PIK3CA and breast cancer: A total of one hundred thirty-four mutations were detected, and sixty-nine patients (55.2%) had at least one actionable event for which an FDA-approved drug is currently available; 34.4% (43/125) of the patients had PIK3CA mutations in at least one sample and might benefit from alpelisib therapy, which is already approved for breast cancer.16 Eleven patients (8.8%) had BRCA1/2 mutations.