Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine), a targeted therapy medicine, was approved by the U.S. Food and Drug Administration (FDA) on Feb. 22, 2013 to treat HER2-positive metastatic breast cancer that has previously been treated with Herceptin (chemical name: trastuzumab) and a taxane chemotherapy.
Kadcyla is a combination of Herceptin and the chemotherapy medicine emtansine. In Kadcyla, the emtansine is attached to the Herceptin.
In earlier studies on Kadcyla, it was reported that the chemotherapy medicine maytansine was attached to Herceptin to form Kadcyla. 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.
Kadcyla 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.
The FDA approval of Kadcyla is based on results from the EMILIA study, which showed that women diagnosed with HER2-positive metastatic breast cancer that had stopped responding to a standard targeted therapy regimen lived longer with or without the cancer growing (overall survival) when they got Kadcyla compared to women who got a different targeted therapy regimen. The women who got Kadcyla also lived longer without the cancer growing (progression-free survival) compared to women who got the other regimen.
The EMILIA study looked at 991 women diagnosed with either metastatic or locally advanced HER2-positive breast cancer that had stopped responding to a standard treatment regimen of Herceptin and a taxane chemotherapy. Paclitaxel (brand name: Taxol), albumin-bound or nab-paclitaxel (brand name: Abraxane), and docetaxel (brand name: Taxotere) are taxanes. Locally advanced breast cancer is cancer that has spread to the chest wall below or the skin above the breast.
The women were randomly assigned to receive one of two treatment regimens:
- half the women got a combination of the targeted therapy Tykerb (chemical name: lapatinib) and the chemotherapy Xeloda (chemical name: capecitabine); this combination already is approved to treat advanced-stage HER2-positive breast cancer that has stopped responding to Herceptin
- half the women got Kadcyla
Half the women were followed for more than a year and the other half were followed for shorter times.
Overall survival – the time the women lived with or without the cancer growing – was 5.8 months longer for women treated with Kadcyla compared to women treated with Tykerb and Xeloda.
Progression-free survival – the time the women lived without the cancer growing – was about 3 months longer for women treated with Kadcyla compared to women treated with Tykerb and Xeloda.
Kadcyla can cause side effects, some of them severe. The most common severe side effects reported in the EMILIA study were:
- low platelet count (14.5% of women)
- higher liver enzyme levels (8% of women)
- low red blood cell count (4.1% of women)
- low potassium levels (2.7% of women)
- nerve problems (2.2% of women)
- tiredness/fatigue (2.5% of women)
According to Genentech, the company that makes Kadcyla, the medicine will be available to people in the United States within 2 weeks.
If you’re being treated for HER2-positive metastatic breast cancer that has stopped responding to a standard targeted therapy regimen, you and your doctor may be considering other treatment options. You may want to ask your doctor about Kadcyla and whether it might be a good treatment option for you based on your unique situation.