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 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 it seems to help men live 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 hold a lot of promise as cancer treatments.

Drugs called checkpoint inhibitors can be used for people whose prostate cancer cells have tested positive for specific gene changes, such as a high level of microsatellite instability (MSI-H), or changes in one of the mismatch repair (MMR) genes. Changes in MSI or in MMR genes (or both) are often seen in people with Lynch syndrome. 

The drugs are used for people whose cancer starts growing again after chemotherapy. They might also be used to treat people whose cancer can't be removed with surgery, has come back (recurred) after treatment, or has spread to other parts of the body (metastasized).

PD-1 inhibitor

Pembrolizumab (Keytruda) is a drug that targets PD-1, a checkpoint protein on immune system cells called T cells, that normally helps keep these cells from attacking normal cells in the body. By blocking PD-1, this drug boosts the immune response against prostate cancer cells. It has shown promising results in some men with prostate cancer and continues to be studied.

This drug is given as an intravenous (IV) infusion every 2 or 3 weeks.

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

Other, more serious side effects occur less often. This drug works by basically removing the brakes from 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 health 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.