HER2-positive breast cancer: Biomarker analysis identified women most likely to benefit from T-DM1

For women with metastatic, HER2-positive breast cancer, the amount of HER2 on their tumor might determine how much they benefit from a drug called trastuzumab emtansine (T-DM1), according to data from a subanalysis of the phase III clinical trial that led the U.S. Food and Drug Administration to approve the drug on Feb. 22, 2013.