Trial Design: International, randomised, open label, neo-adjuvant phase II trial in women with newly diagnosed, non-metastatic, high-risk, triple negative breast cancer. The study aims to evaluate the effects of adding ipatasertib to chemotherapy and atezolizumab in patients with and without PI3CA/AKT1/PTEN genetic alterations. Eligible patients will be randomised with an approximately equal ratio (1:1) to either atezolizumab plus chemotherapy vs atezolizumab plus chemotherapy + Ipatasertib. Randomisation will be stratified by PD-L1 expression and tumour size. Patients will receive treatment until surgery, after which they will be followed up for 5 years for disease and survival status. Tumour samples will be collected before, during and on completion of treatment. This study will assess the effects of the study treatments on GzmB+ CD8+ T cell levels, immune infiltrates, immune-related gene expression, PD-L1 expression and MHC-1 expression in tumour tissue before and after treatment. This study will also assess the relationship between the anticipated anti-tumour activity of the study treatment and biological characteristics of subjects’ tumour and blood sample derivatives (cells, plasma and protein and nucleic acid derivatives) at baseline and at the end of treatment to better define the optimal target population and to gain insight in resistance mechanisms to the study treatment. BARBICAN will also investigate the correlations between the microbiome and outcome.