Ado-trastuzumab emtansine (Kadcyla) is the targeted therapy trastuzumab (Herceptin) with the chemotherapy medicine emtansine attached. It may also be called T-DM1.

Ado-trastuzumab emtansine is an antibody-drug conjugate, a treatment that pairs a chemotherapy medicine with a targeted therapy. The trastuzumab helps deliver the chemotherapy directly to the tumor cells. This helps limit the side effects of the chemotherapy on the healthy cells.

Who gets ado-trastuzumab emtansine

The FDA approved ado-trastuzumab emtansine for treatment of metastatic, HER2-positive breast cancer that has grown despite treatment with trastuzumab and taxane chemotherapy.

Ado-trastuzumab emtansine is also approved to treat early-stage, HER2-positive breast cancer. It is only given in early-stage breast cancer if a person has already been given trastuzumab and chemotherapy before surgery, and breast cancer was still found at the time of surgery.

How ado-trastuzumab emtansine works

Trastuzumab attaches to the HER2 protein, allowing the chemotherapy emtansine to enter the cancer cell. Once inside the cell, the emtansine becomes active and kills the cell. This way, ado-trastuzumab emtansine causes cancer cells to die, while leaving healthy cells unharmed.

How ado-trastuzumab emtansine is given

Ado-trastuzumab emtansine is given by vein once every 3 weeks. For metastatic breast cancer, treatment continues as long as it controls the cancer, or until severe side effects develop. For early-stage breast cancer, it is given for 14 cycles.

Side effects and things to remember

Common side effects of ado-trastuzumab emtansine include

Some people who take ado-trastuzumab emtansine develop a low white blood count, which may put you at risk for infection. Call your doctor right away if you show any symptoms of infection, such as a fever with chills.

If you have serious side effects, your doctor may stop treatment for a time or switch you to another treatment.

Before starting ado-trastuzumab emtansine, tell your doctor about any history of heart or lung problems as well as any medicines you are taking, including vitamins, herbal supplements and over-the-counter medicines. You should not become pregnant while taking ado-trastuzumab emtansine.

Your doctor, pharmacist or nurse can help you manage your side effects. You can also go to our section on Side Effects for more information.


Reviewed and updated: July 16, 2019

Reviewed by: Pallav K. Mehta, MD


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