Targeted therapy drugs for prostate cancer precisely attack cancer cells and stop them from growing and spreading. They give you a personalized type of treatment that’s based on the genetic makeup of your particular cancer.
Your doctor might prescribe these medications if you have cancer that:
- Has spread beyond your prostate (called metastatic cancer)
- Doesn’t respond to hormone treatments (called castration-resistant)
- Has certain genetic changes or mutations
More and more targeted treatments are becoming available as researchers learn more about how cancer cells work. Eventually, they may be used to treat a wider group of people with prostate cancer.
You might also hear these medications called molecular targeted therapy or precision medicines.
How Does Targeted Therapy Work?
Targeted therapy medicines zero in on molecules that control some of the functions of cancer cells. Different targeted drugs work in different ways. They may affect the way cancer cells divide, grow, interact with other cells, or repair themselves. Some harness the power of your immune system to fight cancer.
This kind of treatment is different from chemotherapy because it mostly spares healthy cells, which are often damaged along with cancer cells by chemotherapy. Targeted therapies are designed to stop only the growth of cells that have a certain mutation.
Before you’re prescribed a targeted treatment, you’ll get tests that give your doctor information about what genes, proteins, and other factors are present in and on your cancer. This helps your doctor figure out which targeted treatment might work for you.
You may also get other treatments like surgery, chemo, or radiation while having targeted therapy.
What Types of Targeted Medications Are Available?
One category of targeted therapy now used for prostate cancer is PARP inhibitors.
Like healthy cells, cancer cells are damaged all the time, by radiation, ultraviolet light, or harmful molecules called free radicals. PARP enzymes in your cells help repair that damaged DNA. These medications block PARP to keep cancer cells from repairing themselves so they’ll die. The drugs affect cancer cells more often than normal cells.
Because they target mutations in the BRCA genes (which raise your risk for various cancers), doctors only use PARP inhibitors on people who have this gene change. Your doctor can test your blood, saliva, and your tumor to find out if you have it.
- Olaparib (Lynparza). This medicine for metastatic castration-resistant prostate cancer (mCRPC) is prescribed when your cancer keeps growing after you’ve tried hormone therapy drugs like abiraterone or enzalutamide.
- Rucaparib (Rubraca). This drug is used to treat mCRPC that has grown after you’ve tried both chemotherapy and hormone therapy drugs.
You take these PARP inhibitors as pills, twice a day. These medications are also used to treat breast and ovarian cancers.
Another PARP inhibitor, niraparib, has also recently been studied for treating mCRPC.
Your doctor can also use a type of therapy that targets protein-specific membrane antigen (PSMA) to treat prostate cancer. PSMA is a protein found on healthy prostate cells, but there’s more of it on prostate cancer cells. Scientists aren’t sure exactly how PSMA functions, but it’s thought to boost development of the cancer cells.
The FDA has approved a PSMA-targeted therapy called lutetium-177 vipivotide tetraxetan (Pluvicto) for mCRPC that hasn’t responded to other treatments. It works by delivering radiation directly to your tumor, which damages the DNA of the cancer cells. Because it’s so tightly targeted, it doesn’t affect healthy tissues, which means fewer side effects.
You get the medication through an IV every 6 weeks.
Could These Medications Help Me?
Current targeted therapy drugs are used only if you have mCRPC that doesn’t respond to hormone therapy, and if you have certain genetic mutations.
Tests you’ll get before your doctor prescribes one of these drugs might include:
- Testing for inherited genetic mutations throughout your DNA (called germline mutations)
- Genomic sequencing of your tumor tissue to find out the full genetic makeup
- Genomic sequencing of the tumor DNA in your bloodstream
You might also meet with a genetic counselor.
Before you take PARP inhibitors, you need to find out if you have mutations in your DNA repair genes (like BRCA1 and BRCA2). Those mutations make it harder for cancer cells to fix their damaged DNA. And PARP inhibitors block another way for DNA to repair itself. With both pathways blocked, cancer cells can’t repair their DNA and they die.
Studies have shown that about a quarter of people with prostate cancer have the genetic alterations that could make PARP inhibitors more effective.
Before you get PSMA-targeted therapy, you’ll need a special type of PET scan to see if your tumor has high amounts of PSMA.
How Well Does It Work?
The FDA approved both olaparib and rucaparib to treat prostate cancer in 2020. In a clinical trial, men with specific genetic variations (like BRCA) who took olaparib lived twice as long without their cancer progressing than the control group. They also lived longer overall, and their tumors were also more likely to shrink.
In the clinical trial of rucaparib, almost half of the men with BRCA2 alterations had improvement in their tumors while taking the drug.
These early studies have had positive results. The drugs are being studied in larger trials.
Lutetium-177 vipivotide tetraxeta got FDA approval in 2022. A clinical trial found that participants whose treatment included this drug were 38% less likely to die during the study.
What Are the Side Effects?
You might have many side effects from targeted therapy, just a few, or none. They can include:
- Nausea, vomiting, diarrhea, or constipation
- Dry mouth
- Loss of appetite
- Urinary tract infections
- Low red blood cell counts (anemia)
- Ankle swelling
- Joint aches
- Abnormal liver blood tests
- Low blood platelet counts
- Cough or shortness of breath
You can get side effects while you’re being treated, just afterward, or weeks after you’ve finished treatment. Late side effects could show up months or years after taking these medications. In rare cases, people have developed blood cancer after taking these drugs. Some people have had blood clots in their lungs or legs.
Tell your doctor right away if you have any side effects so they can help you feel better. Most side effects can be treated, or they may go away on their own.