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Ontruzant (trastuzumab-dttb) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with breast cancer.
Ontruzant is a human epidermal growth receptor 2 (HER2) targeted medicine. It attaches to HER2, a protein found on some cancer cells. This helps slow the growth of HER2-positive cancer cells and may also help the immune system find and attack them.
In breast cancer, this may help reduce abnormal cancer cell growth.
Ontruzant is a biosimilar of Herceptin (trastuzumab). 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.
Doctors prescribe Ontruzant to treat certain adults with HER2-positive breast cancer. The exact use depends on the stage of cancer and whether it is used with chemotherapy or by itself. Ontruzant may be used:
Ontruzant is given as an intravenous (IV) infusion. It is usually given weekly or once every three weeks, depending on the treatment plan.
For early-stage breast cancer, treatment usually continues for a total of 52 weeks. For breast cancer that has spread, treatment usually continues until the cancer gets worse or side effects become unacceptable or intolerable.
For early-stage breast cancer given with paclitaxel, docetaxel, or docetaxel and carboplatin, the recommended starting dose is 4 milligrams per kilogram by intravenous infusion, followed by 2 milligrams per kilogram once weekly. After the weekly part of treatment, the recommended maintenance dose is 6 milligrams per kilogram every three weeks. When used by itself after anthracycline-based chemotherapy, the recommended starting dose is 8 milligrams per kilogram, followed by 6 milligrams per kilogram every three weeks.
Treatment usually continues for a total of 52 weeks.
For breast cancer that has spread, the recommended starting dose is 4 milligrams per kilogram by intravenous infusion, followed by 2 milligrams per kilogram once weekly. Treatment usually continues until the cancer gets worse or side effects become unacceptable.
Doctors may slow an infusion, pause treatment, delay the next dose, or stop treatment if side effects are serious or too hard to manage.
This information is based on the prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.
In clinical trials of Ontruzant for breast cancer, the most common side effects differed between adjuvant breast cancer and metastatic breast cancer.
For adjuvant breast cancer, side effects reported in at least 5 percent of people include:
For metastatic breast cancer, side effects reported in at least 10 percent of people include:
Ontruzant can cause serious side effects that may require immediate medical attention. These include:
Get medical help right away if you think you are having a serious reaction.
The Ontruzant website offers support through the Organon Access Program. The program may be able to answer questions about insurance coverage, copay assistance for eligible privately insured people, eligibility determination, and out-of-pocket costs.
You can call 866-809-9515 to speak with a representative or visit the Organon Access Program.
Before starting Ontruzant, your doctor will test or check for:
Tell your doctor about all medications you take, including prescription drugs, over-the-counter medicines, and supplements.
Ontruzant 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, and your next dose will be scheduled based on your regular timing. If you miss a dose by more than one week, your doctor may need to restart treatment with a higher, re-loading dose.
Ontruzant can harm your baby if used during pregnancy. 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 Ontruzant passes into human breast milk. Because Ontruzant may stay in the body after treatment ends, consider the seven-month washout period before breastfeeding.
These answers are fact-checked by our editorial staff.
How effective is Ontruzant?
The Ontruzant prescribing information includes study results for trastuzumab treatment in HER2-positive breast cancer.
In early breast cancer, people who received trastuzumab-based treatment lived longer without the cancer coming back or getting worse compared with people who did not receive trastuzumab. In one large analysis, survival after 8.3 years was estimated to be 86.9 percent with trastuzumab-based treatment and 79.4 percent without it.
In breast cancer that had spread, people who received trastuzumab plus chemotherapy lived longer before the cancer got worse. The median time before the cancer got worse was 7.2 months with trastuzumab plus chemotherapy and 4.5 months with chemotherapy alone. Median overall survival was 25.1 months versus 20.3 months.
What tests or monitoring are needed with Ontruzant for breast cancer?
Left ventricular ejection fraction (LVEF), a measure of heart function, should be checked before starting Ontruzant and at regular intervals during treatment. During adjuvant treatment, heart function is measured every three months during treatment and at completion, then 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.
On MyBCTeam, people share their experiences with breast cancer, get advice, and find support from others who understand.
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