Neratinib

Neratinib (Nerlynx) is a targeted therapy for people with HER2-positive breast cancer.

It is the first medicine for people with HER2-positive breast cancer approved as extended therapy, meaning that for early-stage disease, it is given after primary treatment ends to lower the risk of cancer coming back.

In metastatic, HER2-positive breast cancer, neratinib is approved for use with the chemotherapy pill capecitabine (Xeloda) if the cancer grew despite treatment with at least two previous lines of treatment with targeted therapies such as trastuzumab (Herceptin or biosimilar), pertuzumab (Perjeta), and ado-trastuzumab emtansine (Kadcyla).

How neratinib works

Neratinib is a tyrosine kinase inhibitor or TKI. Certain proteins, called tyrosine kinases, tell breast cancer cells to multiply. Neratinib blocks these proteins from working to help keep cancer from growing.

Who gets neratinib

People who have completed treatment for early-stage, HER2-positive early-stage breast cancer with trastuzumab and are at high risk of the cancer returning may be given neratinib.

People with metastatic, HER2-positive breast cancer may be given neratinib with capecitabine if they have already received at least two lines of treatment. Those previous treatments must include other HER2-targeted therapies, such as trastuzumab, pertuzumab, or ado-trastuzumab emtansine.

How neratinib is given

Neratinib is taken as a pill. The recommended dose is six tablets taken at the same time, once per day, for 1 year. It should be taken with food and at about the same time every day.

For metastatic breast cancer, neratinib is given with capecitabine. Capecitabine is also a pill and is taken twice daily for 14 days, followed by a 7 day break. You continue to take neratinib every day even during a break in the capecitabine cycle.

If you take antacids (Tums, Alka-Seltzer, Pepto-Bismol, Milk of Magnesia, for example), do not take any for 3 hours before or 3 hours after taking neratinib. Do not eat grapefruit or foods with grapefruit in them, or drink grapefruit juice while taking neratinib. Eating or drinking grapefruit and its juice can make neratinib build up in your blood, leading to worse side effects.

Always tell your doctor about any other medicines or supplements you’re taking, to make sure they won’t impact how well neratinib works.

Side effects and things to remember

Diarrhea is the most common side effect of neratinib, with 90 percent of people in the ExteNET study reporting it.

Your doctor will likely recommend loperamide (Imodium or its generics) when you start treatment to control the diarrhea. Talk with your doctor about when to take loperamide. He or she will give you a specific schedule to follow.

Other common side effects are:

• stomach pain
• heartburn
• bloating
• mouth sores
• loss of appetite
• weight loss
• nose bleeds
• nail problems or changes
• muscle spasms

Neratinib may harm a fetus, so use safe birth control while taking it to prevent pregnancy. If you’re already pregnant do not start taking neratinib, and talk to your doctor about your treatment options.

If you plan to become pregnant after treatment, wait at least 1 month after your last dose of neratinib before trying to become pregnant. After 1 month the medicine is no longer present in your body.

Do not breastfeed while taking neratinib, and wait at least 1 month after your last dose of neratinib to start breastfeeding.