Among women with advanced, previously treated, HER2-positive breast cancer, trastuzumab emtansine (T-DM1)-an investigational drug that combines Herceptin(r)
(trastuzumab) and a chemotherapy drug-resulted in better progression-free survival than standard treatment. The results of this Phase III clinical trial were presented at the 2012 Annual Meeting of the American Society of Clinical Oncology.
Approximately 20-25% of breast cancers overexpress (make too much of) the HER2 protein. HER2-targeted therapies such as Herceptin have dramatically improved outcomes for women with HER2-positive breast cancer, but researchers continue to explore new approaches to treatment.
T-DM1 links Herceptin with a chemotherapy drug (DM1). T-DM1 delivers Herceptin and DM1 directly to HER2-positive cells, and limits exposure of the rest of the body to the chemotherapy.
To evaluate T-DM1 for the treatment of advanced, HER2-positive breast cancer, researchers conducted a Phase III clinical trial known as EMILIA. The study enrolled close to 1000 women with locally advanced or metastatic HER2-positive breast cancer that had progressed (worsened) in spite of previous chemotherapy and Herceptin. Study participants were treated with either T-DM1 or a standard treatment. The standard treatment consisted of Xeloda(r) (capecitabine) plus
* Survival without cancer progression was 9.6 months among women in the
T-DM1 group and 6.4 months among women in the Xeloda and Tykerb group.
* Two-year overall survival was 65.4% among women in the T-DM1 group and
47.5% among women in the Xeloda and Tykerb group. The survival analysis is still considered preliminary and another analysis is planned for later in the study, and will provide more definitive information about the effect of T-DM1 on overall survival.
* Compared with women treated with Xeloda and Tykerb, women treated with
T-DM1 were less likely to experience side effects such as diarrhea, hand-foot syndrome, and vomiting. The most common serious side effects of T-DM1 were low platelet counts and changes in liver function tests.
These results suggest that T-DM1 may be safe and effective for the treatment of advanced, previously treated, HER2-positive breast cancer.