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Nerlynx (chemical name: neratinib) is a targeted therapy used to treat early-stage, HER2-positive breast cancer for an extended period of time after surgery (doctors calls this extended adjuvant therapy). You take Nerlynx within 2 years after you’ve had surgery and completed a chemotherapy regimen that included Herceptin (chemical name: trastuzumab).

Nerlynx is a pill taken by mouth. The recommended dose of Nerlynx is 240 mg (6 tablets) once per day with food for 1 year.

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How Nerlynx works

HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than HER2-negative breast cancers. Nerlynx is an irreversible pan-HER inhibitor. Nerlynx fights HER2-positive breast cancer by blocking the cancer cells’ ability to receive growth signals.

Nerlynx is a targeted therapy, but unlike Herceptin (chemical name: trastuzumab), Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine), and Perjeta (chemical name: pertuzumab), it is not an immune targeted therapy. Immune targeted therapies are versions of naturally occurring antibodies that work like antibodies made by our immune systems. Nerlynx is a chemical compound, not an antibody.

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Is Nerlynx right for you?

Four different tests can be used to figure out if the cancer is HER2-positive and if it will likely respond to Nerlynx:

IHC (ImmunoHistoChemistry)

IHC is the most commonly used test to see if a tumor has too much of the HER2 receptor protein on the surface of the cancer cells.

The IHC test gives a score of 0 to 3+ that measures the amount of HER2 receptor protein on the surface of cells in a breast cancer tissue sample. If the score is 0 to 1+, it’s called “HER2 negative.” If the score is 2+, it's called "borderline." A score of 3+ is called “HER2 positive.”

If the IHC test results are borderline, it’s likely that a FISH test will be done on a sample of the cancer tissue to determine if the cancer is HER2-positive.

FISH (Fluorescence In Situ Hybridization)

The FISH test also looks to see if the cancer is HER2-positive. This test is the most accurate, but it is more expensive and takes longer to return results. This is why an IHC test is usually the first test done to see if a cancer is HER2-positive. The FISH test shows how many copies of the HER2 gene are in tumor cells. The more copies of the gene, the more HER2 receptors the cells have.

With the FISH test, you get a score of either "positive" or "negative" (some hospitals call a negative test "zero"). If the cancer is FISH positive, it will probably respond well to Nerlynx.

SPoT-Light HER2 CISH (Subtraction Probe Technology Chromogenic In Situ Hybridization)

The SpoT-Light HER2 CISH test looks for how many copies of the HER2 gene are in the tumor cells of a breast cancer tissue sample. The SPoT-Light test is less complicated than the FISH or IHC tests.

With the SPoT-Light test, you get a score of either "positive" or "negative." If the cancer is SPoT-Light HER2-positive, it will probably respond well to Nerlynx.

Inform HER2 Dual ISH (In Situ Hybridization)

The Inform HER2 Dual ISH test uses a special stain that makes HER2 proteins change color. The test can be used on tissue samples that have been stored in wax or other chemicals. The Inform HER2 Dual ISH test offers more precise results than the IHC HER2 test. It is also less expensive and doesn’t need the special microscope of the FISH HER2 test.

With the Inform HER2 Dual ISH test, you get a score of either “HER2 positive” or “HER2 negative.”

Learn more in Breast Cancer Tests.

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What to expect when taking Nerlynx

If you take an antacid medicine, such as a proton pump inhibitor or an H2-receptor antagonist, you should wait 3 hours after taking the antacid to take Nerlynx. Prilosec, Prevacid, and Nexium are common proton pump inhibitors. Pepcid, Tagamet, and Zantac are common H2-receptor antagonists.

You should not take a type of medicine called a CYP3A inhibitor at the same time as Nerlynx because it increases the effects of Nerlynx. This class of medicines includes antifungal medicines such as Onmel (chemical name: itraconazole) and Biaxin (chemical name: clarithromycin), as well as antiretroviral drugs used to treat HIV such as Kaletra (chemical names: lopinavir and ritonavir).

You should not take a type of medicine called a CYP3A inducer at the same time as Nerlynx because it decreases the effects of Nerlynx. This class of medicines includes Rifamate (chemical name: rifampin), an antibiotic used to treat tuberculosis, and Carbatrol (chemical name: carbamazepine), which is used to control certain types of seizures in people with epilepsy.

You should not eat grapefruit or pomegranate or drink grapefruit juice or pomegranate juice, because they can increase the effects of Nerlynx.

Women who are pregnant or nursing or are planning to get pregnant should not take Nerlynx. Nerlynx can cause embryo death and birth defects. It’s important that you don’t get pregnant while you’re taking Nerlynx; you must use effective birth control.

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Paying for Nerlynx

If your doctor prescribes Nerlynx and you have problems paying for the medicine, the Nerlynx patient support program may be able to help you. Puma Biotechnology, the company that makes Nerlynx, has created a co-pay card for Nerlynx to help people pay for out-of-pocket costs associated with Nerlynx. To be eligible, you must have commercial insurance. For more information, visit the Nerlynx co-pay card webpage.

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Nerlynx side effects

Severe diarrhea soon after starting Nerlynx is a very common side effect. In the ExteNET trial, about 40% of the women treated with Nerlynx had severe diarrhea as a side effect.

The FDA approval recommends that loperamide (brand names include Imodium, Kaopectate 1-D, and Pepto Diarrhea Control) be given with Nerlynx for the first 56 days of treatment and then as needed to help manage diarrhea.

Other common side effects of Nerlynx are:

In rare cases, Nerlynx may cause serious liver problems. Tell your doctor right away if you have any of the following signs of liver problems:

  • yellowing of the skin or the whites of the eyes
  • dark or brown urine
  • feeling very tired
  • loss of appetite
  • pain on the upper right side of the abdomen
  • bleeding or bruising more easily than normal

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  1. Nerlynx (neratinib) prescribing information. Puma. Los Angeles, CA. 2018. Available at:

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