atezolizumab + fulvestrant

**Atezolizumab + fulvestrant** is an experimental combination therapy comprising atezolizumab, a monoclonal antibody targeting programmed death-ligand 1 (PD-L1) utilized as an immune checkpoint inhibitor, and fulvestrant, a selective estrogen receptor degrader (SERD) and pure antiestrogen. The combination is being investigated in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) advanced or metastatic breast cancer (MBC), with the rationale of uniting immunotherapy with endocrine therapy to overcome resistance and enhance antitumor effects. Early-phase clinical trials suggest tolerability and a signal for preliminary efficacy, but the combination is not an approved standard of care and remains under clinical investigation[4].