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Generic name: ado-trastuzumab emtansineAY-doe-tras-TOOZ-ue-mab-em-TAN-seen ]
Drug class: HER2 inhibitors

Medically reviewed by Judith Stewart, BPharm. Last updated on Apr 22, 2024.

What is Kadcyla?

Kadcyla is a cancer medicine that interferes with the growth and spread of cancer cells in the body.

Kadcyla is used to treat HER2-positive breast cancer.

Kadcyla is used both for early breast cancer and for breast cancer that has spread to other parts of the body (metastatic).

Kadcyla is usually given after other cancer medications have been tried without success.

Kadcyla should not be used in place of Herceptin (trastuzumab).


Do not use Kadcyla if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.

You may need to have a negative pregnancy test before starting this treatment.

Kadcyla can harm your liver. Call your doctor at once if you have upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Before you receive each Kadcyla injection, your heart function may need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

Before taking this medicine

You should not use Kadcyla if you are allergic to ado-trastuzumab emtansine.

Do not use Kadcyla if you are pregnant. It could harm the unborn baby or cause birth defects. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 7 months after your last dose.

Tell your doctor if you become pregnant during treatment.

To make sure Kadcyla is safe for you, tell your doctor if you have ever had:

You should not breast-feed while using this medicine.

How is Kadcyla given?

Kadcyla is given as an infusion into a vein. A healthcare provider will give you this injection.

This medicine must be given slowly, and the infusion can take 30 to 90 minutes to complete.

Tell your caregivers if you feel any burning, pain, or swelling around the IV needle when Kadcyla is injected.

Kadcyla is usually given once every 3 weeks. Your doctor will determine how long to treat you.

You may need frequent medical tests to be sure this medicine is not causing harmful effects. Your cancer treatments may be delayed based on the results.

Dosing information

Usual Adult Dose for Breast Cancer:

3.6 mg/kg IV every 3 weeks (21-day cycle) until disease progression or unacceptable toxicity
Maximum dose: 3.6 mg/kg IV every 3 weeks

-Administer the first infusion over 90 minutes. Subsequent infusions may be administered over 30 minutes as tolerated.
-Observe patients during and for at least 90 minutes following the initial dose for fever, chills, or other infusion-related reactions.
-Patients should have a HER2 positive tumor status confirmed prior to starting therapy.
-Do not substitute trastuzumab emtansine for or with trastuzumab.
-If a planned dose is delayed or missed, it should be administered as soon as possible; do not wait until the next planned cycle.

Use: As a single agent, for HER2-positive, metastatic breast cancer in patients who previously received trastuzumab and a taxane, separately or in combination; patients should have either:
-Received prior therapy for metastatic disease
-Developed disease recurrence during or within 6 months of completing adjuvant therapy

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your Kadcyla injection.

What happens if I overdose?

Since this medication is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

What to avoid

Avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

Ado-trastuzumab emtansine can pass into body fluids (urine, feces, vomit). For at least 48 hours after you receive a dose, avoid allowing your body fluids to come into contact with your hands or other surfaces. Caregivers should wear rubber gloves while cleaning up a patient's body fluids, handling contaminated trash or laundry or changing diapers. Wash hands before and after removing gloves. Wash soiled clothing and linens separately from other laundry.

Kadcyla side effects

Get emergency medical help if you have signs of an allergic reaction to Kadcyla: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your caregiver right away if you feel cold, light-headed, feverish or sweaty, or have chest tightness, rapid heartbeats, or trouble breathing.

Call your doctor at once if you have:

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common Kadcyla side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Kadcyla?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Other drugs may interact with ado-trastuzumab emtansine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Popular FAQ

In the DESTINY-Breast03 study in people with HER2-positive metastatic breast cancer, treatment with Enhertu lengthened the amount of time people lived without their cancer getting worse (called progression free survival) by 72% when compared to another HER2 inhibitor treatment called Kadcyla. Continue reading

Monoclonal antibodies (mAbs) are man-made proteins that mimic the natural antibodies produced by our immune systems. Monoclonal antibodies can be formulated into medicines to treat various types of illnesses, such as cancer, rheumatoid arthritis or psoriasis. Continue reading

T-DM1 chemotherapy refers to treatment with Kadcyla, which is a targeted treatment that may be used to treat HER2-positive breast cancer in women who meet certain criteria. The chemical name for Kadcyla is T-DM1 (also called ado-trastuzumab emtansine) and it is a combination of two medicines: trastuzumab which is a targeted treatment and DM1 which is a cytotoxic agent (also known as mertansine). Trastuzumab targets HER2-expressing breast cancer cells and delivers DM1 directly to them. Continue reading

For HER2+ early-stage breast cancer, Kadcyla is given as an intravenous (IV) injection every 3 weeks for a total of 14 cycles. For HER2+ metastatic breast cancer that has spread, Kadcyla is given once every 3 weeks on an ongoing basis. In both cases, you may need to stop treatment if the cancer returns or the side effects are intolerable. Continue reading

Kadcyla is made up of two cancer-fighting medicines: a HER2-targeted drug treatment and a chemotherapy drug. It is used for the treatment of patients with HER2+ breast cancer. When you receive Kadcyla, you are getting both medications at the same time. Continue reading

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Kadcyla only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.