Among patients with HER2-positive, metastatic breast cancer that had progressed despite treatment with two or more forms of HER2-targeted therapy (trastuzumab [Herceptin] and lapatinib [Tykerb]), median overall survival was increased for those treated with ado-trastuzumab emtansine (aka T-DM1 [Kadcyla]) compared with those who received treatment of physician’s choice, according to results from the phase III TH3RESA clinical trial presented by Hans Wildiers, MD, PhD, Professor of Medical Oncology at KU Leuven in Belgium, and colleagues at the 2015 San Antonio Breast Cancer Symposium.1
“The National Comprehensive Cancer Network guidelines, which are widely used as the standard for cancer care, were recently changed to recommend using [ado-trastuzumab emtansine] as a preferred treatment for patients with trastuzumab-exposed HER2-positive, metastatic breast cancer, meaning that it is generally used after a patient’s metastatic disease has progressed following treatment with a combination of a taxane-based chemotherapy and trastuzumab, with or without pertuzumab (Perjeta),” said Dr. Wildiers.
“However, there are a lot of patients who received second- or later-line treatment before this recommendation was put in place, and TH3RESA was designed to establish whether [ado-trastuzumab emtansine] could benefit patients in later lines as well,” he added.
“Previously published results from TH3RESA showed that [ado-trastuzumab emtansine] almost doubled progression-free survival,” said Dr. Wildiers. “Here we show that [the drug] actually increased overall survival for heavily pretreated patients with HER2-positive, metastatic breast cancer. This is very important because several breast cancer therapies that increase progression-free survival do not increase overall survival, and these patients urgently need new treatment options.”
After a median follow-up of 30.5 months, the median overall survival was significantly longer among the 404 patients assigned to ado-trastuzumab emtansine compared with the 198 patients assigned to treatment of physician’s choice: 22.7 months compared with 15.8 months. The overall survival benefit was seen regardless of patient age, hormone-receptor status, visceral involvement, and number of prior treatment regimens.
“Not only did the population of patients assigned to [ado-trastuzumab emtansine] have increased median overall survival, they also had reduced incidence of grade 3 and higher adverse events,” said Dr. Wildiers. ■
Disclosure: This study was supported by Roche. Dr. Wildiers has received lecture fees from Roche, Pfizer, Novartis, Teva, and Baxter Belgium and travel expenses from Roche.
1. Wildiers H, et al: 2015 San Antonio Breast Cancer SymposiumAbstract. Abstract S5-05. Presented December 11, 2015.