Randomized, phase II trial to evaluate the efficacy and safety of atezolizumab plus capecitabine adjuvant therapy compared to capecitabine monotherapy for triple receptor-negative breast cancer with residual invasive cancer after neoadjuvant chemotherapy (MIRINAE trial, KCSG-BR18-21)

Triple-negative breast cancer (TNBC) is an aggressive subtype with poor prognosis, especially in patients with residual disease post-neoadjuvant chemotherapy. This phase II MIRINAE trial (KCSG-BR18-21) evaluates the efficacy and safety of atezolizumab combined with capecitabine versus capecitabine monotherapy as adjuvant treatment in TNBC patients with residual invasive cancer. The primary endpoint is the 5-year invasive disease-free survival (IDFS) rate. Secondary endpoints include IDFS in PD-L1 positive patients, distant relapse-free survival (DRFS), and overall survival (OS). This study addresses the limitations of KEYNOTE-522 by providing data on post-neoadjuvant therapies, potentially establishing a new standard of care for TNBC. Trial registration This trial is registered at ClinicalTrials.gov (NCT03756298).