Understanding HER2+ breast cancer

What is HER2-positive (HER2+) breast cancer?

All the cells in the body—healthy and cancerous—have HER2 receptors. But HER2+ breast cancer cells have too many HER2 receptors, which makes them grow and divide faster than other types of cells. This causes tumors to form.



How does my doctor know that my breast cancer is HER2+?

Your doctor will know that your breast cancer is HER2+ by ordering a HER2 test. This test should be done before any breast cancer treatment is started. PHESGO has been shown to work only in people with HER2+ breast cancer.

Early vs metastatic breast cancer

You might have been told you have early breast cancer or metastatic breast cancer. You may even have experience with both.

If you have early breast cancer, that means the cancer started in the breast and has not spread to other parts of the body. However, cancer cells may also be in nearby glands called lymph nodes.

Metastatic breast cancer means the cancer has spread to other parts of the body, such as the lungs, liver, or bones.

PHESGO can be used for both early and metastatic, but each has a different treatment plan.

You can explore what your treatment schedule might look like here:

What else should I know about HER2+ breast cancer?

Not all HER2+ breast cancers are the same. Before recommending a treatment plan for you, your healthcare team will consider a number of other factors about your particular cancer, as well as your personal medical history and condition. This is because some treatments are more appropriate for different patients. Here are some of the things your healthcare team will look at:

Your doctor will check if the cancer cells are also in the glands around or near the collarbone, near the breastbone, or in the armpits. These are called lymph nodes. If cancer cells are found in one or more lymph nodes, the cancer is said to be “node-positive” (node+).

Two hormones naturally made by the body are called estrogen and progesterone. These hormones attach to hormone receptors on cells. Some tumors have hormone receptors—they can have estrogen receptors, progesterone receptors, or both. This is called “hormone receptor-positive” breast cancer. “Hormone receptor-negative” breast cancer is when the cancer cells do not have hormone receptors.

The size of the tumor is how large it is at its widest point. The grade of the tumor is how different cancer cells look from healthy cells.

Tumor grades
Grade 1 Cells are growing more slowly and look more like normal breast tissue.
Grade 2 Cells look somewhat different from healthy breast tissue and are growing faster than in grade 1, but not as fast as in grade 3.
Grade 3 Cells look very different from normal tissue and will probably grow and spread more quickly.

Important Safety Information & Uses

What does PHESGO treat?

PHESGO® (pertuzumab, trastuzumab, and hyaluronidase-zzxf) is a prescription medicine approved for use in combination with chemotherapy for:

  • use prior to surgery (neoadjuvant treatment) in adults with HER2-positive, locally advanced, inflammatory, or early stage breast cancer (tumor is greater than 2 cm in diameter or node-positive). PHESGO should be used as part of a complete treatment regimen for early breast cancer. 
  • use after surgery (adjuvant treatment) in adults with HER2-positive early breast cancer that has a high likelihood of coming back.

PHESGO is a prescription medicine approved for use in combination with docetaxel in adults who have HER2-positive breast cancer that has spread to different parts of the body (metastatic) and who have not received anti-HER2 therapy or chemotherapy for metastatic breast cancer.

What are the most serious side effects of PHESGO?

PHESGO may cause heart problems, including those without symptoms (such as reduced heart function) and those with symptoms (such as congestive heart failure).

  • The risk for and seriousness of these heart problems are highest in people who received both PHESGO and a certain type of chemotherapy (anthracycline)
  • Your doctor will check for signs of heart problems before, during, and after treatment with PHESGO. Based on test results, your doctor may hold or discontinue treatment with PHESGO
  • Contact a healthcare professional immediately for any of the following: new onset or worsening shortness of breath, cough, swelling of the ankles/legs, swelling of the face, palpitations, weight gain of more than 5 pounds in 24 hours, dizziness or loss of consciousness

Receiving PHESGO during pregnancy can result in the death of an unborn baby and birth defects.

  • Birth control should be used while receiving PHESGO and for 7 months after your last dose of PHESGO. If you are a mother who is breastfeeding, you should talk with your doctor about either stopping breastfeeding or stopping PHESGO
  • If you think you may be pregnant, you should contact your healthcare provider immediately
  • If you are exposed to PHESGO during pregnancy, or become pregnant while receiving PHESGO or within 7 months following the last dose of PHESGO, you are encouraged to report PHESGO exposure to Genentech at 1-888-835-2555

PHESGO may cause serious lung problems.

  • Your doctor may check for signs of lung problems including:
    • Severe shortness of breath
    • Fluid in or around the lungs
    • Weakening of the valve between the heart and the lungs
    • Not enough oxygen in the body
    • Swelling of the lungs
    • Scarring of the lungs

Who should not receive PHESGO?

  • PHESGO should not be used in patients who are allergic to pertuzumab, trastuzumab, hyaluronidase, or to any of the ingredients in PHESGO

What are other possible serious side effects?

  • PHESGO may worsen low white blood cell counts caused by chemotherapy: Low white blood cell counts can be life threatening and were seen more often in patients receiving Herceptin® (trastuzumab) plus chemotherapy than in patients receiving chemotherapy alone. Your doctor may check for signs of low white blood cell counts when he or she examines you
  • PHESGO may cause administration-related reactions: PHESGO is given as an injection. The active ingredients in PHESGO have been associated with severe administration reactions, including hypersensitivity or anaphylaxis, which can be fatal. Talk to your doctor if you feel any symptoms. The most common symptoms include dizziness, nausea, chills, fever, vomiting, diarrhea, hives, swelling of the skin, breathing problems, or chest pain

What are the most common side effects?

The most common side effects of PHESGO when given with chemotherapy as part of an early breast cancer regimen are:

  • Hair Loss
  • Nausea
  • Diarrhea
  • Low levels of red blood cells
  • Weakness

The most common side effects of PHESGO when given with docetaxel for treatment of breast cancer that has spread to other parts of the body (metastatic) are:

  • Diarrhea
  • Hair loss
  • Low levels of white blood cells with or without fever
  • Nausea
  • Feeling tired
  • Rash
  • Damage to the nerves (numbness, tingling, pain in hands/feet)

What should I know about side effects with PHESGO?

  • Not all people have serious side effects; however, side effects with PHESGO therapy are common. It is important to know what side effects may happen and what symptoms you should watch for
  • Your doctor may stop treatment if serious side effects happen. Be sure to contact your healthcare team right away if you have questions or are worried about any side effects

You are encouraged to report side effects to Genentech and the FDA. You may report side effects to the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Genentech at 1-888-835-2555.

Talk to a healthcare professional for more information about the benefits and risks of PHESGO. 

Please see full Prescribing Information for additional Important Safety Information, including most serious side effects.

If you cannot afford your medication, visit phesgo.com/financial-support for financial assistance information.