Dr. Blackwell Discusses the T-DM1 EMILIA Trial Endpoints

Kimberly L. Blackwell, MD, professor of medicine and assistant professor of radiation oncology at Duke Cancer Institute at Duke University, discusses the coprimary endpoints of the phase III EMILIA trial that examined the antibody-drug conjugate TDM-1 (trastuzumab emtansine) for patients with HER2-positive locally advanced or metastatic breast cancer.

The trial randomized 978 patients with HER2-positive breast cancer 1:1 to receive either T-DM1 or the standard therapy of capecitabine (Xeloda) plus lapatinib (Tykerb). The trial had coprimary endpoints of both progression-free survival (PFS) and overall survival (OS).

The endpoint of PFS was improved by 3.2 months for patients receiving T-DM1 (hazard ratio [HR] = 0.650; P <.0001). However, despite demonstrating an increase in OS of 65.4% versus 47.5% in the control arm (HR = 0.621; P = .0005) the trial did not meet the OS endpoint.

Blackwell explains that the coprimary endpoints of this trial created a very high target P value for statistical significance. According to calculations, the P value needed to reach .0003 in order to be deemed statistically significant. A final analysis of OS will be conducted at a later time.