Cancer vaccines and checkpoint inhibitors are approved immunotherapies for prostate cancer. CAR T-cell therapy is a new treatment that doctors are learning more about in clinical trials.
You might be a good candidate for one of these treatments if your cancer didn't stop growing or it came back after surgery or hormone therapy. Immunotherapy could help some people with prostate cancer live longer, but it does have some risks to discuss with your doctor.
Prostate Cancer Vaccine – Sipuleucel-T (Provenge)
Most vaccines prevent you from getting sick. They prime your immune system to recognize germs and defend against them. Sipuleucel-T is a different kind of vaccine. It treats cancer by teaching your immune system to find and kill cancer cells.
Sipuleucel-T can't help everyone who has prostate cancer. It might be an option for you if:
Sipuleucel-T is the only approved prostate cancer vaccine. It's tailor-made for you using your own immune cells.
To give you this treatment, first your medical team connects you to a machine that filters some of the immune cells out of your blood. You go back home. The sample of cells go to a lab. The lab staff exposes them to a protein that stimulates the cells and programs them to fight prostate cancer.
Once the cells are ready about 3 days later, you visit your doctor's office or hospital again. They give the powered-up cells back to you in an IV. You get three doses in total, 2 weeks apart. Each dose takes about an hour.
Sipuleucel-T doesn't stop prostate cancer cells from growing. It also doesn't lower your level of PSA, a protein in your blood that signals prostate cancer. But it might help you live longer.
If you have side effects from sipuleucel-T, they usually start after you get the IV of the treated cells. The most common side effects from sipuleucel-T are like the flu:
They should go away in 1 to 2 days and are usually mild to moderate. A small number of people have more severe symptoms like trouble breathing and high blood pressure. Your medical team can treat these symptoms.
Checkpoints are proteins that help prostate cancer hide from your immune system. Checkpoint inhibitors block these proteins to boost your immune response against cancer. They can help lower PSA levels in people who have already used other prostate cancer treatments.
Pembrolizumab (Keytruda) and dostarlimab (Jemperli) are checkpoint inhibitors. They block a protein called PD-1 on immune cells. Blocking PD-1 is like taking the brakes off immune cells so they can attack prostate cancer. You get this treatment through an IV about once every 3 weeks.
A checkpoint inhibitor might be an option for you if:
- Your cancer has spread.
- The cancer started to grow again after chemotherapy or hormone therapy.
- You can't have surgery.
These treatments only work for people who have certain changes to genes that fix damaged DNA. Up to 10% of men with late-stage prostate cancer have these gene changes, which sometimes affect people with an inherited condition called Lynch syndrome.
Your medical team will test for these gene changes in a piece of your cancer that they remove during a biopsy. The test can show whether a checkpoint inhibitor is right for you.
Checkpoint inhibitors rev up your immune system so it can fight your cancer. Rarely, the immune system revs up too much and attacks healthy organs like the lungs, kidneys, or liver. If that happens, your care team might give you steroids to calm your immune system.
CAR T-Cell Therapy
T cells are your immune system's army of cancer fighters. CAR T-cell therapy is an experimental treatment that trains your T cells to find and kill prostate cancer. Right now, you can only get this treatment in a clinical trial.
To get CAR T-cell therapy, first, your medical team will connect you to a machine that filters T cells out of your blood. In a lab, the staff puts a protein called a chimeric antigen receptor on the outside of your cells. This protein will help your T cells find the cancer.
The lab makes many more of the new CAR T cells, which can take a few weeks. Once the cells are ready, you go back to your doctor's office and get them through an IV.
This treatment can cause side effects. As CAR T cells multiply, your body releases proteins called cytokines. A flood of cytokines can rev up the immune system too much. The name for this side effect is cytokine release syndrome (CRS). It causes symptoms like:
- High fever
- Trouble breathing
- Nausea, vomiting, and diarrhea
- Fast heartbeat
CAR T-cell therapy can sometimes affect the brain. If it does, you might have symptoms like headaches, confusion, or seizures. Your medical team will watch you very closely and treat any problems that happen.
CAR T-cell therapy has helped some people with blood cancers go into remission, meaning there were no signs of their cancer. It hasn't worked as well against prostate cancer. One reason is that solid tumors have more barriers that block T cells from reaching the cancer. Prostate cancer also weakens the immune system response.
Doctors are testing other CAR T-cell treatments to see if they work better against prostate cancer. A CAR T-cell therapy called P-PSMA-101 helped lower PSA by more than 50% in a few men, and it made one tumor disappear.
The Future of Immunotherapy
Doctors are studying new immunotherapy treatments in clinical trials. One is called PROSTVAC. It's a vaccine for people with late-stage prostate cancer. PROSTVAC works a lot like sipuleucel-T, but it isn't made for each person.
Studies are trying to find out whether adding CAR T-cell therapy to treatments like chemotherapy, hormone therapy, or targeted therapy might help it work better. If you're interested in trying a new immunotherapy, your doctor can tell you whether there is a trial that's a good fit for you.