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When prostate cancer spreads or stops responding to treatment, what comes next? Thanks to newer types of medicine — such as immunotherapy — people living with prostate cancer have more treatment options than ever before. Immunotherapy works differently from hormonal therapy or chemotherapy and may be used along with them. It’s not used in all cases of prostate cancer, and it’s not a cure. But for some people with advanced prostate cancer, it can control the growth of cancer and help them live longer.
In this article, we’ll discuss how immunotherapy fits into prostate cancer treatment. We’ll cover when it’s used and what drugs have been approved by the U.S. Food and Drug Administration (FDA). We’ll also go over possible side effects of immunotherapy and how to learn more about ongoing clinical trials for prostate cancer.
Immunotherapy is a treatment that helps your body fight cancer on its own. It works with your immune system, not against it. Your immune system is your body’s personal security team. Immune cells — including T cells — are bodyguards who find and destroy things that don’t belong in your body, like germs or damaged cells.
Cancer cells, including prostate cancer cells, can be tricky. Sometimes, they can hide from the immune response or send signals that tell immune cells to stop working. Immunotherapy helps remove those signals. This allows the body’s immune system to better recognize and attack cancer cells.
In prostate cancer, immunotherapy harnesses the ways immune cells send and receive chemical messages. The messengers are called cytokines. Cytokines enable communication between immune cells, telling them when to stop, start, or stay active. Prostate cancer can disrupt these signals, which weakens the immune response.
Some immunotherapy drugs are called immune checkpoint inhibitors. These drugs block proteins that normally act like brakes on immune cells. When these brakes are removed, immune cells can stay active longer and respond more strongly to prostate cancer cells.
Another type of immunotherapy involves the use of monoclonal antibodies, which are lab-made versions of immune proteins. Monoclonal antibodies help immune cells target specific proteins found on prostate cancer cells. Once activated, immune cells can travel through the blood and lymph system and respond in areas where cancer has spread.
Cancer vaccines are another approach used in prostate cancer. These vaccines are made to train the immune system to recognize proteins found on prostate cancer cells. In this case, the goal of the vaccine is not to prevent disease, but to help immune cells better identify and attack cancer over time.
Immunotherapy isn’t usually part of the treatment plan for people with early-stage prostate cancer. It’s mainly used when the disease has become metastatic (has spread beyond the prostate) and other treatments aren’t controlling it well enough.
Immunotherapy is often considered for prostate cancer that gets worse or comes back while someone is taking hormonal therapy. This type of prostate cancer is known as castration-resistant prostate cancer (CRPC) or hormone-refractory prostate cancer (HRPC). At this stage, prostate cancer may also be metastatic, meaning it has spread to other parts of the body, such as the bones or lymph nodes. Metastatic cancer is also referred to as stage 4 (sometimes rendered with Roman numerals as stage IV).
Immunotherapy may be recommended after hormone therapy and sometimes after other treatments, like chemotherapy or targeted therapy. It may also be used for those whose cancer can’t be treated with surgery. In some cases, genetic testing of the cancer can help determine whether an immunotherapy drug is likely to work.
Your oncology team will consider your symptoms, past treatments, test results, and overall health when making treatment recommendations.
As of January 2026, the only immunotherapy specifically approved by the FDA for prostate cancer is sipuleucel-T (Provenge). However, some immune checkpoint inhibitors, like pembrolizumab (Keytruda) and dostarlimab (Jemperli), can be used for prostate cancers with certain rare genetic features, under broader approvals for all “solid tumors” with those features. These situations are uncommon in prostate cancer.
Sipuleucel-T is a cancer vaccine designed to treat metastatic castration-resistant prostate (mCRPC). It is usually used for adults whose prostate cancer has spread and is no longer responding to hormone therapy, especially if symptoms are absent or mild. This therapy uses a person’s own immune cells, trained to recognize a prostate cancer protein called prostatic acid phosphatase (PAP), and aims to help people live longer.
Pembrolizumab is an immune checkpoint inhibitor. It works by blocking a protein called PD-1, helping immune cells better attack cancer cells. The drug is not specifically approved for prostate cancer. However, it can be considered if the prostate cancer is found to have certain uncommon genetic changes — microsatellite instability-high (MSI-H), mismatch repair deficient (dMMR), or tumor mutational burden-high (TMB-H) — and other treatments have stopped working.
These are “tissue-agnostic” FDA approvals, meaning they apply to any solid tumor with these features, not just prostate cancer. All of these biomarkers are rare in prostate cancer.
Dostarlimab is another immune checkpoint inhibitor that targets PD-1. Like pembrolizumab, it’s not specifically approved for prostate cancer. It can be used for prostate cancers (or other solid tumors) that have progressed after other treatments if they are shown to have dMMR changes, as determined by an FDA-approved test. This is a rare finding in prostate cancer, but the approval applies to all solid tumors with this genetic feature.
Side effects of immunotherapy can vary depending on the exact drug used and how a person’s body responds. Because immunotherapy works by activating the immune system, side effects differ from those caused by chemo or radiation.
The most common side effects of immunotherapy drugs for prostate cancer are usually mild to moderate. They include:
Sometimes, the immune system can become too active and start affecting healthy cells. This is called an immune-related or autoimmune side effect. These are less common but can be more serious if left untreated. They include:
Always tell your healthcare team about any new or worsening symptoms right away.
Researchers are actively working on new immunotherapy approaches for prostate cancer. Many studies are focused on helping the immune system respond more strongly and for longer periods of time. For example, some prostate cancers — known as “cold tumors” — are hard for the immune system to identify. New research is testing ways to make prostate cancer easier for immune cells to see and attack.
Other studies are looking at combining immunotherapy with other treatment options, like hormonal therapy or targeted therapy. The goal is to slow cancer growth, help you live longer, and limit side effects.
If you’re curious about participation in clinical trials, talk to your oncologist or search for studies recruiting near you online at ClinicalTrials.gov.
On MyProstateCancerTeam, people share their experiences with prostate cancer, get advice, and find support from others who understand.
Have you used immunotherapy to treat your advanced prostate cancer? What were your experiences? Share with others in the comments below.
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