Trastuzumab emtansine is an antibody-drug conjugate

Antibody-drug conjugate

Antibody-drug conjugates are a new type of targeted therapy, used for example for cancer. They consist of an antibody linked to a payload drug . Hence, they are a type of immunoconjugate and often an immunotoxin.The antibody causes the ADC to bind to the target cancer cells...

 consisting of the antibody trastuzumab

Trastuzumab

Trastuzumab is a monoclonal antibody that interferes with the HER2/neu receptor.The HER receptors are proteins that are embedded in the cell membrane and communicate molecular signals from outside the cell to inside the cell, and turn genes on and off...

 (Herceptin) linked to the cytotoxin mertansine

Mertansine

Mertansine is a cytotoxic agent also known as DM1. It is a maytansinoid .Its patent rights are owned by ImmunoGen Inc.- Uses :...

 (DM1).

It is in clinical trials for breast cancer

Breast cancer

Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

, especially of the HER2 positive type. Early results in Nov 2011 from an open-label phase II trial on 137 patients with HER2-positive advanced breast cancer were very encouraging.

It is starting multiple phase III trials for HER2-positive metastatic breast cancer:

• The EMILIA study will compare T-DM1 vs lapatinib
  Lapatinib
  Lapatinib , used in the form of lapatinib ditosylate, is an orally active drug for breast cancer and other solid tumours. It is a dual tyrosine kinase inhibitor which interrupts the HER2 growth receptor pathway. It is used in combination therapy for HER2-positive breast cancer...
  
   (Tykerb) plus capecitabine (Xeloda) in 980 patients;
• the MARIANNE study will compare docetaxel/trastuzumab vs T-DM1 vs T-DM1 plus pertuzumab
  Pertuzumab
  Pertuzumab is a monoclonal antibody. The first of its class in a line of agents called "HER dimerization inhibitors". By binding to HER2, it inhibits the dimerization of HER2 with other HER receptors, which is hypothesized to result in slowed tumor growth...
  
  ;
• the TH3RESA study is comparing T-DM1 vs best supportive care in the salvage setting.