PIK3CA and breast cancer: Furthermore, it has been reported at the 2023 San Antonio Breast Cancer Symposium that inavolisib, another PI3K inhibitor, was more effective than placebo when combined with palbociclib and fulvestrant in the first-line treatment of patients with PIK3CA-mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer (phase III INAVO1209).