PIK3CA and breast cancer: To answer that question, another clinical trial, BYLieve was conducted which was a phase 2, open-label, non-comparative study that enrolled patients with HR-positive, HER2-negative, advanced breast cancer with tumor PIK3CA mutation, following progression on or after previous therapy, including CDK4/6 inhibitors with no more than two previous anticancer treatments and no more than one previous chemotherapy regimen.