HER2-Positive Metastatic Breast Cancer
Resources, expertise, and survivor support to help you after a diagnosis

Breast cancer classified as HER2-positive tends to exhibit faster growth, increased likelihood of spreading (metastasis), and a higher chance of recurrence. Despite its aggressive nature, HER2-positive cancer responds well to treatments that specifically target HER2 proteins.

There are no distinct symptoms or specific risk factors associated with HER2-positive breast cancer, although research indicates that this type of cancer may be more prevalent among younger women.

There are a few basic things you can do to help manage the process when you first learn of your cancer diagnosis. Dr. Heather Yeo, a colorectal surgeon at Weill Cornell and an advisor to SurvivorNet, has these tips for patients:

• Have someone come with you to the doctor

It is important to bring a close friend or family member not only to support you, but also to help you understand and digest all the information.

• Take notes

Writing down what you hear can help you focus and create a record of the information so you can refer to it later on.

• Don’t be afraid to get a second opinion

Your doctor won’t be offended if you get a second opinion. It is extremely important to go through the process with a doctor you trust — and make sure you’re getting the best care possible with a doctor you feel comfortable with.

“How am I going to get through this?” It is often one of the first questions a person will ask after a cancer diagnosis.

“My advice is to take one day at a time,” says Dr. Susan Parsons, Director of Survivorship Care at Tufts University, “and be kind to yourself.”

Survivors also tells us it’s key to ask for the support you need — both mentally and physically. There is life after cancer so the goal is to keep hopeful and strong, and cut yourself some slack.

“What would you do if someone in your family got cancer?” We put that question to some of the most renowned cancer doctors in the country.

National Cancer Institute Chief of Surgery Dr. Steven Rosenberg recommends seeking out multiple professional opinions to confirm a diagnosis and figure out the options.

Highly respected doctors sometimes disagree on the right course of treatment, and advances in genetics and immunotherapy are creating new options.

With advanced breast cancer in particular, doctors may have differing opinions on how to proceed with treatment.

Although there will always be limitations on how much time a doctor can spend with any given patient, the doctor-patient relationship is extremely important after a cancer diagnosis.

You’ll want to make sure you are working with a doctor you trust, who will respect your opinion and keep you informed about all of the treatment options for your particular diagnosis.

Dr. Nina Shah, a hematologist at UCSF Medical Center, stressed the importance of patients feeling comfortable enough to voice concerns to their doctors.

“It’s on us to make sure that we are emotionally available to the patients, and as available as we can be with our time, although there are always limitations there,” Dr. Shah explained.

Part of the doctor-patient relationship involves the patient feeling seen and heard — and advocating for themselves where they see fit.

Several other factors must be taken into consideration to determine the best treatment approach such as your performance status, patient preferences, past medical history, receptor status of your tumor, tumor mutational burden, germline mutations, previous therapies tried, and the extent of your cancer. All of these help to drive the shared decision making between you and your oncologist.

Tremendous progress has been made in the treatment of HER2 positive breast cancers and now patients have many more options than they did even a decade ago.

“The good news is that there are a lot of new treatments available that target the HER2 receptor,” Dr. Comen explained.

These include Herceptin and Pertuzumab (brand name Perjeta), which can be used together with chemotherapy and are usually used as front line treatments. That means it will be the first treatment you receive.

Enhertu (Fam-trastuzumab deruxtecan-nxki) is another drug that may be used if patients progress through first line therapy. Another drug that used is T-DM1 (brand name Kadcyla), which is used if you have already been treated with Herceptin.

Lastly, another exciting new drug available called Tucatinib (brand name Tukysa), is now available for women who have not responded to Herceptin or Pertuzumab (brand name Perjeta). This is an oral drug that targets HER2 and is typically used in conjunction with chemotherapy and Herceptin. Other drugs such as lapatinib and neratinib function in a similar manner and are typically combined with chemotherapy or other HER2 directed treatments.

Below is a summary of the major drugs utilized for metastatic HER2-positive breast cancer, how they function, and their potential side effects.

HERCEPTIN for HER2-positive breast cancer

Herceptin is used as part of first line as well as subsequent lines of treatment for patients with HER2-positive metastatic breast cancer. It is typically used with other HER2 directed therapies like Perjeta or the oral agents such as lapatinib as well as chemotherapy. It forms the backbone of many treatment regimens and has firmly established itself in the treatment of this disease.

How Herceptin works

1. Targeting HER2: Herceptin works by binding to the HER2 receptors on the surface of cancer cells, blocking the signals that promote their growth.
2. Immune System Activation: It also stimulates the immune system to attack and destroy the cancer cells.

Possible side effects 

Side Effects: While Herceptin is effective, it may cause certain side effects. Common side effects include:

1. Infusion Reactions: Patients may experience fever, chills, nausea, and headache during or after the infusion.
2. Cardiotoxicity: Herceptin can affect the heart, leading to reduced heart function. Regular monitoring of cardiac function is essential.
3. Fatigue: Feeling tired or weak is a common side effect.
4. Diarrhea and Nausea: Gastrointestinal symptoms such as diarrhea and nausea may occur.
5. Pain: Some patients may experience muscle or joint pain.
6. Infections: There is an increased risk of infections, as Herceptin can affect the immune system.

ENHERTU for HER2-positive breast cancer

ENHERTU is a targeted cancer therapy used in the treatment of certain types of breast cancer. The generic name for ENHERTU is trastuzumab deruxtecan. It is an antibody-drug conjugate designed to deliver chemotherapy directly to cancer cells that overexpress the human epidermal growth factor receptor 2 (HER2).

How ENHERTU works

1. Antibody Binding: ENHERTU consists of an antibody that specifically targets the HER2 receptor on the surface of cancer cells.
2. Drug Delivery: Attached to the antibody is a potent chemotherapy drug. Once the antibody binds to the HER2 receptor, it is internalized by the cancer cell, releasing the chemotherapy payload directly into the cell.
3. Cell Destruction: The chemotherapy drug induces cell death, targeting and destroying the cancer cells.

Possible Side Effects:

ENHERTU, like any medication, can cause side effects. Common side effects may include:

1. Nausea and Vomiting: Gastrointestinal symptoms, such as nausea and vomiting, may occur.
2. Fatigue: Patients may experience fatigue or weakness.
3. Decreased Appetite: Some individuals may have a reduced appetite.
4. Hair Loss: Hair loss or thinning may be observed.
5. Low Blood Cell Counts: ENHERTU can affect blood cell counts, leading to a risk of anemia, neutropenia, and thrombocytopenia.
6. Interstitial Lung Disease (ILD): ILD is a potential serious side effect, and patients should be monitored for respiratory symptoms such as cough or difficulty breathing.

Kadcyla for HER2-positive breast cancer

The drug can be used to treat HER2-positive breast cancer that has spread to other parts of the body (metastatic breast cancer) after prior treatment with trastuzumab (Herceptin®) and a taxane.

Prior treatment could have been for the initial treatment of breast cancer or for the treatment of cancer that had spread to other parts of the body.

How Kadcyla works

It attaches to a HER2 receptor: it’s designed to find HER2+ cells and attach to them. It tells the cells to stop growing and tells the body’s immune system to destroy them.

Goes inside the cell: it also goes inside the cell to keep fighting from the inside.

Breaks apart inside the cell: kadcyla releases the chemotherapy inside the cell.

Works to help kill the cell: The chemotherapy goes to work inside the cell, causing the cell to die.

Possible side effects

The most common side effects in people taking kadcyla for breast cancer are tiredness, nausea, liver problems, pain that affects the bones, muscles, ligaments, and tendons, bleeding, low platelet count, headache, weakness, numbness, and pain in the hands and feet, and joint pain.

It can cause severe liver problems that can be life-threatening. It also may cause heart problems, including those without symptoms (such as reduced heart function) and those with symptoms (such as congestive heart failure). Receiving kadcyla during pregnancy can result in the death of an unborn baby and birth defects.

Other possible serious side effects include:

• Lung problems
• Infusion-related reactions
• Serious bleeding
• Low platelet count
• Nerve damage
• Skin reactions around the infusion site

Perjeta for HER2-positive breast cancer

Perjeta is given with another targeted treatment called Herceptin. Both treatments are designed to fight cancer cells that have too many HER2 receptors, but in different ways.

Perjeta is thought to block one of the methods of signaling so that certain receptors are unable to pair with HER2. These drugs work on different parts of the HER2 receptor, so they work together to build a stronger blockade.

A goal of metastatic breast cancer treatment is to help control cancer growth.

Perjeta and Herceptin-based therapy may be an appropriate option for people with HER2+ metastatic breast cancer that has spread to other parts of the body and has NOT been treated with traditional chemotherapy or HER2-targeted treatments before.

Tukysa for HER2-positive breast cancer

Tukysa is a targeted (biological) therapy. Targeted therapies interfere with processes in cells that help cancer grow.

It is is a tyrosine kinase inhibitor. Tyrosine kinases are enzymes that help control how cells grow and divide, among other functions. If the enzyme is too active or if a cell has too much of the enzyme, it can make cells grow uncontrollably.

Tukysa blocks a specific area of the HER2 gene in cancer cells, which stops the cells from growing and spreading.

Who is eligible?

You may be offered Tukysa if you have HER2 positive breast cancer that has spread to another part of the body or cannot be removed by surgery.

It’s given to people who have already had two or more other treatments specifically for HER2 positive breast cancer.

How it works

Tukysa helps control how cells grow and divide. It blocks the HER2 protein in the cancer cells, which stops the cells from growing and spreading.

How is it given?

Tukysa is taken by mouth as a tablet twice a day, every day. It can be taken with or without food.

It is taken in combination with trastuzumab (Herceptin) and capecitabine.

On the days you take capecitabine, you can take it at the same time as tucatinib.

Possible side effects

Like any treatment, Tukysa can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be managed and those described here will not affect everyone.

It is given together with capecitabine and trastuzumab, so you may have side effects from those treatments too.

Some possible side effects include:

• Severe diarrhea, which can cause dehydration, low blood pressure, and severe kidney problems.
• Liver problems, including elevated liver enzymes.
• Nausea, vomiting and upset stomach
• Feeling tired (Fatigue)
• Mouth sores
• Decreased appetite
• Headache
• Anemia
• Rash

Common side effects for patients receiving chemotherapy include but are not limited to hair loss, low blood counts, diarrhea, nausea, fatigue, and cough.

There are a lot of myths about how chemotherapy impacts people’s lives. It’s sometimes assumed that while undergoing chemotherapy you’ll be restricted to your home, and unable to move around but this is certainly not the case in many situations, Dr. Marleen Meyers, an oncologist at NYU Perlmutter Cancer Center, told SurvivorNet.

Many people can continue to work through treatment and Dr. Meyers encourages her patients to exercise, even if it’s just a walk. It can make a huge difference when dealing with fatigue, a common side effect of chemotherapy.

There are also treatments to help with the side effects of chemotherapy. Many medications are available for treating nausea and vomiting as well as anemia.

For some people, scalp-cooling devices may be able to help prevent hair loss. For others, hair loss may be inevitable — and that can lead to a lot of anxiety.

While many survivors embrace their temporary looks, others really struggle with the idea of people seeing them without hair. For women especially, hair is often very much a part of identity.

There are plenty of options available, including some created by cancer survivors, to help keep you comfortable during this time — including wigs, head wraps, and hats.

Many people going through cancer treatment feel a sense of dread associated with the thought of losing their hair.

Such a drastic physical change may lead to anxiety and sleepless nights.

Patients can speak to their caregivers to see if any interventions are possible, and should also look into products that are specifically made for people dealing with temporary hair loss — like wigs, head wraps, and more.

Talking about these anxieties can help, but it’s also OK to say so if you are not comfortable discussing it, Psychiatrist Dr. Samantha Boardman stressed.