Immunotherapy for Prostate Cancer

Immunotherapy is the use of medicines to stimulate a person’s own immune system to recognize and destroy cancer cells more effectively. Certain types of immunotherapy can be used to treat prostate cancer.

Cancer vaccine

Sipuleucel-T (Provenge) is a cancer vaccine. Unlike traditional vaccines, which boost the body’s immune system to help prevent infections, this vaccine boosts the immune system to help it attack prostate cancer cells.

The vaccine is used to treat advanced prostate cancer that's no longer responding to hormone therapy but that is causing few or no symptoms.

This vaccine is made specifically for each man. To make it, white blood cells (cells of the immune system) are removed from your blood over a few hours while you are hooked up to a special machine.

The cells are then sent to a lab, where they are mixed with a protein from prostate cancer cells called prostatic acid phosphatase (PAP). The white blood cells are then sent back to the doctor’s office or hospital, where they are given back to you by infusion into a vein (IV).

This process is repeated 2 more times, 2 weeks apart, so that you get 3 doses of cells. The cells help your other immune system cells attack the prostate cancer.

The vaccine hasn’t been shown to stop prostate cancer from growing, but studies suggest it may help men live an average of several months longer. As with hormone therapy and chemotherapy, this type of treatment has not been shown to cure prostate cancer.

Possible side effects of vaccine treatment

Common side effects from the vaccine can include fever, chills, fatigue, back and joint pain, nausea, and headache. These most often start during the cell infusions and last no more than a couple of days. A few men may have more severe symptoms, including problems breathing and high blood pressure, which usually get better after treatment.

Immune checkpoint inhibitors

An important part of the immune system is its ability to keep itself from attacking the body’s normal cells. To do this, it uses “checkpoint” proteins on immune cells, which act like switches that need to be turned on (or off) to start an immune response. Cancer cells sometimes use these checkpoints to keep the immune system from attacking them. But drugs that target these checkpoints, known as checkpoint inhibitors, hold a lot of promise as cancer treatments.

For example, pembrolizumab (Keytruda) and dostarlimab (Jemperli) are drugs that target PD-1, a checkpoint protein on immune system cells called T cells. By blocking PD-1, these drugs boost the immune response.

One of these drugs might be an option to treat some advanced prostate cancers, although this is rare.

Pembrolizumab can be used if the cancer cells have any of the following:

• A high level of microsatellite instability (MSI-H) or a defect in a mismatch repair gene (dMMR)
• A high tumor mutational burden (TMB-H), meaning the cancer cells have many gene mutations

Dostarlimab can be used if the cancer cells have a defect in a mismatch repair gene (dMMR).

Unfortunately, these types of changes aren’t common in prostate cancer. But for men whose cancer cells have one of these changes, one of these drugs might be helpful.

These drugs are given as an intravenous (IV) infusion, typically every 3 to 6 weeks.

Doctors are also studying these and other checkpoint inhibitors combined with other types of medicines in treating prostate cancer.

Possible side effects

Side effects of these drugs can include fatigue, cough, nausea, itching, skin rash, decreased appetite, constipation, joint pain, and diarrhea.

Other, more serious side effects occur less often.

Infusion reactions: Some people might have an infusion reaction while getting one of these drugs. This is like an allergic reaction, and can include fever, chills, flushing of the face, rash, itchy skin, feeling dizzy, wheezing, and trouble breathing. It’s important to tell your doctor or nurse right away if you have any of these symptoms while getting this drug.

Autoimmune reactions: These drugs work by basically removing one of the safeguards on the body’s immune system. Sometimes the immune system starts attacking other parts of the body, which can cause serious or even life-threatening problems in the lungs, intestines, liver, hormone-making glands, kidneys, or other organs.

It’s very important to report any new side effects to your cancer care team promptly. If serious side effects do occur, treatment may need to be stopped and you may get high doses of corticosteroids to suppress your immune system.