The PD-L1 inhibitor atezolizumab received US FDA accelerated approval as treatment for PD-L1-positive metastatic triple-negative breast cancer (TNBC). In IMpassion130, combining atezolizumab with first-line nab-paclitaxel for metastatic TNBC significantly improved progression-free survival and showed a clinically meaningful effect on overall survival in patients with PD-L1-positive tumors. The placebo-controlled randomized Phase III IMpassion132 (NCT03371017) trial is evaluating atezolizumab with first-line chemotherapy (capecitabine [mandatory in platinum-pretreated patients] or gemcitabine/carboplatin) for inoperable locally advanced/metastatic TNBC recurring ≤12 months after completing standard (neo)adjuvant anthracycline and taxane chemotherapy. Stratification factors are: visceral metastases, tumor immune cell PD-L1 status and selected chemotherapy. Patients are randomized to atezolizumab 1200 mg or placebo every 3 weeks with the chosen chemotherapy, continued until progression, unacceptable toxicity or withdrawal. The primary end point is overall survival.