PIK3CA and breast cancer: Combining paclitaxel with a PI3K-inhibitor induced apoptosis via Bax and PARP and enhanced drug sensitivity when compared to paclitaxel alone.58 Alpelisib, a PI3K inhibitor, was recently approved for the treatment of hormone receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2−) PIK3CA-mutant breast cancer.