Alpelisib  Alpelisib (INN; development code BYL719; brand name Piqray) is a medication sold by Novartis and used to treat certain types of breast cancer. It is used together with fulvestrant. It is taken by mouth. Common side effects include high blood sugar, kidney problems, diarrhea, rash, low blood cells, liver problems, pancreatitis, vomiting, and hair loss. It is an alpha-specific PI3K inhibitor. It was approved for medical use in the United States in May 2019. In May 2019, alpelisib was approved in the United States for use in combination with the endocrine therapy fulvestrant, to treat postmenopausal women, and men, with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, PIK3CA-mutated, advanced or metastatic breast cancer following progression on or after an endocrine-based regimen. The U.S. Food and Drug Administration (FDA) also approved the companion diagnostic test, therascreen PIK3CA RGQ PCR Kit, to detect the PIK3CA mutation in a tissue and/or a liquid biopsy. The efficacy of alpelisib was studied in the SOLAR-1 trial (NCT02437318), a randomized trial of 572 postmenopausal women and men with HR-positive, HER2-negative, advanced or metastatic breast cancer whose cancer had progressed while on or after receiving an aromatase inhibitor. The FDA granted the application for alpelisib priority review designation and granted approval of Piqray to Novartis. The FDA granted approval of the therascreen PIK3CA RGQ PCR Kit to Qiagen Manchester, Ltd.