Background: Early stage triple negative breast cancer (TNBC) is associated with a high risk of distant relapse. Because TNBC does not currently have specific targeted agents approved for use in the early setting, it is treated primarily with chemotherapy. TNBC may be more immunogenic than other subtypes of breast cancer. Atezolizumab (an anti–PD-L1 antibody), in combination with nab-paclitaxel has been approved in >70 countries for the treatment of PD-L1-positive unresectable locally advanced or metastatic TNBC based on the results of the randomized phase 3 IMpassion130 trial. The phase 3 IMpassion031 study, evaluating atezolizumab in combination with chemotherapy (nab-paclitaxel followed by doxorubicin and cyclophosphamide) in comparison to placebo plus chemotherapy as neoadjuvant treatment demonstrated a statistically significant and clinically meaningful improvement in pCR in both PD-L1 positive and PD-L1 negative tumors. ALEXANDRA/IMpassion030 is a global, prospective, randomized, open-label, phase 3 trial currently investigating the efficacy, safety and pharmacokinetic profile of adjuvant atezolizumab plus standard anthracycline/taxane adjuvant chemotherapy versus chemotherapy alone in early stage TNBC. Methods: ALEXANDRA/IMpassion030 will randomize 2300 patients with operable stage II-III TNBC, confirmed by central pathology review. Patients are stratified by type of surgery, nodal status, and centrally assessed PD-L1 status. Adjuvant chemotherapy consist of weekly paclitaxel 80 mg/m² for 12 weeks followed by dose dense anthracycline (epirubicin 90 mg/m² or doxorubicin 60 mg/m²) and cyclophosphamide 600 mg/m² for 4 doses every 2 weeks or the same chemotherapy regimen (T-EC/AC) given concomitantly with atezolizumab 840 mg every 2 weeks followed by maintenance atezolizumab 1200 mg every 3 weeks until completion of 1 year of atezolizumab. The primary endpoint is invasive disease-free survival (iDFS) and secondary endpoints include, iDFS in the PD-L1 selected tumour status (IC1/2/3) and node-positive subpopulations, overall survival, safety, patient functioning and health related quality of life (HRQoL). Tumor tissue and blood samples will be collected for biomarker research. The first site was activated on May 4 2018, and approximately 373 sites in 30 countries are currently participating in this trial. This trial is sponsored by F. Hoffmann-La Roche Ltd and conducted in partnership with the Breast International Group, Frontier Science and Technology Research Foundation, Institute Jules Bordet and Alliance Foundation Trials. Clinical trial information: NCT03498716