Trastuzumab Emtansine Improves Overall Survival in HER2-positive Breast Cancer

Trastuzumab emtansine improves overall survival compared with physician’s choice of therapy among patients with HER2-positive breast cancer, according to an article published in The Lancet Oncology.¹

The phase 3 TH3RESA study (ClinicalTrials.gov Identifier: NCT01419197) previously showed a progression-free survival benefit with trastuzumab emtansine among patients with previously treated, HER2-positive advanced disease. In this paper the authors published the overall survival results of TH3RESA.

Of 972 patients assessed for eligibility, 602 were randomly assigned 2:1 to receive trastuzumab emtansine (404 patients) or physician’s choice of therapy (198 patients).

The median ages in the physician’s choice group and trastuzumab emtansine group were 54 and 53, respectively; the median number of previous treatments was 4 in both groups. Crossover was allowed.

By data cutoff, nearly half of patients in the physician’s choice group crossed over to the trastuzumab emtansine group. Despite crossover, median overall survival in the trastuzumab emtansine group was 22.7 months vs 15.8 months in the physician’s choice group.

Forty percent of patients who received trastuzumab emtansine had a grade 3 or worse adverse event; there were 3 treatment-related deaths. In the physician’s choice group 47% of patients had a grade 3 or worse adverse event and there was 1 treatment-related death.

The authors concluded that trastuzumab emtansine is an effective treatment for patients with HER2-positive breast cancer despite previous treatment regimens. They noted that these results have “profound implications for drug development in HER2-positive metastatic breast cancer, suggesting that other drugs targeting HER2 might provide patients with additional clinical benefit.”

Reference

1. Krop IE, Kim SB, Martin AG, et al. Trastuzumab emtansine versus treatment of physician’s choice in patients with previously treated HER2-positive metastatic breast cancer (TH3RESA): final overall survival results from a randomised open-label phase 3 trial. Lancet Oncol. 2017 May 16. doi: 10.1016/S1470-2045(17)30313-3 [Epub ahead of print]