PARP inhibitors are a promising new treatment for specific types of treatment-resistant or advanced prostate cancer. The Food and Drug Administration (FDA) has approved two PARP inhibitors for prostate cancer, and others are in clinical trials.

Prostate cancer is a disease that affects thousands of people each year. It occurs when cells in your prostate gland begin to grow uncontrollably. Current treatments for prostate cancer include:

One promising new treatment is poly ADP ribose polymerase (PARP) inhibitors. These are a type of targeted therapy that block the actions of proteins called PARP enzymes. These enzymes are essential in helping damaged cells repair themselves, and cancer cells primarily rely on this process to survive and grow.

This article will explore how PARP inhibitors help treat prostate cancer, who might benefit from them, and their potential side effects. We’ll also look at ongoing research to explore the future of this emerging treatment.

PARP inhibitors block a protein in cancer cells called PARP, an integral part of the DNA repair process. Cancer cells can no longer repair their DNA when PARP is blocked. By blocking PARP enzymes, PARP inhibitors can prevent cancer cells from repairing DNA damage, which can ultimately lead to cell death and tumor shrinkage.

According to a 2021 research review, PARP inhibitors are paving the way for precision medicine in prostate cancer.

“Precision medicine” is a term that refers to the practice of using information about a person, such as their genetics, to guide treatment. PARP inhibitors have a role in precision medicine because they specifically target cancer cells and show promising results in people with prostate cancer.

PARP inhibitors are particularly effective in people with specific mutations in genes involved in DNA repair, such as BRCA1, BRCA2, or ATM.

Combination therapy

A 2021 review notes that one promising approach to using PARP inhibitors in prostate cancer is to combine them with other drugs, such as those that damage the DNA.

Another 2021 review notes the success of combining PARP inhibitors with immunotherapy drugs. This approach relies on the PARP inhibitors to trigger a response in the immune system, which then recognizes the cancer cells as foreign and attacks them. But more research is still needed in this area.

Doctors may also use PARP inhibitors with antihormone drugs. A phase 2 clinical trial found positive results when using a PARP inhibitor with abiraterone (Zytiga).

Cancer is typically due to mutations in one or more of three types of genes:

  • oncogenes
  • tumor suppressor genes
  • DNA repair genes

A doctor may recommend PARP inhibitors if a mutation in DNA repair genes (like BRCA or ATM) is causing your prostate cancer. While prostate cancer isn’t usually due to just one gene mutation, some types of prostate cancer are more likely to demonstrate mutations in these genes.

According to a 2022 article, doctors may recommend PARP inhibitors for:

However, it does not mean that PARP inhibitors are a cure for prostate cancer. They can extend the time the disease is managed before it spreads further.

The National Cancer Institute (NCI) mentions that the FDA has approved two PARP inhibitors to treat prostate cancer in specific populations — olaparib (Lynparza) and rucaparib (Rubraca).

Olaparib (Lynparza)

Olaparib is a PARP inhibitor you take by mouth. It is specifically approved to treat people with mCRPC with specific genetic mutations, such as BRCA1, BRCA2, or ATM.

Rucaparib (Rubraca)

The FDA approved rucaparib for people with advanced prostate cancer whose tumors have BRCA or ATM mutations. It’s a pill you take twice daily with or without food, as directed by a healthcare professional.

A 2023 study of over 400 participants showed that those taking rucaparib survived longer without the cancer progressing than those taking a control drug.

Two other potential PARP inhibitors for prostate cancer include niraparib and talazoparib.


Niraparib is an oral PARP inhibitor that has shown promising results in clinical trials for the treatment of prostate cancer. In a 2023 clinical trial, patients with mCRPC who had received previous chemotherapy improved radiographic progression-free survival and overall survival with niraparib treatment.


Talazoparib was approved by the FDA in 2018 for breast cancer. It does not have approval for prostate cancer use, but studies show promise. In a 2021 phase 2 trial of people with mCRPC, 29.8% of participants had a response to talazoparib.

Common side effects of PARP inhibitors include:

  • fatigue
  • nausea
  • vomiting
  • diarrhea
  • abdominal pain
  • dizziness
  • cough

Rare but serious side effects of PARP inhibitors include:

Talk with a doctor about potential side effects and what to expect before starting PARP inhibitors.

Here are some of the most frequently asked questions about PARP inhibitors for prostate cancer.

How effective are PARP inhibitors in treating prostate cancer?

The FDA approved olaparib and rucaparib after successful trials that showed excellent results.

People treated with olaparib lived more than twice as long as people on other prostate cancer treatments without their cancer progressing. They were also 16 times more likely to have their tumors shrink. The benefit was greatest in people with BRCA1, BRCA2, or ATM mutations.

In the rucaparib trial that led to its accelerated approval, participants with BRCA2 mutations had a tumor response rate of 45%.

How much do PARP inhibitors cost?

According to a 2021 study, the median cost for a 30-day supply of PARP inhibitors was $13,342. That means the price was higher half the time and lower half the time. But the median out-of-pocket cost for people with commercial insurance was $44.

But costs may vary depending on your insurance coverage and where you live. It may be best to consult your doctor and insurance provider before committing to one brand or drug to get the most coverage and reduce your out-of-pocket expense.

Does Medicare cover PARP inhibitors?

Yes, Medicare should cover both olaparib and rucaparib. But it’s good to confirm with your doctor that your medical situation is fully covered.

You should also note that Medicare may not cover PARP inhibitors to the same extent as commercial insurers. The 2021 study cited above noted that the median out-of-pocket cost for PARP inhibitors was more than eight times higher ($370) for people on Medicare.

How do I join a clinical trial for PARP inhibitors for prostate cancer?

To join a clinical trial, consider speaking with your doctor or visiting the official clinical trials website.

PARP inhibitors for metastatic prostate cancer show promising results to extend the lifetime of someone with prostate cancer by increasing the period of time the condition can be managed. PARP inhibitors have a very significant benefit for people with BRCA or ATM mutations, but not as much of an effect in others.

The FDA has approved two medications — olaparib and rucaparib — that your insurance may cover. Other potential options are in the pipeline.

The use of this treatment may depend on your medical background and the severity of prostate cancer. While PARP inhibitors do not cure cancer, they can help you live a longer, happier, and more fulfilling life.