In 2016, Loibl et al. published a pooled analysis of data deriving from different clinical trials (GeparQuattro [50], GeparQuinto [51], GeparSixto [52], NeoALTTO [53] and CHERLOB [54]) to assess whether PIK3CA mutations could impact the achievement of pathologic complete response (pCR) in HER2+ BC treated with neoadjuvant anti-HER2 agents in association with chemotherapy. The gene discussed is PIK3CA; the disease is breast cancer.