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 may be used for treatment [4].

Learn about genetic testing to guide breast cancer treatment.

Learn more about BRCA1/2 inherited gene mutations.

Also, see animated videos from the NCCN on genetic testing for BRCA1/2 gene mutations, and tests done on the tumor for metastatic breast cancer treatment.

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 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.

Compared to chemotherapy alone, adding 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 spreads [46-47].


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.

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, it can cause acute myeloid leukemia.


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

In rare cases, it can cause acute myeloid leukemia.

Adapted from select sources [46-49].

Monitoring metastatic breast cancer

You’ll be monitored (checked) regularly with scans to see if the cancer is responding to treatment. If it’s no longer working, or if the side effects are not manageable, your health care provider will change your treatment.

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.

Consider joining a clinical trial when your oncologist is considering changing treatments, before starting a new treatment or when there are limited treatment options.

Susan G. Komen® Breast Care Helpline

If you or a loved one needs information or resources about clinical trials, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877- 465- 6636) or email

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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.

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

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.

Some drugs are off-patent and may have a generic form. Generic drugs cost less than the name brands but are just as effective.

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

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.

Funding is available for eligible individuals undergoing breast cancer treatment at any stage or living with metastatic breast cancer (stage IV).

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

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

Insurance coverage of oral cancer drugs

Cancer medications given by vein (through an IV) or 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 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.


  • If you or a loved one needs more information about breast health or breast cancer, contact the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email All calls are answered by a trained specialist or oncology social worker, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. Se habla español.
  • Komen Patient Navigators can help guide you through the health care system as you go through a breast cancer diagnosis. They can help to remove barriers to high-quality breast care. For example, they can help you with insurance, local resources, communication with health care providers and more. Call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email to learn more about our Patient Navigator program, including eligibility.
  • We offer an online support community through our closed Komen Metastatic Breast Cancer 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. Visit Facebook, search for Komen Metastatic Breast Cancer (Stage IV) Group and request to join the closed group.
  • 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 MBC and discover practical resources to help make decisions for improved physical and emotional health. To learn more and register visit
  • Our podcast series Real Pink covers many relevant topics for people living with metastatic breast cancer and caregivers.
  • Our fact sheets, booklets and other education materials offer additional information.

Komen Perspectives

Read our perspective on metastatic breast cancer.*

Learn More

*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.

Updated 07/07/22


Questions to Ask Your Doctor

Research Fast Facts