Study Assessing the Efficacy and Safety of Alpelisib + Nab-paclitaxel in Subjects With Advanced TNBC Who Carry Either a PIK3CA Mutation or Have PTEN Loss

The recruitment of Part A was halted on 11-Nov-2022 due to slow recruitment. Since Part B1 did not meet its primary objective for confirmed overall response rate, the Part B2 was not initiated, and the recruitment was halted for the entire study. Upon confirming either PIK3CA mutation and/or PTEN loss status, advanced TNBC participants meeting all other eligibility criteria were assigned to either Part A (PIK3CA mutation regardless of PTEN loss) or Part B1 (PTEN loss with PIK3CA unknown or non-mutant). In Part A, participants were randomized a 1:1 to receive either: * alpelisib 300 mg daily orally + nab-paclitaxel 100 mg/m\^2 intravenously (IV) on Days 1, 8, and 15 of each 28-day cycle or * placebo + nab-paclitaxel 100 mg/m\^2 IV on Days 1, 8, and 15 of each 28-day cycle. In Part B1, participants received alpelisib 300 mg daily orally + nab-paclitaxel 100 mg/m\^2 IV on Days 1, 8, and 15 of each 28-day cycle.