Phase III Trial Investigates Atezolizumab in Triple-Negative Breast Cancer
An ongoing phase III study—IMpassion 131 (ClinicalTrials.gov identifier NCT03125902)—is testing the safety and efficacy of atezolizumab plus paclitaxel versus placebo in patients with inoperable locally advanced or metastatic triple-negative breast cancer. Study details were presented at the 2017 San Antonio Breast Cancer Symposium (SABCS; Abstract OT1-01-01).
Lead author, David Miles, MBBS, BSc, MD, FRCP, of the Mount Vernon Cancer Centre in Northwood, UK, and colleagues chose to target triple-negative breast cancer because its high programmed cell death ligand 1 (PD-L1) expression may effectively demonstrate whether atezolizumab is successful in restoring antitumor immunity. This global, multicenter, double-blind study builds upon the progress made in IMpassion 130.
Investigators plan to randomize approximately 495 patients 2:1 to receive atezolizumab plus paclitaxel or placebo plus paclitaxel. Eligible patients will be stratified by PD-L1 expression, presence of liver metastases, and geographic region. Progression-free survival will be the primary endpoint, and tumor biopsies will be analyzed at baseline, on treatment, and at disease progression to determine biomarkers of response and immune escape. Furthermore, the study will tackle the need for treatments other than chemotherapy, including paclitaxel, for patients with this breast cancer subtype.