TDM-1 Better Than Trastuzumab in HER2-, HR-Positive Breast Cancer

“Results from a phase II trial showed that neoadjuvant TDM-1 is effective in treating HER2-positive, hormone receptor (HR)-positive breast cancer, with or without endocrine therapy, in comparison with trastuzumab and endocrine therapy. Results of the study (abstract 506) were presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting held May 29 to June 2 in Chicago.

“The WSG-ADAPT trial is an umbrella trial that included around 5,000 patients. This sub-study of that trial included patients with HER2-positive, HR-positive early breast cancer; it enrolled 376 patients at 48 sites, and this interim analysis included 130 of those patients. The trial has been closed early because efficacy was reached.

“The patients were randomized to receive either TDM-1 monotherapy (37 patients), TDM-1 with endocrine therapy (48 patients), or trastuzumab with endocrine therapy (45 patients). ‘This was not a low-risk population,’ said study presenter Nadia Harbeck, MD, PhD, of the University of Munich, noting that over half of the patients were premenopausal and about half had tumors that were larger than 2 cm.”