ONTRUZANT® (trastuzumab-dttb) for Injection, for Intravenous Use 21 mg/mL


Get to know your medicine and how it may help you fight your type of breast cancer.

ONTRUZANT is a biological biosimilar prescription medicine that can help you fight your breast cancer. Your doctor chose it for you because it treats the type of cancer you have: HER2-positive (HER2+) breast cancer. ONTRUZANT is called a biosimilar because it is a biological medicine that is highly similar to another drug called Herceptin (trastuzumab).

How is it thought to work?

  • ONTRUZANT is a targeted therapy designed to interrupt tumor cell growth in HER2+ breast cancer
  • ONTRUZANT may stop the HER2 receptors from signaling cancer cells to grow
  • ONTRUZANT may also be able to identify tumor cells to be destroyed by the immune system
  • Normal cells can have HER2, so HER2-targeted therapies can also affect normal cells and can cause side effects, including possible serious side effects.
ONTRUZANT® (trastuzumab-dttb) Is a Targeted Therapy Designed to Interrupt Tumor Cell Growth in HER2+ Breast Cancer HER2 receptors

Biological medicines are made from a living cell

ONTRUZANT is a biosimilar of Herceptin

ONTRUZANT is an FDA-approved biosimilar of Herceptin for the treatment of HER2+ breast cancer.

ONTRUZANT and Herceptin both

  • Work the same way in the body
  • Have the same dosage
  • Are given the same way

Similar in effectiveness and safety
This means you can expect similar treatment benefits from ONTRUZANT, and similar potential side effects, as you would from Herceptin.

What should I know about Herceptin?
Herceptin has been used to treat HER2+ breast cancer for over 20 years. It has been studied in more than 10,000 women with HER2+ breast cancer.
What is a biosimilar?
A biosimilar is a type of biological medicine. Biosimilars are approved by the US Food and Drug Administration, or FDA, as being highly similar to an already approved biological medicine. Thus the name "biosimilar." ONTRUZANT is an FDA-approved biosimilar of the drug Herceptin.
Are biosimilars like generic medicines?
No, they are not. Biosimilars are made from living cells and are more complex than generics, which are made from a simpler chemical process. Therefore, the approval standards for biosimilars and generics are different, but each has its own set of rigorous standards that it needs to meet.
What makes breast cancer HER2+?
HER2 receptors are proteins found on the surfaces of cells. In a healthy breast cell, HER2 receptors send signals telling cells to grow and divide. However, HER2-positive breast cancer cells have a higher-than-normal number of HER2 receptors. Having too many HER2 receptors may make the cancer grow and divide faster.
Are there patient support groups for me?
Emotional support, education, and information sharing are important throughout your journey. There is a range of support groups for patients with breast cancer and their families. Ask your doctor for a recommendation on the support group best suited for you.


ONTRUZANT treatment can result in heart problems. Serious and sometimes fatal events have occurred. Some patients have had serious and fatal infusion reactions and lung problems. Symptoms usually occur during or within 24 hours of administration. ONTRUZANT can cause harm to an unborn baby, in some cases death of the unborn baby, when taken by a pregnant woman. ONTRUZANT treatment may lead to a worsening of low white blood cell count.