What is Immunotherapy?
Immunotherapy is a type of treatment that uses your own immune system to fight cancer cells.
Your immune system protects you from harmful things. But cancer cells can hide from your immune system. Immunotherapy can work in various ways. It can teach your immune cells to spot and kill cancer cells. And it can boost your immune system or take the “brakes” off it so it attacks cancer more strongly.
Researchers have been studying different kinds of immunotherapy for prostate cancer. Currently, a treatment called Sipuleucel-T is the only FDA-approved immunotherapy for prostate cancer.
What Is Sipuleucel-T?
Sipuleucel-T helps your own immune system recognize and attack prostate cancer cells. It is sometimes described as a cancer vaccine.Sipuleucel-T is used to treat some men with advanced metastatic castration-resistant prostate cancer (mCRPC). In clinical studies, treatment with sipuleucel-T reduced the risk of death by 22% in men with advanced mCRPC.
Sipuleucel-T does not work in the same way as chemotherapy or many hormone treatments. The goal is to train the immune system to kill cancer cells rather than using medicine to directly kill cancer cells.
Researchers are studying other cancer vaccines for prostate cancer, including a vaccine called PROSTVAC. However, these vaccines have not been approved for routine treatment and are generally available only through clinical trials.
How Does Sipuleucel-T Work?
Sipuleucel-T is made using your own immune cells. The treatment involves several steps:
- Your white blood cells are collected. Blood is removed from your body with a complex machine, and the white blood cells are taken out and collected. The rest of your blood is sent back into your body. This process is called leukapheresis.
- Your white blood cells are prepped to recognize prostate cancer. In a lab, your immune cells are exposed to a protein. This helps teach them to recognize and target prostate cancer cells.
- The treated cells are returned to you. The cells are infused back into your bloodstream, where they can help your immune system fight the cancer.
This process is repeated as a series of treatments.
Immune Checkpoint Inhibitors
Another type of immunotherapy is called an immune checkpoint inhibitor. These medicines work by taking the "brakes" off the immune system. This lets immune cells attack cancer more effectively.
Researchers have done many studies to see if immune checkpoint inhibitors might help men with advanced prostate cancer. Some studies have tested these medicines alone. Other studies have combined them with other prostate cancer treatments, such as:
- Androgen deprivation therapy (ADT)
- Novel hormonal therapies, such as enzalutamide
- Other immunotherapy medicines
Although some early studies produced encouraging results, larger studies have generally not shown enough benefit for these treatments to become standard therapy for most men with advanced prostate cancer.
One key exception is a medicine called pembrolizumab. The FDA has approved pembrolizumab for certain advanced cancers, including prostate cancer, when the tumor has a genetic feature called microsatellite instability-high (MSI-high).
MSI-high tumors have problems repairing damaged DNA. This is uncommon in prostate cancer, occurring in approximately 3% of men with advanced prostate cancer.
Talking with Your Healthcare Team
For now, sipuleucel-T remains the only FDA-approved prostate cancer treatment that works by specifically stimulating the immune system. Pembrolizumab is available for a small number of people with MSI-high prostate cancer.
If you have advanced prostate cancer, ask your doctor if sipuleucel-T, pembrolizumab, or a clinical trial for immunotherapy might be right for you.