Triple-B Study;Carboplatin-cyclophosphamide Versus Paclitaxel With or Without Atezolizumab as First-line Treatment in Advanced Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a difficult to treat molecular subtype with a poor survival. TNBC can be divided into at least two molecular entities; BRCA-like and non-BRCA-like. In this trial we would like to investigate whether a molecular subgroup exists within TNBCs that derives a benefit from atezolizumab added to first line chemotherapy.

Atezolizumab, a humanized monoclonal antibody that targets human programmed death-ligand 1 (PD-L1) has shown activity in TNBC. Early clinical trials with anti-PD-(L)1 monotherapy have shown that the median duration to response in TNBC is remarkably long (18 weeks) compared to cytotoxic chemotherapy. Since advanced TNBC is characterized by rapid disease progression, most patients with TNBC may not have the opportunity to derive benefit from immunotherapy. We hypothesize that by combining atezolizumab with paclitaxel or carboplatin-cyclophosphamide the desired rapid tumor control will be obtained with chemotherapy and subsequently atezolizumab can result in durable responses in a significant subset of patients. It is unknown whether addition of atezolizumab to first line chemotherapy in TNBC is more beneficial than adding this antibody to a second line treatment schedule. Because of this and because of the poor outcome of patients with advanced TNBC experiencing disease progression after first line palliative chemotherapy, patients who were randomized to a chemotherapy only arm in this study will be offered the opportunity to cross over to the other chemotherapy regimen plus atezolizumab at disease progression.