PARP therapy: Stopping cancer in those with BRCA gene mutations

Ovarian cancer that has spread to other parts of your body can be difficult to treat.

Once removed, cancer has a high chance of coming back within a few years.

But a decade ago, a new class of drugs went on the market that has allowed people with ovarian and other cancers to live longer, better lives. Here’s how PARP treatment works.

A crucial enzyme blocked in cancer cells

Poly (ADP-ribose) polymerase, or PARP, inhibitors are a family of chemotherapy drugs that target a particular protein in cancer cells that helps make those cells grow.

The DNA of cells in your body are constantly being damaged and repaired. That includes cancer cells.

PARP is an enzyme used in DNA repair, so, by blocking the PARP enzyme in cancer cells, PARP inhibitors keep cancer cells from repairing their DNA. That leads to cancer cells dying off.

Living longer with PARP treatment

PARP inhibitors have completely changed the landscape of treating advanced ovarian cancer.

Among patients with ovarian cancer treated with a PARP inhibitor, 67% on average live at least seven years after starting treatment. Many live much longer than that — some because their cancer never returns.

The first PARP inhibitor, olaparib, went on the market in 2014. Now, two others are approved to treat ovarian cancer: niraparib and rucaparib.

What types of cancers do you treat with PARP inhibitors?

PARP inhibitors are being used to treat these types of cancer:

• Breast
• Ovarian
• Prostate
• Pancreatic

How PARP inhibitors can help those with BRCA1 or BRCA2 mutations

PARP inhibitors work especially well for:

• people with cancerous cells containing gene mutations that prevent the repair of DNA
• people with an inherited mutation on a gene that puts them at much higher risk for cancer

That mutation may occur on the breast cancer gene 1 or 2, also known as BRCA1 or BRCA2.

If you have a mutation on either of the two BRCA genes, you’re at higher risk of getting not only breast cancer but also ovarian cancer and some other cancers, such as prostate cancer. That risk increases by anywhere from 5% to 40% over a lifetime. That’s 30 times more than someone who does not have a mutation on either of the BRCA genes.

Even if you don’t have either BRCA mutation, PARP inhibitors show a benefit in fighting off cancer.

When are PARP inhibitors prescribed?

PARP inhibitors are often prescribed to people as maintenance medications. They’ll take them to keep cancer from returning after their cancer has been treated using other medicines.

PARP inhibitors aren’t typically taken at the same time as other traditional chemotherapy medications. However, sometimes PARP inhibitors may be given at the same time as medicines that restrict blood supply to cancerous tumors.

PARP inhibitors typically are prescribed for two to three years to keep cancer from coming back. After no longer taking a PARP inhibitor, cancer may remain in remission.

If cancer returns, treatment will likely begin again, possibly with surgery and chemotherapy along with other therapies.

Side effects of PARP inhibitors

PARP inhibitors are taken as a pill once or twice a day. People tend to tolerate them well, but they may experience some side effects, including:

• low red blood cells (anemia)
• low white blood cells
• low platelets
• fatigue
• nausea
• headaches

Does Medicare cover PARP inhibitors?

Yes, Medicare covers PARP inhibitors and so do many other health insurance policies.

Over the past decade, we’ve seen a lot of success with PARP inhibitors. Patients we used to think were uncurable now witness their cancers go away and stay away. That’s encouraging to us and to the people we treat.