A Study of Atezolizumab and Paclitaxel Versus Placebo and Paclitaxel in Participants With Previously Untreated Locally Advanced or Metastatic Triple Negative Breast Cancer (TNBC)

This Phase 3, multicenter, randomized, double-blind, placebo controlled study is designed to evaluate the efficacy and safety of atezolizumab (MPDL3280A, an anti-programmed death-ligand 1 \[PD-L1\] antibody) administered in combination with paclitaxel compared with placebo in combination with paclitaxel in participants with previously untreated, inoperable locally advanced or metastatic, centrally confirmed TNBC. Participants will be randomized in a 2:1 ratio to receive atezolizumab or placebo plus paclitaxel until disease progression or unacceptable toxicity or end of study, whichever occurs first (maximum up to approximately 40 months). In addition, the Sponsor may decide to terminate the study at any time.