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Perjeta (chemical name: pertuzumab) used in combination with Herceptin (chemical name: trastuzumab), another targeted therapy medicine, and Taxotere (chemical name: docetaxel), a type of chemotherapy, to treat HER2-positive, metastatic breast cancer that hasn’t been treated with either Herceptin or chemotherapy yet. Perjeta was called Omnitarg in earlier studies.

Perjeta also is approved:

  • to be used in combination with Herceptin and Taxotere before surgery to treat HER2-positive, early-stage (the cancer must be larger than 2 cm or cancer must be in the lymph nodes), inflammatory, or locally advanced-stage breast cancer with a high risk of metastasizing or becoming fatal
  • to be used in combination with Herceptin and chemotherapy after surgery to treat HER2-positive, early-stage breast cancer with a high risk of recurrence

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How Perjeta works

Cancer cells grow in an uncontrolled fashion. Perjeta works on the surface of the cancer cell by blocking the chemical signals that can stimulate this uncontrolled growth.

Genes are like instruction manuals that tell each cell of our body how to grow, what kind of cell to become, and how to behave. Genes do this by ordering the cell to make special proteins that cause a certain activity — such as cell growth, rest, or repair.

Some cancer cells have abnormalities in genes that tell the cell how much and how fast to grow. Sometimes the cancer cells have too many copies of these genes with abnormalities. When there are too many copies of these genes, doctors refer to it as "overexpression." With some forms of gene overexpression, cancer cells will make too many of the proteins that control cell growth and division, causing the cancer to grow and spread.

Some breast cancer cells make (overexpress) too many copies of a particular gene known as HER2. The HER2 gene makes a protein known as a HER2 receptor. HER2 receptors are like ears, or antennae, on the surface of all cells. These HER2 receptors receive signals that stimulate the cell to grow and multiply. But breast cancer cells with too many HER2 receptors can pick up too many growth signals and so start growing and multiplying too much and too fast. Breast cancer cells that overexpress the HER2 gene are said to be HER2-positive.

Like Herceptin, Perjeta is a HER2 inhibitor targeted therapy that works by attaching itself to the HER2 receptors on the surface of breast cancer cells and blocking them from receiving growth signals. Perjeta targets a different area on the HER2 receptor than Herceptin does, so it’s believed to work in a way that is complementary to Herceptin. By blocking the signals, Perjeta can slow or stop the growth of the breast cancer. Perjeta and Herceptin are examples of immune targeted therapy.

In addition to blocking HER2 receptors, Perjeta can also help fight breast cancer by alerting the immune system to destroy cancer cells onto which it is attached.

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Is Perjeta 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 Perjeta:

  • 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 indicates the amount of HER2 receptor protein in tumors. If the tumor scores 0 to 1+, it's called "HER2 negative." If it scores 2+ or 3+, it's called "HER2 positive."

    Women with IHC positive scores tend to respond favorably to Perjeta. The drug is not considered effective for tumors with IHC scores of 0 or 1+.

    It's important to note that results on the IHC test may vary from lab to lab, and that some labs are more proficient at HER2 testing than others. Discuss with your doctor whether you might want to get a FISH test, especially if you have a 1+ or 2+ result from IHC. That way you can get another measure of whether the tumor might respond well to Perjeta.

    The IHC test results are most reliable for fresh or frozen tissue samples. IHC tends to be an unreliable way to test tissue that's preserved in wax or other chemicals. FISH testing is the preferred way to assess preserved tissue samples.
  • FISH (Fluorescence In Situ Hybridization)

    The FISH test looks for the HER2 gene abnormality. This test is the most accurate, but less available, way to find out if a breast tumor is likely to respond to Perjeta. 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 Perjeta.
  • 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. The SPoT-Light test can be used on fresh tissue samples or tissue samples that have been stored in wax or other chemicals, but it doesn't work on frozen tissue samples.

    With the SPoT-Light test, you get a score of either "positive" or "negative." If the cancer is SPoT-Light positive, it will probably respond well to Perjeta.
  • 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 about Breast Cancer Tests.

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What to expect when taking Perjeta

Perjeta is prescribed with Herceptin, another targeted therapy medicine, and chemotherapy. All these medicines are given intravenously, which means they’re delivered directly into your bloodstream through an IV or a port.

The first dose of Perjeta is the largest and takes about an hour to complete. After that, it takes 30 to 60 minutes to get Perjeta, which is usually given every 3 weeks in a doctor’s office. Most people get Perjeta every 3 weeks for 18 to 25 months.

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

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Paying for Perjeta

If your doctor prescribes Perjeta and you have any problems getting it covered by insurance or don’t have insurance, you can get in touch with Access Solutions, sponsored by Genentech (the maker of Perjeta). Access Solutions can help investigate your insurance coverage benefits, appeal denied claims, and provide other assistance. You also can call Access Solutions at 1-866-422-2377.

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Perjeta side effects

The most common side effects of Perjeta are:

Because Perjeta is likely to be given with Herceptin, it’s important to know that problems with heart function or developing heart failure can sometimes be side effects of Herceptin. While research has found that adding Perjeta to Herceptin doesn’t increase the risk of heart problems, your doctor will likely want to test your heart function before and during treatment with Perjeta, Herceptin, and chemotherapy.

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  1. Perjeta (pertuzumab) prescribing information. Genentech. San Francisco, CA. 2018. Available at:

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