Alpelisib (BYL719, NVP-BYL719, Vijoice, Novartis Pharmaceuticals) is a drug administered orally that has proven to be very efficient when associated with fulvestrant in human epidermal growth factor receptor 2 (HER2)-positive breast cancer in advanced stages, efficiently inhibiting PI3Kα [164]. The gene discussed is ERBB2; the disease is breast cancer.