Ado-trastuzumab emtansine, known as Kadcyla or T-DM1, is an antibody-drug conjugate. It combines trastuzumab with a chemotherapy called DM1 and directly delivers the chemotherapy to HER2-positive cancer cells.

Ado-trastuzumab emtansine is used to treat some women with HER2-positive early breast cancer who have cancer remaining in their breast or lymph nodes after neoadjuvant therapy, or treatment that’s given before surgery.

Ado-trastuzumab emtansine is given through an IV into a vein every 3 weeks for 14 cycles.

Side effects may include nausea, fatigue, muscle and joint pain, constipation, neuropathy, low platelet counts and headache. It can also cause liver problems and in rare cases, heart problems, so these organs are monitored before and during treatment.

For more information, visit the HER2-Targeted Therapies page within the Treatment section of komen.org.

Ado-trastuzumab emtansine is also used to treat HER2-positive metastatic breast cancer. For more information, see the Living with Metastatic Breast Cancer chapter of this tool.