Immunotherapy for Prostate Cancer

July 1, 2024

This page was reviewed under our medical and editorial policy by Tanya Barauskas Dorff, M.D., professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

Immunotherapy, a treatment option for patients with prostate cancer, helps the immune system find and destroy cancer cells. It may be recommended to some patients with metastatic prostate cancer — cancer that has spread beyond the prostate — when the cancer is not responding to other treatments, such as hormone therapy for prostate cancer. To check whether the patient is a candidate for some types of immunotherapy, the care team will also look for certain genetic features in the prostate cancer cells.

Immunotherapy for prostate cancer is usually administered through an intravenous (IV) line and delivered to the bloodstream through a catheter (a tiny plastic tube). For prostate cancer, there are two main types of immunotherapy: cancer vaccines and immune checkpoint inhibitors.

How Does Prostate Cancer Immunotherapy Work?

The immune system is designed to find and destroy abnormal cells in the body. In a perfect world, the immune system would destroy all cancer cells. However, cancer cells have ways of disguising themselves so they are less visible. Some examples of how they can hide from the immune system include the behaviors described below.

• They may have genetic changes that make them difficult for the immune system to identify.
• They may have surface proteins to block an immune cell attack.
• They may modify cells surrounding a tumor to change the immune cells’ response.

Immunotherapy is a way to supercharge the body's immune system to fight disease. The therapy may be an option in advanced prostate cancers that no longer respond to other treatments. Immunotherapy for prostate cancer may involve either an IV medication or an infusion of the patient’s own immune cells that have been “trained” in the laboratory to destroy cancer cells.

Immunotherapy is tailored to each patient, and the decision to include immunotherapy treatment will be guided by the patient’s oncologist and the care team.

Immunotherapy Drugs for Prostate Cancer

When immunotherapy is used for prostate cancer, it's most commonly administered in conjunction with androgen deprivation therapy (ADT).

Cancer Vaccines

Cancer vaccines are unlike other vaccines used in routine care because they are given after the patient receives a cancer diagnosis. 

Sipuleucel-T (Provenge^®) is approved for the treatment of metastatic (advanced) cancer in men with few or no symptoms and for whom other treatments haven’t worked. With this type of immunotherapy, the patient’s immune cells are removed from the bloodstream and sent to a laboratory, where they are mixed with a prostate cancer protein called prostatic acid phosphatase (PAP). The goal is to help the patient’s immune cells better detect prostate cancer cells. After this process, the cells are sent back to the doctor to be injected into the patient’s body.

The steps for this type of immunotherapy are:

• Blood is drawn from the patient (this takes a few hours).
• The blood is sent to the laboratory, where the immune cells are enhanced to better target cancer.
• About three days after blood is drawn, the cells are infused back into the patient’s blood through an IV (this takes about 60 minutes or more).
• The treatment is usually done three times, two weeks apart.

Immune Checkpoint Inhibitors

Every cell has a checkpoint protein that keeps the immune system from becoming too strong and destroying healthy cells. These checkpoints interact with proteins on T cells (a type of immune cell) to turn off and on. Cancer cells can send a signal to the T cells to turn off, which makes the immune cells unable to destroy the cancer.

Some medications work to block these proteins, which makes the cancer cells unable to send an off signal and allows the immune cells to produce a strong response to the cancer cells. For some patients, these drugs may be used to treat advanced prostate cancer when the cancer is not responding well to other treatments, such as hormone therapy or chemotherapy.

Two medications affect a specific checkpoint protein called PD-1, which increases the body’s immune response:

• Pembrolizumab (Keytruda^®) has been approved for treating several types of cancerous tumors, including metastatic prostate cancer tumors with specific genetic features that make the cancer more likely to respond to the immunotherapy drug. These genetic features include a defect in the mismatch repair gene and a high number of genetic mutations in the cancer cells overall. The infusion is typically given every three to six weeks, and each IV infusion takes about 30 minutes. This medication is usually given when the cancer has continued to progress even after other treatments have been used.
• Dostarlimab (Jemperli) may be considered in men with advanced prostate cancer when a defect is found in the mismatch repair gene of the cancer cells, and in patients who are not responding to other treatments. It is typically given in an IV over 30 minutes, every three weeks for four doses, followed by every six weeks.

Immunotherapy Side Effects

The majority of patients who undergo immunotherapy experience flu-like symptoms that last a few days after treatment. Patients may be given acetaminophen and/or an antihistamine to lessen these side effects.

Vaccines

The most common side effects of the vaccine sipuleucel-T (Provenge) include:

• Fever
• Chills
• Fatigue
• Back and joint pain
• Nausea
• Headache

Rare symptoms may include difficulty breathing and elevated blood pressure.

Checkpoint inhibitors

Common side effects may include:

• Cough
• Nausea
• Tiredness
• Itching
• Skin rash
• Decreased appetite
• Constipation or diarrhea
• Joint pain

Infusion reactions resemble an allergic reaction and typically start at the injection site. These may include:

• Fever
• Chills
• Facial flushing
• Red, itchy skin
• Rash
• Dizziness
• Wheezing and difficulty breathing

While side effects can be challenging, many will resolve within a few days, while others may need more immediate attention and care.

Throughout the journey, the care team can help patients prepare for and manage the side effects of prostate cancer treatment.