In the clinic, two randomized controlled trial (RCT) studies, PEGGY (NCT01740336) (Vuylsteke et al., 2016) and BELLE-4 (NCT01572727) (Martín et al., 2017), were conducted to evaluate the efficiency of adding PI3K inhibitors to paclitaxel in advanced BC. The gene discussed is PIK3CA; the disease is breast cancer.