ImPassion 131

A Phase III, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study of Atezolizumab (Anti-Pd-L1 Antibody) in Combination With Paclitaxel Compared With Placebo With Paclitaxel for Patients With Previously Untreated Inoperable Locally Advanced or Metastatic Triple Negative Breast Cancer


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.

Study Arms

  • Experimental: Atezolizumab and Paclitaxel
  • Placebo Comparator: Placebo and Paclitaxel


  • Participants with locally advanced or metastatic, histologically documented TNBC (absence of human epidermal growth factor receptor 2 [HER2], estrogen receptor [ER], and progesterone receptor [PR] expression), not amenable to surgical therapy
  • Participants eligible for taxane monotherapy
  • No prior chemotherapy or targeted systemic therapy (including endocrine therapy) for inoperable locally advanced or metastatic TNBC
  • Availability of formalin-fixed paraffin-embedded (FFPE) tumor block (preferred) or at least 25 unstained slides, collected ≤3 months prior to randomization, with an associated pathology report, if available