Breast cancer is the most frequently occurring form of cancer in women.  Whilst 5-year survival rates for localized disease approach 99%, cases of advanced breast cancer have a much poorer prognosis, with 5-year survival of around 27%.  Therefore, new treatment modalities for this indication are clearly welcome.  The Novartis drug PIQRAYTM (alpelisib) is the first -selective PI3Kinase inhibitor to be approved by the FDA for treatment of cases of advanced Hormone Receptor +ve / HER2 -ve breast cancer that also harbour activating mutations in the PIK3CA gene.  There are present in about 40% of cases, and therefore, it is necessary to use a companion diagnostic (CDx) test to identify patients eligible for treatment.  The therascreen PIK3CA RGQ PCR Kit is a rapid and reliable test, able to detect the presence of any of the 11 clinically actionable PIK3CA mutations in DNA from both FFPE tumor tissue and plasma specimens.  Clinically validated during the SOLAR-1 clinical trial, this test is currently the only FDA-approved CDx for this indication.  Available in the USA since May 2019, the Kit supports the delivery of precision medicine to patients for whom few other treatment options may remain.