This trial compared treatment with trastuzumab (herceptin) in combination with docetaxel, to a new combination drug called trastuzumab emtansine.

Some breast cancer cells have certain receptors on their surface that respond to growth inducing molecules. These cancers are referred to as being human epidermal growth factor receptor type 2 positive (HER2+). HER2+ cancers are known to respond to a drug called trastuzumab (herceptin), which targets and blocks the action of these receptors. Trastuzumab is often used in combination with chemotherapy, especially in the case of advanced cancers. Docetaxel is an example of a commonly used chemotherapeutic drug.

Nowadays, a new form of trastuzumab is being developed. Trastuzumab emtansine (T-DM1), combines trastuzumab, and directly tied to it a chemotherapy drug called mertansine. When trastuzumab attaches to its target on breast cancer cells, the chemotherapeutic drug is delivered directly into the cancer cells. This could potentially reduce many of the side effects associated with chemotherapy and improve patient outcome.  

137 women with advanced HER2+ breast cancer were treated with either T-DM1 or with trastuzumab and docetaxel.

 Results showed that patients treated with T-DM1 had a longer period of time before their cancer progressed. Additionally, T-DM1 was showed to be safer, with only 46.4% of patients suffering severe adverse events. This compared to 90.4% of patients in the trastuzumab and docetaxel treatment group.

Overall this study shows trastuzumab emtansine (T-DM1) to be a safe and effective treatment option for HER2 positive breast cancer.

This trial is an early phase study (phase II), involving only a small group of patients. Additional research is still needed on this new treatment option.

Consult with your physician on recent advances in the treatment of HER2+ breast cancers.