classesPARP Inhibitors

PARP Inhibitors: Uses, most common brand names, and safety information

Medically reviewed by Jamie Winn, PharmD

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There are more than 200 different types of cancer, and each is diagnosed and treated in a particular way. There are 17 million new cancer diagnoses each year worldwide, with an estimated 9.6 million cancer-related deaths occurring in 2018. While traditional chemotherapy is still recommended for many cancer patients, targeted cancer therapies are often associated with more favorable patient outcomes and fewer side effects. Poly-ADP ribose polymerase inhibitors (PARP inhibitors) are a class of targeted therapy medications used to treat certain types of cancer. PARP inhibitors block the DNA-repairing mechanism of PARP, which interferes with cancer cell replication and results in cell death. PARP inhibitors are used as single agents or as combination therapy to treat certain types of ovarian, prostate, breast, and pancreatic cancer. Here we will discuss in more depth the properties, brand names, pricing, and safety of PARP inhibitors.

The list below includes FDA-approved PARP inhibitors and their pricing:

List of PARP Inhibitors

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A fifth PARP inhibitor, Veliparib is currently undergoing clinical trials but is not yet approved for use in clinical practice.

What are PARP inhibitors?

PARP inhibitors are a type of treatment called targeted therapy. They target PARP1, PARP2, and PARP3 enzymes that help repair DNA damage. PARP1 is vital for the repair of DNA single-strand breaks. DNA can be damaged by many causes, including exposure to radiation, chemotherapy, or UV light. By blocking these enzymes, PARP inhibition stops cancer cells from repairing their DNA which results in the death of tumor cells. Although PARP inhibitors have side effects, these medications are often better tolerated than traditional chemotherapy.

What is the mechanism of action of PARP inhibitors?

PARP enzymes in your body help to repair single and double-strand DNA breaks. BRCA genes such as BRCA1 and BRCA2 also help with DNA repair through a separate repair pathway. In cancers where the BRCA gene does not work properly, damage to the cancer cells is only repaired by PARP. PARP inhibitors block the repair of damaged DNA by PARP, which causes the cancer cells to trigger their own death and stops the growth of the tumor.

What conditions are PARP inhibitors used to treat?

PARP inhibitors are approved by the U.S. Food and Drug Administration (FDA) as:

Maintenance treatment of BRCA-mutant ovarian, fallopian tube, or peritoneal cancer
Maintenance therapy of homologous recombination deficiency (HRD)-positive ovarian, fallopian tube, or peritoneal cancer in combination with Avastin (bevacizumab)
Maintenance treatment of recurrent advanced ovarian cancer, fallopian tube cancer, or primary peritoneal cancer
Inherited BRCA1 or BRCA2 mutation ovarian cancer
Germline BRCA-mutated HER2-negative metastatic breast cancer
Maintenance treatment of germline BRCA-mutated metastatic pancreatic cancer
Metastatic castration-resistant prostate cancer with BRCA or HRR gene mutations
Improve response rate and progression-free survival in women with recurrent platinum-sensitive ovarian cancer
In combination with chemotherapy in triple-negative breast cancer.

Are PARP inhibitors safe?

The use of PARP inhibitors is relatively safe and effective when taken as prescribed. Before beginning treatment with PARP inhibitors, tell your healthcare provider if you have any of the following:

Liver or kidney disease
Bleeding disorders
History of blood clots
Are pregnant, plan on becoming pregnant, or are breastfeeding
Lung disease
Heart problems such as high blood pressure

What are some common side effects of PARP inhibitors?

The adverse effects you experience from PARP inhibitors will depend on several factors including the medication and dose. Some common side effects of PARP inhibitors seen in clinical trials include:

Nausea
Vomiting
Diarrhea
Abdominal pain
Indigestion
Fatigue
Increased risk of sunburn (photosensitivity)
Anemia (low red blood cells)
Loss of appetite
Change in taste
Headache
Increased risk of infection
Rash
Fever
Shortness of breath
Edema (swelling)
Hair loss

PARP inhibitors can sometimes cause more serious side effects, including:

Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML)
Posterior reversible encephalopathy syndrome (seizure, headache, altered mental status, vision problems, or high blood pressure)
Pneumonitis (lung inflammation)
Increased risk of blood clots
Low platelet counts
Serious, life-threatening allergic reactions
Increased heart rate and blood pressure
Harm to your unborn baby

This is not a complete list of side effects and we encourage you to consult with your healthcare professional for medical advice about any possible side effects.

What are some contraindications of PARP inhibitors?

PARP inhibitors should be avoided if you have a known hypersensitivity to a PARP inhibitor or any of its inactive ingredients.

What are some drug interactions with PARP inhibitors?

The use of PARP inhibitors with certain foods or medications can affect how they work or increase the frequency and severity of side effects. Make sure your healthcare provider is aware of all the over-the-counter and prescription medications you are taking, including:

Grapefruit and Seville oranges as well as their juices
CYP3A4 enzyme inhibitors and inducers
CYP1A2, CYP3A, CYP2C9, or CYP2C19 enzyme substrates
P-gp and BCRP inhibitors

Is a PARP inhibitor a type of immunotherapy?

Poly-ADP ribose polymerase inhibitors (PARP inhibitors) are a type of targeted therapy. They target cancer cells and mostly avoid affecting healthy cells, which makes them safer to use than other treatment options.

How long can you stay on PARP inhibitors?

Studies have been conducted for up to 3 years with these medications but there aren’t any long-term safety data beyond the 3-year mark. Your doctor will determine how long you can stay on a PARP inhibitor.

Why do PARP inhibitors stop working?

A team of scientists from the Institute of Cancer Research in London identified DNA mutations that make cancer cells resistant to PARP inhibitors such as olaparib, which is marketed by AstraZeneca as Lynparza. Current approaches to overcome this resistance are combining PARP inhibitors with DNA-damaging medications (doxorubicin and carboplatin), immune-checkpoint inhibitors, or targeted therapies.

How much do PARP inhibitors cost?

PARP inhibitors are very expensive with an average cost of around $10,000 per year.

You can purchase PARP inhibitors for $49 per month from NiceRx if eligible for assistance. Prices at the pharmacy vary by location, strength, and quantity, as well as your insurance status.

Related resources for PARP inhibitors

The content on this website is intended for information purposes only. It does not constitute medical advice. The information on this website should not be relied upon and is not a substitute for professional medical advice. You should always speak to your doctor regarding the risks and benefits of any treatment.