The U.S. Food and Drug Administration (FDA) has granted priority review to T-DM1, an experimental targeted therapy medicine, to treat HER2-positive, metastatic breast cancer.
T-DM1 is a combination of the targeted therapy medicine Herceptin (chemical name: trastuzumab) and the chemotherapy medicine emtansine. In T-DM1, the emtansine is attached to the Herceptin.
(In some early studies on T-DM1, it was reported that the chemotherapy medicine maytansine was attached to Herceptin to form T-DM1. Emtansine is a derivative of maytansine.)
Herceptin is approved by the FDA to treat advanced-stage, HER2-positive breast cancers and to lower the risk of recurrence of early-stage, HER2-positive breast cancer with a high risk of recurrence. HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals.
Emtansine, like some other chemotherapy medicines, disrupts the way cells grow. Emtansine isn’t a targeted medicine, which means it can affect healthy cells as well as cancer cells.
T-DM1 was designed to deliver emtansine to cancer cells in a targeted way by attaching emtansine to Herceptin. Herceptin then carries emtansine to the HER2-positive cancer cells.
Metastatic breast cancer is breast cancer that has spread to other parts of the body away from the breast, such as the bones or liver.
Research has shown that women diagnosed with HER2-positive, metastatic breast cancer that had stopped responding to a standard targeted therapy regimen:
- lived longer without the cancer growing (progression free survival)
- lived longer whether or not the cancer grew (overall survival)
when they got T-DM1 compared to women who got a different targeted therapy regimen.
Priority review means that the FDA will review the approval application for T-DM1 within 6 months. According to Genentech, the company that makes T-DM1, the FDA action date is Feb. 26, 2013.
Stay tuned to Breastcancer.org for updates on the approval process for T-DM1.