Herceptin Hylecta (Trastuzumab/Hyaluronidase-Oysk) for Breast Cancer

Herceptin Hylecta (trastuzumab/hyaluronidase-oysk) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with HER2-overexpressing breast cancer.

How Herceptin Hylecta Works and How It’s Taken

Herceptin Hylecta is a type of targeted therapy called a human epidermal growth factor receptor 2 (HER2) blocker. HER2 is a protein found in high amounts on some cancer cells. Trastuzumab, one part of Herceptin Hylecta, attaches to HER2 and helps slow the growth of cancer cells that overexpress this protein.

It may also help the body’s immune system attack HER2-overexpressing cancer cells. The hyaluronidase part helps the medication move through tissue under the skin so it can be given as an injection.

Doctors prescribe Herceptin Hylecta when an adult with HER2-overexpressing breast cancer needs one of the following types of breast cancer treatment:

As part of a treatment plan for early-stage breast cancer with chemotherapy that includes doxorubicin, cyclophosphamide, and either paclitaxel or docetaxel.
With docetaxel and carboplatin for certain adults with early-stage breast cancer.
By itself after anthracycline-based chemotherapy for certain adults with early-stage breast cancer.
With paclitaxel as the first treatment for HER2-overexpressing metastatic breast cancer.
By itself for HER2-overexpressing metastatic breast cancer after one or more chemotherapy treatments.

The cancer must show HER2 protein overexpression or HER2 gene amplification using an FDA-authorized test.

Herceptin Hylecta is given as an injection under the skin by a healthcare professional, usually once every three weeks.

For early-stage breast cancer, treatment is usually given for a total of 52 weeks or until the cancer comes back, whichever happens first. Treatment beyond one year is not recommended.

For metastatic breast cancer, treatment continues until the cancer gets worse or side effects become unacceptable.

Typical Dosing for Breast Cancer

The recommended dose of Herceptin Hylecta for breast cancer is 600 milligrams of trastuzumab and 10,000 units of hyaluronidase, given subcutaneously (under the skin) over about 2 minutes to 5 minutes once every three weeks. No loading dose is required.

Doctors may pause or stop treatment if side effects are serious or too difficult to manage.

This information is based on the prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Herceptin Hylecta Side Effects

In clinical studies of Herceptin Hylecta for HER2-positive breast cancer in adults, the most common side effects differed between adjuvant and metastatic breast cancer. The side effects below were reported in at least 10 percent of people.

For adjuvant breast cancer, these side effects included:

Fatigue
Myalgia (muscle pain)
Arthralgia (joint pain)
Diarrhea
Injection-site reactions
Upper respiratory tract infection
Rash
Nausea
Edema (swelling)
Flushing (hot flashes)
Pyrexia (fever)
Cough
Pain in the arms or legs
Alopecia (hair loss)
Nail disorders
Vomiting
Stomatitis (mouth sores or mouth inflammation)
Abdominal pain (stomach pain)
Mucosal inflammation
Leukopenia (low white blood cell counts)
Anemia
Back pain
Peripheral neuropathy (numbness, tingling, or nerve pain in the hands or feet)
Incision-site pain
Decreased appetite
Headache

For metastatic breast cancer, these side effects included:

Fever
Chills
Headache
Infection
Congestive heart failure
Insomnia (trouble sleeping)
Cough
Rash

Serious Side Effects and Warnings

Herceptin Hylecta can cause serious side effects that may require immediate medical attention. These include:

Cardiomyopathy — Heart problems can include weakened heart function, heart failure, abnormal heart rhythm, high blood pressure, and cardiac death.
Pulmonary toxicity — Lung problems can include interstitial pneumonitis, pulmonary infiltrates, pleural effusions, noncardiogenic pulmonary edema, pulmonary insufficiency, hypoxia, acute respiratory distress syndrome, and pulmonary fibrosis.
Embryo-fetal toxicity — Exposure during pregnancy can cause low amniotic fluid, lung problems, skeletal abnormalities, and neonatal death.
Hypersensitivity and administration-related reactions — These can include anaphylaxis, angioedema, chest pain, breathing problems, chills, fever, nausea, vomiting, diarrhea, dizziness, and hives. They can be severe or life-threatening and may occur during or within 24 hours after treatment.
Exacerbation of chemotherapy-induced neutropenia — Severe low white blood cell counts can increase the risk of serious infection.

Get medical help right away if you think you are having a serious reaction.

How To Save on Herceptin Hylecta

Genentech, the manufacturer of Herceptin Hylecta, offers the Genentech Oncology Co-Pay Assistance Program. Eligible people with commercial insurance may pay as little as $0 per treatment for Herceptin Hylecta.

The program is not available to people whose prescriptions are reimbursed through Medicare, Medicaid, TRICARE, or other federal, state, or government-funded insurance programs.

The Herceptin Hylecta website also offers help understanding insurance coverage and out-of-pocket costs. Case managers may work with a person’s healthcare provider, health insurance plan, and specialty pharmacy to help them access their medication.

To learn more, visit the financial assistance page or call 888-249-4918.

What To Know Before Taking Herceptin Hylecta

Before starting Herceptin Hylecta, your doctor will check:

Your heart function, including left ventricular ejection fraction (LVEF)
Whether your tumor has HER2 protein overexpression or HER2 gene amplification
Pregnancy status, if you can become pregnant

Tell your doctor if you are allergic to trastuzumab/hyaluronidase-oysk.

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

If you miss a dose, it should be given as soon as possible. The time between doses should not be less than three weeks.

Herceptin Hylecta can harm your baby if you are pregnant. Your doctor should verify your pregnancy status before you start treatment. Females who can become pregnant should use effective birth control during treatment and for seven months after the last dose.

It is not known whether trastuzumab/hyaluronidase-oysk passes into human breast milk. Because Herceptin Hylecta may stay in the body after treatment ends, consider the seven-month washout period before breastfeeding.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Herceptin Hylecta?

In the HannaH study, 596 people with HER2-positive operable or locally advanced breast cancer were treated with either Herceptin Hylecta or intravenous trastuzumab. At surgery, no invasive cancer cells were found in the breast in 45.4 percent of people who received Herceptin Hylecta. This compared with 40.7 percent of people who received intravenous trastuzumab.

After more than 70 months of follow-up, event-free survival (the length of time people lived without their cancer getting worse, coming back, or causing death) and overall survival (the length of time people lived after starting treatment) were similar in the two groups.

In another study, SafeHER, 1,864 people with HER2-positive breast cancer received Herceptin Hylecta every three weeks for 18 cycles. No new safety concerns were found. In this study, 7 percent of people had a disease-free survival event, and 1.5 percent had an overall survival event.

How often is Herceptin Hylecta taken for breast cancer?

Herceptin Hylecta is given as an injection under the skin once every three weeks. The recommended dose is 600 milligrams of trastuzumab and 10,000 units of hyaluronidase. The injection is given over about 2 minutes to 5 minutes.

For adjuvant breast cancer, treatment continues for 52 weeks or until the cancer comes back, whichever happens first. Treatment beyond one year is not recommended. For metastatic breast cancer, treatment continues until the disease progresses.

Can Herceptin Hylecta for breast cancer cause flu-like symptoms or leg pain?

Yes. Common side effects reported in breast cancer studies included fever, chills, fatigue, myalgia, arthralgia, pain in an arm or leg, headache, cough, and upper respiratory tract infection.

Herceptin Hylecta can also cause administration-related reactions. These reactions may include dizziness, nausea, chills, fever, vomiting, diarrhea, breathing problems, or chest pain. Some reactions can be serious, including severe hypersensitivity reactions and anaphylaxis.

Contact your healthcare provider right away if you develop symptoms of a serious reaction after receiving Herceptin Hylecta.