My Life with HER2 Low Metastatic Breast Cancer

“Now that I understand my treatment plan and how it may affect my day-to-day life, I was able to take this trip,” Lisa said. “This vacation meant so much to us and it’s important that I share my story and what I’ve learned along the way to get me to this point.”

An avid skier and cyclist, Lisa has always enjoyed an active lifestyle, career and social life, but acknowledged that after her initial mBC diagnosis in 2015, she was overwhelmed. Determined to understand her specific type of metastatic breast cancer and available treatment options, Lisa decided to meet this new challenge with a positive mindset. “Since my diagnosis, I have extensively researched treatments, maintained a spreadsheet on the latest clinical trials and interviewed different oncologists to gather as much information on available treatment options as I can,” Lisa said.

With guidance from her care and support teams, Lisa completed a biomarker test. The results indicated the presence of HER2, which was a turning point in her treatment journey. “When I was first diagnosed with mBC, my actual breast cancer subtype – HER2 low – was not yet known,” Lisa explained. “In those early days, after my first-line chemotherapy was unsuccessful, I’d come to accept that I would go through a series of trial-and-error treatment regimens, hoping to find one that worked to delay my cancer from progressing.”

Lisa learned that HER2, or human epidermal growth factor receptor 2, is a protein that tells cells to grow and when cells produce too much HER2, they can become cancerous.¹ These HER2-expressing breast cancers can be more difficult to treat and spread to other parts of the body more quickly than breast cancers that are HER2 negative.^2,3 Until 2022, HER2-expressing breast cancers were categorized as either HER2 positive or HER2 negative.⁴ Since then, research indicates that more than half of patients previously diagnosed as HER2 negative can be categorized as HER2 low or have low levels of HER2 expression. This means that certain patients with HER2-low mBC might also benefit from targeted treatment that they may not have been eligible for previously.⁴

Lisa also learned that HER2 status can change over time,^5,6 which makes biomarker testing critical at diagnosis and if the disease has spread or no longer responds to treatment.^1,7 “Biomarker testing helped determine that my type of breast cancer has lower levels of HER2, and once we knew that, my oncologist suggested ENHERTU,” Lisa said.

In August 2022, ENHERTU^® (fam-trastuzumab deruxtecan-nxki) was approved by the FDA as the first and only treatment for adults who have HER2 low breast cancer that cannot be removed by surgery or that has spread to other parts of the body (metastatic), and who have received prior chemotherapy or had their cancer return during or within six months of completing adjuvant chemotherapy (after surgery).⁸ The approval was based on the DESTINY-Breast04 Phase 3 trial, the first study to show a survival benefit from a HER2 targeted therapy for people living with HER2 low mBC.^8,9

ENHERTU can cause serious side effects, including lung problems that may be severe, life threatening, or that may lead to death; low white blood cell count; heart problems that may affect your heart’s ability to pump blood; or harm to an unborn baby. Your healthcare provider will check you for these side effects during your treatment with ENHERTU. Please see Important Safety Information below.

“It’s game-changing to know that there is now treatment for people with HER2 low mBC which can potentially make a difference in the management of their disease. Had I not explored biomarker testing, I may not have known this option,” Lisa said.

She credits the strong partnership she has with her oncologist and her amazing network of friends who have backgrounds in healthcare for helping her navigate treatment and discover ENHERTU. She believes it’s important to pay it forward. “I learned the importance of becoming educated and advocating for myself, and so many people helped me get to where I am with knowledge, education and support,” Lisa explained. “Not everyone has access to the kinds of medical information I’ve been fortunate to have, so helping others with breast cancer navigate their road ahead and hopefully avoid pitfalls is important to me.”

Lisa’s advice for others living with mBC is to find an oncologist who you’re comfortable building a long-term relationship with. Learn about your mBC subtype, and if you have a HER2 subtype, talk to your doctor about your level of HER2 expression, because it could help inform treatment decisions. Stay in close communication with your healthcare team about the evolving treatment landscape and how it may apply to your mBC care. “I’m grateful for treatment options like ENHERTU,” Lisa said. “I live with metastatic breast cancer. It’s in me and that’s not going to change, but I’m optimistic. In many ways, this experience has taught me to be more present throughout the journey. H.O.P.E.: Hang on, Possibilities Emerge.”

To learn more about HER2 low mBC and ENHERTU, visit www.ENHERTU.com. Also see Important Safety Information below.

Important Safety Information

What is the most important information I should know about ENHERTU?

ENHERTU can cause serious side effects, including:

Lung problems that may be severe, life-threatening or that may lead to death. If you develop lung problems your healthcare provider may treat you with corticosteroid medicines. Tell your healthcare provider right away if you get any of the following signs and symptoms:

• Cough
• Trouble breathing or shortness of breath
• Fever
• Other new or worsening breathing symptoms (such as chest tightness, wheezing)

Low white blood cell count (neutropenia). Low white blood cell counts are common with ENHERTU and can sometimes be severe. Your healthcare provider will check your white blood cell counts before starting ENHERTU and before starting each dose. Tell your healthcare provider right away if you develop any signs or symptoms of an infection or have fever or chills during treatment with ENHERTU.

Heart problems that may affect your heart’s ability to pump blood. Your healthcare provider will check your heart function before starting treatment with ENHERTU. Tell your healthcare provider right away if you get any of the following signs and symptoms:

• New or worsening shortness of breath
• Coughing
• Feeling tired
• Swelling of your ankles or legs
• Irregular heartbeat
• Sudden weight gain
• Dizziness or feeling light-headed
• Loss of consciousness

Your healthcare provider will check you for these side effects during your treatment with ENHERTU. Your healthcare provider may reduce your dose, delay treatment or completely stop treatment with ENHERTU if you have severe side effects.

Harm to your unborn baby. Tell your healthcare provider right away if you become pregnant or think you might be pregnant during treatment with ENHERTU.

• If you are able to become pregnant, your healthcare provider should do a pregnancy test before you start treatment with ENHERTU.
• Females who are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 7 months after the last dose.
• Males who have female partners that are able to become pregnant should use effective birth control (contraception) during treatment with ENHERTU and for 4 months after the last dose.

Before you receive ENHERTU, tell your healthcare provider about all of your medical conditions, including if you:

• Have lung or breathing problems.
• Have signs or symptoms of an infection.
• Have or have had any heart problems.
• Are breastfeeding or plan to breastfeed. It is not known if ENHERTU passes into your breast milk.
• Do not breastfeed during treatment with ENHERTU and for 7 months after the last dose.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

How will I receive ENHERTU?

• You will receive ENHERTU into your vein through an intravenous (IV) line by your healthcare provider.
• ENHERTU is given 1 time every three weeks (21-day treatment cycle).
• Your healthcare provider will decide how many treatments you need.
• Your healthcare provider will give you medicines before your infusion to help prevent nausea and vomiting.
• Your healthcare provider may slow down or temporarily stop your infusion of ENHERTU if you have an infusion-related reaction, or permanently stop ENHERTU if you have severe infusion reactions.
• If you miss a planned dose of ENHERTU, call your healthcare provider right away to schedule an appointment. Do not wait until the next planned treatment cycle.

What are the possible side effects of ENHERTU?

ENHERTU can cause serious side effects. See “What is the most important information I should know about ENHERTU?”

The most common side effects of ENHERTU when used at the 5.4 mg/kg dose include:

• Nausea
• Low white blood cell counts
• Low red blood cell counts
• Feeling tired
• Low platelet counts
• Increased liver function tests
• Vomiting
• Hair loss
• Constipation
• Decreased appetite
• Low levels of blood potassium
• Diarrhea
• Muscle or bone pain
• Stomach-area pain

ENHERTU may cause fertility problems in males, which may affect the ability to father children. Talk to your healthcare provider if you have concerns about fertility.

These are not all of the possible side effects of ENHERTU. Call your doctor for medical advice about side effects. You may report side effects to Daiichi Sankyo at 1-877-437-7763 or to FDA at 1-800-FDA-1088.

What is ENHERTU?

ENHERTU is a prescription medicine used to treat adults who have:

• HER2-low breast cancer that cannot be removed by surgery or that has spread to other parts of your body (metastatic), and who have received a prior chemotherapy:
  • for metastatic disease, or
  • your disease has returned during or within 6 months of completing adjuvant chemotherapy (after surgery). Your healthcare provider will perform a test to make sure ENHERTU is right for you.

It is not known if ENHERTU is safe and effective in children.

Please see full Prescribing Information, including Boxed WARNINGS, and Medication Guide.

References:

1. American Cancer Society. Biomarker Tests and Cancer Treatment. Accessed September 2024.
2. American Cancer Society. Breast Cancer HER2 Status. Accessed September 2024.
3. Tapia M, et al. Cancers. 2023;15(18):4522.
4. Tarantino P, et al. J Clin Oncol. 2020;38(17):1951-1962.
5. Bergeron A, et al. Nature. 2023;129:122-134.
6. Breastcancer.org. Breast Cancer’s Hormone Receptor and HER2 Status Can Change After Diagnosis. Accessed September 2024.
7. Robertson S, et al. Breast Cancer Res Treat. 2019;174(3):795-805.
8. ENHERTU Prescribing Information.
9. Modi S, et al. N Engl J Med. 2022;387:9-20.

ENHERTU® is a registered trademark of Daiichi Sankyo Company, Limited.                                                                  ©2024 Daiichi Sankyo, Inc. and AstraZeneca.                                                                                                                                PP-US-ENB-3643 10/24

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