PIK3CA and neoplasm: All three AR+/PIK3CA mutant TNBCs demonstrated a high allele frequency for the H1047R mutation (77%, 67%, and 53%), greater than the expected frequency for a heterozygous mutation (in a tumor cellularity >80%), suggesting that either the other allele had lower expression or that the mutant allele was amplified (Additional file 2: Figure S1B).