PIK3CD and triple-negative breast carcinoma: Two studies provided the first evidence that a PI3K inhibitor induces impairment of DNA homologous recombination in BRCA-proficient triple-negative breast cancer, with an increase in poly-ADP-ribosylation and downregulation of BRCA1/2 (Condorelli & Andre, 2017; Ibrahim et al., 2012; Juvekar et al., 2012; Rehman, Lord & Ashworth, 2012).