree from the State University of New York at Buffalo and completed residency in internal medicine at the Mount Sinai Hospital in New York. She subsequently completed a medical oncology fellowship at the University of California, San Francisco, where she also received a master's degree in clinical research.
