PARP Inhibitors for Metastatic Breast Cancer

What are PARP inhibitors?

Olaparib (Lynparza) and talazoparib (Talzenna) are poly(ADP-ribose) polymerase (PARP) inhibitors.

PARP is an enzyme involved in DNA repair. Some chemotherapy drugs damage tumor DNA. PARP inhibitors work to stop PARP from repairing tumor DNA. This can help the chemotherapy kill the cancer cells.

The PARP inhibitors FDA-approved for metastatic breast cancer treatment are:

Drug name

Brand name

How is it given?







PARP inhibitors and BRCA1 and BRCA2 inherited gene mutations

PARP inhibitors are only used to treat breast cancers in people who have a BRCA1 or BRCA2 (BRCA1/2) inherited gene mutation.

BRCA1/2-related breast cancers have problems repairing tumor DNA. These breast cancers seem to be sensitive to DNA damage caused by PARP inhibitors. Treating BRCA1/2-related breast cancers with a PARP inhibitor makes it even harder for the breast cancer to repair itself, leading to tumor cell death.

The National Comprehensive Cancer Network (NCCN) recommends everyone diagnosed with metastatic breast cancer get BRCA1/2 genetic testing to see if a PARP inhibitor can be used for treatment [4]. This recommendation includes patients who don’t have a family history of breast cancer [4].

Learn about genetic testing to guide breast cancer treatment.

Learn more about BRCA1/2 inherited gene mutations.

PARP inhibitors and metastatic breast cancer treatment

Olaparib and talazoparib are used to treat HER2-negative metastatic breast cancer in people who have a BRCA1 and BRCA2 (BRCA1/2) inherited gene mutation and have been treated with chemotherapy at least once in the past (including chemotherapy for early breast cancer).

If the metastatic breast cancer is hormone receptor-positive, people should have also been treated with hormone therapy in the metastatic setting at least once in the past. (Hormone therapy is usually the first treatment for hormone receptor-positive metastatic breast cancer.)

Compared to chemotherapy alone, chemotherapy plus olaparib or talazoparib may give women with a BRCA1/2 inherited gene mutation who have HER2-negative metastatic breast cancer more time before the cancer worsens [57-59].


For a summary of research studies on PARP inhibitors and metastatic breast cancer treatment, visit the Breast Cancer Research Studies section.

Learn more about treatment for metastatic breast cancer.

Learn more about emerging areas in treatment for metastatic breast cancer.

Learn about the PARP inhibitor olaparib in the treatment of early breast cancer.

How are PARP inhibitors given?

The PARP inhibitors olaparib and talazoparib are pills.

Side effects of PARP inhibitors

Although they have side effects, PARP inhibitors are often easier to tolerate than chemotherapy drugs.

Before you begin taking olaparib or talazoparib, talk with your health care provider about possible side effects and how to manage them.

PARP Inhibitor

Side Effects


Possible side effects include anemia (low red blood cell counts), low white blood cell counts, nausea, vomiting and fatigue.

In rare cases, olaparib can cause acute myeloid leukemia.


Possible side effects include fatigue, anemia (low red blood cell counts), nausea, vomiting, headache and diarrhea.

In rare cases, talazoparib can cause acute myeloid leukemia.

Adapted from select sources [57-61].

Ashley Fernandez, living with metastatic breast cancer

“What keeps me going is my new normal. My life with cancer is completely different, I know I have it and I live with it every single day but it doesn’t take over every single day.”

Treatment guidelines for metastatic breast cancer

Although the exact treatment for metastatic breast cancer varies from person to person, guidelines help make sure high-quality care is given. These guidelines are based on the latest research and agreement among experts.

The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) are respected organizations that regularly review and update their guidelines.

In addition, the National Cancer Institute (NCI) has treatment overviews.

Talk with your health care team about which treatment guidelines they follow.

Monitoring metastatic breast cancer

You’ll be monitored (checked) regularly with scans to see if the cancer is responding to treatment. If the treatment is no longer working, or you’re having a lot of side effects, your health care provider will change your treatment or discuss other options.

Learn more about how metastatic breast cancer is monitored.

Clinical trials

Clinical trials offer the chance to try new treatments and possibly benefit from them.

Many clinical trials are available. Some are available as the first treatment for metastatic breast cancer. Others are for treatments later in the disease course. Consider joining a clinical trial when you’re newly diagnosed, when your oncologist is considering changing treatments or when there are limited treatment options.

Susan G. Komen® Patient Care Center

If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email

Se habla español.

Metastatic Trial Search

The Metastatic Trial Search is a web-based clinical trial matching tool that can help you find clinical trials that fit your needs. You can also register to receive Trial Alerts.

Learn more about clinical trials for people with metastatic breast cancer.

Learn what Komen is doing to help people find and participate in breast cancer clinical trials, including trials supported by Komen.

Prescription drug assistance

The cost of drug therapies for metastatic breast cancer can quickly become a financial burden for you and your family.

Medicare and many insurance companies offer prescription drug plans. One may already be included in your policy, or you may be able to buy an extra plan for prescriptions.

You may also qualify for programs that help with drug costs or offer low-cost or free prescriptions.

Many cancer centers have financial counselors who can discuss insurance and cost coverage with you.

Learn more about insurance plans and prescription drug assistance programs.

Learn more about other financial assistance programs.

Komen Financial Assistance Program

Susan G. Komen® created the Komen Financial Assistance Program to help those struggling with the costs of breast cancer treatment by providing financial assistance to eligible individuals.

To learn more about this program and other helpful resources, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email

Se habla español.

Susan G. Komen®‘s position on fairness in oral cancer drug coverage

Insurance coverage of oral cancer drugs

Cancer medications given through an IV into a vein or by an injection (under the skin or into a muscle) are usually covered under a health insurance plan’s medical benefit. However, cancer medications that are pills (oral cancer drugs) are usually covered under a health insurance plan’s prescription drug benefit.

As a result, people often find themselves facing high out-of-pocket costs when filling prescriptions for oral cancer drugs. Sometimes these costs can be thousands of dollars a month.

The impact of high cost-sharing

High prescription drug costs and the resulting out-of-pocket burden on patients are a barrier to care. They can prevent people from getting the medications prescribed by their health care providers.

No one should be forced to get less appropriate treatment because an insurer gives more coverage for IV and injectable drugs than for pills.

Efforts to increase fairness in drug coverage

Komen supports state and federal efforts to require insurers to provide the same or better coverage for oral cancer drugs as they do for IV and injectable cancer drugs. This would help make sure patients have access to affordable, appropriate treatment.

Become a Komen Advocacy Insider

Sign up to be a Komen Advocacy Insider and get informed when action is needed on drug coverage issues at the state or national level.


  • Do you need help with a metastatic breast cancer diagnosis? We’re here for you. The Komen Patient Care Center is your trusted, go-to source for timely, accurate breast health and breast cancer information, services and resources. Our navigators offer free, personalized support to patients, caregivers and family members, including education, emotional support, financial assistance, help accessing care and more. Get connected to a Komen navigator by contacting the Breast Care Helpline at 1-877-465-6636 or email to get started. All calls are answered Monday through Thursday, 9 a.m to 7 p.m. ET and Friday, 9 a.m. to 6 p.m. ET. Se habla español.
  • We offer an online support community through our closed Komen Metastatic Breast Cancer (Stage IV) Group. The Facebook group provides a place where those living with metastatic breast cancer, and those who love them, can find support, friendship and information. Click the link above or visit Facebook and search for Komen Metastatic Breast Cancer (Stage IV) Group and request to join.
  • Our free MBC Impact Series provides people living with metastatic breast cancer and their loved ones a safe, collaborative space to gather information related to metastatic breast cancer and discover practical resources to help make decisions for improved physical and emotional health. To learn more and register visit
  • Our Real Pink podcast series covers many relevant topics for people living with metastatic breast cancer and caregivers.
  • Our fact sheets, booklets and other education materials offer additional information.

Updated 03/24/24


Questions to Ask Your Doctor

Research Fast Facts