Hercessi (Trastuzumab-Strf) for Breast Cancer

Hercessi (trastuzumab-strf) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with HER2-overexpressing breast cancer.

How Hercessi Works and How It’s Taken

Hercessi is a human epidermal growth factor receptor 2 (HER2) blocker. HER2 is a protein that can help some cancer cells grow. Some breast cancers have too much HER2.

Hercessi attaches to HER2. It can help slow the growth of cancer cells that have too much HER2. It may also help the body’s immune system attack these cancer cells.

In HER2-positive breast cancer, this kind of targeted therapy may help slow cancer growth by focusing on the HER2 protein.

Doctors prescribe Hercessi when adults have HER2-positive breast cancer in certain early-stage or metastatic settings. The exact use depends on the stage of cancer and prior treatment. Hercessi may be used:

After initial treatment for early-stage breast cancer, usually with chemotherapy or by itself after anthracycline-based treatment
With paclitaxel as the first treatment for breast cancer that has spread
By itself for breast cancer that has spread after one or more chemotherapy treatments

Hercessi is a biosimilar of Herceptin. This means it is made from living cells and is designed to work like the original medicine. The FDA requires biosimilars to have no meaningful differences in safety or how well they work.

Hercessi is given as an intravenous (IV) infusion. It is usually given weekly or once every three weeks, depending on the treatment plan and whether it is being used for early-stage or metastatic disease.

For early-stage breast cancer, treatment usually continues for a total of 52 weeks. For metastatic breast cancer, treatment usually continues until the cancer gets worse or side effects become unacceptable or intolerable.

Typical Dosing for Breast Cancer

For early-stage breast cancer, the recommended starting dose is usually 4 milligrams per kilogram by IV infusion, followed by 2 milligrams per kilogram weekly during chemotherapy. After that, the recommended maintenance dose is 6 milligrams per kilogram every three weeks. When used by itself after anthracycline-based treatment, the recommended starting dose is 8 milligrams per kilogram, followed by 6 milligrams per kilogram every three weeks.

For early-stage breast cancer, treatment usually continues for 52 weeks.

For metastatic breast cancer, the recommended starting dose is 4 milligrams per kilogram by IV infusion. After that, the recommended dose is 2 milligrams per kilogram once weekly. Treatment usually continues until the cancer gets worse or side effects become unacceptable.

Doctors may pause treatment, slow an infusion, or stop treatment if side effects are serious or hard to manage.

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

Hercessi Side Effects

In studies, the most common side effects of Hercessi differed by breast cancer setting.

For early breast cancer after initial treatment, the most common side effects, reported in 5 percent or more of people, were:

Headache
Diarrhea
Nausea
Chills

For breast cancer that has spread, the most common side effects, reported in 10 percent or more of people, were:

Fever
Chills
Headache
Infection
Congestive heart failure
Trouble sleeping
Cough
Rash

Serious Side Effects and Warnings

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

Heart problems — Hercessi can cause weakened heart function, heart failure, irregular heartbeat, high blood pressure, and rarely death.
Infusion reactions — Serious reactions during or within 24 hours after treatment can include trouble breathing, low blood pressure, and severe allergic reactions.
Lung problems — These can include interstitial pneumonitis, fluid around the lungs, low oxygen levels, acute respiratory distress syndrome, pulmonary fibrosis, and other severe breathing problems.
Embryo-fetal toxicity — This medicine can harm your baby if you are pregnant, including causing low amniotic fluid, lung and bone problems, or neonatal death.
Severe low white blood cell counts with chemotherapy — This can raise the risk of serious infection, including fever with low white blood cells.

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

How To Save on Hercessi

Accord BioPharma, the manufacturer of Hercessi, offers the AccordCares Co-Pay Program. Eligible people with commercial insurance may pay as little as $0 copay per Hercessi treatment. This program is not valid for people enrolled in state or federally funded insurance programs, including Medicare, Medicaid, TRICARE, Veterans Affairs healthcare, state prescription drug assistance programs, and some other government health plans.

The AccordCares Co-Pay Program also offers benefits investigation, prior authorization support, billing and coding information, and alternate funding referral. To learn more, visit the Hercessi patient support page or call 866-258-7151.

What To Know Before Taking Hercessi

Before starting Hercessi, your doctor will test or check for:

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 about all medications you take, including prescription drugs, over-the-counter medicines, and supplements.

Hercessi is also FDA-approved to treat gastric and gastroesophageal junction adenocarcinoma.

If you miss a dose by one week or less, it should usually be given as soon as possible. If you miss a dose by more than one week, your doctor should usually restart treatment with a re-loading dose.

Hercessi can harm your baby if you are pregnant. Your doctor should verify 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 Hercessi passes into human breast milk. Because Hercessi 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 Hercessi?

In studies of early breast cancer with too much HER2, adding trastuzumab to certain chemotherapy plans helped people live longer compared with chemotherapy alone.

After about eight years, the estimated survival rate was 86.9 percent with trastuzumab plus chemotherapy. It was 79.4 percent with chemotherapy alone.

In another study, people who received trastuzumab for one year had a lower chance of their cancer coming back, getting another cancer, or dying compared with people who were only observed after treatment. Taking trastuzumab for two years did not show added benefit compared with one year.

In a study of breast cancer that had spread, or metastatic breast cancer, adding trastuzumab to chemotherapy helped delay cancer growth. The median time before the cancer got worse was 7.2 months with trastuzumab plus chemotherapy. It was 4.5 months with chemotherapy alone.

People who received trastuzumab plus chemotherapy also lived longer in this study. Median overall survival was 25.1 months with trastuzumab plus chemotherapy and 20 months with chemotherapy alone.

What tests or monitoring are needed with Hercessi for breast cancer?

Heart function testing is needed before starting Hercessi and at regular intervals during treatment. Left ventricular ejection fraction should be checked before treatment, every three months during treatment, and when treatment is completed.

If Hercessi is held because of heart-related changes, testing is repeated every four weeks. For adjuvant breast cancer, heart monitoring continues every six months for at least two years after treatment ends. Pregnancy status should also be checked before starting treatment in females of reproductive potential.