Efficacy and Safety of Atezolizumab Plus Capecitabine Adjuvant Therapy for Triple Receptor-Negative Breast Cancer

Inclusion Criteria: * \- Male or female ≥ 19 years of age * Patients must have histologically confirmed estrogen receptor (ER)-, progesterone receptor (PR)- and HER2-negative (triple-negative) with residual invasive breast cancer, as defined by the 2010 and 2013 American Society of Clinical Oncology (ASCO) College of American Pathologists (CAP) guidelines (Wolff AC, Hammond MEH), after completion of neoadjuvant chemotherapy; residual disease must be ≥ 1 cm in greatest dimension, and/or have macroscopically positive lymph nodes (ypN+) observed on pathologic exam * Patients must not have metastatic disease (i.e., must be M0) * Patients must have a minimum of 20, available unstained slides from the residual (post-neoadjuvant) invasive tumor in primary site or lymph node to be submitted to determine PD-L1 expression and other biomarker analysis * Patients must have had neoadjuvant chemotherapy followed by surgery; the recommended neoadjuvant treatment should include 16-24 weeks of a third generation chemotherapy regimen as recommended by National Comprehensive Cancer Network (NCCN) guidelines for triple negative breast cancer. Patients who cannot complete all planned treatment cycles for any reason are considered high risk and therefore are eligible for the study if they have residual disease * Patients must have completed their final breast surgery with clear resection margins for invasive cancer and ductal carcinoma in situ (DCIS) within 90 days prior to screening * Patients f…